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  1. West Africa

    Atmospheric Science Data Center

    2013-04-16

    ... article title:  Hazy and Dusty Skies over Western Africa     View Larger Image ... of agricultural fires that were burning throughout western Africa during December and early January, and was likely to have been ...

  2. West Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    With its vast expanses of sand, framed by mountain ranges and exposed rock, northwestern Africa makes a pretty picture when viewed from above. This image was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft. The Canary Islands can be seen on the left side of the image just off Africa's Atlantic shore. The light brown expanse running through the northern two thirds of the image is the Sahara Desert. The desert runs up against the dark brown Haut Atlas mountain range of Morocco in the northwest, the Atlantic Ocean to the west and the semi-arid (light brown pixels) Sahelian region in the South. The Sahara, however, isn't staying put. Since the 1960s, the desert has been expanding into the Sahelian region at a rate of up to 6 kilometers per year. In the 1980s this desert expansion, combined with over cultivation of the Sahel, caused a major famine across west Africa. Over the summer months, strong winds pick up sands from the Sahara and blow them across the Atlantic as far west as North America, causing air pollution in Miami and damaging coral reefs in the Bahamas and the Florida Keys. The white outlines on the map represent country borders. Starting at the top-most portion of the map and working clockwise, the countries shown are Morocco, Western Sahara, Mauritania, Senegal, Mali, Burkina Fasso, Nigeria, Mali (again), and Algeria. Image by Reto Stockli, Robert Simmon, and Brian Montgomery, NASA Earth Observatory, based on data from MODIS

  3. Drought in West Africa

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Drought settled over West Africa's Ivory Coast region when wet season rains came late in 2007. Instead of beginning in February, the rainy season didn't start until March, and steady rains didn't start until late March, said the Famine Early Warning System Network. Though the rain had started to alleviate the drought, vegetation was still depressed in parts of Cote d'Ivoire (Ivory Coast) between March 22 and April 6, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured the data used to make this image. The image shows current vegetation conditions compared to average conditions recorded since 2000. Areas where plants are growing more slowly or more sparsely than average are brown, while areas where vegetation is denser than average are green. The brown tint that dominates the image indicates that plants through most of the country are more sparse than normal. Among the crops affected by the lack of rain was West Africa's cocoa crop. About 70 percent of the world's cocoa comes from West Africa, and Cote d'Ivoire is a top grower, said Reuters. Cocoa prices climbed as the crop fell short. Farmers called the drought the worst in living memory, Reuters said. The delay in rainfall also led to water shortages in parts of Cote d'Ivoire, according to the United Nations Office for the Coordination of Humanitarian Affairs.

  4. Ebola in West Africa

    PubMed Central

    Raka, Lul; Guardo, Monica

    2015-01-01

    Ebola viral disease (EVD) is a severe and life-threatening disease. The current Ebola outbreak in West Africa entered its second year and is unprecedented because it is the largest one in history, involved urban centers and affected a large number of health care workers. It quickly escalated from medical into a humanitarian, social, economic, and security crisis. The primary pillars to prevent EVD are: early diagnosis, isolation of patients, contact tracing and monitoring, safe burials, infection prevention and control and social mobilization. The implementation of all these components was challenged in the field. Key lessons from this Ebola outbreak are that countries with weak health care systems can’t withstand the major outbreaks; preparedness to treat the first confirmed cases is a national emergency; all control measures must be coordinated together and community engagement is the great factor to combat this disease.

  5. Ebola in West Africa.

    PubMed

    Raka, Lul; Guardo, Monica

    2015-03-15

    Ebola viral disease (EVD) is a severe and life-threatening disease. The current Ebola outbreak in West Africa entered its second year and is unprecedented because it is the largest one in history, involved urban centers and affected a large number of health care workers. It quickly escalated from medical into a humanitarian, social, economic, and security crisis. The primary pillars to prevent EVD are: early diagnosis, isolation of patients, contact tracing and monitoring, safe burials, infection prevention and control and social mobilization. The implementation of all these components was challenged in the field. Key lessons from this Ebola outbreak are that countries with weak health care systems can't withstand the major outbreaks; preparedness to treat the first confirmed cases is a national emergency; all control measures must be coordinated together and community engagement is the great factor to combat this disease. PMID:27275217

  6. Africa.

    ERIC Educational Resources Information Center

    Happel, Sue; Loeb, Joyce

    Although the activities in this unit are designed primarily for students in the intermediate grades, the document's text, illustrations, and bibliographic references are suitable for anyone interested in learning about Africa. Following a brief introduction and map work, the document is arranged into six sections. Section 1 traces Africa's history…

  7. Africa.

    ERIC Educational Resources Information Center

    Martz, Carlton

    2001-01-01

    This publication explores issues related to Africa. It examines the U.S. response to the Barbary pirate states (Morocco, Algiers, Tunis, Tripoli) in the early 19th century; the current AIDS crisis in Africa; and 14th century Mali and other Islamic lands through the eyes of Ibn Battuta, who traveled throughout the Muslim world. Each article…

  8. Namibia [South-West Africa].

    PubMed

    1983-01-01

    Namibia, a country of 1,051,700 inhabitants of whom 85.6% are blacks of diverse ethnic and linguistic origins, 7.5% are white, and the rest are of mixed ancestry, has been illegally administered by South Africa since 1966, when a League of Nations mandate was revoked by the UN. The Namibian Desert was a barrier to European expansion until the late 18th century, when the area came under German and British influence. Efforts to bring about an orderly and peaceful transition to independent status are hampered at present by the lack of parallel progress toward withdrawal of Cuban combat forces from Angola. Beginning in 1980, considerable executive power was transferred from the administrator general appointed by the South African Government to an interim 3-tier system of elected representatives dividing responsibility between central, ethnic, and local authorities. The judicial structure has separate overlapping systems for whites, westernized blacks and coloreds and for indigenous blacks. Namibian society is highly politicized, with 4 white and about 40 nonwhite political groups. The South West Africa People's Organization (SWAPO) remains an active party inside Namibia despite simultaneous detention of its entire leadership in 1979 by the South African Government. Namibia's economy is dual, with a modern market sector of mining, ranching and fishing producing most of the wealth and a traditional subsistence sector supporting most of the labor force. About 60% of the work force of 500,000 in 1981 worked in agriculture, 19% in industry and commerce, 6% in mining, 8% in services, and 7% in government. Namibia's gross domestic product in 1980 was $1.712 billion, representing an average growth rate of 2.5% from 1970-80. However, real growth since 1978 has been negative because of persistent drought, political uncertainty, low demand for mineral products, and previous overfishing. Namibia has no separate representation in any international body. The country may have the

  9. Cultural Astronomy of parts of West Africa

    NASA Astrophysics Data System (ADS)

    Urama, J. O.

    Indigenous endogenous traditional or cultural astronomy focuses on the many ways that people and cultures interact with celestial bodies West Africa like the rest of Africa is home to many long-standing cultural traditions that include beliefs practices and observations relating to the sky However the cultural astronomy of the West African sub-region is among the least investigated in the African continent The cultural astronomy of West Africa is rich with mythic figures cosmology and cosmogony divination methods that utilize observations of celestial bodies and many other sky-related beliefs and traditions In a region such as West Africa where there is little or no interest in modern astronomy cultural astronomy is a very powerful tool for creating general awareness and sensitization on modern astronomy Here we discuss some aspects of the culture and tradition of some of the ethnic groups in this region and how they relate to and could serve as a means of popularization of modern astronomy

  10. Mastomys natalensis and Lassa fever, West Africa.

    PubMed

    Lecompte, Emilie; Fichet-Calvet, Elisabeth; Daffis, Stéphane; Koulémou, Kékoura; Sylla, Oumar; Kourouma, Fodé; Doré, Amadou; Soropogui, Barré; Aniskin, Vladimir; Allali, Bernard; Kouassi Kan, Stéphane; Lalis, Aude; Koivogui, Lamine; Günther, Stephan; Denys, Christiane; ter Meulen, Jan

    2006-12-01

    PCR screening of 1,482 murid rodents from 13 genera caught in 18 different localities of Guinea, West Africa, showed Lassa virus infection only in molecularly typed Mastomys natalensis. Distribution of this rodent and relative abundance compared with M. erythroleucus correlates geographically with Lassa virus seroprevalence in humans. PMID:17326956

  11. Mastomys natalensis and Lassa Fever, West Africa

    PubMed Central

    Fichet-Calvet, Elisabeth; Daffis, Stéphane; Koulémou, Kékoura; Sylla, Oumar; Kourouma, Fodé; Doré, Amadou; Soropogui, Barré; Aniskin, Vladimir; Allali, Bernard; Kan, Stéphane Kouassi; Lalis, Aude; Koivogui, Lamine; Günther, Stephan; Denys, Christiane; ter Meulen, Jan

    2006-01-01

    PCR screening of 1,482 murid rodents from 13 genera caught in 18 different localities of Guinea, West Africa, showed Lassa virus infection only in molecularly typed Mastomys natalensis. Distribution of this rodent and relative abundance compared with M. erythroleucus correlates geographically with Lassa virus seroprevalence in humans. PMID:17326956

  12. Nitrogen in West Africa: the regional cycle

    SciTech Connect

    Robertson, G.P.; Rosswall, T.

    1986-03-01

    A nitrogen cycle budget has been calculated for West Africa south of the northern Sahara that quantifies biologically important pools of nitrogen in the region and major fluxes associated with these pools. Major compartments of the model include noncultivated systems broken down by vegetation zone, successional status, and plant components, annual and perennial crops each broken down by crop species and plant and harvest components; wetlands; anthropic systems, and soils and sediments. Base reference year is 1978. Biological nitrogen fixation and precipitation fluxes dominated nitrogen inputs to West Africa in 1978. Approximately 12 x 10/sup 9/ kg were fixed in noncultivated systems; about half of this was fixed in early successional (0-6 yr) rain forests, and much of the rest in grazed or fallow savanna grasslands and woodlands. Less than 0.7 x 10/sup 9/ kg were fixed in cultivated systems; legumes accounted for approx. = 25% of this. Total anthropic sources (fossil fuel combustion, fertilizer production, and agricultural commodity imports) were minor (< 0.3 x 10/sup 9/ kg). Precipitation inputs to the region were approx. = 0.4 x 10/sup 9/ kg. Most nitrogen leaving West Africa did so volatilized by fire (approx. = 8.3 x 10/sup 9/ kg), principally in non-cropped systems. Major losses also occurred via hydrologic export to the Atlantic Ocean (1.5 x 10/sup 9/ kg) and via denitrification (1.1 x 10/sup 9/ kg). Total N losses from West Africa exceeded 11.0 x 10/sup 9/ kg. The overall budget balances within 1%, despite independent calculations of all major fluxes. The balance portrays a nitrogen cycle dominated by pools and fluxes in noncropped systems. Indirect human influences, however, mainly through effects on vegetation cover, appear to be a major determinant of both the rates at which nitrogen is cycled in West Africa and the relative importance of most pools and fluxes.

  13. Problem of hepatocellular carcinoma in West Africa

    PubMed Central

    Ladep, Nimzing G; Lesi, Olufunmilayo A; Mark, Pantong; Lemoine, Maud; Onyekwere, Charles; Afihene, Mary; Crossey, Mary ME; Taylor-Robinson, Simon D

    2014-01-01

    The incidence of hepatocellular carcinoma (HCC) is known to be high in West Africa with an approximate yearly mortality rate of 200000. Several factors are responsible for this. Early acquisition of risk factors; with vertical or horizontal transmission of hepatitis B (HBV), environmental food contaminants (aflatoxins), poor management of predisposing risk factors and poorly-managed strategies for health delivery. There has been a low uptake of childhood immunisation for hepatitis B in many West African countries. Owing to late presentations, most sufferers of HCC die within weeks of their diagnosis. Highlighted reasons for the specific disease pattern of HCC in West Africa include: (1) high rate of risk factors; (2) failure to identify at risk populations; (3) lack of effective treatment; and (4) scarce resources for timely diagnosis. This is contrasted to the developed world, which generally has sufficient resources to detect cases early for curative treatment. Provision of palliative care for HCC patients is limited by availability and affordability of potent analgesics. Regional efforts, as well as collaborative networking activities hold promise that could change the epidemiology of HCC in West Africa. PMID:25429316

  14. West Africa 2013: Re-examining Ebola.

    PubMed

    Bausch, Daniel G; Rojek, Amanda

    2016-06-01

    The outbreak of Ebola virus disease (EVD) that occurred from 2013 to 2016 in the West African countries of Guinea, Liberia, and Sierra Leone, with imported cases to three neighboring African countries as well as to the United States and Europe, constituted a major humanitarian disaster. The outbreak numbered over 28,500 cases, more than 10 times the number cumulatively registered from all previous EVD outbreaks combined, with at least 11,000 deaths, and resulted in billions of dollars of lost economic growth to an already impoverished region. The unprecedented scale of West Africa 2013 took the world by surprise and laid bare deficiencies in our response capacity to complex humanitarian disasters of highly infectious and lethal pathogens. However, the magnitude of West Africa 2013 also provided an, albeit unwelcome, unique opportunity and obligation to better understand the biology and epidemiology of EVD and, equally as important, the many scientific, economic, social, political, ethical, and logistical challenges in confronting emerging diseases in the modern era. Here we re-examine EVD, reviewing the unique challenges and scientific advances of West Africa 2013, contrasting them with the prior assumptions and classical teachings, identifying what they have taught us and what we still have to learn. PMID:27337474

  15. Simulation of Rainfall Variability Over West Africa

    NASA Astrophysics Data System (ADS)

    Bader, J.; Latif, M.

    The impact of sea surface temperature (SST) and vegetation on precipitation over West Africa is investigated with the atmospheric general circulation model ECHAM4.x/T42. Ensemble experiments -driven with observed SST- show that At- lantic SST has a significant influence on JJA precipitation over West Africa. Four- teen experiments were performed in which the climatological SST was enhanced or decreased by one Kelvin in certain ocean areas. Changing SST in the eastern tropi- cal Atlantic only caused significant changes along the Guinea Coast, with a positive SSTA increasing rainfall and a negative reducing it. The response was nearly linear. Changing SST in other ocean areas caused significant changes over West Africa, es- pecially in the Sahel area. The response is found to be non linear, with only negative SSTA leading to significant reduction in Sahel rainfall. Also, the impact of the SSTAs from the different ocean regions was not additive with respect to the rainfall. Four simulations with a coupled model (the simple dynamic vegetation model (SVege) and the ECHAM4-AGCM were coupled) were also performed, driven with observed SST from 1945 to 1998. The standard ECHAM-AGCM -forced by the same observed SST- was able to reproduce the drying trend from the fifties to the mid-eighties in the Sahel, but failed to mirror the magnitude of the rainfall anomalies. The coupled model was not only able to reproduce this drying trend, but was also able to better reproduce the amplitudes of the rainfall anomalies. The dynamic vegetation acted like an amplifier, increasing the SST induced rainfall anomalies.

  16. Niobium content of soils from West Africa

    USGS Publications Warehouse

    Grimaldi, F.S.; Berger, I.A.

    1961-01-01

    Analysis of twenty lateritic soil samples from West Africa has shown them to contain an average 24 p.p.m. of niobium; four similar samples taken from within a few miles from a niobium deposit contain from 79 to 87 p.p.m. niobium. It has been shown that as the aluminum content of the soils increases, the following depletion sequence is obtained: Si > Nb > Al = Fe The data indicate that, in general, high enrichments of niobium are not to be expected in lateritic soils. ?? 1961.

  17. Strategies for containing Ebola in West Africa.

    PubMed

    Pandey, Abhishek; Atkins, Katherine E; Medlock, Jan; Wenzel, Natasha; Townsend, Jeffrey P; Childs, James E; Nyenswah, Tolbert G; Ndeffo-Mbah, Martial L; Galvani, Alison P

    2014-11-21

    The ongoing Ebola outbreak poses an alarming risk to the countries of West Africa and beyond. To assess the effectiveness of containment strategies, we developed a stochastic model of Ebola transmission between and within the general community, hospitals, and funerals, calibrated to incidence data from Liberia. We find that a combined approach of case isolation, contact-tracing with quarantine, and sanitary funeral practices must be implemented with utmost urgency in order to reverse the growth of the outbreak. As of 19 September, under status quo, our model predicts that the epidemic will continue to spread, generating a predicted 224 (134 to 358) daily cases by 1 December, 280 (184 to 441) by 15 December, and 348 (249 to 545) by 30 December. PMID:25414312

  18. Marriage in West Africa--A Composite. Mini-Module.

    ERIC Educational Resources Information Center

    African-American Inst., New York, NY. School Services Div.

    This module contains a description of the responsibilities and ceremony of marriage in west Africa, seven discussion questions exploring the differences between Western and African marriage customs, five enrichment activities, and a bibliography of five books about love and marriage in Africa. The general discussion relates the engagement of a…

  19. West Africa prepares for busy season. [Petroleum exploration in West Africa

    SciTech Connect

    Not Available

    1982-06-20

    Although there has been a decrease in oil prices, activity along coastal West Africa has tended to increase, with emphasis on field development and production. Because of a world-wide surplus of petroleum, Nigeria has had to cut production by more than half and offshore operations have been affected also. Off the coast of Gabon exploration activity has increased with numerous wildcat rigs which are potentially highly productive. Overall production in Gabon has decreased slightly since 1980. The People's Republic of the Congo, on the other hand, has increased productivity due to new successful fields, while in the Angola/Cabinda area new offshore programs are forming. Production and exploration increases are also expected for Ghana, Zaire, Cameroon, and South Africa. (JBF)

  20. Markets, Climate Change and Food Security in West Africa

    NASA Technical Reports Server (NTRS)

    Brown, Molly E.; Hintermann, Beat; Higgins, Nathaniel

    2009-01-01

    West Africa is one of the most food insecure regions of the world. Sharply increased food and energy prices in 2008 brought the role of markets in food access and availability around the world into the spotlight, particularly in urban areas. The period of high prices had the immediate consequence of sharply increasing the number of hungry people in the region without boosting farmer incomes significantly. In this article, the interaction between markets, food prices, agricultural technology and development is explored in the context of West Africa. To improve food security in West Africa, sustained commitment to investment in the agriculture sector will be needed to provide some protection against global swings in both production and world markets. Climate change mitigation programs are likely to force global energy and commodity price increases in the coming decades, putting pressure on regions like West Africa to produce more food locally to ensure stability in food security for the most vulnerable.

  1. Vocational Education Processes of Yoruba Women in West Africa.

    ERIC Educational Resources Information Center

    Bawubya, Maria

    1988-01-01

    Describes traditional training methods for the occupations of Yoruba women of West Africa, such as weaving, dyeing, and pottery-making. Suggests that these vocational training methodologies could be applied to contemporary African economic problems. (SK)

  2. Phytoplankton off the West Coast of Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Just off the coast of West Africa, persistent northeasterly trade winds often churn up deep ocean water. When the nutrients in these deep waters reach the ocean's surface, they often give rise to large blooms of phytoplankton. This image of the Mauritanian coast shows swirls of phytoplankton fed by the upwelling of nutrient-rich water. The scene was acquired by the Medium Resolution Imaging Spectrometer (MERIS) aboard the European Space Agency's ENVISAT. MERIS will monitor changes in phytoplankton across Earth's oceans and seas, both for the purpose of managing fisheries and conducting global change research. NASA scientists will use data from this European instrument in the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) program. The mission of SIMBIOS is to construct a consistent long-term dataset of ocean color (phytoplankton abundance) measurements made by multiple satellite instruments, including the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate-Resolution Imaging Spectroradiometer (MODIS). For more information about MERIS and ENVISAT, visit the ENVISAT home page. Image copyright European Space Agency

  3. Mapping and analyzing urban growth in West Africa

    NASA Astrophysics Data System (ADS)

    Adhikari, P.; de Beurs, K. M.

    2014-12-01

    Africa has experienced the highest urban growth (~3.5% per year) in the developing world. West Africa in particular has seen significant urban growth mainly driven by the high natural population growth rate and the increasing percentage of population moving to urban areas. Urban growth in West Africa is expected to continue in decades to come. This study uses Landsat data at five different time steps (1970, 1980, 1990, 2000, and 2010) to map four cities from four different eco-regions of West Africa since the early 1970s. The selected four cities, Kumasi in Ghana, Abuja in Nigeria, Tahoua in Niger and Ouagadoughou in Burkina Faso, are some of the fastest growing cities in the region. We selected the cities in the following ecoregions: Eastern Guinean Forest, Guinean Forest-Savanna Mosaic, Sahelian Acacia Savanna and West Sudanian Savanna. We hypothesize that urban growth in West Africa is different compared to the other parts of the world primarily due to the dependency of about 60 percent of active labor force on subsistence agriculture in the region. As agriculture productivity is dependent on favorable climatic conditions (i.e., good rainfall, suitable temperature), any variability in climate impends the livelihood of subsistence farmers triggering the movements of more people towards the cities. Therefore, studying urban growth based on ecoregions help to better explain the urban development in West Africa. After mapping the urban areas, this study makes a comparative analysis of the temporal and spatial pattern of the urban growths across the ecoregions in West Africa.

  4. Four rigs refurbished for West Africa drilling

    SciTech Connect

    Not Available

    1991-06-10

    In April and May 1990, Shell Petroleum Development Co. of Nigeria Ltd. awarded Noble Drilling West Africa Inc. four separate contracts to drill oil and gas wells in the inland waterways of Nigeria. The contracted rigs included a shallow water jack up, the NN-1, and three posted barges, the Gene Rosser, the Chuck Syring, and the Lewis Dugger. The jack up was built in 1978, and the three posted barges are 1980s vintage. Three of the rigs have been idle for a number of years. The Shell Nigeria contracts required major modifications to the rigs before putting them into international service. Noble replaced or refurbished all major pieces of equipment in the drilling, power, and service systems on the rigs. Rig crews serviced all other equipment. A significant amount of general service piping and electrical wiring was replaced. Each rig also required additional motor control centers to support the new drilling and mud processing equipment. Alfa-Laval waste-heat water desalination plants and new sewage treatment units were installed on all four rigs. Because of the tidal variances and high silt conditions expected in the African waterways, all engine cooling systems were converted from heat exchangers to radiators. Rotary tables were made common on all rigs at 37 1/2 in. Noble had all traveling equipment completely inspected and modified as necessary. Strict attention was paid to certification and documentation of all equipment. Safety upgrades conformed to both Shell and Noble standards. Fire and gas detection systems were installed throughout each rig. Water and foam deluge systems were installed in the wellhead areas, and new foam systems and monitors were installed on the helldecks.

  5. Kimberlites of the Man craton, West Africa

    NASA Astrophysics Data System (ADS)

    Skinner, E. M. W.; Apter, D. B.; Morelli, C.; Smithson, N. K.

    2004-09-01

    The Man craton in West Africa is an Archaean craton formerly joined to the Guyana craton (South America) that was rifted apart in the Mesozoic. Kimberlites of the Man craton include three Jurassic-aged clusters in Guinea, two Jurassic-aged clusters in Sierra Leone, and in Liberia two clusters of unknown age and one Neoproterozoic cluster recently dated at ˜800 Ma. All of the kimberlites irrespective of age occur as small pipes and prolific dykes. Some of the Banankoro cluster pipes in Guinea, the Koidu pipes in Sierra Leone and small pipes in the Weasua cluster in Liberia contain hypabyssal-facies kimberlite and remnants of the so-called transitional-facies and diatreme-facies kimberlite. Most of the Man craton kimberlites are mineralogically classified as phlogopite kimberlites, although potassium contents are relatively low. They are chemically similar to mica-poor Group 1A Southern African examples. The Jurassic kimberlites are considered to represent one province of kimberlites that track from older bodies in Guinea (Droujba 153 Ma) to progressively younger kimberlites in Sierra Leone (Koidu, 146 Ma and Tongo, 140 Ma). The scarcity of diatreme-facies kimberlites relative to hypabyssal-facies kimberlites and the presence of the so-called transitional-facies indicate that the pipes have been eroded down to the interface between the root and diatreme zones. From this observation, it is concluded that extensive erosion (1-2 km) has occurred since the Jurassic. In addition to erosion, the presence of abundant early crystallizing phlogopite is considered to have had an effect on the relatively small sizes of the Man craton kimberlites.

  6. [Familial modernity and plurality in West Africa].

    PubMed

    Vimard, P

    1993-01-01

    Changes in the family system of West Africa have accompanied the numerous economic, demographic, and social changes occurring after colonization and especially since independence. This work uses monographic data from Togo and the Ivory Coast to examine to what degree lineage structures have been supplanted by autonomy of domestic groups and the emergence of new forms of family organization, to what extent intrafamilial social relations and behavior have been affected by the market economy, and whether the spread of western culture has led to a plurality of family models. The integration of rural African societies into market economies has been achieved primarily through their progressive absorption into plantation economic systems. Appropriation of manpower by plantation economies has largely removed control over the reproduction and use of the labor force from the lineage to a smaller family group. Individual relationships are undergoing redefinition within the new structures of socially and economically autonomous domestic groups. Lineages have lost control over matrimonial alliances; marriage has ceased to represent an exchange between social groups and has become an alliance between individuals. The weakened integration of couples into traditional family structures has increased the instability of unions. The emergence of the domestic group as an autonomous institution has engendered a redefinition of roles and practices within families, and new forms of social relations between the husbands, wives, and their children. Economic and social roles today depend less on belonging to extended structures such as lineages or age classes and more on nonpredetermined factors susceptible to change that characterize the family and economic position, such as educational level, marital status, and occupation. Changes in power relations between spouses have led to greater independence but also greater precariousness in women;s positions. The status of children has undergone a

  7. The Lion in West Africa Is Critically Endangered

    PubMed Central

    Henschel, Philipp; Coad, Lauren; Burton, Cole; Chataigner, Beatrice; Dunn, Andrew; MacDonald, David; Saidu, Yohanna; Hunter, Luke T. B.

    2014-01-01

    The African lion has declined to <35,000 individuals occupying 25% of its historic range. The situation is most critical for the geographically isolated populations in West Africa, where the species is considered regionally endangered. Elevating their conservation significance, recent molecular studies establish the genetic distinctiveness of West and Central African lions from other extant African populations. Interventions to save West African lions are urgently required. However formulating effective conservation strategies has been hampered by a lack of data on the species' current distribution, status, and potential management deficiencies of protected areas (PAs) harboring lions. Our study synthesized available expert opinion and field data to close this knowledge gap, and formulate recommendations for the conservation of West African lions. We undertook lion surveys in 13 large (>500 km2) PAs and compiled evidence of lion presence/absence for a further eight PAs. All PAs were situated within Lion Conservation Units, geographical units designated as priority lion areas by wildlife experts at a regional lion conservation workshop in 2005. Lions were confirmed in only 4 PAs, and our results suggest that only 406 (273–605) lions remain in West Africa, representing <250 mature individuals. Confirmed lion range is estimated at 49,000 km2, or 1.1% of historical range in West Africa. PAs retaining lions were larger than PAs without lions and had significantly higher management budgets. We encourage revision of lion taxonomy, to recognize the genetic distinctiveness of West African lions and highlight their potentially unique conservation value. Further, we call for listing of the lion as critically endangered in West Africa, under criterion C2a(ii) for populations with <250 mature individuals. Finally, considering the relative poverty of lion range states in West Africa, we call for urgent mobilization of investment from the international community to assist range

  8. Regional paleogeographic evolution of west Africa: Implications for hydrocarbon exploration

    SciTech Connect

    Hempton, M.R.; Rosen, M.A.; Coughlin, R.M.; Scardina, A.D.; Hagen, E.S.; Nordstrom, P.J. )

    1991-03-01

    New paleogeographic reconstructions of west African continental margins provide a regional framework to contrast differences in hydrocarbon habitat and tectonostratigraphic style. Five regional provinces are delineated: (1) Northwest Africa margin from mauritania to Sierra Leone, (2) Transform margin from Liberia to Benin, (3) Niger delta of Nigeria, Cameroon, and Equatorial Guinea, (4) South Atlantic Salt basin margin from Cameroon to Angola, and (5) Southwest Africa margin of Namibia and South Africa. Computer-constrained paleogeographic reconstructions based on exploration data depict the separation of west Africa from South and North America during the Late Triassic to the present along three rift systems. In northwest Africa rifting began in the Late Triassic associated with the opening of the Central Atlantic. In southwest Africa rifting began between the southern tips of Africa and South America in the Early Cretaceous (Valanginian) and propagated northward to the Benue Trough, a broad zone of left-lateral shear and extensional basins that began to open in the Aptian. Between these two rift systems, the Transform margin rift system initiated in the Early Cretaceous (Barremain) as a wrench-fault dominated eastward extension of the Proto-Caribbean ocean that propagated to the Benue Trough by the middle Albian. The most important variables affecting the tectonostratigraphic and hydrocarbon evolution of the west African margins include (1) the geometry, kinematics, and duration of rifting; (2) distribution of rift basins relative to paleoclimate zones (which affects the deposition of lacustrine source rocks and evaporites while influencing the type and quantity of sediment derived from land); (3) sea-level fluctuations; and (4) distribution of deltaic and turbiditic depocenters.

  9. Child Trafficking in West Africa: Policy Responses. Innocenti Insight.

    ERIC Educational Resources Information Center

    United Nations Children's Fund, Florence (Italy). Innocenti Research Centre.

    This report examines policy responses and programming trends to combat the growing specter of child trafficking, focusing on the region of west and central Africa where strenuous advocacy efforts by UNICEF and its partners have helped to bring this problem to national and international attention. The report focuses on policy trends on child…

  10. Teaching in West Africa: Dig beneath the Surface

    ERIC Educational Resources Information Center

    Briam, Carol

    2007-01-01

    In this article, the author shares her experience teaching English to adult learners at the American Cultural Center in Dakar, Senegal, a poor, primarily Muslim country and former French colony in West Africa. Her class was composed of about 30 students, whose age ranged from about 18 to 50. They were mostly men and mostly Senegalese, along with a…

  11. Agricultural Adaptations to Climate Changes in West Africa

    NASA Astrophysics Data System (ADS)

    Guan, K.; Sultan, B.; Lobell, D. B.; Biasutti, M.; Piani, C.; Hammer, G. L.; McLean, G.

    2014-12-01

    Agricultural production in West Africa is highly vulnerable to climate variability and change and a fast growing demand for food adds yet another challenge. Assessing possible adaptation strategies of crop production in West Africa under climate change is thus critical for ensuring regional food security and improving human welfare. Our previous efforts have identified as the main features of climate change in West Africa a robust increase in temperature and a complex shift in the rainfall pattern (i.e. seasonality delay and total amount change). Unaddressed, these robust climate changes would reduce regional crop production by up to 20%. In the current work, we use two well-validated crop models (APSIM and SARRA-H) to comprehensively assess different crop adaptation options under future climate scenarios. Particularly, we assess adaptations in both the choice of crop types and management strategies. The expected outcome of this study is to provide West Africa with region-specific adaptation recommendations that take into account both climate variability and climate change.

  12. The Diploma Disease and Unemployment in Francophone West Africa.

    ERIC Educational Resources Information Center

    Kogoe, Akrima

    The rapid rise in the numbers of degreed and certificated diploma holders since independence, coupled with a lack of job opportunities in the areas for which these persons have been trained, have led to unemployment and underemployment of educated persons in Francophone West Africa. Suggested solutions include but are not limited to secondary and…

  13. How Ebola has been evolving in West Africa.

    PubMed

    Liu, Si-Qing; Rayner, Simon; Zhang, Bo

    2015-07-01

    The ongoing Ebola outbreak in West Africa has generated fears of a global epidemic. Particularly, estimates of higher substitution rates have raised concerns about increased transmissibility or virulence. A recent study using a more comprehensive datasets demonstrates lower variation, highlighting the importance of representative datasets and limitations of computational modelling. PMID:25986056

  14. Information Technology and Information Training in West Africa.

    ERIC Educational Resources Information Center

    Alemna, A. Anaba

    1990-01-01

    Outlines current and past library and information education and training in West Africa, focusing on the impacts of technological advancement; suggests information technologies that training programs should be able to access; and discusses formulating new curricula, staffing requirements, and further implications for the countries in this region…

  15. Intense convection over West Africa during AMMA SOP3 experiment

    NASA Astrophysics Data System (ADS)

    Lenouo, André; Sall, Saïdou Moustapha; Badiane, Daouda; Gaye, Amadou Thierno; Kamga Mkankam, F.

    2016-11-01

    ERA-Interim product from the European Center for Medium-Range Weather Forecast (ECMWF) assimilation of African Monsoon Multidisciplinary Analysis (AMMA) resources, Meteosat satellite images, and synoptic observations were used to study local- and regional-scale environments associated with intense convective systems during the AMMA-SOP3 experiment over West Africa in the Northern Hemisphere of summer 2006. The convective system, from the 21st to 23rd of August 2006, was more active at 0000 and 1800 UTC showing diurnal cycle of deep convection over West Africa where the African easterly waves (AEWs) are developed downstream. Downstream barotropic and baroclinic energy conversions associated with strong AEWs are important for the maintenance of AEW activity in West Africa. Barotropic energy conversions dominate south of the African easterly jet (AEJ), while baroclinic energy conversions are most important north of the AEJ. From a dynamical viewpoint, the low-level vorticity presents strong positive values over the sea and Sahara zone, indicating that exists on the cyclonic shear side of the African easterly jet, which is consistent with baroclinic growth. The 925-hPa equivalent potential temperature structure show a maximum over the Sahara which corresponds to the depression observed in this region. A mosaic of three hourly infrared (IR) satellite images, depicts a very distinct signal from an initial region of convection, developing through several stages and moving off the African coast. These observations, along with those available from the World Weather Watch, provide an opportunity to carry out numerical weather prediction (NWP) studies over West Africa utilizing high resolution limited area models.

  16. Fluid inclusions in quartz crystals from South-West Africa.

    NASA Technical Reports Server (NTRS)

    Kvenvolden, K. A.; Roedder, E.

    1971-01-01

    Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one substance or a combination of substances. These substances include organic liquid, moderately saline aqueous liquid, dark-colored solid, and a vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights.

  17. [One century of "sleeping sickness" in West Africa].

    PubMed

    Courtin, F; Jamonneau, V; Duvallet, G; Camara, M; Kaba, D; Solano, P

    2008-06-01

    This paper summarizes the geography of sleeping sickness disease (or Human African Trypanosomiasis, HAT) over the last 100 years in West Africa, with the objective of identifying today's priority areas for the sleeping sickness surveillance. The history and geography of the disease are based on a bibliographic review of old reports and recent publications on recent results obtained from medical surveys conducted in West Africa up to 2007. This allowed us to situate the historical geography of HAT from the beginning of the 20th century to nowadays. For instance, active HAT foci seem to have moved from the North (savannah area) to the South (forest area) in the last century. Taking into account the limited nature of the information available, endemic HAT presently appears to be limited to areas where annual rainfall is higher than 1,200 mm, although the reasons for this remain unknown. During this period of time there has also been a shift towards the south of the isohyets and of the northern distribution limit of tsetse. Currently the most severely affected countries are Guinea and Ivory Coast, whereas the northern countries seem less affected, but many parts of West Africa still lack information on HAT and remain to be investigated. These observations, put back in the current context of demographic growth and climatic global change, responsible for landscape evolution, political instability and population movements, raise the question of HAT becoming. PMID:18681221

  18. Surveillance of Lassa fever in missionaries stationed in West Africa

    PubMed Central

    Frame, John D.

    1975-01-01

    To determine the distribution of Lassa virus in West Africa, a serological survey was undertaken. A number of mission hospital supplied sera from patients admitted with a history of fever and specimens were also collected in New York from missionaries who had experienced an unusual febrile illness while working in Africa. More cases of Lassa fever were detected among missionaries than among Africans, possibly because many African patients had left hospital before the complement fixation tests had become positive. Although most adults had fairly high fever and some were prostrated, fever was less severe in the children examined. In general the findings confirm that not all Lassa fever patients have the severe syndrome described in the original reports. PMID:1085213

  19. WRF/ARPEGE-CLIMAT simulated climate trends over West Africa

    NASA Astrophysics Data System (ADS)

    Vigaud, N.; Roucou, P.; Fontaine, B.; Sijikumar, S.; Tyteca, S.

    2011-03-01

    The Weather Regional Forecast (WRF) model is used in this study to downscale low-resolution data over West Africa. First, the performance of the regional model is estimated through contemporary period experiments (1981-1990) forced by ARPEGE-CLIMAT GCM output (ARPEGE) and ERA-40 re-analyses. Key features of the West African monsoon circulation are reasonably well represented. WRF atmospheric dynamics and summer rainfall compare better to observations than ARPEGE forcing data. WRF simulated moisture transport over West Africa is also consistent in both structure and variability with re-analyses, emphasizing the substantial role played by the West African Monsoon (WAM) and African Easterly Jet (AEJ) flows. The statistical significance of potential climate changes for the A2 scenario between 2032 and 2041 is enhanced in the downscaling from ARPEGE by the regional experiments, with substantial rainfall increases over the Guinea Gulf and eastern Sahel. Future scenario WRF simulations are characterized by higher temperatures over the eastern Tropical Atlantic suggesting more evaporation available locally. This leads to increased moisture advection towards eastern regions of the Guinea Gulf where rainfall is enhanced through a strengthened WAM flow, supporting surface moisture convergence over West Africa. Warmer conditions over both the Mediterranean region and northeastern Sahel could also participate in enhancing moisture transport within the AEJ. The strengthening of the thermal gradient between the Sahara and Guinean regions, particularly pronounced north of 10°N, would support an intensification of the AEJ northwards, given the dependance of the jet to the position/intensity of the meridional gradient. In turn, mid-tropospheric moisture divergence tends to be favored within the AEJ region supporting southwards deflection of moist air and contributing to deep moist convection over the Sahel where late summer rainfall regimes are sustained in the context of the A2

  20. Mothers have heavy burden in West Africa.

    PubMed

    1998-01-01

    This article summarizes findings from a study of women's health during pregnancy, delivery, and the postpartum periods in West African countries. The sample included about 20,300 reproductive-age women. One in three women reported a health problem of some kind during the course of pregnancy. One in 16 reported a very severe problem. 1 in 340 died as a result of the pregnancy. 33% of severe complications were due to obstructed labor. 21% were due to hemorrhage before or during delivery. Eclampsia and hypertensive complications were the cause of 10% of severe complications. Only 1.5% of complications were due to infections, but these infections were the cause of most maternal mortality. One woman in five reported a current unwanted pregnancy. 80% of pregnant women delivered in a health facility. 83% were full-term pregnancies. 22% of births weighed under 2500 g (low birth weight). Most women had at least two prenatal visits by the 8th month of pregnancy, but consultations were not successful in identifying complications. Researchers recommend improved training of health providers, strengthened care during the 3rd trimester, and training of motivated persons to assist at the birth. PMID:12293572

  1. Laboratory Response to Ebola - West Africa and United States.

    PubMed

    Sealy, Tara K; Erickson, Bobbie R; Taboy, Céline H; Ströher, Ute; Towner, Jonathan S; Andrews, Sharon E; Rose, Laura E; Weirich, Elizabeth; Lowe, Luis; Klena, John D; Spiropoulou, Christina F; Rayfield, Mark A; Bird, Brian H

    2016-01-01

    The 2014-2016 Ebola virus disease (Ebola) epidemic in West Africa highlighted the need to maintain organized laboratory systems or networks that can be effectively reorganized to implement new diagnostic strategies and laboratory services in response to large-scale events. Although previous Ebola outbreaks enabled establishment of critical laboratory practice safeguards and diagnostic procedures, this Ebola outbreak in West Africa highlighted the need for planning and preparedness activities that are better adapted to emerging pathogens or to pathogens that have attracted little commercial interest. The crisis underscored the need for better mechanisms to streamline development and evaluation of new diagnostic assays, transfer of material and specimens between countries and organizations, and improved processes for rapidly deploying health workers with specific laboratory expertise. The challenges and events of the outbreak forced laboratorians to examine not only the comprehensive capacities of existing national laboratory systems to recognize and respond to events, but also their sustainability over time and the mechanisms that need to be pre-established to ensure effective response. Critical to this assessment was the recognition of how response activities (i.e., infrastructure support, logistics, and workforce supplementation) can be used or repurposed to support the strengthening of national laboratory systems during the postevent transition to capacity building and recovery. This report compares CDC's domestic and international laboratory response engagements and lessons learned that can improve future responses in support of the International Health Regulations and Global Health Security Agenda initiatives.The activities summarized in this report would not have been possible without collaboration with many U.S. and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html). PMID:27389781

  2. Dynamics of Ebola epidemics in West Africa 2014

    PubMed Central

    Evans, Robin J.; Mammadov, Musa

    2015-01-01

    This paper investigates the dynamics of Ebola virus transmission in West Africa during 2014. The reproduction numbers for the total period of epidemic and for different consequent time intervals are estimated based on a simple linear model. It contains one major parameter - the average infectious period that defines the dynamics of epidemics. Numerical implementations are carried out on data collected from three countries Guinea, Sierra Leone and Liberia as well as the total data collected worldwide. Predictions are provided by considering different scenarios involving the average times of infectiousness for the next few months and the end of the current epidemic is estimated according to each scenario. PMID:26834975

  3. Mathematical modeling of the West Africa Ebola epidemic.

    PubMed

    Chretien, Jean-Paul; Riley, Steven; George, Dylan B

    2015-01-01

    As of November 2015, the Ebola virus disease (EVD) epidemic that began in West Africa in late 2013 is waning. The human toll includes more than 28,000 EVD cases and 11,000 deaths in Guinea, Liberia, and Sierra Leone, the most heavily-affected countries. We reviewed 66 mathematical modeling studies of the EVD epidemic published in the peer-reviewed literature to assess the key uncertainties models addressed, data used for modeling, public sharing of data and results, and model performance. Based on the review, we suggest steps to improve the use of modeling in future public health emergencies. PMID:26646185

  4. Climate change impacts on runoff in West Africa: a review

    NASA Astrophysics Data System (ADS)

    Roudier, P.; Ducharne, A.; Feyen, L.

    2014-07-01

    This review summarizes the impacts of climate change on runoff in West Africa, assesses the uncertainty in the projections and describes future research needs for the region. To do so, we constitute a meta-database made of 19 studies and 301 future runoff change values. The future tendency in streamflow developments is overall very uncertain (median of the 301 points is 0% and mean +5.2%), except for (i) the Gambia River, which exhibits a significant negative change (median = -4.5%), and (ii) the Sassandra and the Niger rivers, where the change is positive (+14.4% and +6.1%). A correlation analysis revealed that runoff changes are tightly linked to changes in rainfall (R = 0.49), and to a smaller extent also to changes in potential evapotranspiration. Other parameters than climate - such as the carbon effect on plant water efficiency, land use dynamics or water withdrawals - could also significantly impact on runoff, but they generally do not offset the effects of climate change. In view of the potential changes, the large uncertainty therein and the high vulnerability of the region to such changes, there is an urgent need for integrated studies that quantify the potential effects of these processes on water resources in West Africa and for more accuracy in climate models rainfall projections. We especially underline the lack of information concerning projections of future floods and droughts, and of interannual fluctuations in streamflow.

  5. Climatology of radar anomalous propagation over West Africa

    NASA Astrophysics Data System (ADS)

    Kaissassou, Samuel; Lenouo, André; Tchawoua, Clément; Lopez, Philippe; Gaye, Amadou Thierno

    2015-02-01

    A comprehensive examination of 5 years of European Centre for Medium-Range Weather Forecasts (ECMWF) data from T511 L60 version of the ECMWF model to determine ducting conditions over West Africa and the computation of statistical distributions of the vertical gradient of refractivity determined from 2 years of radiosonde data over Dakar (14.41°N, 17.26°W), Douala (4°N, 9.7°E) and Niamey (13.35°N, 2.03°E) were carried out. It is found that diurnal and seasonal variations of the refractivity of the atmosphere are influenced by air temperature and water vapor pressure fluctuation. Refractivity gradients lower than -157 km-1 often results in spurious returned echoes and misinterpretation of radar images such as erroneous precipitation detection. The results obtained show that the local climate has an appreciable influence on the vertical profile of refractivity, especially the seasonal north-south movement of the Inter Tropical Discontinuity which is associated with the alternance of wet and dry seasons over the region. It is found that most of ducts occur in the night, morning (0000, 0600 UTC) and late afternoon (1800 UTC). The occurrence probability of abnormal propagation events, such as ducts, can provide some valuable information about the propagation of electromagnetic waves over West Africa.

  6. Evaluating Subcriticality during the Ebola Epidemic in West Africa.

    PubMed

    Enanoria, Wayne T A; Worden, Lee; Liu, Fengchen; Gao, Daozhou; Ackley, Sarah; Scott, James; Deiner, Michael; Mwebaze, Ernest; Ip, Wui; Lietman, Thomas M; Porco, Travis C

    2015-01-01

    The 2014-2015 Ebola outbreak is the largest and most widespread to date. In order to estimate ongoing transmission in the affected countries, we estimated the weekly average number of secondary cases caused by one individual infected with Ebola throughout the infectious period for each affected West African country using a stochastic hidden Markov model fitted to case data from the World Health Organization. If the average number of infections caused by one Ebola infection is less than 1.0, the epidemic is subcritical and cannot sustain itself. The epidemics in Liberia and Sierra Leone have approached subcriticality at some point during the epidemic; the epidemic in Guinea is ongoing with no evidence that it is subcritical. Response efforts to control the epidemic should continue in order to eliminate Ebola cases in West Africa. PMID:26484544

  7. The Legacy of Christianity in West Africa, with Special Reference to Burkina Faso

    ERIC Educational Resources Information Center

    Ouedraogo, Philippe

    2010-01-01

    In the following paper, I am going to discuss education and religion and consider the legacy of Christianity in education in West Africa with particular reference to the Evangelical churches in Burkina Faso. The paper will start with a general introduction to West Africa and the place of missionaries' activities in the region. I will then attempt…

  8. Trends and Issues in Vocational Technical Education in Francophone West Africa.

    ERIC Educational Resources Information Center

    Kogoe, Akrima

    Francophone West Africa has committed itself to the goal of universal formal education as the most effective method of insuring rapid economic and national development. (Francophone West Africa is composed of Senegal, Mauritania, Guinea, Mali, Ivory Coast, Togo, Benin, Niger, and Burkina-Faso.) The costly investments of limited fiscal resources in…

  9. Isoprene emissions modelling for West Africa using MEGAN

    NASA Astrophysics Data System (ADS)

    Ferreira, J.; Reeves, C. E.; Murphy, J. G.; Garcia-Carreras, L.; Parker, D. J.; Oram, D. E.

    2010-03-01

    Isoprene emissions are the largest source of reactive carbon to the atmosphere, with the tropics being a major source region. These natural emissions are expected to change with changing climate and human impact on land use. As part of the African Monsoon Multidisciplinary Analyses (AMMA) project the Model of Emissions of Gases and Aerosols from Nature (MEGAN) has been used to estimate the spatial and temporal distribution of isoprene emissions over the West African region. During the AMMA field campaign, carried out in July and August 2006, isoprene mixing ratios were measured on board the FAAM BAe-146 aircraft. These data have been used to evaluate the model performance. MEGAN was firstly applied to a large area covering much of West Africa from the Gulf of Guinea in the south to the desert in the north and was able to capture the large scale spatial distribution of isoprene emissions as inferred from the observed isoprene mixing ratios. In particular the model captures the transition from the forested area in the south to the bare soils in the north, but some discrepancies have been identified over the bare soil, mainly due to the emission factors used. Sensitivity analyses were performed to assess the model response to changes in driving parameters, namely Leaf Area Index (LAI), Emission Factors (EF), temperature and solar radiation. A high resolution simulation was made of a limited area south of Niamey, Niger, where the higher concentrations of isoprene were observed. This is used to evaluate the model's ability to simulate smaller scale spatial features and to examine the influence of the driving parameters on an hourly basis through a case study of a flight on 17 August 2006. This study highlights the complex interactions between land surface processes and the meteorological dynamics and chemical composition of the PBL. This has implications for quantifying the impact of biogenic emissions on the atmospheric composition over West Africa and any changes that

  10. HIV epidemic among key populations in west Africa

    PubMed Central

    Djomand, Gaston; Quaye, Silas; Sullivan, Patrick S.

    2015-01-01

    Purpose of review Globally, HIV infection remains a significant issue for key populations such as men who have sex with men (MSM) and female sex workers. A review of recent articles was conducted for west African countries to assess the burden of disease among female sex workers and MSM, access to services and identify barriers to implementation of services for key populations. Recent findings In west Africa, key populations engage in high-risk practices for the acquisition of HIV and other sexually transmitted infections. Available HIV prevalence data fluctuate across and within countries for both MSM and female sex workers and may be five to ten times as high as that of the general population. HIV prevalence varied from 15.9% in The Gambia to 68% in Benin among female sex workers, whereas it ranged from 9.8% in The Gambia to 34.9% in Nigeria for MSM. Yet, important data gaps exist, including key populations size estimations in several countries as well as HIV prevalence, incidence and other biomarkers of HIV risk. Because of sociocultural, legal, political and economic challenges, exacerbated by a poor health system infrastructure, the HIV response is not strategically directed toward programs for key populations in countries with concentrated epidemics. Noteworthy is the low coverage of prevention care and treatment interventions offered to key populations. Summary Sufficient planning and political will with legal and structural frameworks that reconcile public health and human rights are needed to prioritize HIV prevention, care and treatment programming for key populations programs in west Africa. PMID:25010898

  11. 77 FR 74265 - In the Matter of the Designation of Movement for Unity and Jihad in West Africa; Also Known as...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ... Matter of the Designation of Movement for Unity and Jihad in West Africa; Also Known as Movement for Oneness and Jihad in West Africa; Also Known as Unity Movement for Jihad in West Africa; Also Known as... Movement for Unity and Jihad in West Africa, also known as Movement ] for Oneness and Jihad in West...

  12. Analysing MODIS Phenometrics Quality on Cropped Land in West Africa

    NASA Astrophysics Data System (ADS)

    Vintrou, Elodie; Begue, Agnes; Baron, Christian; Lo Seen, Danny; Alexandre, Saad; Traore, Seydou

    2012-04-01

    Crop phenology is essential information when evaluating crop production in the food insecure regions of West Africa. The only currently available global product that includes phenological variables is the MODIS Land Cover Dynamics Yearly (MCD12Q2) product. This product is produced each year at 500 m spatial resolution, from the 8-day vegetation index EVI (Enhanced Vegetation Index) calculated from the NBAR reflectance (Nadir Bidirectional Reflectance Distribution Function - Adjusted Reflectance). In order to analyze the information content of MODIS MCD12Q2 product, the phenological variables were extracted for areas previously identified as cropped on eight specific sites in Mali and compared to rainfall data and expert knowledge on Malian agriculture. MODIS MCD12Q2 data analysis showed that only 70% of the cropped pixels in Southern Mali had a complete phenology information on the whole vegetation cycle (four phenometrics values), and that a large part of the pixels displayed unrealistic late Start-Of-Season (SOS) values. A close analysis of the original EVI data indicated that these inconsistent SOS values were due to missing EVI data during the vegetation development phase (due to the presence of cloud cover) conducting to a false detection of SOS. We then proposed a simple way to correct the SOS values. In Africa, food security systems could benefit from such a phenology product, by utilizing its spatially continuous information in agro-meteorological modeling, and thus improving agricultural production estimation.

  13. Nitrogen emission and deposition budget in West and Central Africa

    NASA Astrophysics Data System (ADS)

    Galy-Lacaux, C.; Delon, C.

    2014-12-01

    Atmospheric nitrogen depends on land surface exchanges of nitrogen compounds. In Sub Saharan Africa, deposition and emission fluxes of nitrogen compounds are poorly quantified, and are likely to increase in the near future due to land use change and anthropogenic pressure. This work proposes an estimate of atmospheric N compounds budget in West and Central Africa, along an ecosystem transect, from dry savanna to wet savanna and forest, for years 2000-2007. The budget may be considered as a one point in time budget, to be included in long term studies as one of the first reference point for Sub Saharan Africa. Gaseous dry deposition fluxes are estimated by considering N compounds concentrations measured in the frame of the IDAF network (IGAC/DEBITS/AFrica) at the monthly scale and modeling of deposition velocities at the IDAF sites, taking into account the bi directional exchange of ammonia. Particulate dry deposition fluxes are calculated using the same inferential method. Wet deposition fluxes are calculated from measurements of ammonium and nitrate chemical content in precipitations at the IDAF sites combined with the annual rainfall amount. In terms of emission, biogenic NO emissions are simulated at each IDAF site with a surface model coupled to an emission module elaborated from an artificial neural network equation. Ammonia emissions from volatilization are calculated from literature data on livestock quantity in each country and N content in manure. NOx and NH3 emission from biomass burning and domestic fires are estimated from satellite data and emission factors. The total budget shows that emission sources of nitrogen compounds are in equilibrium with deposition fluxes in dry and wet savannas, with respectively 7.40 (±1.90) deposited and 9.01 (±3.44) kgN ha-1 yr-1 emitted in dry savanna, 8.38 (±2.04) kgN ha-1 yr-1 deposited and 9.60 (±0.69) kgN ha-1 yr-1 emitted in wet savanna. In forested ecosystems, the total budget is dominated by wet plus dry

  14. Mathematical modeling of the West Africa Ebola epidemic

    PubMed Central

    Chretien, Jean-Paul; Riley, Steven; George, Dylan B

    2015-01-01

    As of November 2015, the Ebola virus disease (EVD) epidemic that began in West Africa in late 2013 is waning. The human toll includes more than 28,000 EVD cases and 11,000 deaths in Guinea, Liberia, and Sierra Leone, the most heavily-affected countries. We reviewed 66 mathematical modeling studies of the EVD epidemic published in the peer-reviewed literature to assess the key uncertainties models addressed, data used for modeling, public sharing of data and results, and model performance. Based on the review, we suggest steps to improve the use of modeling in future public health emergencies. DOI: http://dx.doi.org/10.7554/eLife.09186.001 PMID:26646185

  15. Socioeconomic consequences of blinding onchocerciasis in west Africa.

    PubMed Central

    Evans, T. G.

    1995-01-01

    Onchocerciasis or river blindness, a major cause of irreversible blindness among adults, has been the focus of international disease control efforts for over 20 years in West Africa. This paper employs the international classification of impairment, disability and handicap (ICIDH) to interpret results from a field study to assess the socioeconomic consequences of onchocerciasis in Guinea in 1987. In a sample of 136 blind, 94 visually impaired and 89 well-sighted persons, decreasing visual acuity is strongly associated with mobility, occupational and marital handicaps. Individual, household and disease correlates were explored. The implications of these findings for the ICIDH concept of handicap are discussed with particular emphasis on the need to extend analysis beyond the individual when assessing the socioeconomic consequences of disabling disease. PMID:7554022

  16. Regional Model Nesting Within GFS Daily Forecasts Over West Africa

    NASA Technical Reports Server (NTRS)

    Druyan, Leonard M.; Fulakeza, Matthew; Lonergan, Patrick; Worrell, Ruben

    2010-01-01

    The study uses the RM3, the regional climate model at the Center for Climate Systems Research of Columbia University and the NASA/Goddard Institute for Space Studies (CCSR/GISS). The paper evaluates 30 48-hour RM3 weather forecasts over West Africa during September 2006 made on a 0.5 grid nested within 1 Global Forecast System (GFS) global forecasts. September 2006 was the Special Observing Period #3 of the African Monsoon Multidisciplinary Analysis (AMMA). Archived GFS initial conditions and lateral boundary conditions for the simulations from the US National Weather Service, National Oceanographic and Atmospheric Administration were interpolated four times daily. Results for precipitation forecasts are validated against Tropical Rainfall Measurement Mission (TRMM) satellite estimates and data from the Famine Early Warning System (FEWS), which includes rain gauge measurements, and forecasts of circulation are compared to reanalysis 2. Performance statistics for the precipitation forecasts include bias, root-mean-square errors and spatial correlation coefficients. The nested regional model forecasts are compared to GFS forecasts to gauge whether nesting provides additional realistic information. They are also compared to RM3 simulations driven by reanalysis 2, representing high potential skill forecasts, to gauge the sensitivity of results to lateral boundary conditions. Nested RM3/GFS forecasts generate excessive moisture advection toward West Africa, which in turn causes prodigious amounts of model precipitation. This problem is corrected by empirical adjustments in the preparation of lateral boundary conditions and initial conditions. The resulting modified simulations improve on the GFS precipitation forecasts, achieving time-space correlations with TRMM of 0.77 on the first day and 0.63 on the second day. One realtime RM3/GFS precipitation forecast made at and posted by the African Centre of Meteorological Application for Development (ACMAD) in Niamey, Niger

  17. A Regional Model Study of Synoptic Features Over West Africa

    NASA Technical Reports Server (NTRS)

    Druyan, Leonard M.; Fulakeza, Matthew; Lonergan, Patrick; Saloum, Mahaman; Hansen, James E. (Technical Monitor)

    2001-01-01

    Synoptic weather features over West Africa were studied in simulations by the regional simulation model (RM) at the NASA/Goddard Institute for Space Studies. These pioneering simulations represent the beginning of an effort to adapt regional models for weather and climate prediction over West Africa. The RM uses a cartesian grid with 50 km horizontal resolution and fifteen vertical levels. An ensemble of four simulations was forced with lateral boundary conditions from ECMWF global analyses for the period 8-22 August 1988. The simulated mid-tropospheric circulation includes the skillful development and movement of several African wave disturbances. Wavelet analysis of mid-tropospheric winds detected a dominant periodicity of about 4 days and a secondary periodicity of 5-8 days. Spatial distributions of RM precipitation and precipitation time series were validated against daily rain gauge measurements and ISCCP satellite infrared cloud imagery. The time-space distribution of simulated precipitation was made more realistic by combining the ECMWR initial conditions with a 24-hr spin-up of the moisture field and also by damping high frequency gravity waves by dynamic initialization. Model precipitation "forecasts" over the Central Sahel were correlated with observations for about three days, but reinitializing with observed data on day 5 resulted in a dramatic improvement in the precipitation validation over the remaining 9 days. Results imply that information via the lateral boundary conditions is not always sufficient to minimize departures between simulated and actual precipitation patterns for more than several days. In addition, there was some evidence that the new initialization may increase the simulations' sensitivity to the quality of lateral boundary conditions.

  18. Aetiology of uveitis in Sierra Leone, west Africa.

    PubMed Central

    Ronday, M J; Stilma, J S; Barbe, R F; McElroy, W J; Luyendijk, L; Kolk, A H; Bakker, M; Kijlstra, A; Rothova, A

    1996-01-01

    BACKGROUND: In 1992, non-onchocercal uveitis caused 9% of blindness, 8% of visual impairment, and 11% of uniocular blindness among patients visiting an eye hospital in Sierra Leone, west Africa. The aim of this study was to determine the aetiology of uveitis in this population. METHODS: General and ophthalmic examination complemented by serum and aqueous humour analyses for various infectious agents was performed for 93 uveitis patients and compared with serum (n = 100) and aqueous humour (n = 9) analysis of endemic controls. RESULTS: At the initial examination, 45 patients (48%) proved to be severely visually handicapped. After clinical and laboratory analyses, an aetiological diagnosis was established for 49 patients (52%). Toxoplasma gondii was the most important cause of uveitis (40/93; 43%). Anti-toxoplasma IgM antibodies were detected in serum samples of seven of 93 patients (8%) compared with one of 100 controls (1%, p < 0.05). At least six patients (15%) with ocular toxoplasmosis had acquired the disease postnatally. Antibodies against Treponema pallidum were detected in 18 of 92 patients (20%) and in 21 controls (21%). Other causes of uveitis were varicella zoster virus (one patient), herpes simplex virus (two patients), and HLA-B27 positive acute anterior uveitis with ankylosing spondylitis (one patient), while one patient had presumed HTLV-I uveitis. CONCLUSIONS: In a hospital population in Sierra Leone, west Africa, uveitis was associated with severe visual handicap and infectious diseases. Toxoplasmosis proved to be the most important cause of the uveitis. Although the distribution of congenital versus acquired toxoplasmosis in this population could not be determined, the results indicate an important role of postnatally acquired disease. The results further suggested minor roles for HIV, tuberculosis, toxocariasis, and sarcoidosis as causes of uveitis in this population. PMID:8976721

  19. Paleozoic basins in West Africa and the Mauritanide thrust belt

    NASA Astrophysics Data System (ADS)

    Villeneuve, Michel

    2005-10-01

    The evolution of the Paleozoic basins of West Africa is strongly depending on the structuration of the different belts which are surrounding the West African Craton. We distinguish the "Taoudeni Basin" located in the center of the craton from the basins located on the West African Craton margin (Tindouf, Tamale and several troughs limiting the western side of the Taoudeni Basin). Other basins are located on top of the Pan-African or Hercynian belts (Bové, Kandi, Ouallen in Semmen and Diourbel basins) or on top of the Proterozoic shields (The Ghana basins). Some are evidenced underneath the Mesozoic-Cenozoic coastal basins (Bové and Ghana basins). The sedimentation started with the Marinoan glacial event (620-580 Ma) and ended with the carbonates of the Early Carboniferous. The main tectonic or climatic events that occurred during this period are registered by the sediments. Among them are, the "Série pourprée glaciogenic deposits, the Pan-African II tectonic event (550-500 Ma) which affects the southwestern part of the Taoudeni Basin, the Late Ordovician glaciogenic event, the Early Silurian marine transgression, the Early Devonian marine regression and the Hercynian tectonic event (330-270 Ma) which affects the Paleozoic basins located on the western and northern parts of the West African Craton. The second part of this paper is devoted to a synthetic review of the Mauritanides Belt which is extending from Southern Senegal to the Moroccan High Atlas. This belt includes both old Pan-African belts and Paleozoic sediments (belonging to the western part of the Bové, Taoudeni and Tindouf basins) tectonised and metamorphosed during the Hercynian orogen. The third part points out the close relationships between the Paleozoic basins and the main tectonic event for the main periods of the West African Craton evolution.

  20. Qur'anic and "Ajami" Literacies in Pre-Colonial West Africa

    ERIC Educational Resources Information Center

    Diallo, Ibrahima

    2012-01-01

    Traditional African literacy practices have often been ignored in the wake of European colonialism and the educational policies of colonial governments. Nonetheless, literacy had been established in parts of Africa following the introduction of Islam. This paper will examine the developments of literacy in pre-colonial West Africa. In this region,…

  1. Education and Indigenous Knowledge in Africa: Traditional Bonesetting and Orthopaedic Medicine in West Africa

    NASA Astrophysics Data System (ADS)

    Ezeanya, Chika A.

    The underlying philosophy of education in contemporary Africa has been established to be alien, and detached from the indigenous knowledge of the people. Modern day formal education in sub-Saharan Africa came about, for the most part, as a result of missionary activities and colonial efforts of Europe. The education bequeathed to Africa was, therefore, fundamentally European in paradigm and lacking in authenticity. The end of colonialism across sub-Saharan Africa did not herald any tangible transformation in the curriculum of study. Education in Africa is still dependent on foreign input for sustainability, thereby stifling research, creativity and innovation. Sustainable development is founded on indigenous knowledge. When such grassroots knowledge assumes the foundation of learning, home-grown development is easily fostered in all sectors of a national economy. In the field of medicine, indigenous knowledge of healing has been considered unscientific by western biomedical practitioners. Since the days of the missionaries, many Africans have considered indigenous medicine to be fetish; the Christian converts would not be associated with its practice and patronage. However, traditional bonesetting has been proven to be highly efficacious with little supernatural content, it continues to attract huge patronage from Africans, cutting across social and religious boundaries. This study attempts an exploration of the disconnect between indigenous knowledge, practices and learning, on the one hand, and formal education in Africa, on the other. With a focus on traditional bonesetting, the study seeks to determine why that branch of indigenous medicine attracts huge patronage, but is granted very little recognition by modern orthopaedic medical education.

  2. Holocene mangrove swamps of West Africa sedimentology and soils

    NASA Astrophysics Data System (ADS)

    Marius, C.; Lucas, J.

    The mangrove swamps of West African Coast belong to the Atlantic type which is characterized by a small number of species. They colonize tidal environments which are dissected by numerous meandering tidal channels and are presently subject to a low rate of sediment accumulation. The mangrove vegetation exhibits a characteristic zonation pattern that basically reflects the adaptation of the various species to saline conditions. The typical zonation sequence is: Rhizophora racemosa (or Rh. mangle), Rh. mangle + Avicennia africana, Avicennia, flooded tanne, barren tanne, herbaceous tanne. The tannes are generated by aridic climatic conditions, heavy soil and water salt content, and are, in a way a peculiar feature of mangrove swamps in West Africa. The sediment colonized by the mangroves is relatively homogenous. Mineralogically, they are dominated by quartz and clay to which are associated halite, pyrite and jarosite. The clay suite is mainly composed of smectite and kaolinite. Smectite is predominant in the inlet areas and is replaced inland by kaolinite. Chemically, the sediments contain very low amounts of Ca, bases and trace elements. The mangrove swamp floodwaters have a chemical composition similar to that of seawater. It is dominated by sodium and chloride. Morphologically, the ripening of the soils appears with a chestnut mash colour horizon and buttery consistency in relation with the decomposition of fibrous roots of Rhizophora and also with pale yellow jarosite mottles in the top horizons of the tanne profiles due to the oxidation of pyrine. The two main properties of the mangrove soils of West Africa are acidity and salinity; the first is related to the high content of sulphur and the second to the sea influence. The acidity has to be connected mainly to the Rhizophora vegetation whose the root system is a real trap for catching the pyrites resulting from the reduction of the sulphates of sea water by the sulphate reducing bacteria, in a reduced

  3. Energy consumption and economic development in West Africa

    SciTech Connect

    Chima, C.M.

    1987-01-01

    This study evaluates the commercial energy sector of the Economic Community of West African States (ECOWAS). Presently, an economic union exists between the 16 countries of West Africa that are members of ECOWAS. Although the ECOWAS region has plentiful resources of commercial energy, it faces problems in this sector for two reasons. First is the problem resulting from the diminishing traditional energy resources such as wood fuel and charcoal. Second, most ECOWAS members, except Nigeria, are net importers of commercial energy, and hence face a high import burden for oil. Liquid petroleum is the dominant form of commercial energy used in the ECOWAS despite the availability of other resources. This author basically argues that the best policy and strategy solution for dealing with energy problems is through a combination of regional cooperative effort, and a more-intensive country level. The intensity-of-use hypothesis is tested with case studies of Ghana, the Ivory Coast, and Nigeria. The results indicate that newly developing countries can deviate from the expectations of the hypothesis.

  4. An interventional model to develop health professionals in West Africa.

    PubMed

    Sanou, Anselme Simeon; Awoyale, Florence Adeola; Diallo, Abdoulaye

    2014-01-01

    The health sector is characterized by a human resource base lacking in numbers, specialized skills, and management skills. West African Health Organization (WAHO) recognizes the need within the West Africa sub-region for bilingual professionals who are skilled in public health, management, leadership, and information technology to build human capacity in public health and developed the Young Professionals Internship Program (YPIP). Our study explores the evolution of the programme. YPIP program has successfully carried out its original aims and objectives to equip young professionals with basic principles of public health, management, and leadership, acquire competence in a second official language (French, English, and Portuguese), information and communication technology. Contributing factors towards this successful evaluation included positive ratings and commentary from previous interns about the relevance, usefulness, and quality of the programme, encouraging feedback from WAHO management, trainers, administrators, and intern employers on the impact of the YPIP program on young professionals, supporting evidence that demonstrates increased knowledge in professional skills and language competency. PMID:25419290

  5. Desertification, refugees and regional conflict in west Africa.

    PubMed

    Nnoli, O

    1990-06-01

    This article documents the potential for inter-state conflict in the migration of hundreds of thousands of famine refugees across international borders in West Africa. Nigeria and Ghana, for example, have to deal not only with the effects of land degradation in their northern territories but also with the influx of famine victims from Mali, Niger, Chad and Burkino Faso. These migrations put an enormous extra burden on the fragile and already overstretched social and economic infrastructures of the host countries. The construction of dams for irrigation and electricity generation in international river basins, is another cause of inter-state conflict related to land degradation. The capacity of West African states to find peaceful solutions to these problems is being undermined by the increasing impoverishment and marginalisation of their populations. A self-serving neo-colonialist governing elite is caught in the economic stranglehold of the advanced capitalist nations. While there is thus no short term solution to the problem of land degradation, immediate steps should at least be taken to give legal protection to those who are forced to cross international borders because of drought and famine. PMID:20958699

  6. An interventional model to develop health professionals in West Africa

    PubMed Central

    Sanou, Anselme Simeon; Awoyale, Florence Adeola; Diallo, Abdoulaye

    2014-01-01

    The health sector is characterized by a human resource base lacking in numbers, specialized skills, and management skills. West African Health Organization (WAHO) recognizes the need within the West Africa sub-region for bilingual professionals who are skilled in public health, management, leadership, and information technology to build human capacity in public health and developed the Young Professionals Internship Program (YPIP). Our study explores the evolution of the programme. YPIP program has successfully carried out its original aims and objectives to equip young professionals with basic principles of public health, management, and leadership, acquire competence in a second official language (French, English, and Portuguese), information and communication technology. Contributing factors towards this successful evaluation included positive ratings and commentary from previous interns about the relevance, usefulness, and quality of the programme, encouraging feedback from WAHO management, trainers, administrators, and intern employers on the impact of the YPIP program on young professionals, supporting evidence that demonstrates increased knowledge in professional skills and language competency. PMID:25419290

  7. Sustainable Development of Research Capacity in West Africa

    NASA Astrophysics Data System (ADS)

    Liebe, J. R.; Rogmann, A.; Falk, U.; Nyarko, B. K.; Amisigo, B.; Barry, B.; Vlek, P. L.

    2010-12-01

    In West Africa, the management and efficient use of natural resources is becoming ever more important. This is largely due to steeply increasing demand through population growth and economic development, and through the effects of greater uncertainty due to climate and environmental change. Developing research capacity in these countries is an essential step in enabling them to assess their natural resources independently, and to develop national strategies and policies to manage their natural resources in the light of growing demand and increasing climatic uncertainty. The project “Sustainable Development of Research Capacity in West Africa based on the GLOWA Volta Project” (SDRC) is an 18 month project, funded by the German Ministry of Education and Research, to strengthen the research capacity in West Africa. The SDRC is based on three columns: I. knowledge transfer and strengthening of human capacity; II. strengthening of infrastructural research capacity; and III. strengthening the institutional capacity. The SDRC makes use of the wide range of research results and decision support tools developed in the GLOWA Volta Project (GVP), a nine-year, interdisciplinary research project (2000-2009) with a regional focus on the Volta Basin. The tools and models that have been transferred and trained in the framework of GVP and SDRC cover a range of topics, such as modeling the onset of the rainy season, hydrological, economic, hydro-economic modeling, GIS and Remote Sensing, and the training of database managers, to name a few. Infrastructural capacity is developed by the transfer of a micro-meteorological research network to the Meteorological Service of Burkina Faso, joint operation of a tele-transmitted hydrological gauging network with the Hydrological Service of Ghana, and the provision of hard- and software capacity to use the trained models. At the center of the SDRC effort is the strengthening of the Volta Basin Authority, a newly established river basin

  8. Water Sources in Cape Verde and West Africa. Water in Africa.

    ERIC Educational Resources Information Center

    Maher, Robert

    The Water in Africa Project was realized over a 2-year period by a team of Peace Corps volunteers, World Wise Schools (WWS) classroom teachers, and WWS staff members. As part of an expanded, detailed design, resources were collected from over 90 volunteers serving in African countries, photos and stories were prepared, and standards-based learning…

  9. A re-evaluation of the origin of hepatitis C virus genotype 2 in West Africa

    PubMed Central

    Forbi, Joseph C.; Sue, Amanda; Layden, Jennifer E.; Switzer, William M.; Opare-Sem, Ohene K.; Phillips, Richard O.; Khudyakov, Yury E.

    2015-01-01

    Hepatitis C virus (HCV) is classified into seven genotypes based on genetic diversity, and most genotypes have been found in Africa. Infections with HCV genotype 2 (HCV2) are most prevalent in West Africa and it was suggested that HCV2 originated in West Africa. To better understand the evolutionary epidemiology of HCV2 in Africa, we examined new NS5B sequences of HCV2 strains obtained from Côte d'Ivoire, Ghana and Nigeria sequenced at the Centers for Disease Control and Prevention with those available from West, North and Central Africa. Bayesian phylogeographic analysis using a discrete trait model showed that Ghana was the most likely geographical region for the origin of HCV2. Spread of HCV2 from Ghana did not appear to be through diffusion to adjacent countries along the coast. Rather, it was transmitted from Ghana to many distant countries in Africa, suggesting that certain routes of geographical dissemination were historically more efficient than mere proximity and that the HCV2 epidemic history in West Africa is extremely complex. PMID:25888623

  10. A General Survey of Religious Concepts and Art of North, East, South, and West Africa.

    ERIC Educational Resources Information Center

    Stewart, Rohn

    This paper, a summary of a multi-carousel slide presentation, reviews literature on the cultures, religions, and art of African people. Before focusing on West Africa, highlights of the lifestyles, religions, and icons of non-maskmaking cultures of North, West and South African people are presented. Clarification of West African religious concepts…

  11. Back to Africa: Second Chances for the Children of West African Immigrants

    ERIC Educational Resources Information Center

    Bledsoe, Caroline H.; Sow, Papa

    2011-01-01

    This paper examines the phenomenon of West African parents living in Europe and North America who send their older children back home: from places of high immigrant aspiration to those of hardship and privation. Drawing on a project on West African immigration to Europe and on previous field studies in Africa, we conclude that West African…

  12. Fumonisin contamination of maize in Burkina Faso, West Africa.

    PubMed

    Nikièma, P N; Worrillow, L; Traoré, A S; Wild, C P; Turner, P C

    2004-09-01

    Maize throughout the world is frequently contaminated with a family of mycotoxins, the fumonisins, produced by species of Fusaria. The study investigated the level of fumonisin contamination of maize samples from village farms and large market traders in Burkina Faso, West Africa. Maize samples (5 kg) from each of five to six large storage barns from farms in five villages in the district of N'Dorola, Kénédougou province, western Burkina Faso, were sampled (n = 26) in Jan 1999 (> 1 year storage), and a further 26 maize samples from the same farms were collected directly from the field in October 1999. In addition, 72 maize samples were obtained in July 1999 from large markets in Bobo Dioulasso. Fumonisins were extracted from dried maize, derivatized with o-phthaldialdehyde and quantified by reversed-phase high-performance liquid chromatography with fluorescence detection. All 26 samples from the first (mean 1170 microg kg(-1), range 110-3120 microg kg(-1)) and from the second (mean 130 microg kg(-1), range 10-450 microg kg(-1)) village collection were fumonisin positive. All 72 maize samples from the large markets were also positive for fumonisins, and had the highest levels of contamination (mean 2900 microg kg(-1), range 130-16,040 microg kg(-1)). As fumonisins were a ubiquitous contaminant of maize and given that this crop is a dietary staple in this region, chronic exposure is likely. PMID:15666980

  13. Mites associated with stored grain commodities in Benin, West Africa.

    PubMed

    Zannou, Ignace D; Adebo, Habib O; Zannou, Elisabeth; Hell, Kerstin

    2013-12-01

    After insects, mites are the major arthropod pests that inhabit stored agricultural products worldwide. To determine the acarofauna that infests cowpea, maize, paddy rice and sorghum in Benin (West Africa), surveys were conducted in some principal markets (Dantokpa, Glazoue and Parakou) of this country. A total of 555 samples of grains and debris were collected in May and September 2011. More than 56 species belonging to 24 mite families were recorded in the four products. These mite species included predators, parasites, fungivorous, phytophagous and other groups whose feeding habits are not well known. The family Cheyletidae was the most prevalent and the most diverse predatory mite family encountered, in which Cheyletus malaccensis Oudemans was the most abundant species. Several families of mite pests and mites responsible for allergies (Acaridae, Glycyphagidae, Pyroglyphidae, Pyemotidae and Saproglyphidae) were also detected. The three most dominant and frequent species were C. malaccensis, Suidasia nesbitti (Hughes) and Suidasia sp. Statistical analysis showed that densities of these three mite species were higher in Parakou than in Glazoue and Dantokpa, on one hand, and higher in debris than in grains, on the other hand. The densities of S. nesbitti and Suidasia sp. decreased significantly during the dry season, whereas C. malaccensis remained stable throughout the two samplings. Of all grains, sorghum was the least infested with mites. This study shows that in Benin mites are present in stored agricultural products to which they cause serious damage, and may cause various allergies to people. PMID:23793792

  14. Epidemiological situation of Ebola virus disease in West Africa.

    PubMed

    Arima, Yuzo; Shimada, Tomoe

    2015-01-01

    After Guinea reported an outbreak of Ebola virus disease (EVD) in March 2014, EVD spread to neighboring Sierra Leone and Liberia in West Africa. Since then, the EVD outbreak spread over a wide geographic area among these three countries, and became the largest EVD epidemic ever with unprecedented numbers of confirmed cases and fatalities. As of April 2015, one year past the start of the outbreak, transmission is still ongoing. And, while six other countries, including those outside of the African continent (the United Kingdom, Spain, and the United States), have reported EVD cases, the source of the infection all originated from Guinea, Sierra Leone, or Liberia. As for the pathogen, Ebola virus, the route of transmission and associated prevention measures are well known, and change in the virulence or transmissibility of the virus has not been confirmed. However, there are specific factors that likely contributed to the unprecedented magnitude of the current EVD outbreak. In addition to the limited and poor medical and public health infrastructure in the affected countries, implementing appropriate responses rapidly was challenging for these countries, whose medical community, the general public, and governments had never experienced EVD before. PMID:26923957

  15. The stratigraphy of the Taoudeni basin, west Africa

    SciTech Connect

    Ratcliffe, K.T.; Moody, R.T.J. )

    1993-09-01

    The Taoudeni basin is one of the major structural units of the west African craton, with an areal extent in excess of 2,000,000 km[sup 2]. Sediment thicknesses can reach over 3000 m, but have an average thickness of 1250 m. The majority of the basin-fill sediments are Precambrian to Carboniferous, with Mesozoic rocks present in the eastern margin adjacent to the Adrar des Iforas. Due to the paucity of exploration in the Taoudoni basin, there are no detailed works on source potential, maturity, or reservoir quality. However, within the sediment pile, there are excellent potential reservoirs, in the form of poorly cemented sandstones, and apparently organic-rich sediments, which may have source potential. Three major Paleozoic tectono-sedimentary units are recognized within the basin, all of which are found in the Adrar de Mauritania, which is taken as the [open quotes]type section[close quotes] for the Taoudeni basin. Unit 1 (Upper Riphean) is composed of alternating sandstones, limestones, and mudstones, which show rapid lateral thickness variations. Units 2 and 3 are far more uniform in thickness and distribution. Unit 2 (late Precambrian-Lower Ordovician) is composed of shales and sandstones with minor limestones. The base of this unit is composed of the Triad, or the Eocambrian glacial deposits that can be correlated across west Africa. Unit 3 (Upper Oedovician-Devonian) is composed of a variety of lithofacies varying from a basal glacial unit through basinal graptolitic shales into shallow marine/continental deposits. Each of these units will be discussed in detail and the petroleum potential of the constituent lithofacies considered.

  16. South Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of South Africa was acquired on May 14, 2000, by NASA's Moderate-resolution Imaging Spectroradiometer, or MODIS. The image was produced using a combination of the sensor's 250-m and 500-m resolution visible wavelength bands. As part of the opening ceremony to begin the joint U.S.-South Africa SAFARI Field Experiment, NASA presented print copies of this image as GIFts to Dr. Ben Ngubane, Minister of Arts, Science and Technology, and Honorable Advocate Ngoaka Ramathlodi, Premier of the Northern Province, South Africa. The area shown in this image encompasses seven capital cities and a number of the region's distinctive geological features can be seen clearly. Toward the northern (top) central part of the image, the browns and tans comprise the Kalahari Desert of southern Botswana. The Tropic of Capricorn runs right through the heart of the Kalahari and the Botswanan capital city of Gaborone sits on the Limpopo River, southeast of the Kalahari. Along the western coastline of the continent is the country of Namibia, where the Namib Desert is framed against the sea by the Kaokoveld Mountains. The Namibian capital of Windhoek is obscured by clouds. Looking closely in the center of the image, the Orange River can be seen running from east to west, demarcating the boundary between Namibia and South Africa. On the southwestern corner of the continent is the hook-like Cape of Good Hope peninsula and Cape Town, the parliamentary capital of South Africa. Running west to east away from Cape Town are the Great Karroo Mountains. The shadow in this image conveys a sense of the very steep grade of the cliffs along the southern coast of South Africa. Port Elizabeth sits on the southeasternmost point of South Africa, and a large phytoplankton bloom can be seen in the water about 100 miles east of there. Moving northward along the east coast, the Drakensberg Mountains are visible. The two small nations of Lesotho and Swaziland are in this region, completely

  17. Climate Variability and Predictability in North West Africa

    NASA Astrophysics Data System (ADS)

    Baddour, O.; Djellouli, Y.

    2003-04-01

    North West Africa defined here as the area including Morocco, Algeria and Tunisia, it occupies a large territory in North Africa with more than 3.5 Millions KM2. The geographical contrast is very important: while most of the southern part is desert, the northern and north western part exhibits a contrasting geography including large flat areas in the western part of Morocco, northern Algeria and eastern part of Tunisia, And also the formidable Atlas mountains barrier that extends from south west of Morocco toward north west of Tunisia crossing central Morocco and north Algeria.Agriculture is one of major socio-economic activity in the region with an extensive cash-crop for exporting to Europe especially from Morocco and Tunisia. The influence of the recurring droughts during 80s and 90s was very crucial for the economic and societal aspects of the region. In Morocco, severe droughts has caused GDP fluctuation within past 20 years from 10% increase down to negative values in some particular years. Most of weather systems occurs during frontal excursion through the Atlantic and Europe bringing cold air and cloud and precipitation systems. The active precipitation period extends from October to May with almost 80% of the total rainfall. The dry season extends from June to September. Nevertheless some convective clouds develop occasionally during the dry season due to subtropical humid air mass that converge into the region and trigger the convection especially in the high area and Sahara. These less frequent precipitation systems could lead to weather hazards such as flash floods with damage to population and infrastructure. (The example of OURIKA in August 1995 in Morocco). The far south of the region experiences some tropical influence during August period especially in the south of Algeria when the ITCZ can migrate from the SAHEL area to its northernmost position in the region. Recent studies have investigated seasonal rainfall variability and prediction over

  18. Life in Sierra Leone, West Africa. A Teaching Unit.

    ERIC Educational Resources Information Center

    Corby, Richard A.

    This unit is designed for students in grades 6-12. The unit provides an introduction to Sierra Leone and the continent of Africa through basic concepts and a conceptual framework for learning. The unit is divided into 17 activities. Activities include: (1) "Stereotypes and Myths about African and Africans"; (2) "The Manding Name Game"; (3) "Common…

  19. Estimation of Croplands in West Africa using Global Land Cover and Land Use Datasets: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Adhikari, P.; de Beurs, K.

    2013-12-01

    Africa is vulnerable to the effects of global climate change resulting in reduced agricultural production and worsening food security. Studies show that Africa has the lowest cereal yield compared to other regions of the world. The situation is particularly dire in East, Central and West Africa. Despite their low cereal yield, the population of East, Central and West Africa has doubled between 1980 and 2007. Furthermore, West Africa has a history of severe and long droughts which have occasionally caused widespread famine. To understand how global climate change and land cover change have impacted crop production (yield) it is important to estimate croplands in the region. The objective of this study is to compare ten publicly available land cover and land use datasets, covering different time periods, to estimate croplands in West Africa. The land cover and land use data sets used cover the period from early 1990s to 2010. Preliminary results show a high variability in cropland estimates. For example, in Benin, the estimated cropland area varies from 2.5 to 21% of the total area, while it varies from 3 to 8% in Niger. Datasets with a finer resolution (≤ 1,000 m) have consistently estimated comparable cropland areas across all countries. Several categorical verification statistics such as probability of detection (POD), false alarm ratio (FAR) and critical success index are also used to analyze the correspondence between estimated and observed cropland pixels at the scales of 1 Km and 10 Km.

  20. Fluid inclusions in quartz crystals from South-West Africa

    USGS Publications Warehouse

    Kvenvolden, K.A.; Roedder, E.

    1971-01-01

    Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one or a variable combination of: organic liquid, moderately saline aqueous liquid, dark-colored solid, and vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights. The former include CH4, C2H6, C3H8 and possibly C4H10 as well as CO, CO2, H2O, N2 and H2. High molecular weight components are dominantly n-alkanes and isoprenoid hydrocarbons. The n-alkanes range from at least n-C10 to n-C33. Concentrations of n-alkanes larger than n-C17 decrease regularly with increasing carbon number. An homologous series of isoprenoid hydrocarbons ranging from at least C14 to C20 is present in unusually high concentrations. Pristane (C19) is most abundant, and C17 isoprenoid is least abundant. The molecular composition and distribution of hydrocarbons suggest biological precursors for these components. Consideration of data provided by freezing, crushing and heating experiments suggests that the pressures at the time these in part supercritical fluids were trapped probably exceeded 30-40 atm, and the minimum trapping temperature was about 120-160??C. Both primary and secondary inclusions apparently containing only organic materials were trapped by the growth of the host quartz from aqueous solution. The data obtained neither prove nor preclude Precambrian, Paleozoic or younger sources for the organic materials. ?? 1971.

  1. Land-use change and infectious disease in West Africa

    NASA Astrophysics Data System (ADS)

    Thomson, M. C.; Ericksen, P. J.; Mohamed, A. Ben; Connor, S. J.

    Land-use change has been associated with changes in the dynamics of infectious disease in West Africa. Here we describe the complex interactions of land-use change with three diseases (both vector- and non-vector-borne) of considerable public health significance in this region, namely, malaria and irrigation; epidemic meningitis and land degradation; onchocerciasis and deforestation. We highlight the confounding effect of climate variability, which acts as a driver of both land-use change and human health. We conclude, as have others, that the scale of observation always matters, and complex and dynamic feedbacks among social-ecological systems are not easily teased apart. We suggest that in order to establish the causal chain of interactions between land-use change and human health outcomes two approaches are necessary. The first is to have a thorough understanding of the aetiology of disease and the specific mechanisms by which land-use and climate variability affect the transmission of pathogens. This is achieved by focused, detailed studies encompassing a wide range of potential drivers, which are inevitably small scale and often cover short time periods. The second consists of large-scale studies of statistical associations between transmission indices or health outcomes and environmental variables stratified by known ecological or socio-economic confounders, and sufficient in size to overcome local biases in results. Such research activities need to be designed to inform each other if we are to develop predictive models for monitoring these diseases and to develop integrated programs for human health and sustainable land use.

  2. Response of the Water Cycle of West Africa and Atlantic to Radiative Forcing by Saharan Dust

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Kim, Kyu-Myong; Sud, Yogesh C.; Walker, Gregory L.

    2010-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence in support of the "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feed back triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Easter Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean. region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while long wave has the opposite response. The elevated dust layer warms the air over Nest Africa and the eastern Atlantic. The condensation heating associated with the induced deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface energy fluxes, resulting in cooling of the Nest African land and the eastern Atlantic, and a warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

  3. Autosomal and mtDNA Markers Affirm the Distinctiveness of Lions in West and Central Africa

    PubMed Central

    Bertola, Laura D.; Tensen, Laura; van Hooft, Pim; White, Paula A.; Driscoll, Carlos A.; Henschel, Philipp; Caragiulo, Anthony; Dias-Freedman, Isabela; Sogbohossou, Etotépé A.; Tumenta, Pricelia N.; Jirmo, Tuqa H.; de Snoo, Geert R.

    2015-01-01

    The evolutionary history of a species is key for understanding the taxonomy and for the design of effective management strategies for species conservation. The knowledge about the phylogenetic position of the lion (Panthera leo) in West/Central Africa is largely based on mitochondrial markers. Previous studies using mtDNA only have shown this region to hold a distinct evolutionary lineage. In addition, anthropogenic factors have led to a strong decline in West/Central African lion numbers, thus, the conservation value of these populations is particularly high. Here, we investigate whether autosomal markers are concordant with previously described phylogeographic patterns, and confirm the unique position of the West/Central African lion. Analysis of 20 microsatellites and 1,454 bp of the mitochondrial DNA in 16 lion populations representing the entire geographic range of the species found congruence in both types of markers, identifying four clusters: 1) West/Central Africa, 2) East Africa, 3) Southern Africa and 4) India. This is not in line with the current taxonomy, as defined by the IUCN, which only recognizes an African and an Asiatic subspecies. There are no indications that genetic diversity in West/Central Africa lions is lower than in either East or Southern Africa, however, given this genetic distinction and the recent declines of lion numbers in this region, we strongly recommend prioritization of conservation projects in West/Central Africa. As the current taxonomic nomenclature does not reflect the evolutionary history of the lion, we suggest that a taxonomic revision of the lion is warranted. PMID:26466139

  4. Autosomal and mtDNA Markers Affirm the Distinctiveness of Lions in West and Central Africa.

    PubMed

    Bertola, Laura D; Tensen, Laura; van Hooft, Pim; White, Paula A; Driscoll, Carlos A; Henschel, Philipp; Caragiulo, Anthony; Dias-Freedman, Isabela; Sogbohossou, Etotépé A; Tumenta, Pricelia N; Jirmo, Tuqa H; de Snoo, Geert R; de Iongh, Hans H; Vrieling, Klaas

    2015-01-01

    The evolutionary history of a species is key for understanding the taxonomy and for the design of effective management strategies for species conservation. The knowledge about the phylogenetic position of the lion (Panthera leo) in West/Central Africa is largely based on mitochondrial markers. Previous studies using mtDNA only have shown this region to hold a distinct evolutionary lineage. In addition, anthropogenic factors have led to a strong decline in West/Central African lion numbers, thus, the conservation value of these populations is particularly high. Here, we investigate whether autosomal markers are concordant with previously described phylogeographic patterns, and confirm the unique position of the West/Central African lion. Analysis of 20 microsatellites and 1,454 bp of the mitochondrial DNA in 16 lion populations representing the entire geographic range of the species found congruence in both types of markers, identifying four clusters: 1) West/Central Africa, 2) East Africa, 3) Southern Africa and 4) India. This is not in line with the current taxonomy, as defined by the IUCN, which only recognizes an African and an Asiatic subspecies. There are no indications that genetic diversity in West/Central Africa lions is lower than in either East or Southern Africa, however, given this genetic distinction and the recent declines of lion numbers in this region, we strongly recommend prioritization of conservation projects in West/Central Africa. As the current taxonomic nomenclature does not reflect the evolutionary history of the lion, we suggest that a taxonomic revision of the lion is warranted. PMID:26466139

  5. Southern Africa

    Atmospheric Science Data Center

    2013-04-16

    article title:  Southern Africa     View larger JPEG image ... These Multi-angle Imaging SpectroRadiometer (MISR) images of Africa were acquired on August 25, 2000, during Terra orbit 3655. The left ... of smoke plumes and haze. The southern tip of South Africa is at the bottom of the image, and Zambia is at the top. Distinctive ...

  6. What Factors Might Have Led to the Emergence of Ebola in West Africa?

    PubMed Central

    Alexander, Kathleen A.; Sanderson, Claire E.; Marathe, Madav; Lewis, Bryan L.; Rivers, Caitlin M.; Shaman, Jeffrey; Drake, John M.; Lofgren, Eric; Dato, Virginia M.; Eisenberg, Marisa C.; Eubank, Stephen

    2015-01-01

    An Ebola outbreak of unprecedented scope emerged in West Africa in December 2013 and presently continues unabated in the countries of Guinea, Sierra Leone, and Liberia. Ebola is not new to Africa, and outbreaks have been confirmed as far back as 1976. The current West African Ebola outbreak is the largest ever recorded and differs dramatically from prior outbreaks in its duration, number of people affected, and geographic extent. The emergence of this deadly disease in West Africa invites many questions, foremost among these: why now, and why in West Africa? Here, we review the sociological, ecological, and environmental drivers that might have influenced the emergence of Ebola in this region of Africa and its spread throughout the region. Containment of the West African Ebola outbreak is the most pressing, immediate need. A comprehensive assessment of the drivers of Ebola emergence and sustained human-to-human transmission is also needed in order to prepare other countries for importation or emergence of this disease. Such assessment includes identification of country-level protocols and interagency policies for outbreak detection and rapid response, increased understanding of cultural and traditional risk factors within and between nations, delivery of culturally embedded public health education, and regional coordination and collaboration, particularly with governments and health ministries throughout Africa. Public health education is also urgently needed in countries outside of Africa in order to ensure that risk is properly understood and public concerns do not escalate unnecessarily. To prevent future outbreaks, coordinated, multiscale, early warning systems should be developed that make full use of these integrated assessments, partner with local communities in high-risk areas, and provide clearly defined response recommendations specific to the needs of each community. PMID:26042592

  7. What factors might have led to the emergence of Ebola in West Africa?

    PubMed

    Alexander, Kathleen A; Sanderson, Claire E; Marathe, Madav; Lewis, Bryan L; Rivers, Caitlin M; Shaman, Jeffrey; Drake, John M; Lofgren, Eric; Dato, Virginia M; Eisenberg, Marisa C; Eubank, Stephen

    2015-01-01

    An Ebola outbreak of unprecedented scope emerged in West Africa in December 2013 and presently continues unabated in the countries of Guinea, Sierra Leone, and Liberia. Ebola is not new to Africa, and outbreaks have been confirmed as far back as 1976. The current West African Ebola outbreak is the largest ever recorded and differs dramatically from prior outbreaks in its duration, number of people affected, and geographic extent. The emergence of this deadly disease in West Africa invites many questions, foremost among these: why now, and why in West Africa? Here, we review the sociological, ecological, and environmental drivers that might have influenced the emergence of Ebola in this region of Africa and its spread throughout the region. Containment of the West African Ebola outbreak is the most pressing, immediate need. A comprehensive assessment of the drivers of Ebola emergence and sustained human-to-human transmission is also needed in order to prepare other countries for importation or emergence of this disease. Such assessment includes identification of country-level protocols and interagency policies for outbreak detection and rapid response, increased understanding of cultural and traditional risk factors within and between nations, delivery of culturally embedded public health education, and regional coordination and collaboration, particularly with governments and health ministries throughout Africa. Public health education is also urgently needed in countries outside of Africa in order to ensure that risk is properly understood and public concerns do not escalate unnecessarily. To prevent future outbreaks, coordinated, multiscale, early warning systems should be developed that make full use of these integrated assessments, partner with local communities in high-risk areas, and provide clearly defined response recommendations specific to the needs of each community. PMID:26042592

  8. Snakebite is Under Appreciated: Appraisal of Burden from West Africa

    PubMed Central

    Habib, Abdulrazaq G.; Kuznik, Andreas; Hamza, Muhammad; Abdullahi, Maryam I.; Chedi, Basheer A.; Chippaux, Jean-Philippe; Warrell, David A.

    2015-01-01

    Background Snakebite envenoming (SBE) is a major problem in rural areas of West Africa (WA). Compared to other Neglected Tropical Diseases (NTD), the public health burden of SBE has not been well characterized. We estimated the impact of snakebite mortality and morbidity using the Disability Adjusted Life Years (DALYs) metrics for 16 countries in WA. Methods We used the reported annual number of SB deaths and mean age at time of SB and converted these into years of life lost (YLL). Similarly, the years of life lived with disability (YLD) were estimated by multiplying the number of amputations by the respective disability weight of 0.13. Results In WA, the annual cases of SB mortality and amputations ranged from 24 (95% Confidence Interval: 19–29) and 28 (17–48) respectively in Guinea-Bissau with the highest estimates of 1927 (1529–2333) and 2368 (1506–4043) respectively in Nigeria. We calculated that the annual DALYs associated with a SB death ranged from 1550 DALYs (95%CI: 1227–1873 DALYs) in Guinea Bissau to 124,484 DALYs (95%CI: 98,773–150,712 DALYs) in Nigeria. The annual DALYs associated with amputation for the two countries were 149 DALYs (95%CI: 91–256 DALYs) and 12,621 DALYs (95%CI: 8027–21,549 DALYs) respectively. The total burden of SBE was estimated at 319,874 DALYs (95% CI: 248,357–402,654 DALYs) in the 16 countries in WA. These estimates are similar, and in some instances even higher, than for other NTDs encountered in WA (e.g., Buruli ulcer, Echinococcosis, Intestinal Nematode Infections, Leishmaniasis, Onchocerchiasis, Trachoma and Trypanosomiasis) as reported in the Global Burden of Diseases 2010 (GBD). Conclusions The public health burden of SBE in WA is very substantial and similar to other more widely recognized NTDs. Efforts and funding commensurate with its burden should be made available for the control of snakebite in the sub-region. PMID:26398046

  9. A Multivariate Analysis of Freshwater Variability over West Africa

    NASA Astrophysics Data System (ADS)

    Andam-Akorful, S. A.; He, X.; Ferreira, V. G.; Quaye-Ballard, J. A.

    2015-12-01

    As one of the most vulnerable regions to climate change, West Africa (WA) has since the 1970s suffered sustained reduction in rainfall amounts, leading to droughts and associated negative impacts on its water resources. Although rainfall rates have been reported to have experienced a degree of recovery, dry conditions persist. Additionally, the region faces perennial flooding, thus resulting in a highly variable hydrologic regime due to the extreme climate conditions. This therefore necessitates routine monitoring of the WA's freshwater reserves and its response to climate variations at the short and long term scales to aid sustainable use and management. However, this monitoring is hampered by data deficiency issues within the region. Consequently, dynamics leading to changes in water availability over the region are not completely understood. In this work, the recent flux and state of freshwater availability over WA from 1979 to 2013 is assessed by investigating the coupled variability of GRACE-derived terrestrial water storage (TWS) and its changes (TWSC) estimates with rainfall, evapotranspiration, and land surface air temperature (LSAT), as well as, major global and regional teleconnection indices using complex principal component analysis and wavelet transforms. Since GRACE covers a relatively short period, and thereby present challenges for long to medium term analyses, Artificial Neural Network (ANN) is employed to extend the GRACE series to 1979. The results from the ANN proved to be robust upon evaluation; spatially-averaged series for major basins and sub-climatic zones, as well as, the whole of WA presented RMSE, Nash-Sutcliffe efficient, and coefficient of determination (R2) of 11.83 mm, 0.76 and 0.89 respectively. Overall, the results obtained from this study indicate that, sustained increase in water flux, in terms of TWSC, contributed to a resurgence in freshwater reserves in the 21st century over WA from the low levels in the late 20th century

  10. Risk Maps of Lassa Fever in West Africa

    PubMed Central

    Fichet-Calvet, Elisabeth; Rogers, David John

    2009-01-01

    Background Lassa fever is caused by a viral haemorrhagic arenavirus that affects two to three million people in West Africa, causing a mortality of between 5,000 and 10,000 each year. The natural reservoir of Lassa virus is the multi-mammate rat Mastomys natalensis, which lives in houses and surrounding fields. With the aim of gaining more information to control this disease, we here carry out a spatial analysis of Lassa fever data from human cases and infected rodent hosts covering the period 1965–2007. Information on contemporary environmental conditions (temperature, rainfall, vegetation) was derived from NASA Terra MODIS satellite sensor data and other sources and for elevation from the GTOPO30 surface for the region from Senegal to the Congo. All multi-temporal data were analysed using temporal Fourier techniques to generate images of means, amplitudes and phases which were used as the predictor variables in the models. In addition, meteorological rainfall data collected between 1951 and 1989 were used to generate a synoptic rainfall surface for the same region. Methodology/Principal Findings Three different analyses (models) are presented, one superimposing Lassa fever outbreaks on the mean rainfall surface (Model 1) and the other two using non-linear discriminant analytical techniques. Model 2 selected variables in a step-wise inclusive fashion, and Model 3 used an information-theoretic approach in which many different random combinations of 10 variables were fitted to the Lassa fever data. Three combinations of absence∶presence clusters were used in each of Models 2 and 3, the 2 absence∶1 presence cluster combination giving what appeared to be the best result. Model 1 showed that the recorded outbreaks of Lassa fever in human populations occurred in zones receiving between 1,500 and 3,000 mm rainfall annually. Rainfall, and to a much lesser extent temperature variables, were most strongly selected in both Models 2 and 3, and neither vegetation nor

  11. Groundwater Exploration for Rural Communities in Ghana, West Africa

    NASA Astrophysics Data System (ADS)

    McKay, W. A.

    2001-05-01

    Exploration for potable water in developing countries continues to be a major activity, as there are more than one billion people without access to safe drinking water. Exploration for groundwater becomes more critical in regions where groundwater movement and occurrence is controlled by secondary features such as fractures and faults. Drilling success rates in such geological settings are generally very low, but can be improved by integrating geological, hydrogeological, aerial photo interpretation with land-based geophysical technology in the selection of drilling sites. To help alleviate water supply problems in West Africa, the Conrad N. Hilton Foundation and other donors, since 1990, have funded the World Vision Ghana Rural Water Project (GRWP) to drill wells for potable water supplies in the Greater Afram Plains (GAP) of Ghana. During the first two years of the program, drilling success rates using traditional methods ranged from 35 to 80 percent, depending on the area. The average drilling success rate for the program was approximately 50 percent. In an effort to increase the efficiency of drilling operations, the Desert Research Institute evaluated and developed techniques for application to well-siting strategies in the GAP area of Ghana. A critical project element was developing technical capabilities of in-country staff to independently implement the new strategies. Simple cost-benefit relationships were then used to evaluate the economic advantages of developing water resources using advanced siting methods. The application of advanced methods in the GAP area reveal an increase of 10 to 15 percent in the success rate over traditional methods. Aerial photography has been found to be the most useful of the imagery products covering the GAP area. An effective approach to geophysical exploration for groundwater has been the combined use of EM and resistivity methods. Economic analyses showed that the use of advanced methods is cost-effective when success

  12. Hepatitis A virus in West Africa: Is an epidemiological transition beginning?

    PubMed Central

    Jacobsen, Kathryn H.

    2014-01-01

    Background: Studies of hepatitis A virus (HAV) seroprevalence in sub-Saharan Africa have generally found very high anti-HAV IgG seroprevalence rates, but economic development and improved drinking water access may be contributing to decreasing incidence. Materials and Methods: This review evaluates all 19 articles that have been published on HAV epidemiology in West Africa. Results: Nearly all studies conducted before 1990 found that the majority of preschool-aged children had already developed immunity due to prior infection. However, several recent studies have observed that the age at midpoint of population immunity in some urban populations has shifted to school-aged children. Conclusion: There is preliminary evidence that some West-African countries are beginning the transition towards lower hepatitis A endemicity levels. Additional studies of child seroprevalence rates in diverse parts of West Africa are required in order to clarify the extent to which an early transition may be occurring. PMID:25114360

  13. Modeling the impact of changes in Atlantic sea surface temperature on the climate of West Africa

    NASA Astrophysics Data System (ADS)

    Adeniyi, Mojisola O.

    2016-08-01

    This study assesses the impacts of warming/cooling of the Atlantic sea surface temperature (SST) on the climate of West Africa using Version 4.4 of Regional Climate Model (RegCM4.4) of International Center for Theoretical Physics, Trieste, Italy. The 1-2 K cooling and warming of the Atlantic SST both result in tripole temperature and precipitation change structure, having a northwest-southeast orientation over West Africa. Findings reveal that the responses of precipitation and temperature to the Atlantic SST cooling are opposite to those for the Atlantic SST warming and these responses intensify with increased warming/cooling of the Atlantic SST. The structure of the change in climate is attributed to the response of atmospheric/soil moisture gradient and orientation of orography in West Africa.

  14. Ebola in West Africa--CDC's Role in Epidemic Detection, Control, and Prevention.

    PubMed

    Frieden, Thomas R; Damon, Inger K

    2015-11-01

    Since Ebola virus disease was identified in West Africa on March 23, 2014, the Centers for Disease Control and Prevention (CDC) has undertaken the most intensive response in the agency's history; >3,000 staff have been involved, including >1,200 deployed to West Africa for >50,000 person workdays. Efforts have included supporting incident management systems in affected countries; mobilizing partners; and strengthening laboratory, epidemiology, contact investigation, health care infection control, communication, and border screening in West Africa, Nigeria, Mali, Senegal, and the United States. All efforts were undertaken as part of national and global response activities with many partner organizations. CDC was able to support community, national, and international health and public health staff to prevent an even worse event. The Ebola virus disease epidemic highlights the need to strengthen national and international systems to detect, respond to, and prevent the spread of future health threats. PMID:26484940

  15. Solving a Migration Riddle Using Isoscapes: House Martins from a Dutch Village Winter over West Africa

    PubMed Central

    Hobson, Keith A.; Van Wilgenburg, Steven L.; Piersma, Theunis; Wassenaar, Leonard I.

    2012-01-01

    Background The ability to connect breeding, stopover and wintering locations of populations of migratory birds greatly enhances our understanding of the phenomenon of migration and improves our chances of effectively conserving these species. Among Palearctic-Afrotropical migratory species, aerial insectivores like the house martin (Delichon urbicum) are sensitive to factors influencing the availability of flying insects, and have declined in recent decades. The strict aerial behaviour of martins severely limits ring recoveries on wintering grounds and so there is a dearth of information on where European breeding populations over-winter in Africa, and the relative effects of population regulation on breeding vs. wintering grounds. We used a newly developed multi-isotope (δ2H, δ13C, δ15N) feather isoscape for Africa together with inferences from summarized ring return data based on longitude, to assign winter origins to birds captured at a breeding colony in The Netherlands. Principal Findings Based on isotopic analyses of winter-grown martin feathers, we used a likelihood-based assignment approach to describe potential wintering locations where molt occurred of individual house martins from a Dutch colony by assigning them to four potential isotopically distinct clusters in Africa. We found the overwhelming majority of Dutch martins were assigned to a geographical cluster associated with West Africa. Conclusions/Significance The existence of strong isotopic gradients and patterns in African foodwebs that support migratory wildlife allows for the spatial assignment of tissues grown there. The assignment of Dutch house martins to wintering grounds primarily in West Africa was in strong agreement with independent and indirect methods used to infer winter origins of this species based on the association between the Normalized Difference Vegetation Index (NDVI) in Africa and population patterns in Italy and the United Kingdom. These confirmatory data-sets underscore

  16. Infection Prevention and Control for Ebola in Health Care Settings - West Africa and United States.

    PubMed

    Hageman, Jeffrey C; Hazim, Carmen; Wilson, Katie; Malpiedi, Paul; Gupta, Neil; Bennett, Sarah; Kolwaite, Amy; Tumpey, Abbigail; Brinsley-Rainisch, Kristin; Christensen, Bryan; Gould, Carolyn; Fisher, Angela; Jhung, Michael; Hamilton, Douglas; Moran, Kerri; Delaney, Lisa; Dowell, Chad; Bell, Michael; Srinivasan, Arjun; Schaefer, Melissa; Fagan, Ryan; Adrien, Nedghie; Chea, Nora; Park, Benjamin J

    2016-01-01

    The 2014-2016 Ebola virus disease (Ebola) epidemic in West Africa underscores the need for health care infection prevention and control (IPC) practices to be implemented properly and consistently to interrupt transmission of pathogens in health care settings to patients and health care workers. Training and assessing IPC practices in general health care facilities not designated as Ebola treatment units or centers became a priority for CDC as the number of Ebola virus transmissions among health care workers in West Africa began to affect the West African health care system and increasingly more persons became infected. CDC and partners developed policies, procedures, and training materials tailored to the affected countries. Safety training courses were also provided to U.S. health care workers intending to work with Ebola patients in West Africa. As the Ebola epidemic continued in West Africa, the possibility that patients with Ebola could be identified and treated in the United States became more realistic. In response, CDC, other federal components (e.g., Office of the Assistant Secretary for Preparedness and Response) and public health partners focused on health care worker training and preparedness for U.S. health care facilities. CDC used the input from these partners to develop guidelines on IPC for hospitalized patients with known or suspected Ebola, which was updated based on feedback from partners who provided care for Ebola patients in the United States. Strengthening and sustaining IPC helps health care systems be better prepared to prevent and respond to current and future infectious disease threats.The activities summarized in this report would not have been possible without collaboration with many U.S. and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html). PMID:27390018

  17. Identification of statistically independent climatic pattern in GRACE and hydrological model data over West-Africa

    NASA Astrophysics Data System (ADS)

    Kusche, J.; Forootan, E.; Eicker, A.; Hoffmann-Dobrev, H.

    2012-04-01

    West-African countries have been exposed to changes in rainfall patterns over the last decades, including a significant negative trend. This causes adverse effects on water resources, for instance reduced freshwater availability, and changes in the frequency, duration and magnitude of droughts and floods. Extracting the main patterns of water storage change in West Africa from remote sensing and linking them to climate variability, is therefore an essential step to understand the hydrological aspects of the region. In this study, the higher order statistical method of Independent Component Analysis (ICA) is employed to extract statistically independent water storage patterns from monthly Gravity Recovery And Climate Experiment (GRACE), from the WaterGAP Global Hydrology Model (WGHM) and from Tropical Rainfall Measuring Mission (TRMM) products over West Africa, for the period 2002-2012. Then, to reveal the influences of climatic teleconnections on the individual patterns, these results were correlated to the El Nino-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) indices. To study the predictability of water storage changes, advanced statistical methods were applied on the main independent Sea Surface Temperature (SST) patterns over the Atlantic and Indian Oceans for the period 2002-2012 and the ICA results. Our results show a water storage decrease over the coastal regions of West Africa (including Sierra Leone, Liberia, Togo and Nigeria), associated with rainfall decrease. The comparison between GRACE estimations and WGHM results indicates some inconsistencies that underline the importance of forcing data for hydrological modeling of West Africa. Keywords: West Africa; GRACE-derived water storage; ICA; ENSO; IOD

  18. Cultural Issues in Secondary Education Development in West Africa: Away from Colonial Survivals, towards Neocolonial Influences.

    ERIC Educational Resources Information Center

    Quist, Hubert O.

    2001-01-01

    In urban Ghana and Cote d'Ivoire (Ivory Coast), cultural factors arising from West Africa's "triple cultural heritage" (African, Euro-Christian, and Islamic) and globalization place considerable strains on secondary education and have implications for postcolonial nation-building and development. Surveys of 200 secondary students in the two…

  19. The Ebola epidemic in West Africa: challenges, opportunities, and policy priority areas.

    PubMed

    Buseh, Aaron G; Stevens, Patricia E; Bromberg, Mel; Kelber, Sheryl T

    2015-01-01

    The ongoing Ebola epidemic in West Africa has drawn attention to global health inequalities, in particular the inadequacies of health care systems in sub-Saharan African countries for appropriately managing and containing infectious diseases. The purpose of this article is to examine the sociopolitical and economic conditions that created the environment for the Ebola epidemic to occur, identify challenges to and opportunities for the prevention and control of Ebola and future outbreaks, and discuss policy recommendations and priority areas for addressing the Ebola epidemic and future outbreaks in West Africa. Articles in peer-reviewed journals on health system reforms in developing countries and periodicals of international organizations were used to gather the overview reported in this article. We identify individual, structural, and community challenges that must be addressed in an effort to reduce the spread of Ebola in West Africa. The Ebola epidemic in West Africa underscores the need for the overhaul and transformation of African health care systems to build the capacity in these countries to address infectious diseases. Public-private partnerships for investment in developing countries' health care systems that involve the international community are critical in addressing the current Ebola epidemic and future outbreaks. PMID:25645480

  20. The British and Curriculum Development in West Africa: A Historical Discourse

    ERIC Educational Resources Information Center

    Ofori-Attah, Kwabena Dei

    2006-01-01

    Only recently have African nations begun to make their way towards establishing genuinely autonomous education systems incorporating elements of indigenous culture. The present study examines the historical development of curriculum in British West Africa in its links with the educational activities of the early Christian missionaries and the…

  1. Epidemiological features and trends of Ebola virus disease in West Africa.

    PubMed

    Wang, Ligui; Yang, Guang; Jia, Leili; Li, Zhenjun; Xie, Jing; Li, Peng; Qiu, Shaofu; Hao, Rongzhang; Wu, Zhihao; Ma, Hui; Song, Hongbin

    2015-09-01

    According to a World Health Organization report, the epidemiological features of Ebola virus disease (EVD) have changed significantly in West Africa. In this study, the new epidemiological features and prevalence trends for EVD in Guinea, Liberia, and Sierra Leone are described. It was predicted that the Ebola outbreak would end in June 2015. PMID:26216765

  2. Simulating malaria transmission in the current and future climate of West Africa

    NASA Astrophysics Data System (ADS)

    Yamana, T. K.; Bomblies, A.; Eltahir, E. A. B.

    2015-12-01

    Malaria transmission in West Africa is closely tied to climate, as rain fed water pools provide breeding habitat for the anopheles mosquito vector, and temperature affects the mosquito's ability to spread disease. We present results of a highly detailed, spatially explicit mechanistic modelling study exploring the relationships between the environment and malaria in the current and future climate of West Africa. A mechanistic model of human immunity was incorporated into an existing agent-based model of malaria transmission, allowing us to move beyond entomological measures such as mosquito density and vectorial capacity to analyzing the prevalence of the malaria parasite within human populations. The result is a novel modelling tool that mechanistically simulates all of the key processes linking environment to malaria transmission. Simulations were conducted across climate zones in West Africa, linking temperature and rainfall to entomological and epidemiological variables with a focus on nonlinearities due to threshold effects and interannual variability. Comparisons to observations from the region confirmed that the model provides a reasonable representation of the entomological and epidemiological conditions in this region. We used the predictions of future climate from the most credible CMIP5 climate models to predict the change in frequency and severity of malaria epidemics in West Africa as a result of climate change.

  3. Education and Economics in West Africa: From Unwritten Languages to the Internet

    ERIC Educational Resources Information Center

    Alibrandi, Marsha; Bull, Prince Hycy

    2005-01-01

    Global distribution of West African goods--coffee, chocolate, gold, diamonds (and at one time, ivory)--has linked this region to the outside world for centuries, yet its development remains slow. Not simply the ancestral home of humankind, Africa's western legacies include colonization, partition, and loss of untold millions to slavery and wars of…

  4. Policy Review on Adult Learning: The Adult Non-Formal Education Policy of Mali, West Africa

    ERIC Educational Resources Information Center

    Gadio, Moussa

    2011-01-01

    This article focuses on the issue of policy development for adult learning in Mali, West Africa. On January 2007, the Malian government adopted the "Adult Non-formal Education Policy Document," which was intended to regulate the adult learning sector and federate the actions of policy makers, adult education providers, and adult learners. The…

  5. Mean state and kinematic properties of mesoscale convective systems over West Africa

    NASA Astrophysics Data System (ADS)

    Ogungbenro, Stephen B.; Ajayi, V. O.; Adefolalu, D. O.

    2016-04-01

    A 17-year (1984 to 2000) dataset of brightness temperature (T b) was employed to study the spatial and temporal scales of mesoscale convective systems (MCS) over West Africa. The kinematic properties of MCS were tested using wind products. A threshold brightness temperature (T b) of ≤213 K and spatial coverage specifications of more than 5000 km2 were used as two set criteria for initiating MCS tracking. MCS occurrences vary in seasons and locations over West Africa, and their activities vary with different weather zones. They can appear at any time of the day, but this study revealed a significant preference for early morning hours and night hours over continental West Africa. The well-organized systems occur between July and September in the Sahel, and between May and September in the Savanna band. MCS activities in the Gulf of Guinea peak between March and April, while the Savanna and Sahel zones peak between June and August. The produced annual atlas gives a spatial account of areas of MCS dominance in West Africa. The presence of African Easterly Jet (AEJ) and Tropical Easterly Jet (TEJ), and deep monsoon depth all characterize an environment where MCS thrive. Kinematic study of a typical MCS reveals that the monsoon depth increases at the passage of MCS, with cyclonic vorticity dominating from the surface to 300 hpa while anticyclonic vorticity was observed around 200 hpa, and this confirms the importance of low level convergence and upper level divergence as the major requirements for storm mobilization and maintenance.

  6. The Association between Bullying and Psychological Health among Senior High School Students in Ghana, West Africa

    ERIC Educational Resources Information Center

    Owusu, Andrew; Hart, Peter; Oliver, Brittney; Kang, Minsoo

    2011-01-01

    Background: School-based bullying, a global challenge, negatively impacts the health and development of both victims and perpetrators. This study examined the relationship between bullying victimization and selected psychological variables among senior high school (SHS) students in Ghana, West Africa. Methods: This study utilized data from the…

  7. Vulnerability to changes in malaria transmission due to climate change in West Africa

    NASA Astrophysics Data System (ADS)

    Yamana, T. K.; Eltahir, E. A.

    2012-12-01

    Malaria transmission in West Africa is strongly tied to climate; temperature affects the development rate of the malaria parasite, as well as the survival of the mosquitoes that transmit the disease, and rainfall is tied to mosquito abundance, as the vector lays its eggs in rain-fed water pools. As a result, the environmental suitability for malaria transmission in this region is expected to change as temperatures rise and rainfall patterns are altered. The vulnerability to changes in transmission varies throughout West Africa. Areas where malaria prevalence is already very high will be less sensitive to changes in transmission. Increases in environmental suitability for malaria transmission in the most arid regions may still be insufficient to allow sustained transmission. However, areas were malaria transmission currently occurs at low levels are expected to be the most sensitive to changes in environmental suitability for transmission. Here, we use data on current environment and malaria transmission rates to highlight areas in West Africa that we expect to be most vulnerable to an increase in malaria under certain climate conditions. We then analyze climate predictions from global climate models in vulnerable areas, and make predictions for the expected change in environmental suitability for malaria transmission using the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS), a mechanistic model developed to simulate village-scale response of malaria transmission to environmental variables in West Africa.

  8. Stochastic rainfall modeling in West Africa: Parsimonious approaches for domestic rainwater harvesting assessment

    NASA Astrophysics Data System (ADS)

    Cowden, Joshua R.; Watkins, David W., Jr.; Mihelcic, James R.

    2008-10-01

    SummarySeveral parsimonious stochastic rainfall models are developed and compared for application to domestic rainwater harvesting (DRWH) assessment in West Africa. Worldwide, improved water access rates are lowest for Sub-Saharan Africa, including the West African region, and these low rates have important implications on the health and economy of the region. Domestic rainwater harvesting (DRWH) is proposed as a potential mechanism for water supply enhancement, especially for the poor urban households in the region, which is essential for development planning and poverty alleviation initiatives. The stochastic rainfall models examined are Markov models and LARS-WG, selected due to availability and ease of use for water planners in the developing world. A first-order Markov occurrence model with a mixed exponential amount model is selected as the best option for unconditioned Markov models. However, there is no clear advantage in selecting Markov models over the LARS-WG model for DRWH in West Africa, with each model having distinct strengths and weaknesses. A multi-model approach is used in assessing DRWH in the region to illustrate the variability associated with the rainfall models. It is clear DRWH can be successfully used as a water enhancement mechanism in West Africa for certain times of the year. A 200 L drum storage capacity could potentially optimize these simple, small roof area systems for many locations in the region.

  9. Traditional Apprenticeship in West Africa: Recent Evidence and Policy Options. Discussion Paper No. 34.

    ERIC Educational Resources Information Center

    Fluitman, Fred

    Apprenticeship is the main avenue to self-employment in micro-enterprises and thus a cornerstone of informal sector development in West Africa. Survey results for Ibadan, Lome, Dakar, Niamey, and other cities demonstrate that apprenticeship as practiced by informal sector artisans is often very similar from one country to the next. Dropout rates…

  10. Rural Development in Africa: A Bibliography (Part II: North, South, West). Training & Methods Series, Number 17.

    ERIC Educational Resources Information Center

    Wisconsin Univ., Madison. Land Tenure Center.

    Compiled in December 1971, this bibliography lists approximately 940 books, journals, periodicals, and unpublished mimeographs dealing with rural development in north, west, and southern Africa. All materials are dated between 1953 and 1971. Entries are listed by country under the following headings: agriculture, economic affairs, social affairs,…

  11. Adolescent and Adult Reasoning about Gender Roles and Fairness in Benin, West Africa

    ERIC Educational Resources Information Center

    Conry-Murray, Clare

    2009-01-01

    This study examined reasoning about gender roles in a traditional society in Benin, West Africa. Ninety-seven male and female adolescents and adults evaluated conflicts between a husband and a wife over gender norms to determine whether gender norms, are judged to be moral or conventional. Although most attributed decision-making power to the…

  12. Study Abroad in West Africa: An Interdisciplinary Program of International Education

    ERIC Educational Resources Information Center

    Lowe, Tony B.; Dozier, Cheryl D.; Hunt-Hurst, Patricia; Smith, Bettye P.

    2008-01-01

    This article describes development of an interdisciplinary study abroad program to West Africa at the University of Georgia to help students gain a global perspective. The program is interdisciplinary with several disciplines including social work, clothing and textile, history, and teacher education. This article discusses/highlights a need for a…

  13. Systemic Evaluation of Advisory Services to Family Farms in West Africa

    ERIC Educational Resources Information Center

    Faure, Guy; Rebuffel, Pierre; Violas, Dominique

    2011-01-01

    In West Africa, advisory services for family farms have been promoted to better address producers' needs. The paper aims to show that these services can be understood as a system whose functioning is strongly determined by the financing mechanisms, the governance mechanisms put in place, the quality of human resources delivering advice, and the…

  14. Degradation of tropical soils in the savanna of Benin/West Africa

    NASA Astrophysics Data System (ADS)

    Junge, B.; Skowronek, A.

    2003-04-01

    IMPETUS (an integrated approach to the efficient management of scarce water resources in West Africa) is an interdisciplinary project which researches the effects of global change conditions on regional hydrological processes and on the water availability in Benin and Morocco. Within the last years an increasing settlement has been registered in the middle part of Benin/West Africa, an almost natural area. Accordingly, agricultural use has extended and intensified. The study presents today’s situation of soils and their degree of degradation in the catchment area of the river Aguima (30m2, 100 km W of Parakou). An overview of different soils, of their properties, distribution and evaluation is given at the beginning. Then, results of measurements of current soil erosion by water during the rainy seasons of the years 2001 and 2002 are presented. Runoff plots and sediment traps were installed in the savanna and on cultivated land with different crops (cotton, yam, maize) and different tillage systems (rows, mounds). In addition to soil erosion also chemical degradation has affected the soil due to nonconformist land use during the recent years. Important results and consequences for farming are described. Potential soil loss in that tropical area of investigation is estimated after the Universal Soil Loss Equation. The results are compared to other findings from other parts of West Africa. Finally, a soil loss forecast is made considering climate change and increase of human activities. Possible risks of a continuing erosion impact for food production in West Africa are pointed out.

  15. Mycobacterium africanum—Review of an Important Cause of Human Tuberculosis in West Africa

    PubMed Central

    de Jong, Bouke C.; Antonio, Martin; Gagneux, Sebastien

    2010-01-01

    Mycobacterium africanum consists of two phylogenetically distinct lineages within the Mycobacterium tuberculosis complex, known as M. africanum West African 1 and M. africanum West African 2. These lineages are restricted to West Africa, where they cause up to half of human pulmonary tuberculosis. In this review we discuss the definition of M. africanum, describe the prevalence and restricted geographical distribution of M. africanum West African 1 and 2, review the occurrence of M. africanum in animals, and summarize the phenotypic differences described thus far between M. africanum and M. tuberculosis sensu stricto. PMID:20927191

  16. Lessons of Risk Communication and Health Promotion - West Africa and United States.

    PubMed

    Bedrosian, Sara R; Young, Cathy E; Smith, Laura A; Cox, Joanne D; Manning, Craig; Pechta, Laura; Telfer, Jana L; Gaines-McCollom, Molly; Harben, Kathy; Holmes, Wendy; Lubell, Keri M; McQuiston, Jennifer H; Nordlund, Kristen; O'Connor, John; Reynolds, Barbara S; Schindelar, Jessica A; Shelley, Gene; Daniel, Katherine Lyon

    2016-01-01

    During the response to the 2014-2016 Ebola virus disease (Ebola) epidemic in West Africa, CDC addressed the disease on two fronts: in the epidemic epicenter of West Africa and at home in the United States. Different needs drove the demand for information in these two regions. The severity of the epidemic was reflected not only in lives lost but also in the amount of fear, misinformation, and stigma that it generated worldwide. CDC helped increase awareness, promoted actions to stop the spread of Ebola, and coordinated CDC communication efforts with multiple international and domestic partners. CDC, with input from partners, vastly increased the number of Ebola communication materials for groups with different needs, levels of health literacy, and cultural preferences. CDC deployed health communicators to West Africa to support ministries of health in developing and disseminating clear, science-based messages and promoting science-based behavioral interventions. Partnerships in West Africa with local radio, television, and cell phone businesses made possible the dissemination of messages appropriate for maximum effect. CDC and its partners communicated evolving science and risk in a culturally appropriate way to motivate persons to adapt their behavior and prevent infection with and spread of Ebola virus. Acknowledging what is and is not known is key to effective risk communication, and CDC worked with partners to integrate health promotion and behavioral and cultural knowledge into the response to increase awareness of the actual risk for Ebola and to promote protective actions and specific steps to stop its spread. The activities summarized in this report would not have been possible without collaboration with many U.S. and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html). PMID:27386834

  17. South Africa

    Atmospheric Science Data Center

    2013-04-16

    ... atmospheric and oceanic conditions. At Elands Bay in South Africa's Western Cape province, about 1000 tons of rock lobsters beached ... red tide. At the same time, people came from across South Africa to gather the undersized creatures for food. The effects of the losses ...

  18. [Population growth and global warming: impacts on tsetse and trypanosomoses in West Africa].

    PubMed

    Courtin, F; Sidibé, I; Rouamba, J; Jamonneau, V; Gouro, A; Solano, P

    2009-03-01

    Demographic evolution, climatic change and economical development that happened in West Africa during the XXth century had a lot of consequences on human settlement and landscape. These changes have in turn an impact on the pathogenic system of human and animal trypanosomoses. Since last century, the northern tsetse distribution limit has shifted towards the south, probably due to a decrease in rainfall combined to the impact of human pressure. Sleeping sickness (SS) foci have also shifted from the savannah areas (where there is no more SS) to the forest and mangrove areas of West Africa, but animal trypanosomoses are still present in savannah. We show a decrease of tsetse of the morsitans group as a result of an increase of human densities. On the opposite, tsetse species like Glossina palpalis adapt to high human densities and are found in the biggest urban centres of West Africa. There is a need to promote multidisciplinary studies on this demographic-climatic-vector borne disease topic, especially in Africa to be able to define future areas of presence/absence of these diseases in order to help continental plans of control that have recently begun. PMID:19353946

  19. Assessment of future streamflow changes in major rivers of West Africa

    NASA Astrophysics Data System (ADS)

    Roudier, Philippe; Rojas, Rodrigo; Bisselink, Bernard; Feyen, Luc

    2013-04-01

    Although being one of the most vulnerable regions of the world to climate change, impact studies in West Africa, especially concerning water resources, are still scarce compared to other regions such as Europe, North-America or Asia. Therefore, we investigate in this study how climate change may affect the main rivers of West Africa (Niger, Volta, Senegal) using the global LISFLOOD model. This hydrological rainfall-runoff model, extensively used for pan-European assessments, has been recently set up and calibrated for Africa, allowing such impact analysis. Here, LISFLOOD is set up on a 0.1*0.1 degree grid for the period 1991-2050. Quantifying the uncertainty in climate impact studies is now a fundamental task, especially in West Africa where the agreement among rainfall projections is low. We therefore employ an ensemble of climate experiments originating from 8 different GCM/RCM combinations obtained from the EU FP6 ENSEMBLES project (SRES A1B scenario). Prior to forcing LISFLOOD, bias in the precipitation and temperature fields (Tmin, Tavg and Tmax) is removed with a quantile mapping method using as target the WATCH Forcing Data. In order to take into account the high population growth in West Africa we also account for projected changes in water use. Results first focus on changes in average streamflow conditions and how these changes affect water availability, expressed by the Water Exploitation Index. Second, and as underlined by the recent SREX IPCC report (2012), we show the impacts on extreme events (droughts and floods) using relevant indices such as the 100-year return period flood.

  20. Nutrient content of four edible wild plants from west Africa.

    PubMed

    Glew, Robert S; Vanderjagt, Dorothy J; Chuang, L-T; Huang, Y-S; Millson, M; Glew, Robert H

    2005-12-01

    Non-cereal plant foods in the Western Sahel of Africa contribute significantly to the diets of local residents, especially during periods of grain shortages. In this paper, we analyze four such plant foods including diyan kwakwa (nut of coconut palm, Cocos nucifera L.), muricin giginya (young shoot of Borassus aethiopum), tsamiya biri (fruit of the tree, Tamarindus indica), and yari (a mixture of lichens, mainly Rimelia reticulate) that grows on ebony trees (Diospyros mespiliformis). They were analyzed for their content of amino acids, fatty acids, and minerals. Although diyan kwakwa contained the highest protein content (27.1%), its protein quality fell below the WHO standard in 3 of 8 essential amino acid categories. Yari and muricin giginya contained moderate levels of good quality protein. Only diyan kwakwa contained calorically significant amount of total fatty acid (24.7%); however, none of the plants contained useful amounts of the essential fatty acids, linoleic acid, or alpha-linolenic acid. All four plants contained useful amounts of zinc (> 12 microg/g dry weight), while yari contained the most calcium (14.7 mg/g dry weight) and iron (1.41 mg/g), and diyan kwakwa the most copper. All the four plant foods contained lesser amounts of magnesium, molybdenum, or selenium. These data indicate that the four plants contain useful amounts of various essential nutrients that could supplement the diets of populations inhabiting the Western Sahel. PMID:16395630

  1. Geology of the Douala basin, offshore Cameroon, West Africa

    SciTech Connect

    Pauken, R.J.; Thompson, J.M.; Schumann, J.R. ); Cooke, J.C. )

    1991-03-01

    The Douala basin is predominantly an offshore basin extending from the Cameroon volcanic line in the north to the Corisco arch in the south near the Equatorial Guinea-Gabon border. The basin lies wholly within the territorial borders of Cameroon and Equatorial Guinea. The Douala basin is one of a series of divergent margin basins occurring along the southwest African coastline resulting from the rifting of Africa from South America. Continental rifting in the Doula basin was initiated at least by Aptian-Albian time and possibly as early as Jurassic. The rift stage persisted until Albian time when the onset of drifting occurred. The sedimentary section in the basin has a maximum thickness of 8-10 km, based on exploration drilling and gravity and magnetics modeling. The synrift section consists of Aptian-Albian sands and shales, deposited primarily as submarine fans, fan-deltas, and turbidite deposits. These are overlain by salt, thought to be equivalent to the Ezagna salt of Aptian age in the Gabon basin to the south. The synrift section is separated from the overlying postrift shale sequence of Late Cretaceous and Tertiary age by a major late Albian unconformity. The Douala basin has been explored for hydrocarbons intermittently over the last 25 years. Results show a distinct tendency for gas-proneness. The largest field recorded to date is the Sanaga Sud gas field, discovered in 1979, offshore, near the coastal city of Kribi.

  2. Onchocerciasis: a major social problem in West Africa.

    PubMed

    Quarcoopome, C O

    1983-01-01

    Onchocerciasis is one of the most serious blinding diseases in the world, affecting between 20 and 25 million people, of whom 200-500 thousand are blind. In Africa more than half of the countries on the continent are affected, the basin of the Volta river containing one of the largest endemic areas. In this area the unique Onchocerciasis Control Program (OCP) is being undertaken, involving Benin, Ghana, Ivory Coast, Mali, Niger, Togo and Upper Volta. In this region, surveys have shown that 14.78% of the population have microfilariae in their skin biopsies, while in hyperendemic villages the figure rises to 75.2%. In such a village the prevalence of blindness rises steeply with age, from 0% under age 20, to over 40% in the over 50 age group. Various environmental factors relevant to the prevalence and incidence of systemic and ocular onchocerciasis are discussed, and pharmacologic treatment modalities are described. Prevention activities, centred around vector control by insecticides, have been dramatically effective. PMID:6648587

  3. Influence of Madden-Julian Oscillation (MJO) on Rainfall Variability over West Africa at Intraseasonal Timescale

    NASA Astrophysics Data System (ADS)

    Niang, C.

    2015-12-01

    Intraseasonal variability of rainfall over West Africa plays a significant role in the economy of the region and is highly linked to agriculture and water resources. This research study aims to investigate the relationship between Madden Julian Oscillation (MJO) and rainfall over West Africa during the boreal summer in the the state-of-the-art Atmospheric Model Intercomparison Project (AMIP) type simulations performed by Atmosphere General Circulation Models (GCMs) forced with prescribed Sea Surface Temperature (SST). It aims to determine the impact of MJO on rainfall and convection over West Africa and identify the dynamical processes which are involved in the state-of-the-art climate simulations. The simulations show in general good skills in capturing its main characteristics as well as its influence on rainfall over West Africa. On the global scale, most models simulated an eastward spatio-temporal propagation of enhanced and suppressed convection similar to the observed. However, over West Africa the MJO signal is weak in few of the models although there is a good coherence in the eastward propagation. The influence on rainfall is well captured in both Sahel and Guinea regions thereby adequately producing the transition between positive and negative rainfall anomalies through the different phases as seen in the observation. Furthermore, the results show that strong active convective phase is clearly associated with the African Easterly Jet (AEJ) but the weak convective phase is associated with a much weaker AEJ particularly over coastal Ghana. In assessing the mechanisms which are involved in the above impacts the convectively equatorial coupled waves (CCEW) are analysed separately. The analysis of the longitudinal propagation of zonal wind at 850hPa and outgoing longwave radiation (OLR) shows that the CCEW are very weak and their extention are very limited beyong West African region. It was found that the westward coupled equatorial Rossby waves are needed to

  4. A first molecular epidemiological study of SAT-2 type foot-and-mouth disease viruses in West Africa.

    PubMed Central

    Sangaré, O.; Bastos, A. D.; Venter, E. H.; Vosloo, W.

    2004-01-01

    Thirty-one viruses causing SAT-2 outbreaks in seven West African countries between 1974 and 1991, and four viruses representative of East and Central Africa were genetically characterized in this study. Four major viral lineages (I-IV) were identified by phylogenetic analysis of an homologous 480 nucleotide region corresponding to the C-terminus end of VP1. Lineage I comprised two West African genotypes with viruses clustering according to year of isolation rather than geographical origin. Lineage II was represented by viruses isolated between 1979 and 1983 in two neighbouring West African countries, Senegal and The Gambia. Viruses from Nigeria and Eritrea, representative of West and East Africa respectively, constituted lineage III, whilst lineage IV, comprising viruses from Central and East Africa, was regionally and genetically distinct. This study revealed that unrestricted animal movement in West Africa is a major factor in disease dissemination and has also provided the first indication of trans-regional virus transmission. PMID:15188721

  5. Geology and total petroleum systems of the West-Central Coastal province (7203), West Africa

    USGS Publications Warehouse

    Brownfield, Michael E.; Charpentier, Ronald R.

    2006-01-01

    The West-Central Coastal Province of the Sub-Saharan Africa Region consists of the coastal and offshore areas of Cameroon, Equatorial Guinea, Gabon, Democratic Republic of the Congo, Republic of the Congo, Angola (including the disputed Cabinda Province), and Namibia. The area stretches from the east edge of the Niger Delta south to the Walvis Ridge. The West-Central Coastal Province includes the Douala, Kribi-Campo, Rio Muni, Gabon, Congo, Kwanza, Benguela, and Namibe Basins, which together form the Aptian salt basin of equatorial west Africa. The area has had significant exploration for petroleum; more than 295 oil fields have been discovered since 1954. Since 1995, several giant oil fields have been discovered, especially in the deep-water area of the Congo Basin. Although many total petroleum systems may exist in the West-Central Coastal Province, only four major total petroleum systems have been defined. The area of the province north of the Congo Basin contains two total petroleum systems: the Melania-Gamba Total Petroleum System, consisting of Lower Cretaceous source and reservoir rocks, and the Azile-Senonian Total Petroleum System, consisting of Albian to Turonian source rocks and Cretaceous reservoir rocks. Two assessment units are defined in the West-Central Coastal Province north of the Congo Basin: the Gabon Subsalt and the Gabon Suprasalt Assessment Units. The Congo Basin contains the Congo Delta Composite Total Petroleum System, consisting of Lower Cretaceous to Tertiary source and reservoir rocks. The Central Congo Delta and Carbonate Platform and the Central Congo Turbidites Assessment Units are defined in the Congo Delta Composite Total Petroleum System. The area south of the Congo Basin contains the Cuanza Composite Total Petroleum System, consisting of Lower Cretaceous to Tertiary source and reservoir rocks. The Cuanza-Namibe Assessment Unit is defined in the Cuanza Composite Total Petroleum System. The U.S. Geological Survey (USGS) assessed the

  6. International Commodity Markets, Local Food Prices and Environment in West Africa

    NASA Astrophysics Data System (ADS)

    Brown, M. E.; Hintermann, B.; Higgins, N.

    2008-12-01

    The recent massive increase in food and energy prices in the past five years, coupled with the awareness of the long term challenges of climate change to small holder agriculture in Africa has brought the issue of food security for the world's poorest people to the forefront once again. Asymmetric and limited integration of local commodity markets in West Africa highlights the weak position of Africa's rural countries in the face of climate change and demographic expansion. This paper will describe the functioning of local informal food markets in West African over the past twenty years and evaluate the impact of their limited integration with each other and with global commodity markets. Satellite remote sensing of vegetation has been used as a proxy for agricultural production in economic models to improve prediction of large swings in prices from year to year due to differences in supply. As demand increases, improvements in market functioning will be necessary to counter likely increases in production variability. Increasing Africa's stability in the face of climate change will require investment in agricultural production and transportation infrastructure in order to ensure an affordable flow of food to people in these extremely poor, landlocked countries.

  7. Drought modes in West Africa and how well CORDEX RCMs simulate them

    NASA Astrophysics Data System (ADS)

    Diasso, Ulrich; Abiodun, Babatunde J.

    2015-12-01

    This study presents the spatial-temporal structure of droughts in West Africa and evaluates the capability of CORDEX regional climate models in simulating the droughts. The study characterize droughts with the standardized evapo-transpiration index (SPEI) computed using the monthly rainfall and temperature data from the Climatic Research Unit (CRU) and CORDEX models simulation datasets. To obtain the spatial-temporal structure of the droughts, we applied the principal component analysis on the observed and simulated SPEIs and retained the first four principal factors as the leading drought modes over West Africa. The relationship between the drought modes and atmospheric teleconnections was studied using wavelet coherence analysis, while the ability of the CORDEX models to simulate the drought modes was quantified with correlation analysis. The analysis of the relationship between drought modes and atmospheric teleconnections is based on SPEI from observation dataset (CRU). The study shows that about 60 % of spatial-temporal variability in SPEI over West Africa can be grouped into four drought modes. The first drought mode features drought over east Sahel, the second over west Sahel, the third over the Savanna, and the fourth over the Guinea coast. Each drought mode is linked to sea surface temperature anomalies (SSTAs) over tropical areas of Pacific, Atlantic, and Indian Oceans. Most CORDEX models reproduce at least two of the drought modes, but only two models (REMO and CNRM) reproduce all the four drought modes. REMO and WRF give the best simulation of the seasonal variation of the drought mode over the Sahel in March-May and June-August seasons, while CNRM gives the best simulation of seasonal variation in the drought pattern over the Savanna. Results of this study may guide in selecting appropriate CORDEX models for seasonal prediction of droughts and for downscaling projected impacts of global warming on droughts in West Africa.

  8. Africa: "Yonondio."

    ERIC Educational Resources Information Center

    Bendetson, Jane

    1996-01-01

    Recounts a teacher's experiences on a trip to Africa. Describes her pleasant moments with her fellow travelers; her appreciation of the natural setting; her visit to an impoverished native school; and her confrontation with a Maasai warrior. (TB)

  9. Evaluating the performance of remotely sensed and reanalysed precipitation data over West Africa using HBV light

    NASA Astrophysics Data System (ADS)

    Jütten, Thomas; Jackisch, Dominik; Diekkrüger, Bernd; Kusche, Jürgen; Eicker, Annette; Springer, Anne

    2016-04-01

    Water is one of the most crucial natural resources in West Africa, where the livelihoods of large parts of the population rely heavily on rain-fed agriculture. Therefore, the modelling of the water balance is an important tool to aid in water resource management. Precipitation is one of most important atmospheric drivers of hydrological models. However, ground-based observation networks are sparse in Western Africa and a further decline in station numbers due to a variety of reasons such as the deterioration of stations or political unrest has been observed in recent years. In ungauged river basins, or basins with insufficiently available precipitation data, several studies have shown that remotely sensed or reanalysed precipitation data may be used to compliment or replace missing information. However, the uncertainties of these datasets over Western Africa are not well examined and a need for further studies is apparent. For validation purposes, precipitation datasets are traditionally compared to in-situ ground measurements. This is not possible in ungauged basins. A new approach to assess the quality of satellite and reanalysis data which is gaining popularity among researchers compares different precipitation datasets using hydrological models. In this so-called hydrological evaluation, ground-truth data is no longer necessary in order to validate a product. The chosen model is calibrated for different precipitation products and the simulated streamflow generated for each product is compared to the measured streamflow. Multiple state of the art satellite and reanalysis precipitation datasets with various spatial resolutions were used in this study, namely: CFSR (0.3125°), CHIRPS (0.05°), CMORPH (0.25°), PERSIANN (0.25°), RFE 2.0 (0.1°), TAMSAT (0.0375°), TRMM 3B42 v7 (0.25°) and TRMM 3B42RT (real time) (0.25°). These datasets were evaluated at the regional as well as local scale using the HBV light conceptual hydrological model for several basins

  10. Prevalence, determinants and systems-thinking approaches to optimal hypertension control in West Africa

    PubMed Central

    2014-01-01

    Background In West Africa, hypertension, once rare, has now emerged as a critical health concern and the trajectory is upward and factors are complex. The true magnitude of hypertension in some West African countries, including in-depth knowledge of underlying risk factors is not completely understood. There is also a paucity of research on adequate systems-level approaches designed to mitigate the growing burden of hypertension in the region. Aims In this review, we thematically synthesize available literature pertaining to the prevalence of hypertension in West Africa and discuss factors that influence its diagnosis, treatment and control. We aimed to address the social and structural determinants influencing hypertension in the sub-region including the effects of urbanization, health infrastructure and healthcare workforce. Findings The prevalence of hypertension in West Africa has increased over the past decade and is rising rapidly with an urban-rural gradient that places higher hypertension prevalence on urban settings compared to rural settings. Overall levels of awareness of one’s hypertension status remain consistently low in West African. Structural and economic determinants related to conditions of poverty such as insufficient finances have a direct impact on adherence to prescribed antihypertensive medications. Urbanization contributes to the increasing incidence of hypertension in the sub-region and available evidence indicates that inadequate health infrastructure may act as a barrier to optimal hypertension control in West Africa. Conclusion Given that optimal hypertension control in West Africa depends on multiple factors that go beyond simply modifying the behaviors of the individuals alone, we conclude by discussing the potential role systems-thinking approaches can play to achieve optimal control in the sub-region. In the context of recent advances in hypertension management including new therapeutic options and innovative solutions to expand

  11. Predicted impacts of climate change on malaria transmission in West Africa

    NASA Astrophysics Data System (ADS)

    Yamana, T. K.; Eltahir, E. A. B.

    2014-12-01

    Increases in temperature and changes in precipitation due to climate change are expected to alter the spatial distribution of malaria transmission. This is especially true in West Africa, where malaria prevalence follows the current north-south gradients in temperature and precipitation. We assess the skill of GCMs at simulating past and present climate in West Africa in order to select the most credible climate predictions for the periods 2030-2060 and 2070-2100. We then use the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS), a mechanistic model of malaria transmission, to translate the predicted changes in climate into predicted changes availability of mosquito breeding sites, mosquito populations, and malaria prevalence. We investigate the role of acquired immunity in determining a population's response to changes in exposure to the malaria parasite.

  12. The possible role of local air pollution in climate change in West Africa

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter; Evans, Mat J.; Field, Paul R.; Fink, Andreas H.; Liousse, Catherine; Marsham, John H.

    2015-09-01

    The climate of West Africa is characterized by a sensitive monsoon system that is associated with marked natural precipitation variability. This region has been and is projected to be subject to substantial global and regional-scale changes including greenhouse-gas-induced warming and sea-level rise, land-use and land-cover change, and substantial biomass burning. We argue that more attention should be paid to rapidly increasing air pollution over the explosively growing cities of West Africa, as experiences from other regions suggest that this can alter regional climate through the influences of aerosols on clouds and radiation, and will also affect human health and food security. We need better observations and models to quantify the magnitude and characteristics of these impacts.

  13. Secondary Organic Aerosol from biogenic VOCs over West Africa during AMMA

    NASA Astrophysics Data System (ADS)

    Capes, G.; Murphy, J. G.; Reeves, C. E.; McQuaid, J. B.; Hamilton, J. F.; Hopkins, J. R.; Crosier, J.; Williams, P. I.; Coe, H.

    2009-01-01

    This paper presents measurements of organic aerosols above subtropical West Africa during the wet season using data from the UK Facility for Airborne Atmospheric Measurements (FAAM) aircraft. Measurements of biogenic volatile organic compounds (BVOC) at low altitudes over these subtropical forests were made during the African Monsoon Multidisciplinary Analysis (AMMA) field experiment during July and August 2006 mainly above Benin, Nigeria and Niger. Data from an Aerodyne Quadrupole Aerosol Mass Spectrometer show a median organic aerosol loading of 1.08 μg m-3 over tropical West Africa, which represents the first regionally averaged assessment of organic aerosol mass (OM) in this region during the wet season. This is in good agreement with predictions based on aerosol yields from isoprene and monoterpenes during chamber studies and model predictions based on partitioning schemes, contrasting markedly with the large under representations of OM in similar models when compared with data from mid latitudes.

  14. What aspects of future rainfall changes matter for crop yields in West Africa?

    NASA Astrophysics Data System (ADS)

    Guan, Kaiyu; Sultan, Benjamin; Biasutti, Michela; Baron, Christian; Lobell, David B.

    2015-10-01

    How rainfall arrives, in terms of its frequency, intensity, the timing and duration of rainy season, may have a large influence on rainfed agriculture. However, a thorough assessment of these effects is largely missing. This study combines a new synthetic rainfall model and two independently validated crop models (APSIM and SARRA-H) to assess sorghum yield response to possible shifts in seasonal rainfall characteristics in West Africa. We find that shifts in total rainfall amount primarily drive the rainfall-related crop yield change, with less relevance to intraseasonal rainfall features. However, dry regions (total annual rainfall below 500 mm/yr) have a high sensitivity to rainfall frequency and intensity, and more intense rainfall events have greater benefits for crop yield than more frequent rainfall. Delayed monsoon onset may negatively impact yields. Our study implies that future changes in seasonal rainfall characteristics should be considered in designing specific crop adaptations in West Africa.

  15. The development of cardiac surgery in West Africa--the case of Ghana.

    PubMed

    Edwin, Frank; Tettey, Mark; Aniteye, Ernest; Tamatey, Martin; Sereboe, Lawrence; Entsua-Mensah, Kow; Kotei, David; Baffoe-Gyan, Kofi

    2011-01-01

    West Africa is one of the poorest regions of the world. The sixteen nations listed by the United Nations in this sub-region have some of the lowest gross domestic products in the world. Health care infrastructure is deficient in most of these countries. Cardiac surgery, with its heavy financial outlay is unavailable in many West African countries. These facts notwithstanding, some West African countries have a proud history of open heart surgery not very well known even in African health care circles. Many African health care givers are under the erroneous impression that the cardiovascular surgical landscape of West Africa is blank. However, documented reports of open-heart surgery in Ghana dates as far back as 1964 when surface cooling was used by Ghanaian surgeons to close atrial septal defects. Ghana's National Cardiothoracic Center is still very active and is accredited by the West African College of Surgeons for the training of cardiothoracic surgeons. Reports from Nigeria indicate open-heart surgery taking place from 1974. Cote D'Ivoire had reported on its first 300 open-heart cases by 1983. Senegal reported open-heart surgery from 1995 and still runs an active center. Cameroon started out in 2009 with work done by an Italian group that ultimately aims to train indigenous surgeons to run the program. This review traces the development and current state of cardiothoracic surgery in West Africa with Ghana's National Cardiothoracic Center as the reference. It aims to dispel the notion that there are no major active cardiothoracic centers in the West African sub-region. PMID:22355425

  16. The development of cardiac surgery in West Africa-the case of Ghana

    PubMed Central

    Edwin, Frank; Tettey, Mark; Aniteye, Ernest; Tamatey, Martin; Sereboe, Lawrence; Entsua-Mensah, Kow; Kotei, David; Baffoe-Gyan, Kofi

    2011-01-01

    West Africa is one of the poorest regions of the world. The sixteen nations listed by the United Nations in this sub-region have some of the lowest gross domestic products in the world. Health care infrastructure is deficient in most of these countries. Cardiac surgery, with its heavy financial outlay is unavailable in many West African countries. These facts notwithstanding, some West African countries have a proud history of open heart surgery not very well known even in African health care circles. Many African health care givers are under the erroneous impression that the cardiovascular surgical landscape of West Africa is blank. However, documented reports of open-heart surgery in Ghana dates as far back as 1964 when surface cooling was used by Ghanaian surgeons to close atrial septal defects. Ghana's National Cardiothoracic Center is still very active and is accredited by the West African College of Surgeons for the training of cardiothoracic surgeons. Reports from Nigeria indicate open-heart surgery taking place from 1974. Cote D'Ivoire had reported on its first 300 open-heart cases by 1983. Senegal reported open-heart surgery from 1995 and still runs an active center. Cameroon started out in 2009 with work done by an Italian group that ultimately aims to train indigenous surgeons to run the program. This review traces the development and current state of cardiothoracic surgery in West Africa with Ghana's National Cardiothoracic Center as the reference. It aims to dispel the notion that there are no major active cardiothoracic centers in the West African sub-region. PMID:22355425

  17. Family Planning Programmes in Africa.

    ERIC Educational Resources Information Center

    Pradervand, Pierre

    The countries discussed in this paper are the francophone countries of West Africa and the Republic of Congo, with comparative references made to North Africa (mainly Morocco, Algeria, and Tunisia). Obstacles to the adoption of family planning in the countries of tropical Africa are a very high mortality rate among children; a socioeconomic…

  18. Assessment of Undiscovered Oil and Gas Resources of Four West Africa Geologic Provinces

    USGS Publications Warehouse

    Brownfield, Michael E.; Charpentier, Ronald R.; Cook, Troy A.; Klett, Timothy R.; Pitman, Janet K.; Pollastro, Richard M.; Schenk, Christopher J.; Tennyson, Marilyn E.

    2010-01-01

    Four geologic provinces located along the northwest and west-central coast of Africa recently were assessed for undiscovered oil, natural gas, and natural gas liquids resources as part of the U.S. Geological Survey's (USGS) World Oil and Gas Assessment. Using a geology-based assessment methodology, the USGS estimated mean volumes of 71.7 billion barrels of oil, 187.2 trillion cubic feet of natural gas, and 10.9 billion barrels of natural gas liquids.

  19. Lower Palaeozoic of North-Western and West-Central Africa

    SciTech Connect

    Holland, C.H.

    1985-01-01

    The first compilation in English of the stratigraphy, palaeontology, sedimentology, palaeogeography, and palaeoclimatology of the Lower Palaeozoic found in this area. The fourth volume in the Lower Palaeozoic Rocks of the World Series discusses geological formations such as the lower Cambrian tribolite-bearing sequences of Morocco, those showing evidence of late Ordovician glaciation in West-Central Africa, and the Silurian-Devonian sequences of Morocco and Algeria.

  20. Ebola outbreak in West Africa: real-time estimation and multiple-wave prediction.

    PubMed

    Wang, Xiang-Sheng; Zhong, Luoyi

    2015-10-01

    Based on the reported data until 18 March 2015 and numerical fitting via a simple formula of cumulative case number, we provide real-time estimation on basic reproduction number, inflection point, peak time and final outbreak size of ongoing Ebola outbreak in West Africa. From our simulation, we conclude that the first wave has passed its inflection point and predict that a second epidemic wave may appear in the near future. PMID:26280179

  1. Improving regional health care in West Africa using current space systems and technology

    NASA Technical Reports Server (NTRS)

    Jemison, Mae C.; Thomas, J. Segun

    1992-01-01

    This paper discusses the issues involved with establishing an integrated satellite health network in West Africa based on currently available technology. The system proposed makes use of a central national facility capable of transmitting and receiving voice/data and video signals from the entire country. Regional, field and local facilities provide timely epidemiologic information, sharing of medical expertise through telemedical consultations, enhance optimized resource distribution and build a framework for telecommunications for the entire country.

  2. Improving regional health care in West Africa using current space systems and technology

    NASA Technical Reports Server (NTRS)

    Jemison, Mae C.; Thomas, J. S.

    1992-01-01

    This paper discusses the issues involved with establishing an integrated satellite health network in West Africa based on currently available technology. The system proposed makes use of a central national facility capable of transmitting and receiving voice/data and video signals from the entire country. Regional, field and local facilities provides timely epidemiologic information, sharing of medical expertise through telemedical consultations, enhances optimized resource distribution and builds a framework for telecommunications for the entire country.

  3. Lassa fever in West Africa: evidence for an expanded region of endemicity.

    PubMed

    Sogoba, N; Feldmann, H; Safronetz, D

    2012-09-01

    Lassa virus (LASV) is endemic in Sierra Leone, Guinea and Liberia (known as the Mano River region) and Nigeria and Lassa fever cases from these countries are being reported annually. Recent investigations have found evidence for an expanded endemicity zone between the two known Lassa endemic regions indicating that LASV is more widely distributed throughout the Tropical Wooded Savanna ecozone in West Africa. PMID:22958249

  4. The interaction between vegetation dynamics and dust emissions over West Africa

    NASA Astrophysics Data System (ADS)

    Marcella, M. P.; Eltahir, E. A.

    2012-12-01

    Two thirty-year simulations of RegCM3 coupled to a desert dust emission/aerosol tracer model and a dynamic vegetation model are performed over West Africa. To discern the interaction between vegetation dynamics and dust emissions over West Africa and its monsoon and climate, one simulation includes radiatively active dust emissions with plant functional types that can compete and biomes that evolve, while another allows only for vegetation dynamics and no dust emissions. It is found that RegCM3-IBIS does well in capturing the spatial and temporal distribution of dust suspension when compared to MISR observations. In addition, the vegetation dynamic component of the land surface model does well in modeling the spatial distribution of vegetation biomes over West Africa; that is, the model simulates the rainforest by the Gulf of Guinea, deciduous forests further north, the savanna/grassland of the Sahel and the desert region of the Sahara. Overall, dust emissions over the Sahara and Sahel cause a reduction in the incoming shortwave radiation of 20-40 W/m^2 which results in a reduction in the net radiation at the surface and surface cooling of 1-1.5C over the summer months of JJA The two way interactions between dust and vegetation dynamics, and their impacts on the water and energy cycles will be discussed.

  5. [Retrospective study of foot and mouth disease in West Africa from 1970 to 2003].

    PubMed

    Couacy-Hymann, E; Aplogan, G L; Sangaré, O; Compaoré, Z; Karimu, J; Awoueme, K A; Seini, A; Martin, V; Valarcher, J F

    2006-12-01

    A retrospective study of foot and mouth disease in seven West African countries was conducted for the period 1970 to 2003. The study included three cattle-exporting Sahel countries (Burkina-Faso, Mali and Niger) and four cattle-importing coastal countries (Benin, Côte d'lvoire, Ghana and Togo). Foot and mouth disease has been enzootic in these countries since 1990/1991. Four of the seven serotypes are regularly notified (O, A, SAT 1 and SAT 2). In the seven countries as a whole, 198 biological samples from identified foot and mouth disease outbreaks confirmed the involvement of the following serotypes: O (62 outbreaks); A (32 outbreaks); SAT 1 (18 outbreaks); SAT 2 (86 outbreaks). This result, which is largely underestimated, clearly demonstrates the seriousness of foot and mouth disease in West Africa, whose livestock production system characterised by continual uncontrolled animal movements facilitates the spread of the disease. Unlike in Southern Africa, for foot and mouth disease to be controlled in West Africa it is necessary immediately to introduce a regional strategy involving all countries which takes into account the real situation in the field: transhumance, nomadism and live-animal imports by coastal countries. PMID:17361767

  6. Climate change mitigation by carbon stock - the case of semi-arid West Africa

    NASA Astrophysics Data System (ADS)

    Lykke, A. M.; Barfod, A. S.; Tinggaard Svendsen, G.; Greve, M.; Svenning, J.-C.

    2009-11-01

    Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

  7. Secondary Organic Aerosol from Biogenic VOCs over West Africa during AMMA

    NASA Astrophysics Data System (ADS)

    Capes, G. L.; Murphy, J. G.; Reeves, C. E.; McQuaid, J. B.; Hamilton, J. F.; Hopkins, J. R.; Coe, H.

    2008-12-01

    As part of the international AMMA (African Monsoon Multidisciplinary Analyses) project a large field experiment took place in West Africa during July and August 2006. This involved a number of ground-based facilities and 5 aircraft, including the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146, which was based in Niamey, Niger and made 21 flights. The 146 was equipped with instruments measuring parameters relevant to dynamics, gas phase composition, radiation, aerosols and clouds. The flights made were designed to examine a range of multidisciplinary scientific questions. This paper presents measurements of organic aerosol above subtropical West Africa during the monsoon season using data from the FAAM aircraft. Measurements of biogenic volatile organic compounds (BVOC) at low altitudes over these subtropical forests were made during July and August 2006 mainly above Benin, Nigeria and Niger. In air masses characterised by high BVOC concentrations, data from an Aerodyne Quadrupole Aerosol Mass Spectrometer show an organic aerosol loading of 0.58 μgm-3 over tropical West Africa. In contrast, organic aerosol mass (OM) concentrations were negligible when BVOC concentrations were low. This represents the first regionally averaged assessment of OM in this region during the wet season. This is in good agreement with predictions based on aerosol yields from isoprene and monoterpenes during chamber studies and model predictions based on partitioning schemes, contrasting markedly with the large under representations of OM in similar models when compared with data from mid latitudes.

  8. The British and curriculum development in West Africa: A historical discourse

    NASA Astrophysics Data System (ADS)

    Ofori-Attah, Kwabena Dei

    2006-09-01

    THE BRITISH AND CURRICULUM DEVELOPMENT IN WEST AFRICA: A HISTORICAL STUDY - Only recently have African nations begun to make their way towards establishing genuinely autonomous education systems incorporating elements of indigenous culture. The present study examines the historical development of curriculum in British West Africa in its links with the educational activities of the early Christian missionaries and the imposition of British colonial rule. For over 300 years, the curriculum content was essentially European in nature. African interests and cultural practices were largely excluded, as "bookwork" was favored over "handwork". The colonial curriculum also helped introduce a new social order to West Africa, leading to the rise of new local elites reading, writing, and speaking foreign European languages. This study explores how the idea of a "civilized" person, promoted through the colonial school curriculum, developed new local elites with different sets of values and expectations that often made them strangers in their own societies. It also describes the connection between this curriculum and the repeated failure of education-reform efforts.

  9. Understanding changes in terrestrial water storage over West Africa between 2002 and 2014

    NASA Astrophysics Data System (ADS)

    Ndehedehe, Christopher; Awange, Joseph; Agutu, Nathan; Kuhn, Michael; Heck, Bernhard

    2016-02-01

    With the vast water resources of West Africa coming under threat due to the impacts of climate variability and human influence, the need to understand its terrestrial water storage (TWS) changes becomes very important. Due to the lack of consistent in-situ hydrological data to assist in the monitoring of changes in TWS, this study takes advantage of the Gravity Recovery and Climate Experiment (GRACE) monthly gravity fields to provide estimates of vertically integrated changes in TWS over the period 2002-2014, in addition to satellite altimetry data for the period 1993-2014. In order to understand TWS variability over West Africa, Principal Component Analysis (PCA), a second order statistical technique, and Multiple Linear Regression Analysis (MLRA) are employed. Results show that dominant patterns of GRACE-derived TWS changes are observed mostly in the West Sahel, Guinea Coast, and Middle Belt regions of West Africa. This is probably caused by high precipitation rates at seasonal and inter-annual time scales induced by ocean circulations, altitude and physiographic features. While the linear trend for the spatially averaged GRACE-derived TWS changes over West Africa for the study period shows an increase of 6.85 ± 1.67 mm/yr, the PCA result indicates a significant increase of 20.2 ± 5.78 mm/yr in Guinea, a region with large inter-annual variability in seasonal rainfall, heavy river discharge, and huge groundwater potentials. The increase in GRACE-derived TWS during this period in Guinea, though inconsistent with the lack of a significant positive linear trend in TRMM based precipitation, is attributed to a large water surplus from prolonged wet seasons and lower evapotranspiration rates, leading to an increase in storage and inundated areas over the Guinea region. This increase in storage, which is also the aftermath of cumulative increase in the volume of water not involved in surface runoff, forms the huge freshwater availability in this region. However, the

  10. Crop planting date optimization: An approach for climate change adaptation in West Africa

    NASA Astrophysics Data System (ADS)

    Waongo, Moussa; Laux, Patrick; Kunstmann, Harald

    2014-05-01

    Agriculture is the main source of income for population and the main driver of economy in Africa, particularly in West Africa. West African agriculture is dominated by rainfed agriculture. This agricultural system is characterized by smallholder and subsistence farming, and a limited use of crop production inputs such as machines, fertilizers and pesticides. Therefore, crop yield is strongly influenced by climate fluctuation and is more vulnerable to climate change and climate variability. To reduce climate risk on crop production, a development of tailored agricultural management strategies is required. The usage of agricultural management strategies such as tailored crop planting date might contribute both to reduce crop failure and to increased crop production. In addition, unlike aforementioned crop production inputs, the usage of tailored planting dates is costless for farmers. Thus, efforts to improve crop production by optimizing crop planting date can contribute to alleviate food insecurity in West Africa, in the context of climate change. In this study, the process-based crop model GLAM (General Large Area Model for annual crop) in combination with a fuzzy logic approach for planting date have been coupled with a genetic algorithm to derive Optimized Planting Dates (OPDs) for maize cropping in Burkina Faso, West Africa. For a specific location, the derived OPDs correspond to a time window for crop planting. To analyze the performance of the OPDs approach, the derived OPDs has been compared to two well-known planting date methods in West Africa. The results showed a mean OPD ranging from May 1st (South-West) to July 11th (North) across the country. In comparison with well-known methods, the OPD approach yielded earliest planting dates across Burkina Faso. The deviation of OPDs from planting dates derived from the well known methods ranged from 10 days to 20 days for the northern and central region, and less than 10 days for the southern region. With respect

  11. The current capacity for training in public health nutrition in West Africa.

    PubMed

    Pepping, Fré

    2010-01-01

    This article is based on a paper prepared for the Workshop on Establishing a Regional Institute for Public Health Nutrition Research and Training in West Africa, convened in Dakar, Senegal, 26-28 March, 2009. Information was gathered mainly prior to this workshop; several responses, however, came in after the workshop and these have been included in the current paper. In completion of the article use was made of the views and opinions as expressed during this workshop. Objectives were to provide background information on academic programmes (undergraduate and graduate) and research institutions with a focus on human nutrition in West Africa, to describe the importance of foreign nutrition training programmes for West African students and to detail existing nutrition training activities currently in the region. Data were obtained from a survey of 15 UNICEF country offices in the West African region, previously published reports, United Nations University/International Union of Nutrition Sciences capacity development activities 1996-2009, personal communications and websites of relevant African institutions. Results indicate that West African nutrition academic programmes and research institutes do not adequately meet the demand for nutritionists and technical services in the region. Exceptions seem to be Benin, Ghana and Nigeria. Diploma courses and other short courses have been an important means of attracting people from a variety of disciplines to nutrition. A well-equipped regional institute could directly and indirectly bolster nutrition capacity in the region. To meet the regional nutrition research and training needs in West Africa, it is not necessary to make a choice between creating a new regional institution vs. expanding existing national institutions. Based on solid capacity development principles, both options need action. PMID:21113829

  12. Tracer redistribution by clouds in West Africa: Numerical modeling for dry and wet seasons

    SciTech Connect

    Renard, M.; Chaumerliac, N.; Cautenet, S.; Nickerson, E.C. |

    1994-06-01

    The vertical transport by clouds of an inert tracer and its redistribution by complex West African circulations are examined using a two-dimensional mesoscale meteorological model with explicit microphysics. The model reproduces the tropical distribution of clouds and precipitation along a meridional cross section over West Africa, corresponding to the position of the Intertropical Convergence Zone (ITCZ) during the dry and rainy seasons. The resulting redistribution of the inert tracer is therefore closely related to the northward migration of the ITCZ between January and July. The occurrence of biomass burning during the dry season is shown to be an important source of tracer enrichment at upper levels in the atmosphere.

  13. Shifts in Mycobacterial Populations and Emerging Drug-Resistance in West and Central Africa

    PubMed Central

    Fissette, Kristina; de Rijk, Pim; Uwizeye, Cécile; Nduwamahoro, Elie; Goovaerts, Odin; Affolabi, Dissou; Gninafon, Martin; Lingoupou, Fanny M.; Barry, Mamadou Dian; Sow, Oumou; Merle, Corinne; Olliaro, Piero; Ba, Fatoumata; Sarr, Marie; Piubello, Alberto; Noeske, Juergen; Antonio, Martin; Rigouts, Leen; de Jong, Bouke C

    2014-01-01

    In this study, we retrospectively analysed a total of 605 clinical isolates from six West or Central African countries (Benin, Cameroon, Central African Republic, Guinea-Conakry, Niger and Senegal). Besides spoligotyping to assign isolates to ancient and modern mycobacterial lineages, we conducted phenotypic drug-susceptibility-testing for each isolate for the four first-line drugs. We showed that phylogenetically modern Mycobacterium tuberculosis strains are more likely associated with drug resistance than ancient strains and predict that the currently ongoing replacement of the endemic ancient by a modern mycobacterial population in West/Central Africa might result in increased drug resistance in the sub-region. PMID:25493429

  14. A revised picture of the structure of the ``monsoon'' and land ITCZ over West Africa

    NASA Astrophysics Data System (ADS)

    Nicholson, Sharon E.

    2009-06-01

    This article presents an overview of the land ITCZ (Intertropical Convergence Zone) over West Africa, based on analysis of NCAR-NCEP Reanalysis data. The picture that emerges is much different than the classic one. The most important feature is that the ITCZ is effectively independent of the system that produces most of the rainfall. Rainfall linked directly to this zone of surface convergence generally affects only the southern Sahara and the northern-most Sahel, and only in abnormally wet years in the region. A second feature is that the rainbelt normally assumed to represent the ITCZ is instead produced by a large core of ascent lying between the African Easterly Jet and the Tropical Easterly Jet. This region corresponds to the southern track of African Easterly Waves, which distribute the rainfall. This finding underscores the need to distinguish between the ITCZ and the feature better termed the “tropical rainbelt”. The latter is conventionally but improperly used in remote sensing studies to denote the surface ITCZ over West Africa. The new picture also suggests that the moisture available for convection is strongly coupled to the strength of the uplift, which in turn is controlled by the characteristics of the African Easterly Jet and Tropical Easterly Jet, rather than by moisture convergence. This new picture also includes a circulation feature not generally considered in most analyses of the region. This feature, a low-level westerly jet termed the African Westerly Jet, plays a significant role in interannual and multidecadal variability in the Sahel region of West Africa. Included are discussions of the how this new view relates to other aspects of West Africa meteorology, such as moisture sources, rainfall production and forecasting, desertification, climate monitoring, hurricanes and interannual variability. The West African monsoon is also related to a new paradigm for examining the interannual variability of rainfall over West Africa, one that

  15. A-level Biology in West Africa: A New Syllabus

    ERIC Educational Resources Information Center

    Ewer, D. W.

    1969-01-01

    Describes a biology course developed for West African senior high school students. Ecology is used as an integrating theme, and the approach is problem centered. Discusses the proposed form of examinations in the course. (EB)

  16. Borrelia infection in small mammals in West Africa and its relationship with tick occurrence inside burrows.

    PubMed

    Diatta, Georges; Duplantier, Jean-Marc; Granjon, Laurent; Bâ, Khalilou; Chauvancy, Gilles; Ndiaye, Mady; Trape, Jean-François

    2015-12-01

    Tick-borne relapsing fever (TBRF) is a zoonotic disease caused by several Borrelia species transmitted to humans by Ornithodoros tick vectors. In West Africa, Borrelia crocidurae is a common cause of disease in many rural populations. Small mammals act as reservoirs of infection. We report here the results of surveys that investigated the occurrence of B. crocidurae infection in rodents and insectivores from eight countries of West and Central Africa. Animals were identified at the species level and tested for Borrelia either by examination of thick blood film, intra-peritoneal inoculation of blood or brain tissues into laboratory mice, or by molecular techniques. A total of 4358 small mammals belonging to 38 species and 7 families were collected, including 3225 specimens collected in areas where the occurrence of Ornithodoros sonrai tick in rodent burrows was documented, and 1133 in areas where this tick was absent. In areas with O. sonrai, Borrelia infection was demonstrated in 287 of 3109 (9.2%) small mammals tested, and none was documented in 1004 animals tested from other areas. There was no relationship between the occurrence of Rhipicephalus, Hyaloma and Argas ticks in burrows and the distribution of Borrelia infection in small mammals. The 287 specimens infected by Borrelia belonged to 15 rodent and shrew species, including three Saharo-Sahelian species - Gerbillus gerbillus, Gerbillus occiduus and Gerbillus tarabuli - identified as reservoirs for TBRF with a distribution restricted to this area. In Sudan and Sudano-Sahelian areas, Arvicanthis niloticus, Mastomys erythroleucus and Mastomys huberti were the main reservoir of infection. Although most small mammals species collected had a large distribution in West and Central Africa, the fact that only animals collected in areas with O. sonrai were found infected suggest that this tick is the only vector of TBRF in rodents and insectivores in this part of Africa. PMID:26327444

  17. The role of vegetation dynamics in the climate of West Africa

    NASA Astrophysics Data System (ADS)

    Wang, Guiling

    2000-12-01

    The climate of West Africa exhibits significant variability at the time scale of decades. The persistent drought of the past three decades is an example of such variability. This study investigates the role of vegetation dynamics in shaping the low-frequency variability of the climate over West Africa. A zonally symmetric, synchronously coupled biosphere-atmosphere model (ZonalBAM) which includes explicit representation of vegetation dynamics has been developed, and has been validated using observations on both the atmospheric and biospheric climate. The model is then used to study the dynamics of the coupled biosphere-atmosphere system over West Africa. Based on the model sensitivity to initial conditions and the resilience of the coupled system with respect to perturbations, we demonstrate that the coupled biosphere-atmosphere system over West Africa has multiple equilibrium states, with reversible transitions between different equilibria. The two-way biosphere-atmosphere feedback is a significant process in both climate persistence and climate transition. Based on long-term climate simulations using ZonalBAM driven with the observed sea surface temperature (SST) variations, our study shows that vegetation dynamics is a significant process in shaping the climate variability of West Africa. The response of the regional climate system to large-scale forcings is significantly regulated by vegetation dynamics. The relatively slow response of vegetation to changes in the atmosphere is a significant mechanism that acts to enhance the low-frequency rainfall variability. Climate transitions between different equilibria act as another mechanism contributing to the low-frequency rainfall variability-multi-decadal fluctuations can take place as a collective reflection of climate persistence at one equilibrium and climate transition towards another. Vegetation dynamics seems to play an important role in the development and persistence of the current Sahel drought. The most

  18. Micropaleontology and biostratigraphy of the coastal basins of West Africa

    SciTech Connect

    Kogbe, C.A.; Mehes, K.

    1986-01-01

    This book is intended to meet the need for a single volume on descriptive micropaleontology of West African microfauna assemblage which is different from that of the Boreal, Mediterranean, Pacific and Atlantic regions. The contents include: Preface. Introduction. Systematics: West African foraminifera species: Systematic classification and description. Glossary for the foraminifera. Selected references for the foraminifera. The ostracoda: Systematic classification and description. Glossary for the ostracoda. Selected references for the ostracoda. Stratigraphic Sequences of the West African Coastal Basins: General review. Angola-Cuanza basin. Congo. Gabon. Cameroun-Douala basin. Nigeria. Togo-Benin basin. Ghana. Ivory Coast. Senegal. Appendix: Brief classification of foraminifera. Paleo-ecology of the foraminifera. Testing of samples. Collection of samples. Preparation of samples. Preparation of thin sections. Storage of microfossils. Methods of examination. Index.

  19. Abrupt post-glacial climate events in West Asia and North Africa monsoon domains

    NASA Astrophysics Data System (ADS)

    Gasse, Françoise; Van Campo, Elise

    1994-09-01

    Regions beyond the present or past penetration of the Indian and African monsoons have experienced several large and abrupt climatic fluctuations over the past 13 14C kyr. Pollen and lake records from West Asia (Western Tibet and Rajasthan), East Africa (Ethiopia) and West Africa (Western Sahara, Sahel and subequatorial Africa) were selected on the basis of chronological control, sensitivity of both site and environmental indicators to climate change, the continuity of the record, and interdisciplinary control of the palaeoclimatic interpretation. Conditions wetter than those of today prevailed during the early-mid-Holocene period, but major dry spells are recorded at all sites during the intervals ˜ 11.0-9.5 kyr BP, ˜ 8-7 kyr BP and 3-4 kyr BP. Several records also suggest dry events of minor amplitude around 6 kyr BP. Potential boundary forcings of insolation and sea surface and tropical land surface conditions are discussed. The solar radiation accounts for the general envelop of the post-glacial monsoon fluctuations, but explains neither the timing nor the amplitude of the short-term changes. In spite of apparent covariation between fluctuations in sea surface conditions in the North Atlantic and the monsoon record, no direct mechanism could be found relating the intensity of the oceanic thermohaline conveyor belt to the monsoon strength. Changes in tropical land surface conditions (soil moisture negative feedback, and changes in CH 4 production from wetlands) provide a more satisfactory hypothesis for explaining abrupt reversal events.

  20. Polyglots, Vernaculars and Global Markets: Variable Trends in West Africa

    ERIC Educational Resources Information Center

    Adejunmobi, Moradewun

    2004-01-01

    Using a framework from cultural studies and focusing on theories put forward by Pierre Bourdieu, the goal in this paper is to consider how some West Africans interact with foreign languages and cultures in an era of global capital, especially when it comes to the activities of migrants venturing into overseas labour markets and to the production…

  1. Virtual Reference Service in Academic Libraries in West Africa

    ERIC Educational Resources Information Center

    Sekyere, Kwabena

    2011-01-01

    As technology continues to advance, libraries in Europe and America continue to improve upon their virtual reference services by employing new Web technologies and applying them to existing services. West African academic libraries have begun providing resources electronically to their users but still typically lag behind in the services they…

  2. Missionary Education in West Africa: A Study of Pedagogical Ambition

    ERIC Educational Resources Information Center

    Ustorf, Werner

    2011-01-01

    The history of the North German Mission Society (established 1836 in Hamburg) and its activity on the West African coast (from 1847 onwards among the Ewe, in what is now Ghana and Togo where it was and still is known as the "Bremen Mission") mirrors neatly the various phases of the idea of "mission": its composite motivation (Enlightenment,…

  3. Discovering Karima (Euphorbiaceae), a New Crotonoid Genus from West Tropical Africa Long Hidden within Croton.

    PubMed

    Cheek, Martin; Challen, Gill; Lebbie, Aiah; Banks, Hannah; Barberá, Patricia; Riina, Ricarda

    2016-01-01

    Croton scarciesii (Euphorbiaceae-Crotonoideae), a rheophytic shrub from West Africa, is shown to have been misplaced in Croton for 120 years, having none of the diagnostic characters of that genus, but rather a set of characters present in no known genus of the family. Pollen analysis shows that the new genus Karima belongs to the inaperturate crotonoid group. Analysis of a concatenated molecular dataset combining trnL-F and rbcL sequences positioned Karima as sister to Neoholstia from south eastern tropical Africa in a well-supported clade comprised of genera of subtribes Grosserineae and Neoboutonieae of the inaperturate crotonoid genera. Several morphological characters support the relationship of Karima with Neoholstia, yet separation is merited by numerous characters usually associated with generic rank in Euphorbiaceae. Quantitative ecological data and a conservation assessment supplement illustrations and descriptions of the taxon. PMID:27049519

  4. Discovering Karima (Euphorbiaceae), a New Crotonoid Genus from West Tropical Africa Long Hidden within Croton

    PubMed Central

    Cheek, Martin; Challen, Gill; Lebbie, Aiah; Banks, Hannah; Barberá, Patricia; Riina, Ricarda

    2016-01-01

    Croton scarciesii (Euphorbiaceae-Crotonoideae), a rheophytic shrub from West Africa, is shown to have been misplaced in Croton for 120 years, having none of the diagnostic characters of that genus, but rather a set of characters present in no known genus of the family. Pollen analysis shows that the new genus Karima belongs to the inaperturate crotonoid group. Analysis of a concatenated molecular dataset combining trnL-F and rbcL sequences positioned Karima as sister to Neoholstia from south eastern tropical Africa in a well-supported clade comprised of genera of subtribes Grosserineae and Neoboutonieae of the inaperturate crotonoid genera. Several morphological characters support the relationship of Karima with Neoholstia, yet separation is merited by numerous characters usually associated with generic rank in Euphorbiaceae. Quantitative ecological data and a conservation assessment supplement illustrations and descriptions of the taxon. PMID:27049519

  5. Ebola virus disease control in West Africa: an ecological, one health approach

    PubMed Central

    Meseko, Clement Adebajo; Egbetade, Adeniyi Olugbenga; Fagbo, Shamsudeen

    2015-01-01

    The 2013-2015 Ebola Virus Disease outbreak in West Africa had similar nuances with the 1976 outbreaks in Central Africa; both were caused by the Zaire Ebola Virus strain and originated from rural forested communities. The definitive reservoir host of Ebola virus still remains unknown till date. However, from ecological perspective, it is known that the virus first emerged from forest ecotypes interfacing with human activities. As at March 2015, the outbreak has claimed over 9000 lives, which is unprecedented. Though it remains unproved, the primary sources of infection for past and present outbreaks are forest dwelling, human-hunted fauna. Understanding the ecological factors at play in these forest ecotypes where wild fauna interface with human and causing pathogen spill over is important. A broad based One Health approach incorporating these ecological concepts in the control of Ebola Virus Disease can effectively ameliorate or forestall infection now and in the future. PMID:26401200

  6. Directional changes of the geomagnetic field in West Africa: Insights from the metallurgical site of Korsimoro

    NASA Astrophysics Data System (ADS)

    Donadini, Fabio; Serneels, Vincent; Kapper, Lisa; El Kateb, Akram

    2015-11-01

    This work shows the first archeomagnetic directions from Western Africa measured on 32 iron smelting kilns dated between 650 and 1800 AD. The archeological excavation of the vast metallurgical site of Korsimoro established the existence of four distinct iron-smelting techniques. The time-frame of each technique could be clearly determined with radiocarbon dating. Many of the kilns investigated in this study could also be dated individually with residual charcoals found in their inside. The results indicate that the inclination of the field changed gradually from shallow normal to shallow reversed during 800 to 1300 AD, and then went back to shallow normal around 1600-1700 AD. The declination was instead stable around 10°E between 800 and 1400 AD, thereafter it started changing towards North. This trend correlates well with available secular variation curves from the Balkan and from Spain, and indicates that the field variation in West Africa was similar to the one in Europe.

  7. Infrared radiation budget of the Harmattan haze. [West Africa

    NASA Technical Reports Server (NTRS)

    Kuhn, P. M.; Weickmann, H. K.

    1975-01-01

    Infrared in situ observations of the West African Harmaltan Haze during the 1974 GATE field phase were conducted to determine the radiative properties of the tropospheric phenomenon and to develop a calculation model for radiative transfer through the haze. Radiometric observations of the dust haze were analyzed for haze infrared transmission. Infrared and tropospheric cooling rates are given together with the haze volume absorption rate.

  8. Effects of vegetation feedback on future climate change over West Africa

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Wang, Guiling; Pal, Jeremy S.

    2016-06-01

    This study investigates the impact of climate-vegetation interaction on future climate changes over West Africa using a regional climate model with synchronous coupling between climate and natural vegetation, the RegCM4.3.4-CLM-CN-DV. Based on the lateral boundary conditions supplied by MIROC-ESM and CESM under the greenhouse gas Representative Concentration Pathway 8.5, significant increase of vegetation density is projected over the southern part of Sahel, with an increase of leaf area index and a conversion from grass to woody plants around 7-10°N of Sahel. Regardless of whether the model treats vegetation as static or dynamic, it projects an increase of precipitation in eastern Sahel and decrease in the west. The feedback due to projected vegetation change tends to cause a wet signal, enhancing the projected increase or alleviate the decrease of precipitation in JJA in the areas of projected vegetation increase. Its impact is negligible in DJF. Vegetation feedback slightly enhances projected warming in most of West Africa during JJA, but has a significant cooling effect during DJF in regions of strong vegetation changes. Future changes of surface runoff are projected to follow the direction of precipitation changes. While dynamic vegetation feedback enhances the projected increase of soil water content in JJA, it has a drying effect in DJF. The magnitude of projected ET changes is reduced in JJA and increased in DJF due to vegetation dynamics. A high sensitivity of climate projection to dynamic vegetation feedback was found mainly in semiarid areas of West Africa, with little signal in the wet tropics.

  9. Trends in floods in West Africa: analysis based on 11 catchments in the region

    NASA Astrophysics Data System (ADS)

    Nka, B. N.; Oudin, L.; Karambiri, H.; Paturel, J. E.; Ribstein, P.

    2015-11-01

    After the drought of the 1970s in West Africa, the variability in rainfall and land use changes mostly affected flow, and recently flooding has been said to be an increasingly common occurrence throughout the whole of West Africa. These changes have raised many questions about the impact of climate change on the flood regimes in West African countries. This paper investigates whether floods are becoming more frequent or more severe and to what extent climate patterns have been responsible for these changes. We analyzed the trends in the floods occurring in 11 catchments within West Africa's main climate zones. The methodology includes two methods for sampling flood events, namely the AM (annual maximum) method and the POT (peak over threshold), and two perspectives of analysis are presented: long-term analysis based on two long flood time series and a regional perspective involving 11 catchments with shorter series. The Mann-Kendall trend test and the Pettitt break test were used to detect nonstationarities in the time series. The trends detected in flood time series were compared to the rainfall index trends and vegetation indices using contingency tables in order to identify the main driver of change in flood magnitude and flood frequency. The relation between the flood index and the physiographic index was evaluated through a success criterion and the Cramer criterion calculated from the contingency tables. The results show the existence of trends in flood magnitude and flood frequency time series, with two main patterns. Sahelian floods show increasing flood trends and one Sudanian. catchment presents decreasing flood trends. For the overall catchments studied, trends in the maximum 5-day consecutive rainfall index (R5d) show good coherence with trends in flood, while the trends in normalized difference vegetation indices (NDVIs) do not show a significant agreement with flood trends, meaning that this index has possibly no impact on the behavior of floods in

  10. The WASCAL regional climate simulations for West Africa - how to add value to existing climate projections

    NASA Astrophysics Data System (ADS)

    Arnault, J.; Heinzeller, D.; Klein, C.; Dieng, D.; Smiatek, G.; Bliefernicht, J.; Sylla, M. B.; Kunstmann, H.

    2015-12-01

    With climate change being one of the most severe challenges to rural Africa in the 21st century, West Africa is facing an urgent need to develop effective adaptation and mitigation measures to protect its constantly growing population. WASCAL (West African Science Service Center on Climate Change and Adapted Land Use) is a large-scale research-focused program designed to enhance the resilience of human and environmental systems to climate change and increased variability. An integral part of its climate services is the provisioning of a new set of high resolution, ensemble-based regional climate change scenarios for the region of West Africa. In this contribution, we present the overall concept of the WASCAL regional climate projections and provide information on the dissemination of the data. We discuss the model performance over the validation period for two of the three regional climate models employed, the Weather Research & Forecasting Tool (WRF) and the Consortium for Small-scale Modeling Model COSMO in Climate Mode (COSMO-CLM), and give details about a novel precipitation database used to verify the models. Particular attention is paid to the representation of the dynamics of the West African Summer Monsoon and to the added value of our high resolution models over existing data sets. We further present results on the climate change signal obtained from the WRF model runs for the periods 2020-2050 and 2070-2100 and compare them to current state-of-the-art projections from the CORDEX project. As an example, the figure shows the different climate change signals obtained for the total annual rainfall with respect to the 1980-2010 mean (WRF-E: WASCAL 12km high-resolution run MPI-ESM + WRFV3.5.1, CORDEX-E: 50km medium-resolution run MPI-ESM + RCA4, CORDEX-G: 50km medium-resolution run GFDL-ESM + RCA4).

  11. Impact of the Mycobaterium africanum West Africa 2 Lineage on TB Diagnostics in West Africa: Decreased Sensitivity of Rapid Identification Tests in The Gambia

    PubMed Central

    Ofori-Anyinam, Boatema; Kanuteh, Fatoumatta; Okoi, Catherine; Dolganov, Gregory; Schoolnik, Gary; Secka, Ousman; Antonio, Martin; de Jong, Bouke C.; Gehre, Florian

    2016-01-01

    Background MPT64 rapid speciation tests are increasingly being used in diagnosis of tuberculosis (TB). Mycobacterium africanum West Africa 2 (Maf 2) remains an important cause of TB in West Africa and causes one third of disease in The Gambia. Since the introduction of MPT64 antigen tests, a higher than expected rate of suspected non-tuberculous mycobacteria (NTM) was seen among AFB smear positive TB suspects, which led us to prospectively assess sensitivity of the MPT64 antigen test in our setting. Methodology/Principal Findings We compared the abundance of mRNA encoded by the mpt64 gene in sputa of patients with untreated pulmonary TB caused by Maf 2 and Mycobacterium tuberculosis (Mtb). Subsequently, prospectively collected sputum samples from presumptive TB patients were inoculated in the BACTEC MGIT 960 System. One hundred and seventy-three acid fast bacilli (AFB)-positive and blood agar negative MGIT cultures were included in the study. Cultures were tested on the day of MGIT positivity with the BD MGIT TBc Identification Test. A random set of positives and all negatives were additionally tested with the SD Bioline Ag MPT64 Rapid. MPT64 negative cultures were further incubated at 37°C and retested until positive. Bacteria were spoligotyped and assigned to different lineages. Maf 2 isolates were 2.52-fold less likely to produce a positive test result and sensitivity ranged from 78.4% to 84.3% at the beginning and end of the recommended 10 day testing window, respectively. There was no significant difference between the tests. We further showed that the decreased rapid test sensitivity was attributable to variations in mycobacterial growth behavior and the smear grades of the patient. Conclusions/Significance In areas where Maf 2 is endemic MPT64 tests should be cautiously used and MPT64 negative results confirmed by a second technique, such as nucleic acid amplification tests, to avoid their misclassification as NTMs. PMID:27387550

  12. An Inquiry-based Astronomy Summer School in West Africa

    NASA Astrophysics Data System (ADS)

    Strubbe, Linda; Okere, Bonaventure; Chibueze, James; Lepo, Kelly; White, Heidi; Zhang, Jielai; Okoh, Daniel; Reid, Mike; Hunter, Lisa

    2015-01-01

    In October 2013 over 75 undergraduate science students and teachers from Nigeria and Ghana attended the week-long West African International Summer School for Young Astronomers. The school was organized by a collaboration of astronomers from the University of Toronto, the University of Nigeria, and the Nigerian National Space Research and Development Agency. We designed and led activities that taught astronomy content, promoted students' self-identity as scientists, and encouraged students to think critically and figure out solutions themselves. I will describe the inquiry-based and active learning techniques used in the school, share results from the qualitative and quantitative evaluations of student performance, and describe future plans for holding the school in 2015, supporting our alumni, and building a sustainable partnership between North American and Nigerian universities.

  13. Forecasting droughts in West Africa: Operational practice and refined seasonal precipitation forecasts

    NASA Astrophysics Data System (ADS)

    Bliefernicht, Jan; Siegmund, Jonatan; Seidel, Jochen; Arnold, Hanna; Waongo, Moussa; Laux, Patrick; Kunstmann, Harald

    2016-04-01

    Precipitation forecasts for the upcoming rainy seasons are one of the most important sources of information for an early warning of droughts and water scarcity in West Africa. The meteorological services in West Africa perform seasonal precipitation forecasts within the framework of PRESAO (the West African climate outlook forum) since the end of the 1990s. Various sources of information and statistical techniques are used by the individual services to provide a harmonized seasonal precipitation forecasts for decision makers in West Africa. In this study, we present a detailed overview of the operational practice in West Africa including a first statistical assessment of the performance of the precipitation forecasts for drought situations for the past 18 years (1998 to 2015). In addition, a long-term hindcasts (1982 to 2009) and a semi-operational experiment for the rainy season 2013 using statistical and/or dynamical downscaling are performed to refine the precipitation forecasts from the Climate Forecast System Version 2 (CFSv2), a global ensemble prediction system. This information is post-processed to provide user-oriented precipitation indices such as the onset of the rainy season for supporting water and land use management for rain-fed agriculture. The evaluation of the individual techniques is performed focusing on water-scarce regions of the Volta basin in Burkina Faso and Ghana. The forecasts of the individual techniques are compared to state-of-the-art global observed precipitation products and a novel precipitation database based on long-term daily rain-gage measurements provided by the national meteorological services. The statistical assessment of the PRESAO forecasts indicates skillful seasonal precipitation forecasts for many locations in the Volta basin, particularly for years with water deficits. The operational experiment for the rainy season 2013 illustrates the high potential of a physically-based downscaling for this region but still shows

  14. Diagnosis and Modelling of the Variability of Rainfall in West Africa Within the Impetus Project

    NASA Astrophysics Data System (ADS)

    Fink, A. H.; Born, K.; Hense, A.; Kerschgens, M.; Paeth, H.; Schulz, J.; Simmer, C.; Sogalla, M.; Speth, P.

    2003-04-01

    In the meteorological sub-project of the multi-disciplinary IMPETUS project ('An Integrated Approach to the Efficient Management of Scarce Water Resources in West Africa'), one focus is on the diagnosis and modelling of the major rainfall producing weather systems in Benin and Morocco. Two other foci are on model sensitivity studies to determine the potential of seasonal rainfall forecasting for tropical West Africa, as well as on the impact of land surface characteristics on rainfall patterns. Recent analysis of precipitation trends reveals no return to normal or above-normal monsoon rains in all climatic zones of tropical West Africa. In Morocco, a series of dry winters in the winter-precipitation regime north of the High Atlas occurred in the 1980s and 1990s, while at the Saharan foothills of the Atlas Mountains, wetter than normal conditions prevailed. This behaviour might be explained by a hitherto poorly examined contribution of "Tropical Extratropical Interaction" (TEI) events to the mean annual rainfall south of the Atlas mountains. Such TEI most often occur in the transition seasons and cause convective rainfall events that are supplied with water vapour from tropical moisture plumes. In the West African Tropics, the effect of interactions between the earth's surface and the atmosphere on fresh water availability is investigated with a non-hydrostatic mesoscale model for a river catchment in Benin. Idealised ensemble studies exhibit a dominant influence of initial soil water content and an enhanced dependence of precipitation on vegetation when soil water availability is reduced. It is also shown that a successive increase of the fraction of degraded land surface results in a nearly linear response of moderate rainfall decrease for the area as a whole and a tendency to strong reductions in some regions. Finally, observational data sets and output from the global (ECHAM4) and continental (REMO) general circulation models are used to determine the potential

  15. Potential impact of climate and socioeconomic changes on future agricultural land use in West Africa

    NASA Astrophysics Data System (ADS)

    Farzan Ahmed, Kazi; Wang, Guiling; You, Liangzhi; Yu, Miao

    2016-02-01

    Agriculture is a key component of anthropogenic land use and land cover changes that influence regional climate. Meanwhile, in addition to socioeconomic drivers, climate is another important factor shaping agricultural land use. In this study, we compare the contributions of climate change and socioeconomic development to potential future changes of agricultural land use in West Africa using a prototype land use projection (LandPro) algorithm. The algorithm is based on a balance between food supply and demand, and accounts for the impact of socioeconomic drivers on the demand side and the impact of climate-induced crop yield changes on the supply side. The impact of human decision-making on land use is explicitly considered through multiple "what-if" scenarios. In the application to West Africa, future crop yield changes were simulated by a process-based crop model driven with future climate projections from a regional climate model, and future changes of food demand is projected using a model for policy analysis of agricultural commodities and trade. Without agricultural intensification, the climate-induced decrease in crop yield together with future increases in food demand is found to cause a significant increase in cropland areas at the expense of forest and grassland by the mid-century. The increase in agricultural land use is primarily climate-driven in the western part of West Africa and socioeconomically driven in the eastern part. Analysis of results from multiple scenarios of crop area allocation suggests that human adaptation characterized by science-informed decision-making can potentially minimize future land use changes in many parts of the region.

  16. Impact of land use changes on surface feedbacks in sudanian region of West Africa

    NASA Astrophysics Data System (ADS)

    Cohard, J. M.; Galle, S.; Mamadou, O.; Peugeot, C.; Seghieri, J.; Kounouhewa, B.; Awanou, N. C.

    2014-12-01

    In West Africa, surface atmosphere exchanges have been found to impact both regional and local features of the Monsoon. At local scale the spatial patterns of Evaporative Fraction can drive the trajectories of mesoscale convective systems. Under Sudanian climate a mean of ~80% of the precipitation return to atmosphere through evapotranspiration but this important amount and its dynamics may vary with the vegetation cover. In consequence, any land use or climate changes can lead to modifications on the surface feedbacks and thus on both the atmospheric and the continental water cycle. In West Africa, Sudanian regions are submitted to a ~3% demographical increase per year, which leads to regular deforestation to the benefit of cultivated areas. This study aims at quantifying the changes in evapotranspiration regime caused by such a land use change under Sudanian climate. Within the framework of The AMMA-CATCH observatory, energy and water vapor fluxes were investigated in west Africa since 2007. Herein, a pluri-annual (2007 - 2010) energy budget of a clear forest and a cultivated area located in northern Benin are analysed. Results show that evapotranspiration rates over the sudanian forest are higher than those of cultivated area, because of agricultural practice and water availability for trees. After harvest, the residual vegetation is burned to bring nutriment to soil and to clean the landscape around the villages. Thus, during the dry season, the cultivated areas are bare. At the same time, a significant evapotranspiration is measured over the forest area despite the lack of precipitations. The deep root system of such vegetation allow the trees to get access to water during the dry season. During the rainy season, a significant difference in evapotransiration rates are also observed. These differences lead to a large deficit of water vapor that returns to the atmosphere and will significantly change the continental water cycle when forests will be replaced by

  17. Ocean climate data for user community in West and Central Africa: Needs, opportunities, and challenges

    NASA Technical Reports Server (NTRS)

    Ojo, S. O.

    1992-01-01

    The urgent need to improve data delivery systems needed by scientists studying ocean role in climate and climate characteristics has been manifested in recent years because of the unprecedented climatic events experienced in many parts of the world. Indeed, there has been a striking and growing realization by governments and the general public indicating that national economies and human welfare depend on climate and its variability. In West and Central Africa, for instance climatic events, which have resulted in floods and droughts, have caused a lot of concern to both governments and people of the region. In particular, the droughts have been so widespread that greater awareness and concern have become generated for the need to find solutions to the problems created by the consequences of the climatic events. Particularly in the southern border regions of the Sahara Desert as well as in the Sahel region, the drought episodes considerably reduced food production and led to series of socioeconomic problems, not only in the areas affected by the droughts, but also in the other parts of West Africa. The various climatic variabilities which have caused the climatic events are no doubt related to the ocean-atmosphere interactions. Unfortunately, not much has been done on the understanding of these interactions, particularly as they affect developing countries. Indeed, not much has been done to develop programs which will reflect the general concerns and needs for researching into the ocean-atmosphere systems and their implications on man-environmental systems in many developing countries. This is for example, true of West and Central Africa, where compared with the middle latitude countries, much less is known about the characteristics of the ocean-atmosphere systems and their significance on man-environmental systems of the area.

  18. Potential Risk of Regional Disease Spread in West Africa through Cross-Border Cattle Trade

    PubMed Central

    Dean, Anna S.; Fournié, Guillaume; Kulo, Abalo E.; Boukaya, G. Aboudou; Schelling, Esther; Bonfoh, Bassirou

    2013-01-01

    Background Transboundary animal movements facilitate the spread of pathogens across large distances. Cross-border cattle trade is of economic and cultural importance in West Africa. This study explores the potential disease risk resulting from large-scale, cross-border cattle trade between Togo, Burkina Faso, Ghana, Benin, and Nigeria for the first time. Methods and Principal Findings A questionnaire-based survey of livestock movements of 226 cattle traders was conducted in the 9 biggest cattle markets of northern Togo in February-March 2012. More than half of the traders (53.5%) operated in at least one other country. Animal flows were stochastically simulated based on reported movements and the risk of regional disease spread assessed. More than three quarters (79.2%, range: 78.1–80.0%) of cattle flowing into the market system originated from other countries. Through the cattle market system of northern Togo, non-neighbouring countries were connected via potential routes for disease spread. Even for diseases with low transmissibility and low prevalence in a given country, there was a high risk of disease introduction into other countries. Conclusions By stochastically simulating data collected by interviewing cattle traders in northern Togo, this study identifies potential risks for regional disease spread in West Africa through cross-border cattle trade. The findings highlight that surveillance for emerging infectious diseases as well as control activities targeting endemic diseases in West Africa are likely to be ineffective if only conducted at a national level. A regional approach to disease surveillance, prevention and control is essential. PMID:24130721

  19. Long-Term Water Balance of the Volta River Basin in West Africa

    NASA Astrophysics Data System (ADS)

    van de Giesen, N.; Andreini, M.; Taylor, J.; Steenhuis, T.

    2002-12-01

    The Volta River drains approximately 400,000 km2 of the semi-arid to sub-humid savanna of West Africa. Average rainfall is about 1000 mm per year. The interannual variation is relatively low with a coefficient of variation of 0.07. Most rainfall returns to the atmosphere as evapotranspiration and only 9% becomes available as river runoff. The interannual variation of river flow is much higher than that of rainfall and has a coefficient of variation of 0.57. In this presentation, the coupling between interannual variation in rainfall and runoff is examined. To a large extent, the high variability in river flow can be explained with the relatively small differences in rainfall between years; the watershed strongly amplifies the atmospheric input. The amplifying effect is, however, not constant over space and time. Over all, the basin received less rain than before in the past two decades. Some parts of the basin did indeed produce less runoff but other parts actually produced more runoff, most likely due to changes in landuse. No clear increase or decrease in the interannual variability could be found for different parts of the basin. To examine the interannual variability of water resources availability under future climates, the applicability of General Circulation Models (GCMs) was examined for West Africa. Comparison of historical and GCM rainfall data showed large discrepancies. Different approaches exist to adjust GCM rainfall with the aid of historical rainfall data but for West Africa some problems remained. This presentation concludes with a focus on differences in mid-term (2-10 years) persistence in annual river flow as produced by historical and GCM data.

  20. Model-Based Geostatistical Mapping of the Prevalence of Onchocerca volvulus in West Africa

    PubMed Central

    O’Hanlon, Simon J.; Slater, Hannah C.; Cheke, Robert A.; Boatin, Boakye A.; Coffeng, Luc E.; Pion, Sébastien D. S.; Boussinesq, Michel; Zouré, Honorat G. M.; Stolk, Wilma A.; Basáñez, María-Gloria

    2016-01-01

    Background The initial endemicity (pre-control prevalence) of onchocerciasis has been shown to be an important determinant of the feasibility of elimination by mass ivermectin distribution. We present the first geostatistical map of microfilarial prevalence in the former Onchocerciasis Control Programme in West Africa (OCP) before commencement of antivectorial and antiparasitic interventions. Methods and Findings Pre-control microfilarial prevalence data from 737 villages across the 11 constituent countries in the OCP epidemiological database were used as ground-truth data. These 737 data points, plus a set of statistically selected environmental covariates, were used in a Bayesian model-based geostatistical (B-MBG) approach to generate a continuous surface (at pixel resolution of 5 km x 5km) of microfilarial prevalence in West Africa prior to the commencement of the OCP. Uncertainty in model predictions was measured using a suite of validation statistics, performed on bootstrap samples of held-out validation data. The mean Pearson’s correlation between observed and estimated prevalence at validation locations was 0.693; the mean prediction error (average difference between observed and estimated values) was 0.77%, and the mean absolute prediction error (average magnitude of difference between observed and estimated values) was 12.2%. Within OCP boundaries, 17.8 million people were deemed to have been at risk, 7.55 million to have been infected, and mean microfilarial prevalence to have been 45% (range: 2–90%) in 1975. Conclusions and Significance This is the first map of initial onchocerciasis prevalence in West Africa using B-MBG. Important environmental predictors of infection prevalence were identified and used in a model out-performing those without spatial random effects or environmental covariates. Results may be compared with recent epidemiological mapping efforts to find areas of persisting transmission. These methods may be extended to areas where

  1. Safe and Effective Deployment of Personnel to Support the Ebola Response - West Africa.

    PubMed

    Rouse, Edward N; Zarecki, Shauna Mettee; Flowers, Donald; Robinson, Shawn T; Sheridan, Reed J; Goolsby, Gary D; Nemhauser, Jeffrey; Kuwabara, Sachiko

    2016-01-01

    From the initial task of getting "50 deployers within 30 days" into the field to support the 2014-2016 Ebola virus disease (Ebola) epidemic response in West Africa to maintaining well over 200 staff per day in the most affected countries (Guinea, Liberia, and Sierra Leone) during the peak of the response, ensuring the safe and effective deployment of international responders was an unprecedented accomplishment by CDC. Response experiences shared by CDC deployed staff returning from West Africa were quickly incorporated into lessons learned and resulted in new activities to better protect the health, safety, security, and resiliency of responding personnel. Enhanced screening of personnel to better match skill sets and experience with deployment needs was developed as a staffing strategy. The mandatory predeployment briefings were periodically updated with these lessons to ensure that staff were aware of what to expect before, during, and after their deployments. Medical clearance, security awareness, and resiliency programs became a standard part of both predeployment and postdeployment activities. Response experience also led to the identification and provision of more appropriate equipment for the environment. Supporting the social and emotional needs of deployed staff and their families also became an agency focus for care and communication. These enhancements set a precedent as a new standard for future CDC responses, regardless of size or complexity.The activities summarized in this report would not have been possible without collaboration with many U.S and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html). PMID:27387289

  2. The problem of suboptimal complementary feeding practices in West Africa: what is the way forward?

    PubMed

    Issaka, Abukari I; Agho, Kingsley E; Page, Andrew N; Burns, Penelope L; Stevens, Garry J; Dibley, Michael J

    2015-10-01

    The objective of this paper was to review the policy implications of inadequate complementary feeding among children aged 6-23 months in West Africa. The review was undertaken from the initial results and findings from a series of studies on the comparison of complementary feeding indicators among children aged 6-23 months in four anglophone and seven francophone West African countries. It also examined a study of the determinants of suboptimal complementary feeding practices among children aged 6-23 months in those countries. Among the four complementary feeding indicators, it was only the introduction of solid, semi-solid or soft foods that was adequate among children in all the West African countries surveyed. The rates of the other complementary feeding indicators were found to be inadequate in all countries surveyed, although relatively better among children in the anglophone countries. Alarmingly, low rates of minimum acceptable diet were reported among children from both the anglophone and the francophone countries. Infants 6-11 months of age, children living in poor households, administrative/geographical regional differences and mothers' access to the media were some of the common risk factors for optimal complementary feeding practices in these countries. Assessing complementary feeding indicators and determinants of suboptimal complementary feeding practices in these West African countries is crucial to improving infant and young child feeding practices. It is recommended that governments and stakeholders of the West African countries studied make greater efforts to improve these critical practices in order to reduce child morbidity and mortality in the West Africa sub-region. Intervention studies on complementary feeding should target those socio-demographic factors that pose risks to optimal complementary feeding. PMID:26364791

  3. Impact of immigration on HIV-1 molecular epidemiology in West Africa, Maghreb and Southern Europe.

    PubMed

    Miri, Lamia; Wakrim, Lahcen; Kassar, Hassène; Hemminki, Kari; Khyatti, Meriem

    2014-01-01

    There is global concern about the relation between international migration and the course of the AIDS epidemic. Maghreb is a North African region, which lies between sub-Saharan Africa and Europe. It has been turned recently into a region of immigration, since there are more and more flows of West African migrants hoping to reach European countries. Here we provide an overview on HIV-1 molecular epidemiology particularly in West African countries, Maghreb (Morocco, Algeria, Tunisia) and southern European countries (Spain, France, and Italy). The studies conducted in several countries of the region revealed different features of HIV-1 molecular epidemiology, especially for the distribution of viral subtypes and for transmitted drug resistance profiles. Furthermore, migration from West Africa to Europe seems to be a potential source of non-B subtype mobility to Maghreb and eventually to southern Europe, where HIV-1 non-B variants significantly increased in the last 10 to 15 years. As genetic differences between subtypes might impact the drug resistance pathways, it is important to provide continuous surveillance programs for the early detection of new variants spreading in the population before they become more prevalent, and to identify resistance profiles in different infected populations, especially migrants. PMID:24802562

  4. Empirical analysis of dry spells for agricultural applications in west Africa

    SciTech Connect

    Sivakumar, M.V.K. )

    1992-05-01

    Recurring droughts and decreased agricultural productivity during the last two decades in West Africa point to the need for a clearer understanding of the length of dry spells, their frequencies, and their probabilities. The simplest calculations of dry spells for general applications involve computation of the probabilities of maximum and conditional dry spells exceeding a user-specified threshold value from a given calendar date. For more precise applications in agriculture, it is important to consider the different periods after sowing a crop, since sowing dates in the semiarid West African regions vary from year to year. Using the specific definition of onset of rains in each year as the sowing date, the length of dry spells was calculated from the historical rainfall data. Probability distribution of time to the next wet day and the percentage frequencies of dry spells were computed for successive days after sowing (DAS) a crop. Dry-spell analysis showed a pronounced drop in the drought risk for cereal crops from the panicle initiation phase (20 DAS) to the flowering phase (60 DAS). The relationships between mean annual rainfall and average frequency of dry spells for the selected locations in West Africa showed distinct patterns and permit the prediction of the frequency of dry spells from annual rainfall totals. Applications of the dry-spell analysis for the choice of a crop/variety, supplemental irrigation, and crop water requirements have been described with examples.

  5. Assessing climate adaptation options and uncertainties for cereal systems in West Africa

    NASA Astrophysics Data System (ADS)

    Guan, K.; Sultan, B.; Biasutti, M.; Lobell, D. B.

    2015-12-01

    The already fragile agriculture production system in West Africa faces further challenges in meeting food security in the coming decades, primarily due to a fast increasing population and risks of climate change. Successful adaptation of agriculture should not only benefit in the current climate but should also reduce negative (or enhance positive) impacts for climate change. Assessment of various possible adaptation options and their uncertainties provides key information for prioritizing adaptation investments. Here, based on the several robust aspects of climate projections in this region (i.e. temperature increases and rainfall pattern shifts), we use two well-validated crop models (i.e. APSIM and SARRA-H) and an ensemble of downscaled climate forcing to assess five possible and realistic adaptation options (late sowing, intensification, thermal time increase, water harvesting and increased resilience to heat stress) in West Africa for the staple crop production of sorghum. We adopt a new assessment framework to account for both the impacts of adaptation options in current climate and their ability to reduce impacts of future climate change, and also consider changes in both mean yield and its variability. Our results reveal that most proposed "adaptation options" are not more beneficial in the future than in the current climate, i.e. not really reduce the climate change impacts. Increased temperature resilience during grain number formation period is the main adaptation that emerges. We also find that changing from the traditional to modern cultivar, and later sowing in West Sahel appear to be robust adaptations.

  6. Uncertainties in projected climate changes of the rainy season over West Africa related to bias adjustment

    NASA Astrophysics Data System (ADS)

    Nikulin, Grigory; Bosshard, Thomas; Wilcke, Renate; Yang, Wei; Kjellström, Erik; Bärring, Lars

    2015-04-01

    Bias adjustment has become an integral part of pre-processing of climate simulations for use in impact modeling studies. Considered now as a necessary step to deal with inability of climate models to accurately simulate the present/recent climate, bias adjustment is a statistical approach missing physical arguments. Even if bias adjustment is widely used nowadays it is still a topic for debates and criticism. One of the main questions is what level of uncertainty does bias adjustment introduce to future climate projections? In this study, using an ensemble of the CORDEX-Africa simulations, we investigate potential impact of bias adjustment on the simulated rainy season in West Africa. A number of characteristics reflecting different aspects of the rainy season are used, namely: onset and cessation of the rainy season, mean intensity, total amount of precipitation and intra-seasonal variability within the rainy season. All these characteristics are evaluated in the original CORDEX-Africa simulations and in bias-adjusted ones for a reference period first and then future climate projections of these characteristics are compared between two ensembles. Additionally, we examine how bias adjustment may impact selection of a smaller more manageable ensemble of regional climate simulations from a grand one.

  7. Avian influenza surveillance in Central and West Africa, 2010-2014.

    PubMed

    Fuller, T L; Ducatez, M F; Njabo, K Y; Couacy-Hymann, E; Chasar, A; Aplogan, G L; Lao, S; Awoume, F; Téhou, A; Langeois, Q; Krauss, S; Smith, T B

    2015-07-01

    Avian influenza virus (AIV) is an important zoonotic pathogen, resulting in global human morbidity and mortality and substantial economic losses to the poultry industry. Poultry and wild birds have transmitted AIV to humans, most frequently subtypes H5 and H7, but also different strains and subtypes of H6, H9, and H10. Determining which birds are AIV reservoirs can help identify human populations that have a high risk of infection with these viruses due to occupational or recreational exposure to the reservoir species. To assess the prevalence of AIV in tropical birds, from 2010 to 2014, we sampled 40 099 birds at 32 sites in Central Africa (Cameroon, Central African Republic, Congo-Brazzaville, Gabon) and West Africa (Benin, Côte d'Ivoire, Togo). In Central Africa, detection rates by real-time RT-PCR were 16·6% in songbirds (eight passerine families, n = 1257), 16·4% in kingfishers (family Alcedinidae, n = 73), 8·2% in ducks (family Anatidae, n = 564), and 3·65% in chickens (family Phasianidae, n = 1042). Public health authorities should educate human cohorts that have high exposure to these bird populations about AIV and assess their adherence to biosecurity practices, including Cameroonian farmers who raise small backyard flocks. PMID:25530320

  8. Cost-effectiveness analysis of malaria chemoprophylaxis for travellers to West-Africa

    PubMed Central

    2010-01-01

    Background The importation of malaria to non-endemic countries remains a major cause of travel-related morbidity and a leading cause of travel-related hospitalizations. Currently they are three priority medications for malaria prophylaxis to West Africa: mefloquine, atovaquone/proguanil and doxycycline. We investigate the cost effectiveness of a partial reimbursement of the cheapest effective malaria chemoprophylaxis (mefloquine) for travellers to high risk areas of malaria transmission compared with the current situation of no reimbursement. Methods This study is a cost-effectiveness analysis based on malaria cases imported from West Africa to Switzerland from the perspective of the Swiss health system. We used a decision tree model and made a literature research on the components of travel related malaria. The main outcome measure was the cost effectiveness of malaria chemoprophylaxis reimbursement based on malaria and deaths averted. Results Using a program where travellers would be reimbursed for 80% of the cost of the cheapest malaria chemoprophylaxis is dominant (i.e. cost saving and more effective than the current situation) using the assumption that currently 68.7% of travellers to West Africa use malaria chemoprophylaxis. If the current usage of malaria chemoprophylaxis would be higher, 82.4%, the incremental cost per malaria case averted is € 2'302. The incremental cost of malaria death averted is € 191'833. The most important factors influencing the model were: the proportion of travellers using malaria chemoprophylaxis, the probability of contracting malaria without malaria chemoprophylaxis, the cost of the mefloquine regimen, the decrease in the number of travellers without malaria chemoprophylaxis in the reimbursement strategy. Conclusions This study suggests that a reimbursement of 80% of the cost of the cheapest effective malaria chemoprophylaxis (mefloquine) for travellers from Switzerland to West Africa is highly effective in terms of malaria

  9. Ciguatera fish poisoning on the West Africa Coast: An emerging risk in the Canary Islands (Spain).

    PubMed

    Boada, Luis D; Zumbado, Manuel; Luzardo, Octavio P; Almeida-González, Maira; Plakas, Steven M; Granade, Hudson R; Abraham, Ann; Jester, Edward L E; Dickey, Robert W

    2010-12-01

    Ciguatera fish poisoning (CFP) is endemic in certain tropical and subtropical regions of the world. CFP had not been described on the West Africa Coast until a 2004 outbreak in the Canary Islands. In 2008-2009, two additional outbreaks of ciguatera occurred. Individuals afflicted had consumed lesser amberjack (Seriola rivoliana) captured from nearby waters. Caribbean ciguatoxin-1 (C-CTX-1) was confirmed in fish samples by LC-MS/MS. Ciguatoxic fish in this region may pose a new health risk for the seafood consumer. PMID:20692274

  10. The Predictability of Dry-Season Precipitation in Tropical West Africa

    NASA Astrophysics Data System (ADS)

    Knippertz, P.; Davis, J.; Fink, A. H.

    2012-04-01

    Precipitation during the boreal winter dry season in tropical West Africa is rare but occasionally connected to high-impacts for the local population. Previous work has shown that these events are usually connected to a trough over northwestern Africa, an extensive cloud plume on its eastern side, unusual precipitation at the northern and western fringes of the Sahara, and reduced surface pressure over the southern Sahara and Sahel, which allows an inflow of moist southerlies from the Gulf of Guinea to feed the unusual dry-season rainfalls. These results also suggest that the extratropical influence enhances the predictability of these events on the synoptic timescale. Here we further investigate this question for the 11 dry seasons (November-March) 1998/99-2008/09 using rainfall estimates from TRMM (Tropical Rainfall Measuring Mission) and GPCP (Global Precipitation Climatology Project), and operational ensemble predictions from the European Centre for Medium-Range Forecasts (ECMWF). All fields are averaged over the study area 7.5-15°N, 10°W-10°E that spans most of southern West Africa. For each 0000 UTC analysis time, the daily precipitation estimates are accumulated to pentads and compared with 120-hour predictions starting at the same time. Compared to TRMM, the ensemble mean shows a weak positive bias, whereas there is a substantial negative bias with regard to GPCP. Temporal correlations reach a high value of 0.8 for both datasets, showing similar synoptic variability despite the differences in total amount. Standard probabilistic evaluation methods such as relative operating characteristic (ROC) diagrams indicate remarkably good reliability, resolution and skill, particularly for lower precipitation thresholds. Not surprisingly, forecasts cluster at low probabilities for higher thresholds, but the reliability and ROC score are still reasonably high. The results show that global ensemble prediction systems are capable to predict dry-season rainfall events

  11. [Contribution to the cytotaxonomy of shrews (Mammalia, Insectivora) from West Africa].

    PubMed

    Meylan, A; Vogel, P

    1982-01-01

    Chromosomes analysis of 28 shrews belonging to the genus Crocidura from West Africa allowed the detection of five new karyotypes: C. wimmeri (2n = 50, NF = 84), C. cf. gracilipes (56/86), C. cf. nimbae (46/68), and C. cf. planiceps (44/72). Among the individuals identified morphologically as C. poensis (52/70) a distinct species was recognized on the basis of its chromosome complement, C. nigeriae (50/76). The karyotype of C. occidentalis was confirmed with the study of another subspecies, C. occidentalis manni (50/66). An identical chromosome set characterizes C. odorata giffardi and provides evidence for its relationship with C. occidentalis. PMID:7151493

  12. Ethical challenges posed by the Ebola virus epidemic in West Africa.

    PubMed

    Omonzejele, Peter F

    2014-12-01

    This paper examines how people in West Africa are reacting to the Ebola virus disease, an epidemic presently prevalent in the region. Certain lifestyle changes are suggested. Additionally, the heart of the paper focuses on the request by governments to be allowed access to experimental drugs, such as Zmapp and TKM-Ebola, for their infected populations. The author argues that granting such a request would circumvent research ethics procedures, which could potentially constitute significant risk to users of the drugs. The Pfizer Kano meningitis trial of 1996 is cited as an example to buttress how unapproved drugs could prove fatal. PMID:25387576

  13. Agriculture in West Africa in the Twenty-First Century: Climate Change and Impacts Scenarios, and Potential for Adaptation.

    PubMed

    Sultan, Benjamin; Gaetani, Marco

    2016-01-01

    West Africa is known to be particularly vulnerable to climate change due to high climate variability, high reliance on rain-fed agriculture, and limited economic and institutional capacity to respond to climate variability and change. In this context, better knowledge of how climate will change in West Africa and how such changes will impact crop productivity is crucial to inform policies that may counteract the adverse effects. This review paper provides a comprehensive overview of climate change impacts on agriculture in West Africa based on the recent scientific literature. West Africa is nowadays experiencing a rapid climate change, characterized by a widespread warming, a recovery of the monsoonal precipitation, and an increase in the occurrence of climate extremes. The observed climate tendencies are also projected to continue in the twenty-first century under moderate and high emission scenarios, although large uncertainties still affect simulations of the future West African climate, especially regarding the summer precipitation. However, despite diverging future projections of the monsoonal rainfall, which is essential for rain-fed agriculture, a robust evidence of yield loss in West Africa emerges. This yield loss is mainly driven by increased mean temperature while potential wetter or drier conditions as well as elevated CO2 concentrations can modulate this effect. Potential for adaptation is illustrated for major crops in West Africa through a selection of studies based on process-based crop models to adjust cropping systems (change in varieties, sowing dates and density, irrigation, fertilizer management) to future climate. Results of the cited studies are crop and region specific and no clear conclusions can be made regarding the most effective adaptation options. Further efforts are needed to improve modeling of the monsoon system and to better quantify the uncertainty in its changes under a warmer climate, in the response of the crops to such

  14. Agriculture in West Africa in the Twenty-First Century: Climate Change and Impacts Scenarios, and Potential for Adaptation

    PubMed Central

    Sultan, Benjamin; Gaetani, Marco

    2016-01-01

    West Africa is known to be particularly vulnerable to climate change due to high climate variability, high reliance on rain-fed agriculture, and limited economic and institutional capacity to respond to climate variability and change. In this context, better knowledge of how climate will change in West Africa and how such changes will impact crop productivity is crucial to inform policies that may counteract the adverse effects. This review paper provides a comprehensive overview of climate change impacts on agriculture in West Africa based on the recent scientific literature. West Africa is nowadays experiencing a rapid climate change, characterized by a widespread warming, a recovery of the monsoonal precipitation, and an increase in the occurrence of climate extremes. The observed climate tendencies are also projected to continue in the twenty-first century under moderate and high emission scenarios, although large uncertainties still affect simulations of the future West African climate, especially regarding the summer precipitation. However, despite diverging future projections of the monsoonal rainfall, which is essential for rain-fed agriculture, a robust evidence of yield loss in West Africa emerges. This yield loss is mainly driven by increased mean temperature while potential wetter or drier conditions as well as elevated CO2 concentrations can modulate this effect. Potential for adaptation is illustrated for major crops in West Africa through a selection of studies based on process-based crop models to adjust cropping systems (change in varieties, sowing dates and density, irrigation, fertilizer management) to future climate. Results of the cited studies are crop and region specific and no clear conclusions can be made regarding the most effective adaptation options. Further efforts are needed to improve modeling of the monsoon system and to better quantify the uncertainty in its changes under a warmer climate, in the response of the crops to such

  15. Improving agricultural drought monitoring in West Africa using root zone soil moisture estimates derived from NDVI

    NASA Astrophysics Data System (ADS)

    McNally, A.; Funk, C. C.; Yatheendradas, S.; Michaelsen, J.; Cappelarere, B.; Peters-Lidard, C. D.; Verdin, J. P.

    2012-12-01

    The Famine Early Warning Systems Network (FEWS NET) relies heavily on remotely sensed rainfall and vegetation data to monitor agricultural drought in Sub-Saharan Africa and other places around the world. Analysts use satellite rainfall to calculate rainy season statistics and force crop water accounting models that show how the magnitude and timing of rainfall might lead to above or below average harvest. The Normalized Difference Vegetation Index (NDVI) is also an important indicator of growing season progress and is given more weight over regions where, for example, lack of rain gauges increases error in satellite rainfall estimates. Currently, however, near-real time NDVI is not integrated into a modeling framework that informs growing season predictions. To meet this need for our drought monitoring system a land surface model (LSM) is a critical component. We are currently enhancing the FEWS NET monitoring activities by configuring a custom instance of NASA's Land Information System (LIS) called the FEWS NET Land Data Assimilation System. Using the LIS Noah LSM, in-situ measurements, and remotely sensed data, we focus on the following questions: What is the relationship between NDVI and in-situ soil moisture measurements over the West Africa Sahel? How can we use this relationship to improve modeled water and energy fluxes over the West Africa Sahel? We investigate soil moisture and NDVI cross-correlation in the time and frequency domain to develop a transfer function model to predict soil moisture from NDVI. This work compares sites in southwest Niger, Benin, Burkina Faso, and Mali to test the generality of the transfer function. For several sites with fallow and millet vegetation in the Wankama catchment in southwest Niger we developed a non-parametric frequency response model, using NDVI inputs and soil moisture outputs, that accurately estimates root zone soil moisture (40-70cm). We extend this analysis by developing a low order parametric transfer function

  16. A hindcast study of the extreme wave climate of offshore west Africa (WAX)

    SciTech Connect

    Cardone, V.J.; Cooper, C.K.; Szabo, D.

    1995-12-01

    This paper describes the methodology and selected results of a Joint Industry Project called WAX (West Africa Extremes) whose purpose was to develop estimates of extreme waves for the West Coast of Africa between 5 N and 15 S. Extreme waves there consist of swell propagated from distant sources associated with extratropical storms in deep southern latitudes or from episodic enhancements of anticyclonic southeast winds off South Africa. The basic steps of the hindcast method are described: storm selection, specification of wind fields, application of a directional spectral wave prediction model, model validation and external analysis of results of hindcasts of the historical storm population selected. The validation consisted of a comparison of wave model predictions and measurements of significant wave height, peak spectral period and frequency spectra during several episodes of extreme swell conditions, selected from wave measurements recorded at a platform offshore Nigeria over a two-year period (1981--82) and over a 12-month period (1990--91) by a Waverider buoy moored offshore Cabinda. It was found that despite the special difficulties of hindcasting the wind fields of Southern Hemisphere (SH) storms caused by sparsity of meteorological data, the hindcast skill exhibited in these comparisons is comparable with the good agreement typically achieved in Northern Hemisphere (NH) basins with the hindcast methodology applied. The wave model used for these hindcasts has been well validated in NH basins mainly in extreme storm regimes where the source terms which model the physical mechanisms of wave growth and dissipation dominate the model solution. The WAX extremes are derived from hindcasts of a population of 50 historical storms. The extremes are summarized for selected areas.

  17. Genetic Diversity of Newcastle Disease Virus in Wild Birds and Pigeons in West Africa

    PubMed Central

    Snoeck, Chantal J.; Adeyanju, Adeniyi T.; Owoade, Ademola A.; Couacy-Hymann, Emmanuel; Alkali, Bello R.; Ottosson, Ulf

    2013-01-01

    In West and Central Africa, virulent Newcastle disease virus (NDV) strains of the recently identified genotypes XIV, XVII, and XVIII are enzootic in poultry, representing a considerable threat to the sector. The increasing number of reports of virulent strains in wild birds at least in other parts of the world raised the question of a potential role of wild birds in the spread of virulent NDV in sub-Saharan Africa as well. We investigated 1,723 asymptomatic birds sampled at live-bird markets and sites important for wild-bird conservation in Nigeria and 19 sick or dead wild birds in Côte d'Ivoire for NDV class I and II. Typical avirulent wild-type genotype I strains were found in wild waterfowl in wetlands in northeastern Nigeria. They were unrelated to vaccine strains, and the involvement of inter- or intracontinental migratory birds in their circulation in the region is suggested. Phylogenetic analyses also revealed that genotype VI strains found in pigeons, including some putative new subgenotype VIh and VIi strains, were introduced on multiple separate occasions in Nigeria. A single virulent genotype XVIII strain was found in a dead wild bird in Côte d'Ivoire, probably as a result of spillover from sick poultry. In conclusion, screening of wild birds and pigeons for NDV revealed the presence a variety of virulent and avirulent strains in West Africa but did not provide strong evidence that wild birds play an important role in the spread of virulent strains in the region. PMID:24123735

  18. Robust features of future climate change impacts on sorghum yields in West Africa

    NASA Astrophysics Data System (ADS)

    Sultan, B.; Guan, K.; Kouressy, M.; Biasutti, M.; Piani, C.; Hammer, G. L.; McLean, G.; Lobell, D. B.

    2014-10-01

    West Africa is highly vulnerable to climate hazards and better quantification and understanding of the impact of climate change on crop yields are urgently needed. Here we provide an assessment of near-term climate change impacts on sorghum yields in West Africa and account for uncertainties both in future climate scenarios and in crop models. Towards this goal, we use simulations of nine bias-corrected CMIP5 climate models and two crop models (SARRA-H and APSIM) to evaluate the robustness of projected crop yield impacts in this area. In broad agreement with the full CMIP5 ensemble, our subset of bias-corrected climate models projects a mean warming of +2.8 °C in the decades of 2031-2060 compared to a baseline of 1961-1990 and a robust change in rainfall in West Africa with less rain in the Western part of the Sahel (Senegal, South-West Mali) and more rain in Central Sahel (Burkina Faso, South-West Niger). Projected rainfall deficits are concentrated in early monsoon season in the Western part of the Sahel while positive rainfall changes are found in late monsoon season all over the Sahel, suggesting a shift in the seasonality of the monsoon. In response to such climate change, but without accounting for direct crop responses to CO2, mean crop yield decreases by about 16-20% and year-to-year variability increases in the Western part of the Sahel, while the eastern domain sees much milder impacts. Such differences in climate and impacts projections between the Western and Eastern parts of the Sahel are highly consistent across the climate and crop models used in this study. We investigate the robustness of impacts for different choices of cultivars, nutrient treatments, and crop responses to CO2. Adverse impacts on mean yield and yield variability are lowest for modern cultivars, as their short and nearly fixed growth cycle appears to be more resilient to the seasonality shift of the monsoon, thus suggesting shorter season varieties could be considered a potential

  19. The DACCIWA Project: Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter

    2014-05-01

    Massive economic and population growth and urbanisation are expected to lead to a tripling of anthropogenic emissions from southern West Africa (SWA) between 2000 and 2030, the impacts of which on human health, ecosystems, food security and the regional climate are largely unknown. An assessment of these impacts is complicated by (a) a superposition with effects of global climate change, (b) the strong dependence of SWA on the sensitive West African monsoon, (c) incomplete scientific understanding of interactions between emissions, clouds, radiation, precipitation and regional circulations and (d) by a lack of observations to advance our understanding and improve predictions. The purpose of this contribution is to introduce the research consortium DACCIWA (Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa), which comprises 16 partners in six European and West African countries. The interdisciplinary DACCIWA team will build on the scientific and logistical foundations established by the African Monsoon Multidisciplinary Analysis (AMMA) project and collaborate closely with operational centres. DACCIWA will receive funding of about M8.75€ from the European Commission as part of Framework Programme 7 from 2015 until 2018. The DACCIWA project will conduct extensive fieldwork in SWA to collect high-quality observations, spanning the entire process chain from surface-based natural and anthropogenic emissions to impacts on health, ecosystems and climate. This will include a major field campaign in summer 2015 with three research aircrafts and two ground-based supersites. Combining the resulting benchmark dataset with a wide range of modelling activities will allow us: (a) to assess all relevant physical and chemical processes, (b) to improve the monitoring of climate and compositional parameters from space, (c) to determine health impacts from air pollution, and (d) to develop the next generation of weather and climate models capable of representing coupled

  20. Summer Synoptic-Scale Waves over Tropical West Africa Observed by TRMM

    NASA Technical Reports Server (NTRS)

    Starr, David O. (Technical Monitor); Gu, Guojun; Adler, Robert F.; Huffman, George J.; Curtis, Scott

    2003-01-01

    A 5-year daily rainfall dataset (3B42) from TRMM (Tropical Rainfall Measuring Mission) is used to investigate the activity and properties of westward-propagating synoptic-scale waves over tropical West Africa. Evident wave signals appearing in wavenumber-frequency space show their modulations on the surface rainfall pattern during the boreal summer. Interannual variability exists in both their intensity and spectral properties, i. e., dominant frequency and wavenumber ranges. These variabilities can be partly ascribed to year-to-year variations of their embedded large-scale environment, especially the status of mid-tropospheric African easterly jet (AEJ). Generally, a stronger (weaker) AEJ indicates more (less) instability energy yielding a stronger (weaker) wave activity season. Seasonal mean rainfall has shown an impact on these waves in some years. However, the impact is not as clear and consistent as AEJ, implying the complexity of their relationship with large-scale environment. To fully understand interannual variability of synoptic-scale waves over tropical West Africa, including the variability in their preferred frequencies and wavenumbers, it is therefore necessary to examine possible intra-seasonal variations existing in both wave activity and large-scale fields, in addition to their structure, propagation, and associated convection.

  1. Establishment of a General Medicine Residency Training Program in Rural West Africa

    PubMed Central

    Drislane, Frank W.; Akpalu, Albert; Wegdam, Harry H.J.

    2014-01-01

    Ghana, a developing country in West Africa, has major medical burdens in taking care of a large population with limited resources. Its three medical schools produce more than 200 graduates per year, but most emigrate to developed lands after training. Ghana is working to educate and retain locally trained physicians, but it is difficult to get them to work in rural settings where the need is greatest. This article details the establishment of a General Medicine residency at a 150-bed hospital in rural Ghana. Early training comprises 6 months each in Medicine, Surgery, OB/GYN, and Pediatrics; the hospital in Techiman also has a Surgery residency. House officers choose the program for more hands-on experience than they can get in larger centers. They perform many tasks, including surgery, sooner and more independently than do residents in developed countries. The training program includes a morning report, clinical teaching rounds, and rotations on in-patient wards and in the Emergency Department and clinics. Teaching focuses on history, physical examination, good communication, and proper follow-up, with rigorous training in the OR and some clinical research projects pertinent to Ghana. Trainees work hard and learn from one another, from a dedicated faculty, and by evaluating and treating very sick patients. Ghana’s rural residencies offer rigorous and attractive training, but it is too soon to tell whether this will help stem the “brain drain” of young physicians out of West Africa. PMID:25191148

  2. Clinical manifestations of Waardenburg syndrome in a male adolescent in Mali, West Africa.

    PubMed

    Imperato, Pascal James; Imperato, Gavin H

    2015-02-01

    Waardenburg syndrome (WS) is a genetic disorder of which there are four distinct types. These four types are differentiated by the physical defects which they produce. Presented here is the case of a 13-year-old boy with WS Type I who was observed and physically assessed in Mali, West Africa in 1969. His physical findings included a bright blue coloring to the irises of the eyes, profound sensorineural deafness, mutism, dystopia canthorum (lateral displacement of the inner canthi of the eyes), broad nasal root, bushy eyebrows, and scaphoid deformities of the supraorbital portions of the frontal bone. Because family members were not available for interviews or physical examinations, it was not possible to determine if this patient was suffering from a congenital form of the disorder or from a spontaneous mutation. Given the patient's then location in a remote rural area of Mali where electricity was absent, it was not possible to perform additional diagnostic tests. The patient described here is the first with WS in Mali, West Africa to have been medically observed and evaluated and later documented in the medical literature. A second case of the syndrome in Mali was described in the medical literature in 2011 in an 18-month-old infant who did not have sensorineural hearing loss, but who did have a bilateral cleft lip. An historical overview of WS is presented along with details concerning the characteristics of the four types of the disorder. PMID:25224968

  3. Establishment of a general medicine residency training program in rural West Africa.

    PubMed

    Drislane, Frank W; Akpalu, Albert; Wegdam, Harry H J

    2014-09-01

    Ghana, a developing country in West Africa, has major medical burdens in taking care of a large population with limited resources. Its three medical schools produce more than 200 graduates per year, but most emigrate to developed lands after training. Ghana is working to educate and retain locally trained physicians, but it is difficult to get them to work in rural settings where the need is greatest. This article details the establishment of a General Medicine residency at a 150-bed hospital in rural Ghana. Early training comprises 6 months each in Medicine, Surgery, OB/GYN, and Pediatrics; the hospital in Techiman also has a Surgery residency. House officers choose the program for more hands-on experience than they can get in larger centers. They perform many tasks, including surgery, sooner and more independently than do residents in developed countries. The training program includes a morning report, clinical teaching rounds, and rotations on in-patient wards and in the Emergency Department and clinics. Teaching focuses on history, physical examination, good communication, and proper follow-up, with rigorous training in the OR and some clinical research projects pertinent to Ghana. Trainees work hard and learn from one another, from a dedicated faculty, and by evaluating and treating very sick patients. Ghana's rural residencies offer rigorous and attractive training, but it is too soon to tell whether this will help stem the "brain drain" of young physicians out of West Africa. PMID:25191148

  4. Neogene cratonic erosion fluxes and landform evolution processes from regional regolith mapping (Burkina Faso, West Africa)

    NASA Astrophysics Data System (ADS)

    Grimaud, Jean-Louis; Chardon, Dominique; Metelka, Václav; Beauvais, Anicet; Bamba, Ousmane

    2015-07-01

    The regionally correlated and dated regolith-paleolandform sequence of Sub-Saharan West Africa offers a unique opportunity to constrain continental-scale regolith dynamics as the key part of the sediment routing system. In this study, a regolith mapping protocol is developed and applied at the scale of Southwestern Burkina Faso. Mapping combines field survey and remote sensing data to reconstruct the topography of the last pediplain that formed over West Africa in the Early and Mid-Miocene (24-11 Ma). The nature and preservation pattern of the pediplain are controlled by the spatial variation of bedrock lithology and are partitioned among large drainage basins. Quantification of pediplain dissection and drainage growth allows definition of a cratonic background denudation rate of 2 m/My and a minimum characteristic timescale of 20 Ma for shield resurfacing. These results may be used to simulate minimum export fluxes of drainage basins of constrained size over geological timescales. Background cratonic denudation results in a clastic export flux of ~ 4 t/km2/year, which is limited by low denudation efficiency of slope processes and correlatively high regolith storage capacity of tropical shields. These salient characteristics of shields' surface dynamics would tend to smooth the riverine export fluxes of shields through geological time.

  5. Mechanisms Linking Land Use and Regional Climate Changes in West Africa

    NASA Astrophysics Data System (ADS)

    Wang, G.; Ahmed, K. F.; Yu, M.; JI, Z.; Pal, J. S.

    2014-12-01

    Land use land cover change is an important driver for regional climate changes in West Africa due to the strong land-atmosphere coupling. On the other hand, land use is also strongly influenced by climate changes due to the primarily rain-fed agriculture in this region and the relatively low capacity to adapt. It is therefore important that projections for future climate changes or land use changes account for the impact of the feedback between land use and climate. Land use influences regional climate through several different pathways, including changes in surface biogeophysical properties (e.g., surface albedo, Bowen ratio, surface roughness) that have been widely studied, and changes in the dynamic properties of the land surface influencing dust emission. The relative importance of these two pathways is likely to be model dependent and region dependent. In this study the effects of these two pathways will be evaluated and compared, based on results from a modeling framework that includes a regional climate-vegetation model, a crop growth model, an agricultural economics model, and a land use allocation model. This will be conducted in the context of future land use and climate change projections, with the ultimate objective to assess how agricultural land use in West Africa may change driven by climate and socioeconomic changes, and how the resulting land use change may further modify regional climate in the future.

  6. Temporal variations in the effective reproduction number of the 2014 west Africa ebola outbreak.

    PubMed

    Towers, Sherry; Patterson-Lomba, Oscar; Castillo-Chavez, Carlos

    2014-01-01

    Background The rapidly evolving 2014 Ebola virus disease (EVD) outbreak in West Africa is the largest documented in history, both in terms of the number of people infected and in the geographic spread. The high morbidity and mortality have inspired response strategies to the outbreak at the individual, regional, and national levels. Methods to provide real-time assessment of changing transmission dynamics are critical to the understanding of how these adaptive intervention measures have affected the spread of the outbreak. Methods In this analysis, we use the time series of EVD cases in Guinea, Sierra Leone, and Liberia up to September 8, 2014, and employ novel methodology to estimate how the rate of exponential rise of new cases has changed over the outbreak using piecewise fits of exponential curves to the outbreak data. Results We find that for Liberia and Guinea, the effective reproduction number rose, rather than fell, around the time that the outbreak spread to densely populated cities, and enforced quarantine was imposed on several regions in the countries; this may indicate that enforced quarantine may not be an effective control measure. Conclusions If effective control measures are not put in place, and the current rate of exponential rise of new cases continues, we predict 4400 new Ebola cases in West Africa during the last half of the month of September, with an upper 95% confidence level of 6800 new cases. PMID:25642357

  7. Climate change impacts on river discharge in West Africa: a review

    NASA Astrophysics Data System (ADS)

    Roudier, P.; Ducharne, A.; Feyen, L.

    2014-02-01

    This review summarizes the impacts of climate change on runoff in West Africa, assesses the uncertainty in the projections and describes future research needs for the region. To do so, we constitute a meta-database made of 19 studies and 301 future runoff change values. The future tendency in streamflow developments is overall very uncertain (median of the 301 points is 0% and mean +5.2%), except for (i) the Gambia River which exhibits a significant negative change (median = -4.5%) and (ii) the Sassandra and the Niger Rivers where the change is much more positive (+14.4 and +6.1%). A correlation analysis revealed that runoff changes are tightly linked to changes in rainfall (R = 0.49), and to a smaller extent also to changes in PET. Other parameters than climate such as the carbon effect on plant water efficiency, land use dynamics or water withdrawals could also significantly impact on runoff, but they generally do not offset the effects of climate change. In view of the potential changes, the large uncertainty therein, and the high vulnerability of the region to such changes, there is an urgent need for integrated studies that quantify the potential effects of these processes on water resources in West Africa. We especially underline the lack of information concerning projections of future floods and droughts, and of inter-annual fluctuations in streamflows.

  8. Gravity-driven structures and rift basin evolution: Rio Muni Basin, offshore equatorial West Africa

    SciTech Connect

    Turner, J.P.

    1995-08-01

    Offshore Equatorial Guinea, west Africa, gravity-driven nappes, more than 1 km thick and 15 km from head to toe, provide key evidence in reconstructing the late synrift: evolution of this part of the South Atlantic margin basin system. Furthermore, Aptian-Cenomanian carbonate and clastic rocks in the nappes` allochthonous hanging walls are attracting interest as a new exploration play in west Africa. The nappes exhibit a range of geometries that suggest they share many of the same deformation processes as thin-skin thrust and linked extensional fault systems. Not only are these structures significant in their own right, representing a rare example of gravity tectonics in the virtual absence of major halokinesis, but their presence may record an other-wise undetectable process active during the transition from a rift basin to a passive continental margin. A review of Equatorial Guinea in its pre-Atlantic configuration, alongside neighboring basins in Brazil (the Sergipe-Alagoas basin) and Gabon, suggests that gravity gliding was sustained by a relatively steep, westward paleoslope promoted by east-ward offset of the locus of thermal uplift from the rift basin (i.e., a simple shear model of basin formation). In contrast to gravity-driven structures in most postrift settings, the Equatorial Guinea nappes developed at the close of the Aptian-Albian synrift episode in response to a growing bathymetric deep caused by rapid subsidence outpacing restricted sedimentation.

  9. HOx observations over West Africa during AMMA: impact of isoprene and NOx

    NASA Astrophysics Data System (ADS)

    Stone, D.; Evans, M. J.; Commane, R.; Ingham, T.; Floquet, C. F. A.; McQuaid, J. B.; Brookes, D. M.; Monks, P. S.; Purvis, R.; Hamilton, J. F.; Hopkins, J.; Lee, J.; Lewis, A. C.; Stewart, D.; Murphy, J. G.; Mills, G.; Oram, D.; Reeves, C. E.; Heard, D. E.

    2010-10-01

    Aircraft OH and HO2 measurements made over West Africa during the AMMA field campaign in summer 2006 have been investigated using a box model constrained to observations of long-lived species and physical parameters. "Good" agreement was found for HO2 (modelled to observed gradient of 1.23 ± 0.11). However, the model significantly overpredicts OH concentrations. The reasons for this are not clear, but may reflect instrumental instabilities affecting the OH measurements. Within the model, HOx concentrations in West Africa are controlled by relatively simple photochemistry, with production dominated by ozone photolysis and reaction of O(1D) with water vapour, and loss processes dominated by HO2 + HO2 and HO2 + RO2. Isoprene chemistry was found to influence forested regions. In contrast to several recent field studies in very low NOx and high isoprene environments, we do not observe any dependence of model success for HO2 on isoprene and attribute this to efficient recycling of HOx through RO2 + NO reactions under the moderate NOx concentrations (5-300 ppt NO in the boundary layer, median 76 ppt) encountered during AMMA. This suggests that some of the problems with understanding the impact of isoprene on atmospheric composition may be limited to the extreme low range of NOx concentrations.

  10. Calibration and uncertainty issues of a hydrological model (SWAT) applied to West Africa

    NASA Astrophysics Data System (ADS)

    Schuol, J.; Abbaspour, K. C.

    2006-09-01

    Distributed hydrological models like SWAT (Soil and Water Assessment Tool) are often highly over-parameterized, making parameter specification and parameter estimation inevitable steps in model calibration. Manual calibration is almost infeasible due to the complexity of large-scale models with many objectives. Therefore we used a multi-site semi-automated inverse modelling routine (SUFI-2) for calibration and uncertainty analysis. Nevertheless, the question of when a model is sufficiently calibrated remains open, and requires a project dependent definition. Due to the non-uniqueness of effective parameter sets, parameter calibration and prediction uncertainty of a model are intimately related. We address some calibration and uncertainty issues using SWAT to model a four million km2 area in West Africa, including mainly the basins of the river Niger, Volta and Senegal. This model is a case study in a larger project with the goal of quantifying the amount of global country-based available freshwater. Annual and monthly simulations with the "calibrated" model for West Africa show promising results in respect of the freshwater quantification but also point out the importance of evaluating the conceptual model uncertainty as well as the parameter uncertainty.

  11. Viral bioterrorism: Learning the lesson of Ebola virus in West Africa 2013-2015.

    PubMed

    Cenciarelli, Orlando; Gabbarini, Valentina; Pietropaoli, Stefano; Malizia, Andrea; Tamburrini, Annalaura; Ludovici, Gian Marco; Carestia, Mariachiara; Di Giovanni, Daniele; Sassolini, Alessandro; Palombi, Leonardo; Bellecci, Carlo; Gaudio, Pasquale

    2015-12-01

    Among the potential biological agents suitable as a weapon, Ebola virus represents a major concern. Classified by the CDC as a category A biological agent, Ebola virus causes severe hemorrhagic fever, characterized by high case-fatality rate; to date, no vaccine or approved therapy is available. The EVD epidemic, which broke out in West Africa since the late 2013, has got the issue of the possible use of Ebola virus as biological warfare agent (BWA) to come to the fore once again. In fact, due to its high case-fatality rate, population currently associates this pathogen to a real and tangible threat. Therefore, its use as biological agent by terrorist groups with offensive purpose could have serious repercussions from a psychosocial point of view as well as on closely sanitary level. In this paper, after an initial study of the main characteristics of Ebola virus, its potential as a BWA was evaluated. Furthermore, given the spread of the epidemic in West Africa in 2014 and 2015, the potential dissemination of the virus from an urban setting was evaluated. Finally, it was considered the actual possibility to use this agent as BWA in different scenarios, and the potential effects on one or more nation's stability. PMID:26359111

  12. First report of sylvatic DENV-2-associated dengue hemorrhagic fever in West Africa.

    PubMed

    Franco, Leticia; Palacios, Gustavo; Martinez, José Antonio; Vázquez, Ana; Savji, Nazir; De Ory, Fernando; Sanchez-Seco, María Paz; Martín, Dolores; Lipkin, W Ian; Tenorio, Antonio

    2011-08-01

    Dengue virus (DENV) circulates in human and sylvatic cycles. Sylvatic strains are both ecologically and evolutionarily distinct from endemic viruses. Although sylvatic dengue cycles occur in West African countries and Malaysia, only a few cases of mild human disease caused by sylvatic strains and one single case of dengue hemorrhagic fever in Malaysia have been reported. Here we report a case of dengue hemorrhagic fever (DHF) with thrombocytopenia (13000/µl), a raised hematocrit (32% above baseline) and mucosal bleeding in a 27-year-old male returning to Spain in November 2009 after visiting his home country Guinea Bissau. Sylvatic DENV-2 West African lineage was isolated from blood and sera. This is the first case of DHF associated with sylvatic DENV-2 in Africa and the second case worldwide of DHF caused by a sylvatic strain. PMID:21829739

  13. Sociocultural aspects of risk to pregnant women during the 2013-2015 multinational Ebola virus outbreak in West Africa.

    PubMed

    Strong, Adrienne; Schwartz, David A

    2016-08-01

    Researchers reflect on sociocultural aspects of the Ebola outbreak in West Africa and critically analyze the epidemic's effects on pregnant mothers and their babies. We address structural inequalities contributing to poor maternal health in lower-income countries, while reflecting on how the Ebola outbreak highlights the still-marginalized role of pregnant women. Drawing on prior research in West and East Africa, we discuss health care providers' responses to risk of infection during maternity work under normal circumstances and in times of crisis. We end with recommendations for preventing such detrimental effects on the health of pregnant women in the case of another epidemic. PMID:26985811

  14. Reasons why West Africa continues to be a hotbed for hepatocellular carcinoma

    PubMed Central

    Tognarelli, Joshua; Ladep, Nimzing G.; Crossey, Mary M. E.; Okeke, Edith; Duguru, Mary; Banwat, Edmund; Taylor-Robinson, Simon D.

    2015-01-01

    Hepatocellular carcinoma (HCC) exhibits a huge disease burden on West Africa, with a large proportion of all HCC cases worldwide occurring in the sub-region. The high HCC prevalence is due to the endemicity of a number of risk factors, most notably hepatitis B, C and HIV. West African HCC also displays a poor prognosis. Generally speaking, this is owing to more aggressive tumours, late patient presentation and inadequate management. Exposure to chronic viral hepatitis, more carcinogenic West African strains of hepatitis B virus and carcinogens such as aflatoxin B1 all encourage tumour growth. Lack of patient confidence in the healthcare system contributes to poor health-seeking behaviors and management of the disease can be lacking, due in part to poor health infrastructure, resources available and lack of access to expensive treatment. There is also much we do not know about West African HCC, especially the effect rising obesity and alcohol use may have on this disease in the future. Suggestions for improvement are discussed, including surveillance of high-risk groups. Although there is much to be done before West African HCC is thought to be a curable disease, many steps have been taken to move in the right direction. PMID:26759504

  15. AMMA-CATCH studies in the Sahelian region of West-Africa: An overview

    NASA Astrophysics Data System (ADS)

    Lebel, Thierry; Cappelaere, Bernard; Galle, Sylvie; Hanan, Niall; Kergoat, Laurent; Levis, Samuel; Vieux, Baxter; Descroix, Luc; Gosset, Marielle; Mougin, Eric; Peugeot, Christophe; Seguis, Luc

    2009-08-01

    SummaryThe African Monsoon Multidisciplinary Analysis (AMMA) is an international and interdisciplinary experiment designed to investigate the interactions between atmospheric, oceanic and terrestrial systems and their joint controls on tropical monsoon dynamics in West Africa. This special issue reports results from a group of AMMA studies regrouped in the component " Couplage de l'Atmosphère Tropicale et du Cycle Hydrologique" (CATCH). AMMA-CATCH studies focus on measuring and understanding land surface properties and processes in West Africa, the role of terrestrial systems in altering boundary layer dynamics, and thus the potential that surface hydrology and biology, and human land use practices, may directly or indirectly affect monsoon dynamics and rainfall in the region. AMMA-CATCH studies focus on three intensively instrumented mesoscale sites in Mali, Niger and Benin that sample across the 100-1300 mm/annum rainfall gradient of the Sahel, Sudan and North-Guinean bioclimatic zones. Studies report on: (i) surface-boundary layer interactions that may influence atmospheric convergence and convective processes and thus rainfall type, timing and amount; (ii) vegetation dynamics at seasonal to decadal time-scales that may respond to, and alter, atmospheric processes; (iii) surface-atmosphere fluxes of heat, water and carbon dioxide that directly influence the atmosphere; (iv) soil moisture variability in space and time that provide the proximate control on vegetation activity, evapotranspiration and energy balance; and (v) local and mesoscale modeling of hydrology and land surface-atmosphere exchanges to assess their role in the hydrological, atmospheric and rainfall dynamics of West Africa. The AMMA-CATCH research reported in this issue will be extended in future years as measurements and analysis continue and are concluded within the context of both CATCH and the wider AMMA study. This body of research will contribute to an improved understanding of the

  16. Kinematic structures, diabatic profiles, and precipitation systems in West Africa during summer 2006

    NASA Astrophysics Data System (ADS)

    Davis, Adam James

    This work uses a gridded analysis of radiosonde measurements obtained during AMMA and places those observations in the context of African Monsoon Multidisciplinary Analysis (AMMA) radar data and satellite rainfall estimates to examine the patterns of kinematic and diabatic quantities in West Africa relative to the summer monsoon phase, easterly wave disturbances, precipitation systems, and the diurnal cycle. Many unique aspects of West African weather compared to conditions elsewhere in the tropics are revealed by this study. The meridional transitions related to the West African monsoon comprise the predominant control on the location and intensity of precipitation at seasonal time scales, with variations in convective activity related to the Madden-Julian Oscillation contributing at 25 to 60 day periods. On shorter time scales of two to six days, easterly wave disturbances look to be the principal factor governing the timing of rainfall events, though especially persistent cold pools and residual cloudiness generated by thunderstorm systems also act as constraints on convective evolution on the days following a precipitation episode. One of the most distinctive traits of the study region in West Africa compared to other tropical areas is the particular prevalence of convective downdrafts, chiefly those associated with mesoscale zones of stratiform precipitation in thunderstorm complexes. These features, along with the gravity waves forced by their characteristic heating pattern, have an especially large influence on the time-mean atmospheric structure relative to the majority of the tropics. A comparison of the diabatic profiles from the AMMA dataset with those from other field projects indicates that the signals of both convective downdrafts and diurnal variations of the planetary boundary layer are much stronger in West Africa than in the previously studied regions. Beyond the mentioned differences, though, the AMMA profiles show resemblance to those from both

  17. Disagreements in low-level moisture between (re)analyses over summertime West Africa

    NASA Astrophysics Data System (ADS)

    Roberts, Alexander; Marsham, John; Knippertz, Peter

    2016-04-01

    Reanalysis and operational analysis products are routinely used as the best estimates of the atmospheric state for operational and research purposes. However, different models, assimilation techniques, and assimilated datasets lead to differences between products. Here, such differences in the distribution of low-level water vapor over summertime West Africa are analyzed, as reflected in the zonal mean position of the leading edge of the West African monsoon. Five reanalysis products (NCEP-NCAR, NCEP-DOE, MERRA, CFSR and ECMWF ERA-Interim) and two operational analyses (GFS and ECMWF) are studied over 11 monsoon seasons (2000 to 2010). Specific humidity differences regularly reach 50% of the mean value over areas spanning hundreds of kilometers and often coincide with northward excursions of the ITD. These events can last several days and bring unusual rainfall to the Sahel and Sahara. The retreat phase of the monsoon excursions coincides with the peak disagreement between the ensemble of (re)analysis products and are connected with anomalously high values of aerosol optical depth (AOD). The rainfall patterns and presence of high AOD anomalies are consistent with the production of haboob dust storms. This suggests that known errors in the representation of moist convection and cold pools may contribute to the identified disagreements. Disagreement between products was lowest in 2006. During this monsoon season upper-air observations were enhanced as part of the African Monsoon Multidisciplinary Analysis (AMMA) campaign. This points to insufficient observational constraint of the (re)analyses that was greatly improved in 2006. It is hoped that this work will raise awareness of the limited reliability of (re)analysis products over West Africa during the summer, particularly during northward surges of the ITD, and will instigate further work to improve their quality.

  18. Isoprene emissions modelling for West Africa: MEGAN model evaluation and sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Ferreira, J.; Reeves, C. E.; Murphy, J. G.; Garcia-Carreras, L.; Parker, D. J.; Oram, D. E.

    2010-09-01

    Isoprene emissions are the largest source of reactive carbon to the atmosphere, with the tropics being a major source region. These natural emissions are expected to change with changing climate and human impact on land use. As part of the African Monsoon Multidisciplinary Analyses (AMMA) project the Model of Emissions of Gases and Aerosols from Nature (MEGAN) has been used to estimate the spatial and temporal distribution of isoprene emissions over the West African region. During the AMMA field campaign, carried out in July and August 2006, isoprene mixing ratios were measured on board the FAAM BAe-146 aircraft. These data have been used to make a qualitative evaluation of the model performance. MEGAN was firstly applied to a large area covering much of West Africa from the Gulf of Guinea in the south to the desert in the north and was able to capture the large scale spatial distribution of isoprene emissions as inferred from the observed isoprene mixing ratios. In particular the model captures the transition from the forested area in the south to the bare soils in the north, but some discrepancies have been identified over the bare soil, mainly due to the emission factors used. Sensitivity analyses were performed to assess the model response to changes in driving parameters, namely Leaf Area Index (LAI), Emission Factors (EF), temperature and solar radiation. A high resolution simulation was made of a limited area south of Niamey, Niger, where the higher concentrations of isoprene were observed. This is used to evaluate the model's ability to simulate smaller scale spatial features and to examine the influence of the driving parameters on an hourly basis through a case study of a flight on 17 August 2006. This study highlights the complex interactions between land surface processes and the meteorological dynamics and chemical composition of the PBL. This has implications for quantifying the impact of biogenic emissions on the atmospheric composition over West

  19. Satellite-based Assessment of Fire Impacts on Ecosystem Changes in West Africa

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles

    2008-01-01

    Fires bum many vegetated regions of the world to a variety of degrees and frequency depending on season. Extensive biomass burning occurs in most parts of sub-Saharan Africa, posing great threat to ecosystem stability among other real and potential adverse impacts. In Africa, such landscape-scale fires are used for various agricultural purposes, including land clearing and hunting, although there may be a limited number of cases of fires ignited by accident or due to arson. Satellite remote sensing provides the most practical means of mapping fires, because of their sudden and aggressive nature coupled with the tremendous heat they generate. Recent advancements in satellite technology has enabled, not only the identification of fire locations, but also the measurement of fire radiative energy (FRE) release rate or power (FRP), which has been found to have a direct linear relationship with the rate of biomass combustion. A recent study based on FRP measurements from the Moderate-resolution imaging Spectro-radiometer (MODIS) sensor aboard the Terra and Aqua satellites revealed that, among all the regions of the world where fires occur, African regions rank the highest in the intensity of biomass burning per unit area of land during the peak of the burning season. In this study, we will analyze the burning patterns in West Africa during the last several years and examine the extent of their impacts on the ecosystem dynamics, using a variety of satellite data. The study introduces a unique methodology that can be used to build up the knowledge base from which decision makers can obtain scientific information in fomulating policies for regulating biomass burning in the region.

  20. A Mycobacterial Perspective on Tuberculosis in West Africa: Significant Geographical Variation of M. africanum and Other M. tuberculosis Complex Lineages

    PubMed Central

    Gehre, Florian; Kumar, Samrat; Kendall, Lindsay; Ejo, Mebrat; Secka, Oumie; Ofori-Anyinam, Boatema; Abatih, Emmanuel; Antonio, Martin; Berkvens, Dirk; de Jong, Bouke C.

    2016-01-01

    Background Phylogenetically distinct Mycobacterium tuberculosis lineages differ in their phenotypes and pathogenicity. Consequently, understanding mycobacterial population structures phylogeographically is essential for design, interpretation and generalizability of clinical trials. Comprehensive efforts are lacking to date to establish the West African mycobacterial population structure on a sub-continental scale, which has diagnostic implications and can inform the design of clinical TB trials. Methodology/Principal Findings We collated novel and published genotyping (spoligotyping) data and classified spoligotypes into mycobacterial lineages/families using TBLineage and Spotclust, followed by phylogeographic analyses using statistics (logistic regression) and lineage axis plot analysis in GenGIS, in which a phylogenetic tree constructed in MIRU-VNTRplus was analysed. Combining spoligotyping data from 16 previously published studies with novel data from The Gambia, we obtained a total of 3580 isolates from 12 countries and identified 6 lineages comprising 32 families. By using stringent analytical tools we demonstrate for the first time a significant phylogeographic separation between western and eastern West Africa not only of the two M. africanum (West Africa 1 and 2) but also of several major M. tuberculosis sensu stricto families, such as LAM10 and Haarlem 3. Moreover, in a longitudinal logistic regression analysis for grouped data we showed that M. africanum West Africa 2 remains a persistent health concern. Conclusions/Significance Because of the geographical divide of the mycobacterial populations in West Africa, individual research findings from one country cannot be generalized across the whole region. The unequal geographical family distribution should be considered in placement and design of future clinical trials in West Africa. PMID:26964059

  1. The prevalence, awareness, and control of hypertension among workers in West Africa: a systematic review

    PubMed Central

    Bosu, William K.

    2015-01-01

    Background Interventions in workplace settings are considered to be cost-effective in preventing cardiovascular diseases. A systematic review was conducted to assess the prevalence of hypertension and the level of awareness and control among workers in West Africa. Design A systematic search for studies on formal and informal sector workers aged ≥15 years in West Africa published between 1980 and September 2014 was undertaken using the Ovid Medline, Embase, PubMed, and Google Scholar databases. Clinical and obstetric studies and studies that did not report prevalence were excluded. Data on study settings, characteristics of workers, blood pressure (BP) levels, prevalence of hypertension, and associated demographic factors were extracted. Results A total of 45 studies from six countries were identified involving 30,727 formal and informal sector workers. In 40 studies with a common definition of hypertension, the prevalence ranged from 12.0% among automobile garage workers to 68.9% among traditional chiefs. In 15 of these studies, the prevalence exceeded 30%. Typically sedentary workers such as traders, bank workers, civil servants, and chiefs were at high risk. Among health care workers, the prevalence ranged from 17.5 to 37.5%. The prevalence increased with age and was higher among males and workers with higher socio-economic status. Complications of hypertension, co-morbidities, and clustering of risk factors were common. The crude prevalence of hypertension increased progressively from 12.9% in studies published in the 1980s to 34.4% in those published in 2010–2014. The proportion of hypertensives who were previously aware of their diagnosis, were on treatment or had their BP controlled was 19.6–84.0%, 0–79.2%, and 0–12.7%, respectively. Hypertensive subjects, including health workers, rarely checked their BP except when they were ill. Conclusions There is a high prevalence of hypertension among West Africa's workforce, of which a significant

  2. South Africa.

    PubMed

    1985-05-01

    The 1983 population of South Africa was estimated at 31.1 million, with an annual growth rate of 2.5% (0.8% for whites, 1.8% for blacks and "coloreds," 1.8% for Asians, and 2.8% for Africans). The infant mortality rate was 14.9/1000 live births among whites, 80.6/1000 among blacks and coloreds, and 25.3/1000 among Asians. Life expectancy was 70 years for whites, 59 years for blacks and coloreds, 66 years for Asians, and 55 years for Africans. Racial discrimination has become increasingly institutionalized in South Africa since the ruling National Party came to power in 1948. The policy of apartheid calls for separate political institutions for the 4 major racial groups in the population. Africans are considered citizens of the homelands to which their tribal group is assigned, not permanent citizens of the country. Coloreds and Asians are considered citizens and given some political expression. The new political system envisions broad consensus among whites, coloreds, and Indians, and a parliamentary committee is considering possible abolition of laws against multiracial political activity. The work force totals 11 million, 30% of whom are engaged in agriculture, 29% are employed in industry and commerce, 34% work in the services sector, and 7% work in mining. The GNP in 1983 totalled US$75.5 billion and the GDP stood at US$73.2 billion. Per capita GNP was US$5239. PMID:12178120

  3. The impact of climate change on the main staple crops in West Africa

    NASA Astrophysics Data System (ADS)

    Sultan, B.; Philippe, R.; Baron, C.

    2011-12-01

    Adaptation of agriculture to climate change requires urgent improvement of our understanding of climate impacts on crop yields, particularly in tropical regions where climate directly threatens food security. However past studies report large uncertainties because of inconsistency between climate scenarios and limited representation of the prevailing cereal production systems. More than six years of trials and surveys in Africa enabled the design of SARRA-H, a process-based crop model able to represent accurately the diversity of farmers' cultivars and practices for the two main staple crops, sorghum and millet. Conducting more than 7,000 simulations, we find that, although uncertain, future climate and potential impacts will be very different from what was observed in the recent history because of the adverse role of temperature reducing crop yields whether rainfall increases or decreases. Results demonstrate that cultivars with a high yield potential and a short, nearly constant growth cycle, as pursued by most sorghum and millet breeders until recently to reduce the yield gap in West Africa, will be less adapted to climate change than traditional cultivars selected by farmers for centuries. Breeding strategies need therefore to address the trade-off between intensification of cropping systems and resilience to climate change.

  4. New evidence for hybrid zones of forest and savanna elephants in Central and West Africa.

    PubMed

    Mondol, Samrat; Moltke, Ida; Hart, John; Keigwin, Michael; Brown, Lisa; Stephens, Matthew; Wasser, Samuel K

    2015-12-01

    The African elephant consists of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies have demonstrated marked genetic and morphological differences between forest and savanna elephants, and despite extensive sampling, genetic evidence of hybridization between them has been restricted largely to a few hybrids in the Garamba region of northeastern Democratic Republic of Congo (DRC). Here, we present new genetic data on hybridization from previously unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples--many more than have been previously identified--only two of which are from the Garamba region. The remaining 44 are from three other geographically distinct locations: a major hybrid zone along the border of the DRC and Uganda, a second potential hybrid zone in Central African Republic and a smaller fraction of hybrids in the Pendjari-Arli complex of West Africa. Most of the hybrids show evidence of interbreeding over more than one generation, demonstrating that hybrids are fertile. Mitochondrial and Y chromosome data demonstrate that the hybridization is bidirectional, involving males and females from both subspecies. We hypothesize that the hybrid zones may have been facilitated by poaching and habitat modification. The localized geography and rarity of hybrid zones, their possible facilitation from human pressures, and the high divergence and genetic distinctness of forest and savanna elephants throughout their ranges, are consistent with calls for separate species classification. PMID:26577954

  5. High number of diarrhoeal co-infections in travellers to Benin, West Africa

    PubMed Central

    2014-01-01

    Background Travellers’ diarrhoea (TD) is the most frequent health problem among travellers to the tropics. Using routine techniques, the aetiology mostly remains unresolved, whereas modern molecular methods enable reducing the number of equivocal cases considerably. While many studies address the aetiology of TD in Asian, Central American and North African tourist resorts, only few focus on Western Africa. Methods Stool samples from 45 travellers travelling in Benin, West Africa, were analyzed by a new multiplex qPCR assay for Salmonella, Yersinia, Campylobacter, Vibrio cholerae, Shigella or enteroinvasive (EIEC), enterohaemorrhagic (EHEC), enterotoxigenic (ETEC), enteroaggregative (EAEC), and enteropathogenic Escherichia coli (EPEC). Results All 18 pre-travel samples proved negative for bacterial pathogens. Of the 39/45 (87%) travellers having had TD, EPEC was detected in post-travel samples in 30 (77%) cases, EAEC in 23 (59%), ETEC in 22 (56%), Shigella or EIEC in 7 (18%), EHEC in two (5%), and Salmonella in one (3%). In 31(79%) of the TD cases two or more bacterial pathogens were identified. Two (8%) samples remained negative: both patients had taken antimicrobials for TD. Conclusions EPEC, EAEC and ETEC were the most common findings. 79% of the cases had a co-infection. As modern diagnostics reveals in most patients a multitude of pathogens, the role of each pathogen should be re-evaluated. PMID:24521079

  6. Determinants of Mean Blood Pressure and Hypertension among Workers in West Africa

    PubMed Central

    Bosu, William K.

    2016-01-01

    Background. This review was undertaken to estimate the mean blood pressure and evaluate its determinants as well as the determinants of hypertension among workers in West Africa. Methods. In a follow-up to an earlier study, a systematic search for articles published between 1980 and August 2015 was undertaken using major databases. Results. A total of 55 articles involving 34,919 different cadres of workers from six countries were retrieved. The mean systolic blood pressure (BP) ranged from 116.6 ± 1.3 mmHg to 151.7 ± 13.6 mmHg while the mean diastolic BP ranged from 69.6 ± 11.0 mmHg to 97.1 ± 9.1 mmHg. Population-wide prehypertension was common. The major determinants of mean BP and hypertension were similar and included male sex, older age group, higher socioeconomic status, obesity, alcohol consumption, plasma glucose, and sodium excretion. Ethnicity and educational level were inconsistently associated with hypertension. Workers at higher risk of cardiovascular event did not perceive themselves as such. Conclusion. The prevailing mean prehypertensive BP, low perception of risk, and clustering of risk factors call for interventions such as healthy diets, improved physical activity, and a favourable work environment. Successful models for improving the cardiovascular health of sedentary informal sector workers in Africa are urgently needed. PMID:26949543

  7. Insecticide dissipation from soil and plant surfaces in tropical horticulture of southern Benin, West Africa.

    PubMed

    Rosendahl, Ingrid; Laabs, Volker; Atcha-Ahowé, Cyrien; James, Braima; Amelung, Wulf

    2009-06-01

    In Sub-Saharan Africa, horticulture provides livelihood opportunities for millions of people, especially in urban and peri-urban areas. Although the vegetable agroecosystems are often characterized by intensive pesticide use, risks resulting therefrom are largely unknown under tropical horticultural conditions. The objective of this study therefore was to study the fate of pesticides in two representative horticultural soils (Acrisol and Arenosol) and plants (Solanum macrocarpon L.) after field application and thus to gain first insight on environmental persistence and dispersion of typical insecticides used in vegetable horticulture in Benin, West Africa. On plant surfaces, dissipation was rapid with half lives ranging from 2 to 87 h (alpha-endosulfan < beta-endosulfan < deltamethrin). Soil dissipation was considerably slower than dissipation from plant surfaces with half-lives ranging from 3 (diazinon) to 74 d (total endosulfan), but persistence of pesticides in soil was still reduced compared to temperate climates. Nevertheless, for deltamethrin and endosulfan, a tendency for mid-term accumulation in soil upon repeated applications was observed. The soil and plant surface concentrations of the metabolite endosulfan sulfate increased during the entire trial period, indicating that this compound is a potential long-term pollutant even in tropical environments. PMID:19513446

  8. The mineralogy of global magnetic anomalies. [rock magnetic signatures and MAGSAT geological, and gravity correlations in West Africa

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E. (Principal Investigator)

    1982-01-01

    Problems with the Curie balance, which severely hindered the acquisition of data, were rectified. Chemical analytical activities are proceeding satisfactorily. The magnetization characteristics of metamorphic suites were analyzed and susceptibility data for a wide range of metamorphic and igneous rocks. These rock magnetic signatures are discussed as well as the relationships between geology, gravity and MAGSAT anomalies of West Africa.

  9. The spatial genetic differentiation of the legume pod borer, Maruca vitrata F. (Lepidoptera: Pyralidae) populations in West Africa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The legume pod borer, Maruca vitrata, is an endemic insect pest that causes significant yield loss to the cowpea crop in West Africa, and contributes to food shortages and malnutrition in native human populations. The genetic structure of Maruca vitrata was investigated among five sites from Burkin...

  10. An Evaluation of a Short-Term Service-Learning Study Abroad Program to Ghana, West Africa

    ERIC Educational Resources Information Center

    Foster, Patricia A.

    2011-01-01

    This was a study of a short-term service-learning study abroad program to Ghana, West Africa. The research examined 7 participants' attitudes about and behavioral changes in response to study abroad. How the short-term study abroad experience enhanced and broadened the participants' exposure to other cultures was also studied. The purpose of the…

  11. Lessons from New Experiences in Extension in West Africa: Management Advice for Family Farms and Farmers' Governance

    ERIC Educational Resources Information Center

    Faure, Guy; Kleene, Paul

    2004-01-01

    The emergence of Management Advice for Family Farms in West Africa is closely related to the increased integration of farmers into an open market economy. This is creating a strong demand from farmers for advisory support services, focusing on management of the farm. With the gradual withdrawal of the State from extension services delivery, a…

  12. Monitoring HIV Risk and Evaluating Interventions among Young People in Urban West Africa: Development and Validation of an Instrument

    ERIC Educational Resources Information Center

    Boileau, Catherine; Rashed, Selim; Sylla, Mohamed; Zunzunegui, Maria Victoria

    2008-01-01

    We developed an instrument for HIV/AIDS behavioral surveillance applicable to youth living in urban West Africa. The instrument includes a comprehensive set of constructs borrowed from the sociocognitive theory of planned behavior as well as measures of parental and peer communication An exploratory (n = 189) and validation sample (n = 342) of…

  13. Mapping Transmission Risk of Lassa Fever in West Africa: The Importance of Quality Control, Sampling Bias, and Error Weighting

    PubMed Central

    Peterson, A. Townsend; Moses, Lina M.; Bausch, Daniel G.

    2014-01-01

    Lassa fever is a disease that has been reported from sites across West Africa; it is caused by an arenavirus that is hosted by the rodent M. natalensis. Although it is confined to West Africa, and has been documented in detail in some well-studied areas, the details of the distribution of risk of Lassa virus infection remain poorly known at the level of the broader region. In this paper, we explored the effects of certainty of diagnosis, oversampling in well-studied region, and error balance on results of mapping exercises. Each of the three factors assessed in this study had clear and consistent influences on model results, overestimating risk in southern, humid zones in West Africa, and underestimating risk in drier and more northern areas. The final, adjusted risk map indicates broad risk areas across much of West Africa. Although risk maps are increasingly easy to develop from disease occurrence data and raster data sets summarizing aspects of environments and landscapes, this process is highly sensitive to issues of data quality, sampling design, and design of analysis, with macrogeographic implications of each of these issues and the potential for misrepresenting real patterns of risk. PMID:25105746

  14. Mapping transmission risk of Lassa fever in West Africa: the importance of quality control, sampling bias, and error weighting.

    PubMed

    Peterson, A Townsend; Moses, Lina M; Bausch, Daniel G

    2014-01-01

    Lassa fever is a disease that has been reported from sites across West Africa; it is caused by an arenavirus that is hosted by the rodent M. natalensis. Although it is confined to West Africa, and has been documented in detail in some well-studied areas, the details of the distribution of risk of Lassa virus infection remain poorly known at the level of the broader region. In this paper, we explored the effects of certainty of diagnosis, oversampling in well-studied region, and error balance on results of mapping exercises. Each of the three factors assessed in this study had clear and consistent influences on model results, overestimating risk in southern, humid zones in West Africa, and underestimating risk in drier and more northern areas. The final, adjusted risk map indicates broad risk areas across much of West Africa. Although risk maps are increasingly easy to develop from disease occurrence data and raster data sets summarizing aspects of environments and landscapes, this process is highly sensitive to issues of data quality, sampling design, and design of analysis, with macrogeographic implications of each of these issues and the potential for misrepresenting real patterns of risk. PMID:25105746

  15. Three and half million year vegetation history of South West Africa and its implications for human evolution

    NASA Astrophysics Data System (ADS)

    Maslin, M. A.; Pancost, R. D.

    2010-12-01

    Ocean Drilling Program Site 1085 provides a continuous marine sediment record off South West Africa for at least the last three and half million years. The n-alkane carbon isotope record from this site records past vegetation and provides an indication of the moisture availability of SW Africa over this time period. We compared the n-alkane carbon isotope record with the soil carbonate carbon isotope records of East Africa to better understand the vegetation dynamics of Africa over the Plio-Pleistocene. In SW Africa very little variation, and no trend, is observed in the n-alkane carbon isotope record over 3 million years, suggesting stable long-term conditions despite large changes in East African tectonics and global climate. Slightly higher n-alkane carbon isotope values occur between 3.5 and 2.7 Ma suggesting slightly drier conditions than today. Between 2.5 and 2.7 Ma there is a shift to more negative n-alkane carbon isotope values suggesting slightly wetter conditions during a ~0.2 Ma episode that coincides with the intensification of Northern Hemisphere Glaciation (iNHG). From 2.5 to 0.4 Ma the n-alkane carbon isotope values are very consistent, varying by less than ±0.5 per mil and suggesting little or no long-term change in the moisture availability of South West Africa over the last 2.5 million years. This is in marked contrast to the East African long-term drying trend that was punctuated by periodic extreme wet and dry periods. The comparison of the climate history of these two regions suggests that Southern Africa may have been a safe refuge for hominins and other animals during the last 3.5 Myrs and thus important implications for our understand of early human evolution.

  16. Human immunodeficiency virus and hepatitis C co-infection in sub-Saharan West Africa.

    PubMed

    Mboto, C I; Davies, A; Fielder, M; Jewell, A P

    2006-01-01

    Co-infection with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) is becoming a major global problem, leading to increased morbidity and mortality in developed countries. Co-existence in sub-Saharan West Africa of a high prevalence of HIV and HCV, which share similar behavioural risk factors and modes of transmission, must be seen in the broader context of an emerging third epidemic of HIV and HCV co-infection, as many factors that may affect the spread of HIV and HCV co-infection are endemic in the continent, including host factors such as sexual behaviour, presence of other sexually transmitted diseases, female and male circumcision status, percutaneous and perinatal exposure, and poverty. This review examines the epidemiology, risk factors and transmission of HIV and HCV co-infection and draws attention to the possible emergence of an epidemic of HIV and HCV co-infection in the region. PMID:16613141

  17. Skill of ENSEMBLES seasonal re-forecasts for malaria prediction in West Africa

    NASA Astrophysics Data System (ADS)

    Jones, A. E.; Morse, A. P.

    2012-12-01

    This study examines the performance of malaria-relevant climate variables from the ENSEMBLES seasonal ensemble re-forecasts for sub-Saharan West Africa, using a dynamic malaria model to transform temperature and rainfall forecasts into simulated malaria incidence and verifying these forecasts against simulations obtained by driving the malaria model with General Circulation Model-derived reanalysis. Two subregions of forecast skill are identified: the highlands of Cameroon, where low temperatures limit simulated malaria during the forecast period and interannual variability in simulated malaria is closely linked to variability in temperature, and northern Nigeria/southern Niger, where simulated malaria variability is strongly associated with rainfall variability during the peak rain months.

  18. Remote sensing experiment in West Africa. [drought effects on desert agriculture and vegetation in Niger

    NASA Technical Reports Server (NTRS)

    Macleod, N. H.

    1974-01-01

    There are substantial needs of the Sahelien Zone to detail the state of regional agricultural resources in the face of a sixth year of serious drought conditions. While most of the work has been done in the Republic of Niger, the principles which have emerged from the analysis seem to be applicable to much of the Sahel. The discussion relates to quite specific rehabilitation and development initiations under consideration in Niger which are based in part upon direct analysis of ERTS imagery of the country, in part on field surveys and on discussions with Nigerian officials and technicians. Again, because the entire Sahelien Zone (including Niger) has large zones of similar ecologic characteristics, modificiations of the approaches suggested for Niger are applicable to the solution of rehabilitation of the desert, the savannah and the woodlands of West Africa in general.

  19. Climate forecasts in disaster management: Red Cross flood operations in West Africa, 2008.

    PubMed

    Braman, Lisette Martine; van Aalst, Maarten Krispijn; Mason, Simon J; Suarez, Pablo; Ait-Chellouche, Youcef; Tall, Arame

    2013-01-01

    In 2008, the International Federation of Red Cross and Red Crescent Societies (IFRC) used a seasonal forecast for West Africa for the first time to implement an Early Warning, Early Action strategy for enhanced flood preparedness and response. Interviews with disaster managers suggest that this approach improved their capacity and response. Relief supplies reached flood victims within days, as opposed to weeks in previous years, thereby preventing further loss of life, illness, and setbacks to livelihoods, as well as augmenting the efficiency of resource use. This case demonstrates the potential benefits to be realised from the use of medium-to-long-range forecasts in disaster management, especially in the context of potential increases in extreme weather and climate-related events due to climate variability and change. However, harnessing the full potential of these forecasts will require continued effort and collaboration among disaster managers, climate service providers, and major humanitarian donors. PMID:23066755

  20. Perspectives on West Africa Ebola Virus Disease Outbreak, 2013-2016

    DOE PAGESBeta

    Spengler, Jessica R.; Ervin, Elizabeth D.; Towner, Jonathan S.; Rollin, Pierre E.; Nichol, Stuart T.

    2016-06-01

    The variety of factors that contributed to the initial undetected spread of Ebola virus disease in West Africa during 2013-2016 and the difficulty controlling the outbreak once the etiology was identified highlight priorities for disease prevention, detection, and response. These factors include occurrence in a region recovering from civil instability and lacking experience with Ebola response; inadequate surveillance, recognition of suspected cases, and Ebola diagnosis; mobile populations and extensive urban transmission; and the community's insufficient general understanding about the disease. The magnitude of the outbreak was not attributable to a substantial change of the virus. Finally, continued efforts during themore » outbreak and in preparation for future outbreak response should involve identifying the reservoir, improving in-country detection and response capacity, conducting survivor studies and supporting survivors, engaging in culturally appropriate public education and risk communication, building productive interagency relationships, and continuing support for basic research.« less

  1. Cutaneous anthrax associated with drum making using goat hides from West Africa--Connecticut, 2007.

    PubMed

    2008-06-13

    On August 29, 2007, the Connecticut Department of Public Health was notified by a physician of suspect cutaneous anthrax involving a drum maker and one of his three children. The drum maker had been working with untreated goat hides from Guinea in West Africa. This report summarizes results of the joint epidemiologic and environmental investigation conducted by public health officials, environmental agencies, and law enforcement authorities. The investigation revealed that the drum maker was exposed while working with a contaminated goat hide from Guinea and that his workplace and home were contaminated with anthrax. His child was most likely exposed from cross-contamination of the home. The findings underscore the potential hazard of working with untreated animal hides from areas with epizootic anthrax and the potential for secondary cases from environmental contamination. PMID:18551098

  2. Perspectives on West Africa Ebola Virus Disease Outbreak, 2013–2016

    PubMed Central

    Spengler, Jessica R.; Ervin, Elizabeth D.; Towner, Jonathan S.; Rollin, Pierre E.

    2016-01-01

    The variety of factors that contributed to the initial undetected spread of Ebola virus disease in West Africa during 2013–2016 and the difficulty controlling the outbreak once the etiology was identified highlight priorities for disease prevention, detection, and response. These factors include occurrence in a region recovering from civil instability and lacking experience with Ebola response; inadequate surveillance, recognition of suspected cases, and Ebola diagnosis; mobile populations and extensive urban transmission; and the community’s insufficient general understanding about the disease. The magnitude of the outbreak was not attributable to a substantial change of the virus. Continued efforts during the outbreak and in preparation for future outbreak response should involve identifying the reservoir, improving in-country detection and response capacity, conducting survivor studies and supporting survivors, engaging in culturally appropriate public education and risk communication, building productive interagency relationships, and continuing support for basic research. PMID:27070842

  3. Back-trajectory model of the Saharan dust flux and particle mass distribution in West Africa

    NASA Astrophysics Data System (ADS)

    Sunnu, Albert; Resch, Francois; Afeti, George

    2013-06-01

    A back trajectory model of the Sahara dust flux toward the Gulf of Guinea has been studied. First, the atmospheric circulation over North and West Africa in winter is obtained by the backward trajectory plots with NOAA HYSPLIT to establish the winds responsible for the dust transport. The 'box' model derived by Resch et al. (2007) is used to develop the back trajectory model equations. The dust particle mass distributions at various locations traced back from Kumasi and Tamale to the Harmattan dust origin in the Chad basin can be obtained. The model is first tested with the particle mass concentrations at Tamale in Harmattan 2002 and 2005, which are easily deduced. Sample calculations are shown to illustrate the use of the model to estimate the particle mass concentration distributions at Kano and Maiduguri in Nigeria during the Harmattan 2002 and 2005.

  4. [The colonial state and demographic knowledge in French West Africa, 1904-1960].

    PubMed

    Gervais, R R

    1996-01-01

    "Our lack of knowledge on the production of population estimates in France's colonial empire is in sharp contrast to the efforts of British authorities after 1940. To understand this ¿omission', we have to assess the numerous oppositions existing within the French colonial state.... After the first memoranda of 1904 and 1909, colonial census-taking activities were inexorably merged with everyday administrative tasks: taxation, justice, policing, etc. This shift clearly influenced the form and function of demographic knowledge in French West Africa (AOF).... We conclude with a mixed assessment of attempts to amass demographic knowledge and especially of the influence such knowledge actually had on decision-making." (SUMMARY IN ENG AND SPA) PMID:12292477

  5. Analyzing the implementation of the rural allowance in hospitals in North West Province, South Africa.

    PubMed

    Ditlopo, Prudence; Blaauw, Duane; Bidwell, Posy; Thomas, Steve

    2011-01-01

    Using a policy analysis framework, we analyzed the implementation and perceived effectiveness of a rural allowance policy and its influence on the motivation and retention of health professionals in rural hospitals in the North West province of South Africa. We conducted 40 in-depth interviews with policy-makers, hospital managers, nurses, and doctors at five rural hospitals and found weaknesses in policy design and implementation. These weaknesses included: lack of evidence to guide policy formulation; restricting eligibility for the allowance to doctors and professional nurses; lack of clarity on the definition of rural areas; weak communication; and the absence of a monitoring and evaluation framework. Although the rural allowance was partially effective in the recruitment of health professionals, it has had unintended negative consequences of perceived divisiveness and staff dissatisfaction. Government should take more account of contextual and process factors in policy formulation and implementation so that policies have the intended impact. PMID:21730996

  6. Late Holocene climatic changes in west Africa, a high resolution diatom record from equatorial Cameroon

    NASA Astrophysics Data System (ADS)

    Nguetsop, Victor François; Servant-Vildary, Simone; Servant, Michel

    2004-03-01

    Holocene climatic changes in West Africa are usually explained by increased/decreased activity of the monsoon from the Guinean Gulf toward the continent. According to a diatom record from Lake Ossa (3°50'N, 9°36'E), we suggest that, in the near coastal areas of Cameroon, phases of intensification of the monsoon were marked by reduced precipitation and reduced evaporation, conditions nowadays prevailing South of the equator (4-5°S) during the austral winter. Lake Ossa is a shallow lake located in one of the rainiest area of the African rain forest belt. During the wet season (March-November) it is fed by acid meteoric waters entailing low pH in the lacustrine waters. During the dry season (December-February) groundwater discharges allow the persistence of acid waters near the borders of the lake, but, in the inner parts, the waters tend to be alkaline, alkaliphilous diatoms are abundant in the surface sediment samples and are used as indicators of low precipitation. At that time, atmospheric dust containing reworked diatoms from Saharan Quaternary deposits is transported by the northern trade winds and reaches the Ossa area. Wind blown diatoms are considered as a signature of the northern trade winds. A diatom record from the western deep part of Lake Ossa has provided climatic data for the mid-late Holocene at a resolution of 50-60 years. A major climatic change at 2700 cal yr BP was marked by the appearance of wind blown diatoms. A millennial-scale alternation between low and high precipitation episodes is recorded during the last 5500 years. The low precipitation episodes before 2700 cal yr BP are interpreted as a consequence of a northward extension of the climatic conditions that nowadays characterize the Southern Congo during the austral winter, when the monsoon extends into West Africa and reaches the northern sub-tropical latitudes. The effects of low precipitation on the water balance and on the rain forest were obliterated by an extremely low

  7. Perspectives on West Africa Ebola Virus Disease Outbreak, 2013-2016.

    PubMed

    Spengler, Jessica R; Ervin, Elizabeth D; Towner, Jonathan S; Rollin, Pierre E; Nichol, Stuart T

    2016-06-01

    The variety of factors that contributed to the initial undetected spread of Ebola virus disease in West Africa during 2013-2016 and the difficulty controlling the outbreak once the etiology was identified highlight priorities for disease prevention, detection, and response. These factors include occurrence in a region recovering from civil instability and lacking experience with Ebola response; inadequate surveillance, recognition of suspected cases, and Ebola diagnosis; mobile populations and extensive urban transmission; and the community's insufficient general understanding about the disease. The magnitude of the outbreak was not attributable to a substantial change of the virus. Continued efforts during the outbreak and in preparation for future outbreak response should involve identifying the reservoir, improving in-country detection and response capacity, conducting survivor studies and supporting survivors, engaging in culturally appropriate public education and risk communication, building productive interagency relationships, and continuing support for basic research. PMID:27070842

  8. « Younger-Dryas / African Humid Period »: a notable climatic transition over West Africa

    NASA Astrophysics Data System (ADS)

    Skonieczny, C.; Bory, A. J.; Bout-Roumazeilles, V.; Malaizé, B.; Grousset, F. E.; Abouchami, W.; Galer, S. J.; Francois, R. H.

    2013-05-01

    Every year, several hundreds teragrams of dust are emitted from the Sahara and Sahel regions. These mineral particles sensitively track variations in atmospheric circulation and continental aridity. Sediments of the Northeastern Atlantic Tropical Ocean (NEATO) are fed by this intense dust supply and comprise unique long-term archives of past dust emissions. Past modifications of dust characteristics in these sedimentary archives can provide precious information on changes in environmental conditions in source areas (aridity, weathering), as well as on changes in the characteristics of their atmospheric transport (pathways and strength). Over Africa, gradual increases in local insolation due to changes in the Earth's orbit are accompanied by a migration of the precipitation monsoon-system (associated with the InterTropical Convergence Zone, ITCZ) toward the North. This displacement leads to decrease in West African mineral dust emission. Consequently, Saharan and Sahelian dust deposited in the NEATO sedimentary archives represent an exceptional opportunity to document the environmental and climatic changes that have taken place in West Africa throughout the Quaternary and beyond (Rea, 1994). Here we document changes in the terrigenous supplies to the NETAO throughout the last deglaciation using the marine sediment core MD03-2705 located off Mauritania (18°05N; 21°09W; 3085m water depth) and retrieved from a bathymetric dome, 300 meters above the surrounding seafloor. Considering this particular environmental setting, the terrigenous fraction in this record is assumed to be predominantly of aeolian origin. Multi-proxy analyses of the carbonate-free fraction of the sediment were carried-out, including dust fluxes, grain-size, clay mineralogy and geochemical measurements (major and trace elements as well as Sr & Nd isotopes). We will discuss the most significant changes recorded over the studied period: levels dated from the Younger Dryas and the subsequent African

  9. The Response of Environmental Capacity for Malaria Transmission in West Africa to Climate Change

    NASA Astrophysics Data System (ADS)

    Yamana, T. K.; Eltahir, E. A.

    2011-12-01

    The climate of West Africa is characterized by north-south gradients in temperature and rainfall. Environmental capacity for malaria transmission (e.g. as measured by vectorial capacity) is strongly tied to these two variables; temperature affects the development rate of the malaria parasite, as well as the lifespan of the mosquitoes that transmit the disease, and rainfall is tied to mosquito abundance, as the vector lays its eggs in rain-fed water pools. A change in climate is therefore expected to lead to changes in the distribution of malaria transmission. Current general circulation models agree that the temperature in West Africa is expected to increase by several degrees in the next century. However they predict a wide range of possible rainfall scenarios in the future, from intense drying to significant increases in rainfall (Christensen et al., 2007). The effects these changes will have on environmental capacity for malaria transmission depend on the magnitude and direction of the changes, and on current conditions. For example, malaria transmission will be more sensitive to positive changes in rainfall in dry areas where mosquito populations are currently limited by water availability than in relatively wet areas. Here, we analyze combinations of changes in rainfall and temperature within the ranges predicted by GCMs, and assess the impact these combinations will have on the environmental capacity for malaria transmission. In particular, we identify climate change scenarios that are likely to have the greatest impact on environmental capacity for malaria transmission, as well as geographic "hot spots" where the greatest changes are to be expected. Christensen, J. H., Busuioc, A., & et al. (2007). Regional climate projections. In S. Solomon (Ed.), Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

  10. Factors Associated with Variations in Population HIV Prevalence across West Africa: Findings from an Ecological Analysis

    PubMed Central

    Prudden, Holly J.; Beattie, Tara S.; Bobrova, Natalia; Panovska-Griffiths, Jasmina; Mukandavire, Zindoga; Gorgens, Marelize; Wilson, David; Watts, Charlotte H.

    2015-01-01

    Background Population HIV prevalence across West Africa varies substantially. We assess the national epidemiological and behavioural factors associated with this. Methods National, urban and rural data on HIV prevalence, the percentage of younger (15–24) and older (25–49) women and men reporting multiple (2+) partners in the past year, HIV prevalence among female sex workers (FSWs), men who have bought sex in the past year (clients), and ART coverage, were compiled for 13 countries. An Ecological analysis using linear regression assessed which factors are associated with national variations in population female and male HIV prevalence, and with each other. Findings National population HIV prevalence varies between 0 4–2 9% for men and 0 4–5.6% for women. ART coverage ranges from 6–23%. National variations in HIV prevalence are not shown to be associated with variations in HIV prevalence among FSWs or clients. Instead they are associated with variations in the percentage of younger and older males and females reporting multiple partners. HIV prevalence is weakly negatively associated with ART coverage, implying it is not increased survival that is the cause of variations in HIV prevalence. FSWs and younger female HIV prevalence are associated with client population sizes, especially older men. Younger female HIV prevalence is strongly associated with older male and female HIV prevalence. Interpretation In West Africa, population HIV prevalence is not significantly higher in countries with high FSW HIV prevalence. Our analysis suggests, higher prevalence occurs where more men buy sex, and where a higher percentage of younger women, and older men and women have multiple partnerships. If a sexual network between clients and young females exists, clients may potentially bridge infection to younger females. HIV prevention should focus both on commercial sex and transmission between clients and younger females with multiple partners. PMID:26698854

  11. Regional assessment of the hydropower potential of rivers in West Africa

    NASA Astrophysics Data System (ADS)

    Kling, Harald; Stanzel, Philipp; Fuchs, Martin

    2016-04-01

    The 15 countries of the Economic Community of West African States (ECOWAS) face a constant shortage of energy supply, which limits sustained economic growth. Currently there are about 50 operational hydropower plants and about 40 more are under construction or refurbishment. The potential for future hydropower development - especially for small-scale plants in rural areas - is assumed to be large, but exact data are missing. This study supports the energy initiatives of the "ECOWAS Centre for Renewable Energy and Energy Efficiency" (ECREEE) by assessing the hydropower potential of all rivers in West Africa. For more than 500,000 river reaches the hydropower potential was computed from channel slope and mean annual discharge. In large areas there is a lack of discharge observations. Therefore, an annual water balance model was used to simulate discharge. The model domain covers 5 Mio km², including e.g. the Niger, Volta, and Senegal River basins. The model was calibrated with observed data of 410 gauges, using precipitation and potential evapotranspiration data as inputs. Historic variations of observed annual discharge between 1950 and 2010 are simulated well by the model. As hydropower plants are investments with a lifetime of several decades we also assessed possible changes in future discharge due to climate change. To this end the water balance model was driven with bias-corrected climate projections of 15 Regional Climate Models for two emission scenarios of the CORDEX-Africa ensemble. The simulation results for the river network were up-scaled to sub-areas and national summaries. This information gives a regional quantification of the hydropower potential, expected climate change impacts, as well as a regional classification for general suitability (or non-suitability) of hydropower plant size - from small-scale to large projects.

  12. Projected Impacts of Climate Change on Environmental Suitability for Malaria Transmission in West Africa

    PubMed Central

    Eltahir, Elfatih A.B.

    2013-01-01

    Background: Climate change is expected to affect the distribution of environmental suitability for malaria transmission by altering temperature and rainfall patterns; however, the local and global impacts of climate change on malaria transmission are uncertain. Objective: We assessed the effect of climate change on malaria transmission in West Africa. Methods: We coupled a detailed mechanistic hydrology and entomology model with climate projections from general circulation models (GCMs) to predict changes in vectorial capacity, an indication of the risk of human malaria infections, resulting from changes in the availability of mosquito breeding sites and temperature-dependent development rates. Because there is strong disagreement in climate predictions from different GCMs, we focused on the GCM projections that produced the best and worst conditions for malaria transmission in each zone of the study area. Results: Simulation-based estimates suggest that in the desert fringes of the Sahara, vectorial capacity would increase under the worst-case scenario, but not enough to sustain transmission. In the transitional zone of the Sahel, climate change is predicted to decrease vectorial capacity. In the wetter regions to the south, our estimates suggest an increase in vectorial capacity under all scenarios. However, because malaria is already highly endemic among human populations in these regions, we expect that changes in malaria incidence would be small. Conclusion: Our findings highlight the importance of rainfall in shaping the impact of climate change on malaria transmission in future climates. Even under the GCM predictions most conducive to malaria transmission, we do not expect to see a significant increase in malaria prevalence in this region. Citation: Yamana TK, Eltahir EA. 2013. Projected impacts of climate change on environmental suitability for malaria transmission in West Africa. Environ Health Perspect 121:1179–1186; http://dx.doi.org/10.1289/ehp

  13. Transport and chemistry of formaldehyde by mesoscale convective systems in West Africa during AMMA 2006

    NASA Astrophysics Data System (ADS)

    Borbon, AgnèS.; Ruiz, M.; Bechara, J.; Aumont, B.; Chong, M.; Huntrieser, H.; Mari, C.; Reeves, C. E.; Scialom, Georges; Hamburger, T.; Stark, H.; Afif, C.; Jambert, C.; Mills, G.; Schlager, H.; Perros, P. E.

    2012-06-01

    In situ measurements of formaldehyde (CH2O) onboard four European research aircraft in August 2006 as part of the African Monsoon Multidisciplinary Analysis (AMMA) experiment in West Africa are used (1) to examine the redistribution of CH2O by mesoscale convective systems (MCS) in the tropical upper troposphere (UT), (2) to evaluate the scavenging efficiency (SE) of CH2O by MCS and (3) to quantify the impact of CH2O on UT photooxidant production downwind of MCS. The intercomparison of CH2O measurements is first tested, providing a unique and consistent 3-D-spatially resolved CH2O database in background and convective conditions. While carbon monoxide (CO) is vertically uplifted by deep convection up to 12 km, CH2O is also affected by cloud processing as seen from its ratio relative to CO with altitude. A new observation-based model is established to quantify the SE of CH2O. This model shows that convective entrainment of free tropospheric air cannot be neglected since it contributes to 40% of the convective UT air. For the 4 studied MCS, SE shows a large variability within a 4% to 39% range at a relative standard deviation of 30%, which is consistent with MCS features. A time-dependent photochemical box model is applied to convective UT air. After convection, 60% of CH2O is due to its photochemical production rather than to its direct transport. Model results indicate that CH2O directly injected by convection does not impact ozone and HOx production in the tropical UT of West Africa. NOx and anthropogenic hydrocarbon precursors dominate the secondary production of CH2O, ozone and HOx.

  14. Secondary organic aerosol from biogenic VOCs over West Africa during AMMA

    NASA Astrophysics Data System (ADS)

    Capes, G.; Murphy, J. G.; Reeves, C. E.; McQuaid, J. B.; Hamilton, J. F.; Hopkins, J. R.; Crosier, J.; Williams, P. I.; Coe, H.

    2009-06-01

    This paper presents measurements of organic aerosols above subtropical West Africa during the wet season using data from the UK Facility for Airborne Atmospheric Measurements (FAAM) aircraft. Measurements of biogenic volatile organic compounds (BVOC) at low altitudes over these subtropical forests were made during the African Monsoon Multidisciplinary Analysis (AMMA) field experiment during July and August 2006 mainly above Benin, Nigeria and Niger. Data from an Aerodyne Quadrupole Aerosol Mass Spectrometer show a median organic aerosol loading of 1.07 μg m-3 over tropical West Africa, which represents the first regionally averaged assessment of organic aerosol mass (OM) in this region during the wet season. This is broadly in agreement with global model predictions based on partitioning schemes, although there are large uncertainties associated with such estimates. In contrast our own calculations based on aerosol yields from isoprene and monoterpenes during chamber studies under represent the OM measured in this region on a comparable scale to the under representations of OM by predictive models in the mid latitudes. As global models rely on similar yield calculations in their global estimates, as our calculations this points to further systematic differences between global model estimates and measurements of SOA, most likely caused by use of incorrect BVOC emission rates. The under predictions of OM by our calculations and those in the mid latitudes employ yields extrapolated from chamber data obtained at higher mass concentrations - more recent yield data for α-pinene obtained at ambient concentrations in a flow through chamber (Shilling et al., 2008) show considerably better agreement with our data.

  15. Reasons for hospitalization in HIV-infected children in West Africa

    PubMed Central

    Dicko, Fatoumata; Desmonde, Sophie; Koumakpai, Sikiratou; Dior-Mbodj, Hélène; Kouéta, Fla; Baeta, Novisi; Koné, Niaboula; Akakpo, Jocelyn; Sy, Haby Signate; Ye, Diarra; Renner, Lorna; Lewden, Charlotte; Leroy, Valériane

    2014-01-01

    Introduction Current knowledge on morbidity and mortality in HIV-infected children comes from data collected in specific research programmes, which may offer a different standard of care compared to routine care. We described hospitalization data within a large observational cohort of HIV-infected children in West Africa (IeDEA West Africa collaboration). Methods We performed a six-month prospective multicentre survey from April to October 2010 in five HIV-specialized paediatric hospital wards in Ouagadougou, Accra, Cotonou, Dakar and Bamako. Baseline and follow-up data during hospitalization were recorded using a standardized clinical form, and extracted from hospitalization files and local databases. Event validation committees reviewed diagnoses within each centre. HIV-related events were defined according to the WHO definitions. Results From April to October 2010, 155 HIV-infected children were hospitalized; median age was 3 years [1–8]. Among them, 90 (58%) were confirmed for HIV infection during their stay; 138 (89%) were already receiving cotrimoxazole prophylaxis and 64 children (40%) had initiated antiretroviral therapy (ART). The median length of stay was 13 days (IQR: 7–23); 25 children (16%) died during hospitalization and four (3%) were transferred out. The leading causes of hospitalization were WHO stage 3 opportunistic infections (37%), non-AIDS-defining events (28%), cachexia and other WHO stage 4 events (25%). Conclusions Overall, most causes of hospitalizations were HIV related but one hospitalization in three was caused by a non-AIDS-defining event, mostly in children on ART. HIV-related fatality is also high despite the scaling-up of access to ART in resource-limited settings. PMID:24763078

  16. Hantaviruses in Africa.

    PubMed

    Witkowski, Peter T; Klempa, Boris; Ithete, Ndapewa L; Auste, Brita; Mfune, John K E; Hoveka, Julia; Matthee, Sonja; Preiser, Wolfgang; Kruger, Detlev H

    2014-07-17

    This paper summarizes the progress in the search for hantaviruses and hantavirus infections in Africa. After having collected molecular evidence of an indigenous African hantavirus in 2006, an intensive investigation for new hantaviruses has been started in small mammals. Various novel hantaviruses have been molecularly identified not only in rodents but also in shrews and bats. In addition, the first African hantavirus, Sangassou virus, has been isolated and functionally characterized in cell culture. Less is known about the ability of these hantaviruses to infect humans and to cause diseases. To date, no hantavirus genetic material could be amplified from patients' specimens collected in Africa. Serological studies in West Africa, based on a battery of screening and confirmatory assays, led to the detection of hantavirus antibodies in the human population and in patients with putative hantavirus disease. In addition to this overview, we present original data from seroepidemiological and field studies conducted in the Southern part of Africa. A human seroprevalence rate of 1.0% (n=1442) was detected in the South African Cape Region whereas no molecular evidence for the presence of hantavirus was found in 2500 small animals trapped in South Africa and Namibia. PMID:24406800

  17. Hybrid Gravimetry for the Monitoring of Water Storage Changes in the Critical Zone of West Africa

    NASA Astrophysics Data System (ADS)

    Hector, B.; Hinderer, J.; Séguis, L.; Calvo, M.; Pfeffer, J.

    2015-12-01

    Time-lapse gravimetry is known to be a powerful tool to monitor mass redistributions near the Earth's surface and hence is of interest in various fields (volcanology, hydrology, glaciology, geothermics, C02 sequestration). Hybrid gravimetry relies on the combined use of different types of instruments measuring the earth's gravity changes i.e. relative spring gravimeters (RG) and superconducting gravimeters (SG), as well as ballistic absolute gravimeters (AG) in a specific study. We show here that hybrid gravimetry is able to provide new constraints on underground water storage changes. We will focus on two special cases in West Africa which were investigated in the frame of the GHYRAF (Gravity and Hydrology in Africa) project: one is located in the semi-arid Sahelian zone in Wankama (Niger) and another one in Djougou (Benin) in the humid, hard-rock basement zone. In Wankama, both time-lapse AG and RG are available. In an innovative field survey during 3 months of the rainy season in 2009, we merged relative microgravimetry on a network of 12 stations, magnetic resonance soundings, and hydrological measurements to evaluate both surface and subsurface water storage variations. We show that most of the gravity variations originate from heterogeneities in the vadose zone highlighting the potential of time lapse microgravity surveys for detecting intraseasonal water storage variations in the critical zone. In Djougou, we will present the hydrology results coming from the use of the hybrid gravimetry approach based on a continuous record of a GWR SG installed since 2010 complemented with FG5 AG episodic measurements (4 times a year between 2008 and 2011 then yearly). In addition we also set up repeated micro-gravimetric measurements with a Scintrex CG5 RG on a dense network (more than 100 surveys and 15 stations) around the base station. The continuous SG record allows to bring additional insight on the space and time variable gravity (and hence water storage changes) in

  18. Probabilistic Impact Assessment of Domestic Rainwater Harvesting in Urban Slums: West Africa Case Study

    NASA Astrophysics Data System (ADS)

    Cowden, J. R.; Watkins, D. W.; Mihelcic, J. R.; Fry, L. M.

    2007-12-01

    Urban populations now exceed rural populations worldwide, creating unique challenges in providing basic services, especially in developing countries where informal or illegal settlements grow in peri-urban areas. West Africa is an acute example of the problems created by rapid urban growth, with high levels of urban poverty and low water and sanitation access rates. Although considerable effort has been made in providing improved water access and urban services to slum communities, research indicates that clean water access rates are not keeping up with urbanization rates in several areas of the world and that rapidly growing slum communities are beginning to overwhelm many prior water improvements projects. In the face of these challenges, domestic rainwater harvesting is proposed as a technologically appropriate and economically viable option for enhancing water supplies to urban slum households. However, assessing the reliability, potential health impacts, and overall cost-effectiveness of these systems on a regional level is difficult for several reasons. First, long daily rainfall records are not readily available in much of the developing world, including many regions of sub-Saharan Africa. Second, significant uncertainties exist in the relevant cost, water use, and health data. Third, to estimate the potential future impacts at the regional scale, various global change scenarios should be investigated. Finally, in addition to these technical challenges, there is also a need to develop relatively simple and transparent assessment methods for informing policy makers. A procedure is presented for assessment of domestic rainwater harvesting systems using a combination of scenario, sensitivity, and trade-off analyses. Using data from West Africa, simple stochastic weather models are developed to generate rainfall sequences for the region, which are then used to estimate the reliability of providing a range of per capita water supplies. Next, a procedure is

  19. Cost-Effectiveness of Antivenoms for Snakebite Envenoming in 16 Countries in West Africa

    PubMed Central

    Hamza, Muhammad; Idris, Maryam A.; Maiyaki, Musa B.; Lamorde, Mohammed; Chippaux, Jean-Philippe; Warrell, David A.; Kuznik, Andreas; Habib, Abdulrazaq G.

    2016-01-01

    Background Snakebite poisoning is a significant medical problem in agricultural societies in Sub Saharan Africa. Antivenom (AV) is the standard treatment, and we assessed the cost-effectiveness of making it available in 16 countries in West Africa. Methods We determined the cost-effectiveness of AV based on a decision-tree model from a public payer perspective. Specific AVs included in the model were Antivipmyn, FAV Afrique, EchiTab-G and EchiTab-Plus. We derived inputs from the literature which included: type of snakes causing bites (carpet viper (Echis species)/non-carpet viper), AV effectiveness against death, mortality without AV, probability of Early Adverse Reactions (EAR), likelihood of death from EAR, average age at envenomation in years, anticipated remaining life span and likelihood of amputation. Costs incurred by the victims include: costs of confirming and evaluating envenomation, AV acquisition, routine care, AV transportation logistics, hospital admission and related transportation costs, management of AV EAR compared to the alternative of free snakebite care with ineffective or no AV. Incremental Cost Effectiveness Ratios (ICERs) were assessed as the cost per death averted and the cost per Disability-Adjusted-Life-Years (DALY) averted. Probabilistic Sensitivity Analyses (PSA) using Monte Carlo simulations were used to obtain 95% Confidence Intervals of ICERs. Results The cost/death averted for the 16 countries of interest ranged from $1,997 in Guinea Bissau to $6,205 for Liberia and Sierra Leone. The cost/DALY averted ranged from $83 (95% Confidence Interval: $36-$240) for Benin Republic to $281 ($159–457) for Sierra-Leone. In all cases, the base-case cost/DALY averted estimate fell below the commonly accepted threshold of one time per capita GDP, suggesting that AV is highly cost-effective for the treatment of snakebite in all 16 WA countries. The findings were consistent even with variations of inputs in 1—way sensitivity analyses. In addition

  20. Etiology of urethral discharge in West Africa: the role of Mycoplasma genitalium and Trichomonas vaginalis.

    PubMed Central

    Pépin, J.; Sobéla, F.; Deslandes, S.; Alary, M.; Wegner, K.; Khonde, N.; Kintin, F.; Kamuragiye, A.; Sylla, M.; Zerbo, P. J.; Baganizi, E.; Koné, A.; Kane, F.; Mâsse, B.; Viens, P.; Frost, E.

    2001-01-01

    OBJECTIVE: To determine the etiological role of pathogens other than Neisseria gonorrhoeae and Chlamydia trachomatis in urethral discharge in West African men. METHODS: Urethral swabs were obtained from 659 male patients presenting with urethral discharge in 72 primary health care facilities in seven West African countries, and in 339 controls presenting for complaints unrelated to the genitourinary tract. Polymerase chain reaction analysis was used to detect the presence of N. gonorrhoeae, C. trachomatis, Trichomonas vaginalis, Mycoplasma genitalium, and Ureaplasma urealyticum. FINDINGS: N. gonorrhoeae, T. vaginalis, C. trachomatis, and M. genitalium--but not U. urealyticum--were found more frequently in men with urethral discharge than in asymptomatic controls, being present in 61.9%, 13.8%, 13.4% and 10.0%, respectively, of cases of urethral discharge. Multiple infections were common. Among patients with gonococcal infection, T. vaginalis was as frequent a coinfection as C. trachomatis. M. genitalium, T. vaginalis, and C. trachomatis caused a similar clinical syndrome to that associated with gonococcal infection, but with a less severe urethral discharge. CONCLUSIONS: M. genitalium and T. vaginalis are important etiological agents of urethral discharge in West Africa. The frequent occurrence of multiple infections with any combination of four pathogens strongly supports the syndromic approach. The optimal use of metronidazole in flowcharts for the syndromic management of urethral discharge needs to be explored in therapeutic trials. PMID:11242818

  1. Capacity for scaling up nutrition: a focus on pre-service training in West Africa and a Ghanaian case study.

    PubMed

    Aryeetey, Richmond N O; Laar, Amos; Zotor, Francis

    2015-11-01

    The 2013 Lancet series on maternal and child nutrition is identified and advocated for improved institutional and human capacity in nutrition towards scaling up nutrition (SUN) in countries with high stunting rates. Of the fifty-four countries with high burden of child undernutrition who have committed to the SUN movement, thirty-six are in Africa. In the present paper, the academic platform of the SUN movement in Ghana presents an overview of nutrition pre-service capacity in West Africa with a focus on Ghana. The present paper is based on the findings of a sub-region-wide assessment of degree programmes in nutrition in West Africa, plus another report on pre-service nutrition capacity in diploma awarding nursing and nutrition programmes in Ghana. Although there is inadequate evidence on pre-service nutrition training in the sub-region, the two reports provide useful evidence for action, including inadequate number and distribution of pre-service nutrition training programmes, low nutrition graduate output, poor quality of the programme curriculum and instruction, and sub-optimal capital investment. The present paper calls for urgent action to improve pre-service nutrition capacity building as a critical step towards SUN in West Africa. PMID:25586054

  2. Brazil-Africa geological links

    NASA Astrophysics Data System (ADS)

    Torquato, Joaquim Raul; Cordani, Umberto G.

    1981-04-01

    In this work, the main evidence and conclusions regarding geological links between Brazil and Africa are summarized, with emphasis on the geochronological aspects. Taking into account the geographical position, as well as the similarities in the geochronological pattern, the following main provinces of the two continents are correlated: The Imataca and Falawatra complexes in the Guayana Shield and the Liberian Province of West Africa. The Paraguay-Araguaia and the Rockelide Fold Belts. The Sa˜o Luiz and the West African cratonic areas. The Caririan Fold Belt of northeastern Brazil and the Pan-Africa Belt of Nigeria and Cameroon. The JequiéComplex of Bahia, the Ntem Complex of Cameroon and similar rocks of Gabon and Angola. The Ribeira Fold Belt in Brazil and the West Congo and Damara Belts in West and South Africa. In addition, other geological links are considered, such as some of the major linear fault zones which can be traced across the margins of South America and Africa, in the pre-drift reconstructions. Correlations are also made of the tectonic and stratigraphic evolution of the Paranáand Karroo syneclises, and the Brazilian and African marginal basins around the South Atlantic, during their initial stages. Finally, several similarities in the tectonic evolution of South America and Africa, during and after the onset of drifting, are shown to be compatible with a recent origin for the South Atlantic floor, as required by sea-floor spreading and continental drift between South America and Africa.

  3. A new inventory for two-wheel vehicle emissions in West Africa for 2002

    NASA Astrophysics Data System (ADS)

    Assamoi, Eric-Michel; Liousse, Catherine

    2010-10-01

    Rather surprisingly, urban atmospheric particulate levels in West Africa compare with measured concentrations in Europe and Asia megacities (Liousse, C., Galy-Lacaux, C., Assamoi, E.-M., Ndiaye, A., Diop, B., Cachier, H., Doumbia, T., Gueye, P., Yoboue, V., Lacaux, J.-P., Guinot, B., Guillaume, B., Rosset, R., Castera, P., Gardrat, E., Zouiten, C., Jambert, C., Diouf, A., Koita, O., Baeza, A., Annesi-Maesano, I., Didier, A., Audry, S., Konare, A., 2009. Integrated Focus on West African Cities (Cotonou, Bamako, Dakar, Ouagadougou, Abidjan, Niamey): Emissions, Air Quality and Health Impacts of Gases and Aerosols. Third International AMMA Conference on Predictability of the West African Moosoon Weather, Climate and Impacts. Ouagadougou, Burkina Faso. July 20-24). This pollution mainly derives from road traffic emissions with, in some capitals (e.g. Cotonou), the strong contribution of two-wheel vehicles. Two key questions arise: are presently available emission inventories (e.g. Junker, C., Liousse, C., 2008. A global emission inventory of carbonaceous aerosol from historic records of fossil fuel and biofuel consumption for the period 1860-1997. Atmospheric Chemistry Physics, 8, 1-13; Bond, T.C., Streets, D.G., Yarber, K.F., Nelson, S.M., Woo, J.H., Klimont, Z., 2004. A technology-based global inventory of black and organic carbon emissions from combustion. Journal of Geophysical Research, 1009, D14203, DOI:10.1029/2003JD003697) able to account for these emissions? And, if not, how can we remedy this? The aim of this paper is to develop a methodology to estimate emissions produced by two-wheel vehicles in West Africa for 2002 in a context where reliable information is hardly available. Fuel consumption ratios between two-wheel engines (in this work) and all vehicles issued from UN database ( http://data.un.org/Data.aspx?d=EDATA&f=cmID%3aMO%3btrID%3a1221) are as high as 169%, 264% and 628%, for Burkina Faso, Mali and Chad respectively, indicating that this global

  4. 'FAN the SUN brighter': fortifying Africa nutritionally (FAN) - the role of public private partnership in scaling up nutrition (SUN) in West Africa.

    PubMed

    Sablah, Mawuli; Baker, Shawn K; Badham, Jane; De Zayas, Alfred

    2013-11-01

    The scaling up nutrition (SUN) policy framework requires extensive public–private partnership (PPP). Malnutrition is multi-dimensional and should engage multi-sectoral platforms. The SUN policy however did not fully embrace the dynamics of harnessing PPP. The objectives of the present paper are to highlight the reasons for the apprehension around PPP and illustrate how effective coordination of PPP in West Africa has contributed to implementing large-scale food fortification with micronutrients as a complementary nutrition intervention. The experience of Helen Keller International (HKI) in scaling up food fortification was emphasised with understanding of the factors contributing to indifference by the international community to private sector contribution to SUN. The roles of different stakeholders in a PPP are elucidated and the process linked to who, why and how to engage. The private sector provides direct nutrition services while the public sector creates the enabling environment for the private sector to thrive on social values. Through this approach fortified vegetable oil and wheat flour are now reaching over 70% of the population in West Africa. As a neutral broker HKI coordinated and facilitated dialogue among the different stakeholders. The core competencies of each stakeholder were harnessed and each partner was held accountable. It concludes that multi-sectoral relationship must be transparent, equitable and based on shared mutual interests. The rules and values of PPP offer opportunities for SUN. PMID:24025656

  5. West Africa - a safe haven for frogs? A sub-continental assessment of the chytrid fungus (Batrachochytrium dendrobatidis).

    PubMed

    Penner, Johannes; Adum, Gilbert B; McElroy, Matthew T; Doherty-Bone, Thomas; Hirschfeld, Mareike; Sandberger, Laura; Weldon, Ché; Cunningham, Andrew A; Ohst, Torsten; Wombwell, Emma; Portik, Daniel M; Reid, Duncan; Hillers, Annika; Ofori-Boateng, Caleb; Oduro, William; Plötner, Jörg; Ohler, Annemarie; Leaché, Adam D; Rödel, Mark-Oliver

    2013-01-01

    A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds) environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni ("Vulnerable") and Petropedetes natator ("Near Threatened")) as well as the "Critically Endangered" viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis). PMID:23426141

  6. West Africa - A Safe Haven for Frogs? A Sub-Continental Assessment of the Chytrid Fungus (Batrachochytrium dendrobatidis)

    PubMed Central

    Penner, Johannes; Adum, Gilbert B.; McElroy, Matthew T.; Doherty-Bone, Thomas; Hirschfeld, Mareike; Sandberger, Laura; Weldon, Ché; Cunningham, Andrew A.; Ohst, Torsten; Wombwell, Emma; Portik, Daniel M.; Reid, Duncan; Hillers, Annika; Ofori-Boateng, Caleb; Oduro, William; Plötner, Jörg; Ohler, Annemarie; Leaché, Adam D.; Rödel, Mark-Oliver

    2013-01-01

    A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds) environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni (“Vulnerable”) and Petropedetes natator (“Near Threatened”)) as well as the “Critically Endangered” viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis). PMID:23426141

  7. The nutrition and health impact of cash cropping in west Africa: a historical perspective.

    PubMed

    Brun, T A

    1991-01-01

    The impact of cash cropping in West Africa cannot be isolated from its social and historical background. Among the many changes brought to West African economies by cash cropping since the beginning of the century, the present document shows how the extension of trade with European merchants and colonizers created new sets of values and criteria for wealth. Food crops gradually lost their prominent cultural and economics roles to the benefit of export crops or goods. Traditional systems of agricultural production were profoundly disrupted by military actions. They imposed colonial rule and control of trade of tropical crops and goods. Forced labor and compulsory (poorly paid) work assignments were instituted for private and public enterprises: construction of roads, railways, public buildings and plantations. The main justification was the need for cheap labor to cultivate, transport and build roads for the extraction of raw materials. This in turn caused massive migrations from countries such as Burkina Faso (Upper Volta) to Ivory Coast. Cash cropping made systematic collection of taxes possible. An imposition on a per capita basis became the rule and the major incentive of small farmers to engage in commercial farming. Cash cropping made also possible extensive monetarization of West Africa. This results in both favorable and unfavorable effects on the quality of the diet. In profoundly disrupted traditional societies, the diffusion of new consumption patterns was easier and faster. It led to massive food imports of wheat, rice, sugar, alcohol, etc. Cash cropping was (and still is) practiced as a 'mining' agriculture, exhausting soils and deteriorating their fertility for extended periods of time. In the Sudanian and Sahelian zones cash cropping conflicted with the cultivation of grains because peak demands for labor were similar. Therefore, millet and sorghum production declined. Cash cropping was developed in response to the need of European economies for

  8. An overview of the nutrition transition in West Africa: implications for non-communicable diseases.

    PubMed

    Bosu, William K

    2015-11-01

    The nutrition landscape in West Africa has been dominated by the programmes to address undernutrition. However, with increasing urbanisation, technological developments and associated change in dietary patterns and physical activity, childhood and adult overweight, and obesity are becoming more prevalent. There is an evidence of increasing intake of dietary energy, fat, sugars and protein. There is low consumption of fruit and vegetables universally in West Africa. Overall, the foods consumed are predominantly traditional with the component major food groups within recommended levels. Most of the West African countries are at the early stages of nutrition transition but countries such as Cape Verde, Ghana and Senegal are at the latter stages. In the major cities of the region, children consume energy-dense foods such as candies, ice cream and sweetened beverages up to seven times as frequently as fruit and vegetables. Adult obesity rates have increased by 115 % in 15 years since 2004. In Ghana, the prevalence of overweight/obesity in women has increased from 12·8 % in 1993 to 29·9 % in 2008. In Accra, overweight/obesity in women has increased from 62·2 % in 2003 to 64·9 % in 2009. The age-standardised proportion of adults who engage in adequate levels of physical activity ranges from 46·8 % in Mali to 94·7 % in Benin. The lingering stunting in children and the rising overweight in adults have resulted to a dual burden of malnutrition affecting 16·2 % of mother-child pairs in Cotonou. The prevalence of hypertension has been increased and ranges from 17·6 % in Burkina Faso to 38·7 % in Cape Verde. The prevalence is higher in the cities: 40·2 % in Ougadougou, 46·0 % in St Louis and 54·6 % in Accra. The prevalence of diabetes ranges from 2·5 to 7·9 % but could be as high as 17·9 % in Dakar, Senegal. The consequences of nutrition transition are not only being felt by the persons in the high socioeconomic class, but also in cities such as Accra and

  9. Sustainable Development of Research Capacity in West Africa based on the GLOWA Volta Project

    NASA Astrophysics Data System (ADS)

    Liebe, Jens R.; Rogmann, Antonio; Falk, Ulrike; Amisigo, Barnabas; Nyarko, Kofi; Harmsen, Karl; Vlek, Paul L. G.

    2010-05-01

    The Sustainable Development of Research Capacity (SDRC) in West Africa is an 18 month project, funded by the German Ministry of Education and Research, to strengthen the research capacity, give access to data and models, and to support the establishment of the newly formed Volta Basin Authority. The SDRC project largely builds on the results and models developed in the framework of the GLOWA Volta Project (GVP), a nine-year, interdisciplinary research project (May 2000 - May 2009). The GVP's central objectives were to analyze the physical and socio-economic determinants of the hydrological cycle in the Volta Basin in the face of global change, and to develop scientifically sound decision support resources. Another major achievement of GVP was the extensive capacity building. Of the 81 participating students (57 Ph.D.'s), 44 originated from West Africa, and 85% of the West African graduates returned to their home countries. The SDRC makes use of the wide range of research results and decision support tools developed in the course of the GVP. It is based on three columns: I. knowledge transfer and strengthening of human capacity, which focus on a training on the modeling of the onset of the rainy season, hydrological, economic, and hydro-economic modeling, and training of geospatial database managers; II. strengthening of infrastructural research capacity through the support of a research instrumentation network through the operation and transfer of a weather station network, a network of tele-transmitted stream gauges; and III. the transfer of a publicly accessible online Geoportal for the dissemination of various geospatial data and research results. At the center of the SDRC effort is the strengthening of the Volta Basin Authority, a river basin authority with a transnational mandate, especially through the transfer of the Geoportal, and the associated training and promotion efforts. The Geoportal is an effort to overcome the data scarcity previously observed in

  10. [An approach to food consumption in an urban environment. The case of west Africa].

    PubMed

    Ag Bendech, M; Gerbouin-Rerolle, P; Chauliac, M; Malvy, D

    1996-01-01

    West Africa has undergone rapid economic and political changes during the last 20 years. After the failure of economic policies implemented since independence, programs for structural adjustment have strongly influenced the economy. Food problems affect each country differently. The Sahel has experienced food shortages and starvation whereas in forested countries the food supply has remained stable. Nevertheless, food policies have not succeeded in contributing to urban and rural development. The rate of urbanization in west Africa is generally low but the rate of urban population growth is particularly high, much more than the growth rates of industry and infrastructure. Although metropolitan areas are affected by poverty, they offer more hope and opportunities than rural areas. Urban markets have expanded and diversified as social differences have also increased and contributed to changes in consumption structure. Urban growth has contributed to the increase of imported food: this is indicated by both the strong dependency and the change of food habits towards western food patterns. Recently however, west African urban dwellers are still preferring local items if they are affordable. When imported products are used, they are integrated within a stable meal plan consisting of a single dish with a base and a sauce, which is typical of African food preparation. Surveys of consumption-budgets are still only available on a national scale. These can provide accurate information about food consumption patterns of families, particularly for significant trends. However, they do not provide information about the dynamics of food consumption, neither for urban areas or the individual. Now a significant proportion of individual food consumption occurs outside of the home, mainly with food provided by street vendors. This new consumption habit is a response to the urban food crisis. Consumption of street-vendor-food comprises one component but this cannot be dissociated from

  11. Seasonal Variations of Water, Energy, and Carbon Fluxes Across a Moisture Gradient in West Africa

    NASA Astrophysics Data System (ADS)

    Smith, D.; Baker, I. T.; Denning, S.; Stockli, R.; Orescanin, B.

    2013-12-01

    While grasslands make up nearly 40% of Earth's land surface, many areas remain understudied and under observed. Particularly, tropical grasslands are generally less researched sites due to the remoteness of their location. Model output and satellite data have become key resources when describing and analyzing the ecological processes occurring in these areas. In this project, the Simple Biosphere Model (SiB) and fluorescence data are used alongside each other to summarize the productivity both seasonally and annually in several grassland sites in West Africa. While SiB interpreted the overall meteorological processes fairly well, the model struggled to accurately describe the variations in leaf indices, including; leaf area index, fraction of photosynthetically active radiation, and fluorescence. Specifically, fluorescence data retrieved by satellite showed variability seasonally, whereas, SiB showed very little. To improve SiB's output, the phenology of each grassland site are examined and altered to create a more realistic description than what had been previously used. The adaption resulted in more accurate modeling of ecological processes in West African grasslands. Comparing the Simple Biosphere Model (SiB) to remotely sensed observations.

  12. Moko Jumbies: Dancing Spirits from Africa

    ERIC Educational Resources Information Center

    Bennett, S. A.; Phillips, Claire; Moore, Natalie

    2009-01-01

    The original Moko Jumbie was a spirit dancer from West Africa. "Moko" is a West African word that refers to gods and "Jumbie" means ghost. In West Africa, Moko Jumbies are known to kidnap and eat disobedient children, steal dreams and see into evildoers' hearts and terrorize them. They walk through villages on 10- to 15-foot-high stilts wearing…

  13. Marine Incursion: The Freshwater Herring of Lake Tanganyika Are the Product of a Marine Invasion into West Africa

    PubMed Central

    Wilson, Anthony B.; Teugels, Guy G.; Meyer, Axel

    2008-01-01

    The spectacular marine-like diversity of the endemic fauna of Lake Tanganyika, the oldest of the African Great Lakes, led early researchers to suggest that the lake must have once been connected to the ocean. Recent geophysical reconstructions clearly indicate that Lake Tanganyika formed by rifting in the African subcontinent and was never directly linked to the sea. Although the Lake has a high proportion of specialized endemics, the absence of close relatives outside Tanganyika has complicated phylogeographic reconstructions of the timing of lake colonization and intralacustrine diversification. The freshwater herring of Lake Tanganyika are members of a large group of pellonuline herring found in western and southern Africa, offering one of the best opportunities to trace the evolutionary history of members of Tanganyika's biota. Molecular phylogenetic reconstructions indicate that herring colonized West Africa 25–50MYA, at the end of a major marine incursion in the region. Pellonuline herring subsequently experienced an evolutionary radiation in West Africa, spreading across the continent and reaching East Africa's Lake Tanganyika during its early formation. While Lake Tanganyika has never been directly connected with the sea, the endemic freshwater herring of the lake are the descendents of an ancient marine incursion, a scenario which may also explain the origin of other Tanganyikan endemics. PMID:18431469

  14. A GCM Study of Responses of the Atmospheric Water Cycle of West Africa and the Atlantic to Saharan Dust Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Kim, K. M.; Sud, Y. C.; Walker, G. K.

    2009-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summerr, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are ehanIed over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer overr the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at0

  15. Roles of low-level thermodynamics on surface-convection interactions over West-Africa

    NASA Astrophysics Data System (ADS)

    Guichard, F.; Couvreux, F.; Gounou, A.; Nuret, M.

    2009-09-01

    This study aims to characterize the thermodynamics of the atmospheric low levels across West Africa (WA), on the basis of observations provided by the AMMA project. A dataset made of several thousands of high-resolution soundings is used for this purpose. Moist-convection related indexes, boundary layer (BL) parameters, and a combination of two indexes proposed by Findell and Eltahir (2003) (FE03) are compted for each sounding. These latter indexes are well suited for distinguishing between aspects of surface-atmosphere interactions involving atmospheric vertical structures. The variability of the low levels is found to be stronger in the Sahelian zone than in the Soudanian zone, from daily scale up to the monsoon season (JJAS). FE03 indexes suggest that surface-atmosphere feedbacks are actually significantly operating over West-Africa, but that the feedback loops change sign with latitude and season. Thus, thermodynamic environment at low level is broadly consistent with the idea of daytime convection being either suppressed or favoured over wet surface versus dry ones, depending on latitude and seasonal variations. This finding is consistent with observations that daytime convection is not always favoured over wet land surfaces. It remains to assess the scale down to which the local thermodynamic environment is actually playing a role, and how it combines with other factors, such as turbulence, clouds and mesoscale circulations, to explain observations. Variations of the lifting condensation level (LCL) and level of free convection (LFC) are further consistent with the previous analysis. For instance, in Niamey (Sahelian), a strong diurnal cycle of LCL is found, especially early in the season, while the LFC does not fluctuates much with the hour in the day, but shifts downwards from June to August. The LCL is however not such a good indicator of BL height when the low levels are the driest. This is particularly true in June in the Sahel, on days when none of the

  16. Vegetation dynamics and climate variability in West Africa at seasonal- decadal Scales

    NASA Astrophysics Data System (ADS)

    Xue, Y.; Song, G.; Cox, P.

    2011-12-01

    New evidence emerged from satellite data analyses and modeling study indicate that patterns of vegetation spatial distribution and vegetation structure are important in the soil-vegetation-atmosphere system (SVAS) and including a fully coupled dynamic vegetation/climate process is of imminent important in increasing our understanding and predictive capabilities of the SVAS. We apply the Simplified Simple Biosphere Model version 4/Top-down Representation of Interactive Foliage and Flora Including Dynamics Model (SSiB4/TRIFFID) to investigate the interactions between vegetation dynamics and climate variability for West Africa. The TRIFFID is a dynamic vegetation model, in which the relevant vegetation spatial distribution and structure are modeled based on the surface carbon balance. SSiB4 is a biophysical model based on surface water and energy balance and produces carbon assimilation rate for TRIFFID. The offline SSiB2, which uses specified vegetation spatial distribution and vegetation structure with no inter-annual and decadal variability, and SSiB4/TRIFFID are integrated using the observed precipitation and reanalysis-based meteorological forcing from 1948 to 2006 with 1 degree horizontal resolution over West Africa. West Africa is a diverse climatic and ecosystem region and suffered the most severe and longest drought in the world during the Twentieth Century since the later 1960s. The simulation results indicate that the SSiB4/TRIFFID model was able to produce reasonable vegetation spatial distributions, generally consistent with the products derived from satellites and with the Sahel drought in the 1970s and the 1980s and the partial recovery in the 1990s and the 2000s. The SSiB4/TRIFFID and SSIB2 results show quite different spatial patterns and vegetation structure, which lead to differences in surface net radiation, latent and sensible heat flux partitioning, soil moisture and runoff distribution, and carbon cycles at seasonal and inter-decadal time scales

  17. Gambian-British and Nigerian-British Children's and Families' Experiences of Migration "Back" to West Africa. Research Briefing No. 13

    ERIC Educational Resources Information Center

    Roberts-Holmes, Guy

    2013-01-01

    This research looks at the factors motivating Gambian-British and Nigerian-British parents to send their children "back" to West Africa and what this means for parents, children and families on both continents.

  18. Genetic structure of the population of Cabo Verde (west Africa): evidence of substantial European admixture.

    PubMed

    Parra, E J; Ribeiro, J C; Caeiro, J L; Riveiro, A

    1995-08-01

    The population of Cabo Verde was founded in the fifteenth century (1462), on the basis of slaves brought from the West African coast and a few Europeans, mainly from Portugal. The polymorphism of six red cell enzymes (ADA, AK1, ALAD, ESD, GLO1, and PGD) and ten plasma proteins (AHSG, BF, F13A, F13B, GC, HP, ORM, PLG, TBG, and TF) was studied in a sample of 268 individuals from Cabo Verde (West Africa). There is no statistical evidence of genetic heterogeneity between the two groups of islands which constitute the archipelago, Barlavento and Sotavento. The gene frequency distribution observed in Cabo Verde differs, in many markers, from that of West African populations, suggesting an important European influence. The proportion of Caucasian genes in the population of Cabo Verde has been calculated to be M = 0.3634 +/- 0.0510, and the considerable dispersion of the locus-specific admixture estimates seems to indicate random drift has also played a role in the evolution of the allele frequencies in the archipelago. Partition of the variance of the mean estimate in evolutionary and sampling variance shows the evolutionary variance is more than ten times higher than the sampling variance. When dendrograms are constructed on the basis of different genetic distances, the population of Cabo Verde clusters with Afro-Americans, forming a different group from the populations of the African continent. This is interpreted as a consequence of the importance of Caucasian admixture both in Afro-Americans and in the population of Cabo Verde. PMID:7485435

  19. Extensive nitrogen loss from permeable sediments off North-West Africa

    NASA Astrophysics Data System (ADS)

    Sokoll, Sarah; Lavik, Gaute; Sommer, Stefan; Goldhammer, Tobias; Kuypers, Marcel M. M.; Holtappels, Moritz

    2016-04-01

    The upwelling area off North-West Africa is characterized by high export production, high nitrate and low oxygen concentration in bottom waters. The underlying sediment consists of sands that cover most of the continental shelf. Due to their permeability sands allow for fast advective pore water transport and can exhibit high rates of nitrogen (N) loss via denitrification as reported for anthropogenically eutrophied regions. However, N loss from sands underlying naturally eutrophied waters is not well studied, and in particular, N loss from the North-West African shelf is poorly constrained. During two research cruises in April/May 2010/2011, sediment was sampled along the North-West African shelf and volumetric denitrification rates were measured in sediment layers down to 8 cm depth using slurry incubations with 15N-labeled nitrate. Areal N loss was calculated by integrating volumetric rates down to the nitrate penetration depth derived from pore water profiles. Areal N loss was neither correlated with water depth nor with bottom water concentrations of nitrate and oxygen but was strongly dependent on sediment grain size and permeability. The derived empirical relation between benthic N loss and grains size suggests that pore water advection is an important regulating parameter for benthic denitrification in sands and further allowed extrapolating rates to an area of 53,000 km2 using detailed sediment maps. Denitrification from this region amounts to 995 kt yr-1 (average 3.6 mmol m-2 d-1) which is 4 times higher than previous estimates based on diffusive pore water transport. Sandy sediments cover 50-60% of the continental shelf and thus may contribute significantly to the global benthic N loss.

  20. Vulnerability to climate change of cocoa in West Africa: Patterns, opportunities and limits to adaptation.

    PubMed

    Schroth, Götz; Läderach, Peter; Martinez-Valle, Armando Isaac; Bunn, Christian; Jassogne, Laurence

    2016-06-15

    The West African cocoa belt, reaching from Sierra Leone to southern Cameroon, is the origin of about 70% of the world's cocoa (Theobroma cacao), which in turn is the basis of the livelihoods of about two million farmers. We analyze cocoa's vulnerability to climate change in the West African cocoa belt, based on climate projections for the 2050s of 19 Global Circulation Models under the Intergovernmental Panel on Climate Change intermediate emissions scenario RCP 6.0. We use a combination of a statistical model of climatic suitability (Maxent) and the analysis of individual, potentially limiting climate variables. We find that: 1) contrary to expectation, maximum dry season temperatures are projected to become as or more limiting for cocoa as dry season water availability; 2) to reduce the vulnerability of cocoa to excessive dry season temperatures, the systematic use of adaptation strategies like shade trees in cocoa farms will be necessary, in reversal of the current trend of shade reduction; 3) there is a strong differentiation of climate vulnerability within the cocoa belt, with the most vulnerable areas near the forest-savanna transition in Nigeria and eastern Côte d'Ivoire, and the least vulnerable areas in the southern parts of Cameroon, Ghana, Côte d'Ivoire and Liberia; 4) this spatial differentiation of climate vulnerability may lead to future shifts in cocoa production within the region, with the opportunity of partially compensating losses and gains, but also the risk of local production expansion leading to new deforestation. We conclude that adaptation strategies for cocoa in West Africa need to focus at several levels, from the consideration of tolerance to high temperatures in cocoa breeding programs, the promotion of shade trees in cocoa farms, to policies incentivizing the intensification of cocoa production on existing farms where future climate conditions permit and the establishment of new farms in already deforested areas. PMID:26974571

  1. Promiscuous arbuscular mycorrhizal symbiosis of yam (Dioscorea spp.), a key staple crop in West Africa.

    PubMed

    Tchabi, Atti; Burger, Stefanie; Coyne, Danny; Hountondji, Fabien; Lawouin, Louis; Wiemken, Andres; Oehl, Fritz

    2009-08-01

    Yam (Dioscorea spp.) is a tuberous staple food crop of major importance in the sub-Saharan savannas of West Africa. Optimal yields commonly are obtained only in the first year following slash-and-burn in the shifting cultivation systems. It appears that the yield decline in subsequent years is not merely caused by soil nutrient depletion but might be due to a loss of the beneficial soil microflora, including arbuscular mycorrhizal fungi (AMF), associated with tropical "tree-aspect" savannas and dry forests that are the natural habitats of the wild relatives of yam. Our objective was to study the AMF communities of natural savannas and adjacent yam fields in the Southern Guinea savanna of Benin. AMF were identified by morphotyping spores in the soil from the field sites and in AMF trap cultures with Sorghum bicolor and yam (Dioscorea rotundata and Dioscorea cayenensis) as bait plants. AMF species richness was higher in the savanna than in the yam-field soils (18-25 vs. 11-16 spp.), but similar for both ecosystems (29-36 spp.) according to the observations in trap cultures. Inoculation of trap cultures with soil sampled during the dry season led to high AMF root colonization, spore production, and species richness (overall 45 spp.) whereas inoculation with wet-season soil was inefficient (two spp. only). The use of D. cayenensis and D. rotundata as baits yielded 28 and 29 AMF species, respectively, and S. bicolor 37 species. AMF root colonization, however, was higher in yam than in sorghum (70-95 vs. 11-20%). After 8 months of trap culturing, the mycorrhizal yam had a higher tuber biomass than the nonmycorrhizal controls. The AMF actually colonizing D. rotundata roots in the field were also studied using a novel field sampling procedure for molecular analyses. Multiple phylotaxa were detected that corresponded with the spore morphotypes observed. It is, therefore, likely that the legacy of indigenous AMF from the natural savanna plays a crucial role for yam

  2. Radiative impact of mineral dust on monsoon precipitation variability over West Africa

    SciTech Connect

    Zhao, Chun; Liu, Xiaohong; Leung, Lai-Yung R.; Hagos, Samson M.

    2011-03-01

    The radiative forcing of dust and its impact on precipitation over the West Africa monsoon (WAM) region is simulated using a coupled meteorology and aerosol/chemistry model (WRF-Chem). During the monsoon season, dust is a dominant contributor to AOD over West Africa. In the standard simulation, on 24-hour domain average, dust has a cooling effect (-6.11 W/m2) at the surface, a warming effect (6.94 W/m2) in the atmosphere, and a relatively small TOA forcing (0.83 W/m2). Dust modifies the surface energy budget and atmospheric diabatic heating and hence causes lower atmospheric cooling in the daytime but warming in the nighttime. As a result, atmospheric stability is increased in the daytime and reduced in the nighttime, leading to a reduction of late afternoon precipitation by up to 0.14 mm/hour (30%) and an increase of nocturnal and early morning precipitation by up to 0.04 mm/hour (23%) over the WAM region. Dust-induced reduction of diurnal precipitation variation improves the simulated diurnal cycle of precipitation when compared to measurements. However, daily precipitation is only changed by a relatively small amount (-0.14 mm/day or -4%). On the other hand, sensitivity simulations show that, for weaker-to-stronger absorbing dust, dust longwave warming effect in the nighttime surpasses its shortwave cooling effect in the daytime at the surface, leading to a less stable atmosphere associated with more convective precipitation in the nighttime. As a result, the dust-induced change of daily WAM precipitation varies from a significant reduction of -0.40 mm/day (-12%, weaker absorbing dust) to a small increase of 0.05 mm/day (1%, stronger absorbing dust). This variation originates from the competition between dust impact on daytime and nighttime precipitation, which depends on dust shortwave absorption. Dust reduces the diurnal variation of precipitation regardless of its absorptivity, but more reduction is associated with stronger absorbing dust.

  3. Assessment of undiscovered oil and gas resources of the West African Costal Province, West Africa

    USGS Publications Warehouse

    Brownfield, Michael E.; Charpentier, Ronald R.; Schenk, Christopher J.; Klett, Timothy R.; Cook, Troy A.; Pollastro, Richard M.

    2011-01-01

    The West African Coastal Province along the west African coastline recently was assessed for undiscovered, technically recoverable oil, natural gas, and natural gas liquids resources as part of the U.S. Geological Survey's USGS World Oil and Gas Assessment. Using a geology-based assessment methodology, the USGS estimated mean volumes of 3.2 billion barrels of oil, 23.63 trillion cubic feet of natural gas, and 721 million barrels of natural gas liquids.

  4. DPA1*02012: A DPA1*0201-related Mhc class II allele in West Africa

    SciTech Connect

    Meyer, C.G.; May, J.; Spauke, D.; Schnittger, L.

    1994-12-31

    DNA techniques such as sequence-specific oligonucleotide probe (SSOP) hybridizations, restriction-fragment length polymorphism (RFLP) analyses, and DNA sequencing have greatly supported the characterization of Mhc class II allelic polymorphism. Here the authors describe a DPA 1 allele which has been identified in two male individuals from Liberia and Benin, West Africa, during a survey study on Mhc class II associations with the different manifestations after infection with Onchocerca volvulus. 4 refs., 1 fig.

  5. Early antiretroviral therapy initiation in west Africa has no adverse social consequences: a 24-month prospective study.

    PubMed

    Jean, Kévin; Niangoran, Serge; Danel, Christine; Moh, Raoul; Kouamé, Gérard Menan; Badjé, Anani; Gabillard, Delphine; Eholié, Serge; Dray-Spira, Rosemary; Lert, France; Anglaret, Xavier; Desgrées-Du-LoÛ, Annabel

    2016-06-19

    Based on social indicators collected within the TEMPRANO-ANRS12136 trial, we assessed the social consequences of early antiretroviral therapy (ART) initiation in west Africa. We did not observe any significant differences in the levels or the time trends of various social indicators, including union status, HIV disclosure and HIV-related discrimination, between early and deferred ART initiation. Early ART does not carry detectable adverse social consequences that could impair its clinical and preventive benefits. PMID:27003034

  6. Masked millennial-scale climate variations in South West Africa during the last glaciation

    NASA Astrophysics Data System (ADS)

    Hessler, I.; Dupont, L.; Handiani, D.; Paul, A.; Merkel, U.; Wefer, G.

    2012-04-01

    To address the connection between tropical African vegetation development and high-latitude climate change we present a high-resolution pollen record from ODP Site 1078 (off Angola) covering the period 50-10 ka BP. Although several tropical African vegetation and climate reconstructions indicate an impact of Heinrich Stadials (HSs) in Southern Hemisphere Africa, our vegetation record shows no response. Model simulations conducted with an Earth System Model of Intermediate Complexity including a dynamical vegetation component provide one possible explanation. Because both precipitation and evaporation increased during HSs and their effects nearly cancelled each other, there was a negligible change in moisture supply. Consequently, the resulting climatic response to HSs might have been too weak to noticeably affect the vegetation composition in the study area. Our results also show that the response to HSs in southern tropical Africa neither equals nor mirrors the response to abrupt climate change in northern Africa.

  7. Intercomparison of Evapotranspiration Over the Savannah Volta Basin in West Africa Using Remote Sensing Data

    PubMed Central

    Opoku-Duah, S.; Donoghue, D.N.M.; Burt, T. P.

    2008-01-01

    This paper compares evapotranspiration estimates from two complementary satellite sensors – NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and ESA's ENVISAT Advanced Along-Track Scanning Radiometer (AATSR) over the savannah area of the Volta basin in West Africa. This was achieved through solving for evapotranspiration on the basis of the regional energy balance equation, which was computationally-driven by the Surface Energy Balance Algorithm for Land algorithm (SEBAL). The results showed that both sensors are potentially good sources of evapotranspiration estimates over large heterogeneous landscapes. The MODIS sensor measured daily evapotranspiration reasonably well with a strong spatial correlation (R2=0.71) with Landsat ETM+ but underperformed with deviations up to ∼2.0 mm day-1, when compared with local eddy correlation observations and the Penman-Monteith method mainly because of scale mismatch. The AATSR sensor produced much poorer correlations (R2=0.13) with Landsat ETM+ and conventional ET methods also because of differences in atmospheric correction and sensor calibration over land.

  8. Multisensor monitoring of deforestation in the Guinea Highlands of West Africa

    NASA Technical Reports Server (NTRS)

    Gilruth, Peter T.; Hutchinson, Charles F.

    1990-01-01

    Multiple remote sensing systems were used to assess deforestation in the Guinea Highlands (Fouta Djallon) of West Africa. Sensor systems included: (1) historical (1953) and current (1989) aerial mapping photography; (2) current large-scale, small format (35mm) aerial photography; (3) current aerial video imagery; and (4) historical (1973) and recent (1985) LANDSAT MSS. Photographic and video data were manually interpreted and incorporated in a vector-based geographic information system (GIS). LANDSAT data were digitally classified. General results showed an increase in permanent and shifting agriculture over the past 35 years. This finding is consistent with hypothesized strategies to increase agricultural production through a shortening of the fallow period in areas of shifting cultivation. However, results also show that the total area of both permanent and shifting agriculture had expanded at the expense of natural vegetation and an increase in erosion. Although sequential LANDSAT MSS cannot be used in this region to accurately map land over, the location, direction and magnitude of changes can be detected in relative terms. Historical and current aerial photography can be used to map agricultural land use changes with some accuracy. Video imagery is useful as ancillary data for mapping vegetation. The most prudent approach to mapping deforestation would incorporate a multistage approach based on these sensors.

  9. The "Super Chimpanzee": The Ecological Dimensions of Rehabilitation of Orphan Chimpanzees in Guinea, West Africa.

    PubMed

    Ongman, Lissa; Colin, Christelle; Raballand, Estelle; Humle, Tatyana

    2013-01-01

    To date few studies, especially among non-human primates, have evaluated or monitored rehabilitation effectiveness and identified key species-specific behavioral indicators for release success. This four-months study aimed to identify behavioral indicators of rehabilitation success among ten infant and juvenile orphaned chimpanzees cared for in peer groups at the Centre for Conservation of Chimpanzees (CCC), Guinea, West Africa. Behavioral data focused on foraging skills and activity budget. During bush-outings, rehabilitants spent on average nearly a quarter of their activity budget foraging, resting or traveling, respectively. Neither age, sex, the level of abnormal behaviors demonstrated upon arrival nor human contact during bush-outings predicted individual dietary knowledge. However, individuals who spent more time arboreal demonstrated a greater dietary breadth than conspecifics who dwelled more terrestrially. Although our data failed to demonstrate a role of conspecific observation in dietary acquisition, we propose that the mingling of individuals from different geographical origins may act as a catalyst for acquiring new dietary knowledge, promoted by ecological opportunities offered during bush-outings. This "Super Chimpanzee" theory opens up new questions about cultural transmission and socially-biased learning among our closest living relatives and provides a novel outlook on rehabilitation in chimpanzees. PMID:26487312

  10. Sensitivity of a mesoscale convective system to soil moisture perturbations in West Africa

    NASA Astrophysics Data System (ADS)

    Gantner, L.; Adler, B.; Kalthoff, N.

    2010-09-01

    The response of a mesoscale convective system (MCS) to soil moisture inhomogeneities in West Africa is investigated in a sensitivity study. Convection permitting simulations with the COSMO-Model driven by ECMWF analyses were performed. Several scenarios were investigated, including homogeneous soil type and soil moisture, and homogeneous soil type with a north-south oriented band in which the soil moisture is either reduced or increased. Precipitation related to the MCS was continuously strong in the homogeneous case. When the MCS approached the band with reduced soil moisture precipitation decreased because of higher convective inhibition (CIN) ahead of the band. Over the drier band precipitation increased again. The moist band caused an increase of precipitation before the MCS reached the band and a decrease in the area with higher soil moisture caused by very high CIN values. Soil moisture inhomogeneities induced thermal circulations which led to modified conditions in the lower troposphere and to changes in CIN and accounted for the modification of precipitation of an MCS. In the dry band case, a precipitating cell already developed in the western part of band in the late afternoon, where convergence, generated by thermal circulations and supported by downward mixing of momentum from the African Easterly Jet, triggered convection.

  11. IASI-derived Surface Temperature Under Dusty Conditions: Application to the West Africa Region.

    NASA Astrophysics Data System (ADS)

    Mechri, Rihab; Capelle, Virginie; Chedin, Alain

    2016-04-01

    Giving access to energy and water budgets, Surface Temperature (ST) is considered as a key variable for a wide range of applications in particular for meteorology and climatology. An accurate knowledge of this variable should significantly improve the monitoring of numerous atmospheric and surface processes as well as their interactions. Even-though satellite sensors bring ST global fields at different spatial and temporal scales, the accuracy of these products is still questionable especially over land or for complex atmospheric conditions (presence of clouds, of aerosols, etc.). At LMD, the ST is determined through the simultaneous "Look-up-Table" inversion of satellite METOP/IASI radiances in terms of Aerosol Optical Depth (AOD), dust layer mean altitude and surface temperature . The main aim of this work is to validate IASI ST product and to analyze its spatial and temporal variability, in particular in the presence of dust aerosols. This approach has been first applied to the West Africa region. The accuracy of this ST product will be assessed in terms of bias and standard deviation against ST products from ECMWF forecast, from other satellite products (MODIS AQUA/TERRA, AATSR,…) and from in-situ measurements for different periods ranging from July 2007 to today according to the availability of these validation data.

  12. Long-term assessment of insecticides treatments in West Africa: aquatic entomofauna.

    PubMed

    Yaméogo, L; Crosa, G; Samman, J; Nabé, K; Kondé, F; Tholley, D; Calamari, D

    2001-09-01

    For the control of the Onchocerca volvulus vector in West Africa, up to 18,000 km of rivers from 1975 and up to 50,000 km from 1989 had been partly sprayed weekly with insecticides as part of the Onchocerciasis Control Programme (OCP). To evaluate the possible short-term and long-term effects of the application of insecticides on the non-target fauna, an aquatic monitoring programme was set up during the initial phase of the programme. By analysing the invertebrate data, which were collected using various sampling strategies from four different countries between 1977 and 1996, this paper evaluates the long-term changes of the invertebrate populations with respect to their taxonomic composition as well as their trophic structures. The discussed results of the applied numerical analysis strategy suggest that neither the taxonomic nor the trophic structures are greatly altered from the range of biological, flow-related variation that normally occurs in the studied river systems. This allows us to conclude that the biological variation found here is ecologically acceptable. PMID:11534907

  13. Factors of the chemical composition of seepage and groundwaters in the intertropical zone (West Africa)

    NASA Astrophysics Data System (ADS)

    Roose, Eric Jean; Lelong, Francois

    1981-12-01

    In connection with a large research programme about the actual dynamics of ferrallitic and ferruginous soils of West Africa, 5000 samples of rainfall, throughfall, runoff, drainage and phreatic waters have been analysed during 4-11 years of field observations. Samples of eight stations, representative of different bioclimatic conditions (sub-Equatorial to pre-Sahelian), have been tested. The analysed parameters are: pH, resistivity, major cations and anions, total organic carbon and nitrogen, phosphorus, silica, aluminium and iron. The results show: (1) The slight influence of the bioclimatic differentiation on the mean chemical composition of the waters: all analysed waters are lightly mineralized (strong resistivity, total chemical charge generally lower than 100 mg/l), with an increasing mineralization from rainfall water to seepage water, at 2 m depth, but decreasing at the water table level (except for Si and Na). (2) The marked variability of the amounts of dissolved chemical species compared to the seasons and the flow volumes. (3) The complexity of phenomena controlling the chemical composition of waters. In the soil layers, this composition would depend principally on biological and biochemical processes, in relation to the activity of organisms but at the level of phreatic waters the chemical composition would rather be controlled by physicochemical conditions (solution-mineral equilibria).

  14. Numerical simulation of convectively generated gravity waves in West Africa and comparisons with observations

    NASA Astrophysics Data System (ADS)

    Heinrich, P.; Blanc, E.

    2012-04-01

    Convective clouds in the ITCZ (Intertropical Convergence Zone) are a major source of nonstationary gravity waves, that propagate to the stratosphere and result in upward displacements at low levels, which induces new convection. Simulations of wind fields are performed by the mesoscale meteorological model WRF (Advanced Research Weather Research and Forecasting) over a period of 2 days during active thunderstorm days. Simulations are carried out in a domain covering the ITCZ in West Africa using 2 nested grids with horizontal grid spacing of 27 and 9 km respectively. Simulations are driven by ECMWF winds (defined by 91 levels from surface to 80 km), using 100 levels from surface to 50 Pa and a sponge layer above 45 km. The waves characteristics are compared to observations at the CTBT (Comprehensive Test Ban Treaty) infrasound station in Ivory Coast. The aim of this study is to further understand the mechanisms of wave generation by deep convection and propagation to the stratosphere. In a second part, we also study the effects of gravity waves on the dynamics of the tropical atmosphere and perform sensitivity simulations to the top height of the model.

  15. Farmer-managed natural regeneration enhances rural livelihoods in dryland west Africa.

    PubMed

    Weston, Peter; Hong, Reaksmey; Kaboré, Carolyn; Kull, Christian A

    2015-06-01

    Declining agricultural productivity, land clearance and climate change are compounding the vulnerability of already marginal rural populations in West Africa. 'Farmer-Managed Natural Regeneration' (FMNR) is an approach to arable land restoration and reforestation that seeks to reconcile sustained food production, conservation of soils, and protection of biodiversity. It involves selecting and protecting the most vigorous stems regrowing from live stumps of felled trees, pruning off all other stems, and pollarding the chosen stems to grow into straight trunks. Despite widespread enthusiasm and application of FMNR by environmental management and development projects, to date, no research has provided a measure of the aggregate livelihood impact of community adoption of FMNR. This paper places FMNR in the context of other agroforestry initiatives, then seeks to quantify the value of livelihood outcomes of FMNR. We review published and unpublished evidence about the impacts of FMNR, and present a new case study that addresses gaps in the evidence-base. The case study focuses on a FMNR project in the district of Talensi in the semi-arid Upper East Region in Ghana. The case study employs a social return on investment analysis, which identifies proxy financial values for non-economic as well as economic benefits. The results demonstrate income and agricultural benefits, but also show that asset creation, increased consumption of wild resources, health improvements, and psycho-social benefits created more value in FMNR-adopting households during the period of the study than increases in income and agricultural yields. PMID:25835946

  16. Surface properties in West Africa from spaceborne radars in C and Ku bands

    NASA Astrophysics Data System (ADS)

    Fatras, Christophe; Frappart, Frédéric; Mougin, Eric; Frison, Pierre-Louis; Faye, Gayane; Jarlan, Lionel

    2013-04-01

    We propose to compare the backscattering responses of land surfaces in West Africa for different radar spaceborne sensors: the nadir-looking radar altimeters and the side-looking radar scatterometers at different frequencies (Ku and C bands). The data used come from Envisat-RA2 measurements in Ku-band over the period 2003-2010 and the Jason-2 measurements in C band over mid-2008-2011 for radar altimetry, and from QuikSCAT - SeaWinds in Ku-band and Metop - ASCAT in C-band for radar scatterometry over the same time-spans. Along-track profiles and their temporal variations are analyzed and their behaviours are related to surfaces properties such as soil types, vegetation cover, and surface hydrology. Temporal variations of backscattering coefficients are extracted for main land covers along the bio-climatic transect (stone and sand deserts, saharo-sahelian, sahelian, and soudano-sahelian savannahs, tropical-seasonal and tropical forests) and compared to both rainfall estimates from TRMM and vegetation activity (NDVI) from MODIS. Range of variations of the backscattering signals are given for different surfaces and ecosystems along with delays between peaks of rainfall, backscattering responses of radar altimetry and scatterometry, and vegetation activity. The stability of the backscattering is also estimated over deserts and during the dry season over Sahelian environments. Finally, the complementarity of the different spaceborne sensors for continental surfaces monitoring is pointed out.

  17. Taxonomic diversity and structure of benthic macroinvertebrates in Aby Lagoon (Ivory Coast, West Africa).

    PubMed

    Kouadio, K N; Diomandé, D; Ouattara, A; Koné, Y J M; Gourène, G

    2008-09-15

    The benthic macroinvertebrates of Aby lagoon (West Africa: Ivory coast) was studied during four seasons (high dry season, high rainy season, low dry season and low rainy season, respectively) from June 2006 to March 2007. The distribution of the benthic macroinvertebrates species was recorded at 13 stations on the whole of the lagoon. A total of 62 taxa of benthic macroinvertebrates belonging to 28 families and 10 orders were listed. The molluscs and crustaceans dominate qualitatively by adding up 51 and 24%, respectively of the total number of organisms. Five taxa (Corbula trigona (20%), Pachymelania aurita (12%), Clibernhardius cooki (7%), Oligochaeta (7%) and Crassostrea gasar (6%) accounted for 52% of total abundance. Classification analysis used to perform the characterisation of the lagoon on the basis of benthic macroinvertebrates showed the existence of four main clusters in which the seasonal pattern in benthic macroinvertebrates were very similar in the four seasons. In contrast the species richness and diversity indices were significantly different. Furthermore these indices where higher in the stations closer to the sea and surrounded by mangrove trees (southern area) compared to the inland ones. PMID:19137831

  18. Cryptosporidiosis in infancy and childhood mortality in Guinea Bissau, west Africa.

    PubMed Central

    Mølbak, K; Højlyng, N; Gottschau, A; Sá, J C; Ingholt, L; da Silva, A P; Aaby, P

    1993-01-01

    OBJECTIVE--To investigate the epidemiology of and mortality from cryptosporidiosis in young children in Guinea Bissau, West Africa. DESIGN--Three year community study of an open cohort followed up weekly. SETTING--301 randomly selected houses in a semi-urban area in the capital, Bissau. SUBJECTS--1315 children aged less than 4 years. MAIN OUTCOME MEASURES--Cryptosporidium infection detected by examination of stools during episode of diarrhoea and death of a child. RESULTS--Cryptosporidium spp were found in 239 (7.4%) out of 3215 episodes of diarrhoea. The parasite was most common in younger children (median age 12 months) and at the beginning of the rainy seasons. The prevalence of cryptosporidiosis was 15% (77/513) in cases of persistent diarrhoea compared with 6.1% (148/2428) in diarrhoea lasting less than two weeks (p < 0.0001). Cryptosporidiosis was associated with excess mortality in children who had the infection in infancy, and this excess mortality persisted into the second year of life (relative mortality 2.9 (95% confidence interval 1.7 to 4.9)). The excess mortality could not be explained by malnutrition, or by socioeconomic factors, hygienic conditions, or breast feeding. CONCLUSIONS--Cryptosporidiosis is an important cause of death in otherwise healthy children in developing countries. PMID:8374453

  19. Three new species of Laonice (Polychaete: Spionidae) from West and Southwest Africa.

    PubMed

    Sikorski, Andrey; Pavlova, Lyudmila

    2016-01-01

    Three new species of Laonice (Polychaete: Spionidae): L. galatheae, L. cricketae, L. olgae-are described from South and West Africa (along the coast from 31°14.1'S to 04°44'N) based on Danish and South African zoological collections. Arguments relative to the morphological heterogeneity of the genus Laonice are advanced. The arguments are based on the following characters: degree of fusion of prostomium with peristomium at the anterior margin, degree of variability of all numerical characters, arrangement of anterior capillaries in two or more vertical rows, presence or absence of transversal dorsal membranous crests in the "post nuchal organ" and presence of genital pouches only on very limited number of segments or other pattern. Authors think it is obvious today an existence of at least four morphologically separate groups of species inside the Laonice-genus: "L. cirrata", "L. sarsi", "L. appelloefi" and "L. norgensis" groups. Eight species names from 34 valid names in the genus are still with unclear affiliation. L. quadridentata is treated now as a junior synonym of L. brevicornis. An opinion is expressed about L. insolita not belonging to the genus Laonice because of discrepancy the generic diagnosis. PMID:27394551

  20. Mercury, hydroquinone and clobetasol propionate in skin lightening products in West Africa and Canada.

    PubMed

    Gbetoh, Mètogbé Honoré; Amyot, Marc

    2016-10-01

    Skin lightening products are types of cosmetics (creams, gels, lotions and soaps) applied voluntarily on skin. Several of these products contain a variety of active ingredients that are highly toxic. Among those toxic agents, the present study focuses on mercury, hydroquinone, and clobetasol propionate. Out of the 93 lightening soaps and 98 creams purchased in large city markets in sub-Saharan West Africa and in small ethnic shops in Canada, 68-84% of all creams and 7.5-65% of all soaps exceeded regulatory guidelines for at least one active ingredient when considering different regulations. Mercury was found in high concentrations mainly in soaps, while hydroquinone and clobetasol propionate concentrations exceeded US FDA standards in some creams for all countries included in our study. Concentrations of the three compounds declared on labels of soaps and creams usually did not correspond to concentrations actually measured, particularly for mercury and hydroquinone. Overall, our results indicate that most studied skin-lightening products are potentially toxic and that product labels are frequently inaccurate with respect to the presence of toxic agents. PMID:27372064

  1. Farmer-Managed Natural Regeneration Enhances Rural Livelihoods in Dryland West Africa

    NASA Astrophysics Data System (ADS)

    Weston, Peter; Hong, Reaksmey; Kaboré, Carolyn; Kull, Christian A.

    2015-06-01

    Declining agricultural productivity, land clearance and climate change are compounding the vulnerability of already marginal rural populations in West Africa. `Farmer-Managed Natural Regeneration' (FMNR) is an approach to arable land restoration and reforestation that seeks to reconcile sustained food production, conservation of soils, and protection of biodiversity. It involves selecting and protecting the most vigorous stems regrowing from live stumps of felled trees, pruning off all other stems, and pollarding the chosen stems to grow into straight trunks. Despite widespread enthusiasm and application of FMNR by environmental management and development projects, to date, no research has provided a measure of the aggregate livelihood impact of community adoption of FMNR. This paper places FMNR in the context of other agroforestry initiatives, then seeks to quantify the value of livelihood outcomes of FMNR. We review published and unpublished evidence about the impacts of FMNR, and present a new case study that addresses gaps in the evidence-base. The case study focuses on a FMNR project in the district of Talensi in the semi-arid Upper East Region in Ghana. The case study employs a social return on investment analysis, which identifies proxy financial values for non-economic as well as economic benefits. The results demonstrate income and agricultural benefits, but also show that asset creation, increased consumption of wild resources, health improvements, and psycho-social benefits created more value in FMNR-adopting households during the period of the study than increases in income and agricultural yields.

  2. Healthcare in Equatorial Guinea, West Africa: obstacles and barriers to care

    PubMed Central

    Reuter, Kim Eleanor; Geysimonyan, Aurora; Molina, Gabriela; Reuter, Peter Robert

    2014-01-01

    Introduction The provision of healthcare services in developing countries has received increasing attention, but inequalities persist. One nation with potential inequalities in healthcare services is Equatorial Guinea (Central-West Africa). Mitigating these inequalities is difficult, as the Equatoguinean healthcare system remains relatively understudied. Methods In this study, we interviewed members of the healthcare community in order to: 1) learn which diseases are most common and the most common cause of death from the perspective of healthcare workers; and 2) gain an understanding of the healthcare community in Equatorial Guinea by describing how: a) healthcare workers gain their professional knowledge; b) summarizing ongoing healthcare programs aimed at the general public; c) discussing conflicts within the healthcare community and between the public and healthcare providers; d) and addressing opportunities to improve healthcare delivery. Results We found that some causes of death, such as serious injuries, may not be currently treatable in country, potentially due to a lack of resources and trauma care facilities. In addition, training and informational programs for both healthcare workers and the general public may not be effectively transmitting information to the intended recipients. This presents hurdles to the healthcare community, both in terms of having professional competence in healthcare delivery and in having a community that is receptive to medical care. Conclusion Our data also highlight government-facility communication as an opportunity for improvement. Our research is an important first step in understanding the context of healthcare delivery in Equatorial Guinea, a country that is relatively data poor. PMID:25932082

  3. Regional-scale climate-variability synchrony of cholera epidemics in West Africa

    PubMed Central

    Constantin de Magny, Guillaume; Guégan, Jean-François; Petit, Michel; Cazelles, Bernard

    2007-01-01

    Background The relationship between cholera and climate was explored in Africa, the continent with the most reported cases, by analyzing monthly 20-year cholera time series for five coastal adjoining West African countries: Côte d'Ivoire, Ghana, Togo, Benin and Nigeria. Methods We used wavelet analyses and derived methods because these are useful mathematical tools to provide information on the evolution of the periodic component over time and allow quantification of non-stationary associations between time series. Results The temporal variability of cholera incidence exhibits an interannual component, and a significant synchrony in cholera epidemics is highlighted at the end of the 1980's. This observed synchrony across countries, even if transient through time, is also coherent with both the local variability of rainfall and the global climate variability quantified by the Indian Oscillation Index. Conclusion Results of this study suggest that large and regional scale climate variability influence both the temporal dynamics and the spatial synchrony of cholera epidemics in human populations in the Gulf of Guinea, as has been described for two other tropical regions of the world, western South America and Bangladesh. PMID:17371602

  4. Poverty, health and satellite-derived vegetation indices: their inter-spatial relationship in West Africa

    PubMed Central

    Sedda, Luigi; Tatem, Andrew J.; Morley, David W.; Atkinson, Peter M.; Wardrop, Nicola A.; Pezzulo, Carla; Sorichetta, Alessandro; Kuleszo, Joanna; Rogers, David J.

    2015-01-01

    Background Previous analyses have shown the individual correlations between poverty, health and satellite-derived vegetation indices such as the normalized difference vegetation index (NDVI). However, generally these analyses did not explore the statistical interconnections between poverty, health outcomes and NDVI. Methods In this research aspatial methods (principal component analysis) and spatial models (variography, factorial kriging and cokriging) were applied to investigate the correlations and spatial relationships between intensity of poverty, health (expressed as child mortality and undernutrition), and NDVI for a large area of West Africa. Results This research showed that the intensity of poverty (and hence child mortality and nutrition) varies inversely with NDVI. From the spatial point-of-view, similarities in the spatial variation of intensity of poverty and NDVI were found. Conclusions These results highlight the utility of satellite-based metrics for poverty models including health and ecological components and, in general for large scale analysis, estimation and optimisation of multidimensional poverty metrics. However, it also stresses the need for further studies on the causes of the association between NDVI, health and poverty. Once these relationships are confirmed and better understood, the presence of this ecological component in poverty metrics has the potential to facilitate the analysis of the impacts of climate change on the rural populations afflicted by poverty and child mortality. PMID:25733559

  5. Water and carbon fluxes from savanna ecosystems of the Volta River watershed, West Africa

    NASA Astrophysics Data System (ADS)

    Freitag, Heiko; Ferguson, Paul R.; Dubois, Kristal; Hayford, Ebenezer Kofi; von Vordzogbe, Vincent; Veizer, Ján

    2008-03-01

    The fluxes of water and carbon from terrestrial ecosystems are coupled via the process of photosynthesis. Constraining the annual water cycle therefore allows first order estimates of annual photosynthetic carbon flux, providing that the components of evapotranspiration can be separated. In this study, an isotope mass-balance equation is utilized to constrain annual evaporation flux, which in turn, is used to determine the amount of water transferred to the atmosphere by plant transpiration. The Volta River watershed in West Africa is dominated by woodland and savanna ecosystems with a significant proportion of C 4 vegetation. Annually, the Volta watershed receives ˜ 380 km 3 of rainfall, ˜ 50% of which is returned to the atmosphere via transpiration. An annual photosynthetic carbon flux of ˜ 170 × 10 12 g C yr - 1 or ˜ 428 g C m - 2 was estimated to be associated with this water vapor flux. Independent estimates of heterotrophic soil respiration slightly exceeded the NPP estimate from this study, implying that the exchange of carbon between the Volta River watershed and the atmosphere was close to being in balance or that terrestrial ecosystems were a small annual source of CO 2 to the atmosphere. In addition to terrestrial carbon flux, the balance of photosynthesis and respiration in Volta Lake was also examined. The lake was found to evade carbon dioxide to the atmosphere although the magnitude of the flux was much smaller than that of the terrestrial ecosystems.

  6. Oxygen, hydrogen, and helium isotopes for investigating groundwater systems of the Cape Verde Islands, West Africa

    USGS Publications Warehouse

    Heilweil, V.M.; Solomon, K.D.; Gingerich, S.B.; Verstraeten, Ingrid M.

    2009-01-01

    Stable isotopes (??18O, ??2H), tritium (3H), and helium isotopes (3He, 4He) were used for evaluating groundwater recharge sources, flow paths, and residence times of three watersheds in the Cape Verde Islands (West Africa). Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. In contrast to other active oceanic hotspots, environmental tracers show that deep geothermal circulation does not strongly affect groundwater. Low tritium concentrations at seven groundwater sites indicate groundwater residence times of more than 50 years. Higher tritium values at other sites suggest some recent recharge. High 4He and 3He/4He ratios precluded 3H/3He dating at six sites. These high 3He/4He ratios (R/Ra values of up to 8.3) are consistent with reported mantle derived helium of oceanic island basalts in Cape Verde and provided end-member constraints for improved dating at seven other locations. Tritium and 3H/3He dating shows that S??o Nicolau Island's Ribeira Faj?? Basin has groundwater residence times of more than 50 years, whereas Fogo Island's Mosteiros Basin and Santo Ant??o Island's Ribeira Paul Basin contain a mixture of young and old groundwater. Young ages at selected sites within these two basins indicate local recharge and potential groundwater susceptibility to surface contamination and/or salt-water intrusion. ?? Springer-Verlag 2009.

  7. Invasion genetics of the introduced black rat (Rattus rattus) in Senegal, West Africa.

    PubMed

    Konečný, Adam; Estoup, Arnaud; Duplantier, Jean-Marc; Bryja, Josef; Bâ, Khalilou; Galan, Maxime; Tatard, Caroline; Cosson, Jean-Francois

    2013-01-01

    An understanding of the evolutionary history and dynamics of invasive species is required for the construction of predictive models of future spread and the design of biological management measures. The black rat (Rattus rattus) is a major vertebrate invader with a worldwide distribution. Despite the severe ecological, economic and health impacts of this species, its evolutionary history has been little studied. We carried out extensive specimen sampling in Senegal, West Africa, and used microsatellite markers to describe the pattern and processes of invasion in this large continental area. The genetic data obtained were combined with historical knowledge concerning the presence of this species in Senegal. Data were analysed by a combination of Bayesian clustering and approximate Bayesian computation methods. The invasion pathways closely paralleled the history of human trade routes in Senegal. In several places, we detected the occurrence of multiple introductions from genetically different sources. Long-distance migration between towns and villages was also observed. Our findings suggest that genetic bottlenecks and admixture have played a major role in shaping the genetics of invasive black rats. These two processes may generate genetic novelty and favour rapid evolution along the invasion pathways. PMID:23206272

  8. Middle Miocene oxygen minimum zone expansion offshore West Africa: Evidence for global cooling precursor events

    NASA Astrophysics Data System (ADS)

    Kender, Sev; Peck, Victoria L.; Jones, Robert W.; Kaminski, Michael A.

    2010-05-01

    Three dissolution events ca. 16 Ma, 15.5 Ma, and 14.3 Ma ago have been identified in sediments from the Congo Fan. Multiproxy benthic foraminiferal and sedimentary records suggest an expanded oxygen minimum zone consistent with enhanced upwelling at these times. Low oxygen species Bulimina elongata, Brizalina alazanensis, Bulimina marginata and Valvulineria pseudotumeyensis begin to dominate from ca. 16 Ma, replacing more oxic indicators such as Oridorsalis umbonatus and Cibicidoides crebbsi. The low oxygen faunas are show reduced diversity and exhibit erratic abundance values from 100 to 2000 specimens per gram. Agglutinated foraminifera Glomospira spp. are also associated with these low oxygen faunas. Benthic isotope records from Cibicidoides spp. show shifts similar to those of the global composite, with marked bottom water cooling from ca. 16 Ma. Total organic carbon values show a general increase over the low oxygen intervals. Marine carbonate records from adjacent North Africa indicate coincident episodes of increased continental weathering (John et al., 2003, Geological Society of America Bulletin), suggesting that an intermittently stronger polar front strengthened west African offshore winds, increasing surface water productivity, and enhanced North African weathering during these events. We propose that Columbia River Flood Basalt volcanism, estimated to have released 106 Tg CO2 and 106 Tg SO2 between 16 and 15.6 Ma ago, may have influenced these climatic changes.

  9. Predicting the distribution of tsetse flies in West Africa using temporal Fourier processed meteorological satellite data.

    PubMed

    Rogers, D J; Hay, S I; Packer, M J

    1996-06-01

    An example is given of the application of remotely-sensed, satellite data to the problems of predicting the distribution and abundance of tsetse flies in West Africa. The distributions of eight species of tsetse, Glossina morsitans, G. longipalpis, G. palpalis, G. tachinoides, G. pallicera, G. fusca, G. nigrofusca and G. medicorum in Côte d'Ivoire and Burkina Faso, were analysed using discriminant analysis applied to temporal Fourier-processed surrogates for vegetation, temperature and rainfall derived from meteorological satellites. The vegetation and temperature surrogates were the normalized difference vegetation index and channel-4-brightness temperature, respectively, from the advanced, very-high-resolution radiometers on board the National Oceanic and Atmospheric Administration's polar-orbiting, meteorological satellites. For rainfall the surrogate was the Cold-Cloud-Duration (CCD) index derived from the geostationary, Meteosat satellite series. The presence or absence of tsetse was predicted with accuracies ranging from 67%-100% (mean = 82.3%). A further data-set, for the abundance of five tsetse species across the northern part of Côte d'Ivoire (an area of about 140,000 km2), was analysed in the same way, and fly-abundance categories predicted with accuracies of 30%-100% (mean = 73.0%). The thermal data appeared to be the most useful of the predictor variables, followed by vegetation and rainfall indices. Refinements of the analytical technique and the problems of extending the predictions through space and time are discussed. PMID:8758138

  10. Population genetic structure of Plasmodium falciparum across a region of diverse endemicity in West Africa

    PubMed Central

    2012-01-01

    Background Malaria parasite population genetic structure varies among areas of differing endemicity, but this has not been systematically studied across Plasmodium falciparum populations in Africa where most infections occur. Methods Ten polymorphic P. falciparum microsatellite loci were genotyped in 268 infections from eight locations in four West African countries (Republic of Guinea, Guinea Bissau, The Gambia and Senegal), spanning a highly endemic forested region in the south to a low endemic Sahelian region in the north. Analysis was performed on proportions of mixed genotype infections, genotypic diversity among isolates, multilocus standardized index of association, and inter-population differentiation. Results Each location had similar levels of pairwise genotypic diversity among isolates, although there were many more mixed parasite genotype infections in the south. Apart from a few isolates that were virtually identical, the multilocus index of association was not significant in any population. Genetic differentiation between populations was low (most pairwise FST values < 0.03), and an overall test for isolation by distance was not significant. Conclusions Although proportions of mixed genotype infections varied with endemicity as expected, population genetic structure was similar across the diverse sites. Very substantial reduction in transmission would be needed to cause fragmented or epidemic sub-structure in this region. PMID:22759447

  11. On the tectonics and metallogenesis of West Africa: a model incorporating new geophysical data

    USGS Publications Warehouse

    Hastings, David A.

    1982-01-01

    The gold, diamond and manganese deposits of Ghana have attracted commercial interest, but appropriate geophysical data to delineate the tectonic setting of these and other deposits have been lacking until recently. Recent gravity surveys, however, now cover about 75% of the country. When used in a synthesis of the sometimes contradictory existing theories about the geology and metallogenesis of West Africa, the available gravity, magnetic, and seismic data lead to a preliminary tectonic model that postulates rifting at the time of the (1800-2000 m.y. old) Eburnean orogeny and is consistent with the occurrences of mineral deposits in the region. In this model, diamond-bearing kimberlites formed during the commencement of rifting during the Eburnean orogenesis. Later emplacement of kimberlites was associated with the initiation of Mesozoic rifting of Gondwanaland. Primary gold vein deposits were probably formed by the migration of hydrothermal fluids (associated with the formation of granitoids) into dilatant zones, such as rift-related faults and anticlinal axial areas, toward the end of the Eburnean orogeny. At this time, the major concordant granitoids were formed, with smaller plutonic granitoids forming on the fringes of the concordant masses as partial melting fractions of the latter. Sedimentary manganese deposits were formed along the margins of rift lakes toward the end of the orogeny.

  12. Transport of carbon, nitrogen, phosphorus, and major solutes in the Gambia River, West Africa

    SciTech Connect

    Lesack, L.F.W.; Hecky, R.E.; Melack, J.M.

    1984-07-01

    Transport of solutes and particulate materials and their variation with discharge were studied for 1 year (July 1980-June 1981) in the Gambia River in the tropical savanna of West Africa. The water is a dilute solution of SiO/sub 2/ and HCO/sub 3//sup -/. Na/sup +/, K/sup +/, Cl/sup -/, and total dissolved nitrogen showed no significant relation with discharge. Ca/sup 2 +/, Mg/sup 2 +/, HCO/sub 3//sup -/, conductivity, and SO/sub 4//sup 2 -/ decreased as discharge increased, while total dissolved phosphorus increased with discharge. After an initial increase SiO/sub 2/ was independent of discharge. Dissolved organic carbon displayed counterclockwise hysteresis with rising and falling discharge. Particulate phosphorus and total particulate materials displayed clockwise hysteresis. Total transport amounted to 9.66 t x km/sup -2/ x yr/sup -1/. The transport rates of both dissolved and particulate organic C are among the lowest ever reported. The low transport of total particulates and solutes is attributed to lack of relief and the lithology of the catchment.

  13. The economic impact of strategic risk on petroleum ventures: Examples from West Africa

    SciTech Connect

    Ethetton, L.K.; Brumbaugh, W.D.

    1995-12-31

    Strategic risks attend any and all business ventures. They arise from the nature of the particular business being pursued and the environment in which that business is being conducted. In the petroleum industry, considerable attention is devoted to quantifying technical risks, i.e., the risk of finding and producing hydrocarbons. However, strategic risks often impact economic viability more than technical asks. Accordingly, strategic risk analysis is critical to, realistically evaluating petroleum ventures in today`s turbulent business environment. While difficult to assess and quantify, strategic risks must be accorded equal status with technical risks. Competitor activity, contract terms, environmental sensitivity, political stability and market forces are typical strategic risks. A strategic risk system correlates a company`s capabilities with the quality of possible ventures. Internal strengths and weaknesses are thus matched against external opportunities and threats. This is known in the business literature as a SWOT analysis. The degree of strategic risk is then proportional to the mismatch between the SWOT elements. Such a mismatch was not recognized during exploration of the West Africa Aptian Salt Basins play in the 1980s. Angola, Congo and Gabon all contain examples where failure to consider strategic risk ultimately resulted in {open_quotes}Gambler`s Ruin{close_quotes}.

  14. Microcredit in West Africa: how small loans make a big impact on poverty.

    PubMed

    Gbezo, B E

    1999-01-01

    This article examines the impact of microfinancing schemes in West Africa and the role of the International Labor Organization (ILO) in their development. Microfinancing or microcredit schemes are meant to create the kind of jobs that can keep households severely hit by the economic crisis afloat. They affect not only the financial, but also the agricultural, crafts, financing of social economy, and social protection sectors of the society. Thus, they contribute to improved access to basic social, health and family planning services and to drinking water. The challenge then, is for institutes to adopt microfinancing and to reach out to more than 100 million families in the region. To realize this, nongovernmental organizations are setting up as veritable microfinancing institutions, which are able to realize the resulting benefits so as to be economically viable. In the context of its role in the development of microfinancing schemes, ILO manages a portfolio of technical cooperation and research projects aimed at identifying and removing constraints in the access to credit, savings, insurance, and other financial services through its Social Finance Unit. In addition, ILO is promoting women's entrepreneurship through the International Small Enterprise Programme and the International Programme on More and Better Jobs for Women. PMID:12295602

  15. Mining and environmental change in Sierra Leone, West Africa: a remote sensing and hydrogeomorphological study.

    PubMed

    Akiwumi, Fenda A; Butler, David R

    2008-07-01

    This paper evaluates the environmental changes in southwestern Sierra Leone, West Africa from rutile (titanium dioxide) between 1967 and 1995. Mining in peripheral parts of the world economy is a consequence of larger global economic interests. Historically, long-distance trade and export production of minerals and other natural resources primarily for the benefit of core countries are responsible for transforming the natural environment and landscapes of peripheral sectors of the world economy. Tracking environmental change in developing countries such as Sierra Leone is challenging because of financial and infrastructural constraints on the use of ground methods of evaluation and monitoring. Remote sensing data are invaluable in assessing the human dimensions of Land Use and Land Cover Change (LULCC) with implications for political ecology. Using available multi-date infrared Landsat images supplemented with field hydrological and biophysical data, we monitored the rapid temporal and spatial dynamic characteristic of mining areas in the study area with a focus on physical changes to the landscape. Reservoir construction for mining has caused flooding of alluvial lowlands, deforestation, and the creation of tailings and stockpiles over mined-out portions of the lease. Although the study was conducted at a local scale, it represents the broad, regional, past-to-present manner by which global economic interests exploit natural resources and impact the environment in distant places. PMID:17882524

  16. Bilharziasis survey in British West and East Africa, Nyasaland, and the Rhodesias*

    PubMed Central

    Blair, Dyson M.

    1956-01-01

    The author, in his capacity as a WHO consultant, undertook a survey of bilharziasis in British West and East Africa and Nyasaland during 1950-51. The information thus obtained has been revised and brought up to date and is recorded in the present article together with similar observations on Northern Rhodesia, which was not visited, and on Southern Rhodesia, the author's own country. In Part I, each country is dealt with in turn. The history of the disease and the findings of field surveys are reviewed, and, wherever possible, personal observations have been included. The fact that the information is of a scanty and incomplete nature is an indication that further local studies in all areas are badly needed. In Part II an attempt is made to survey the situation from the point of view of the various aspects of the subjects—methods of obtaining morbidity data, intensity of infection, effects of the disease on human health, treatment, and the molluscan vectors. PMID:13383363

  17. The use of seasonal forecasts in a crop failure early warning system for West Africa

    NASA Astrophysics Data System (ADS)

    Nicklin, K. J.; Challinor, A.; Tompkins, A.

    2011-12-01

    Seasonal rainfall in semi-arid West Africa is highly variable. Farming systems in the region are heavily dependent on the monsoon rains leading to large variability in crop yields and a population that is vulnerable to drought. The existing crop yield forecasting system uses observed weather to calculate a water satisfaction index, which is then related to expected crop yield (Traore et al, 2006). Seasonal climate forecasts may be able to increase the lead-time of yield forecasts and reduce the humanitarian impact of drought. This study assesses the potential for a crop failure early warning system, which uses dynamic seasonal forecasts and a process-based crop model. Two sets of simulations are presented. In the first, the crop model is driven with observed weather as a control run. Observed rainfall is provided by the GPCP 1DD data set, whilst observed temperature and solar radiation data are given by the ERA-Interim reanalysis. The crop model used is the groundnut version of the General Large Area Model for annual crops (GLAM), which has been designed to operate on the grids used by seasonal weather forecasts (Challinor et al, 2004). GLAM is modified for use in West Africa by allowing multiple planting dates each season, replanting failed crops and producing parameter sets for Spanish- and Virginia- type West African groundnut. Crop yields are simulated for three different assumptions concerning the distribution and relative abundance of Spanish- and Virginia- type groundnut. Model performance varies with location, but overall shows positive skill in reproducing observed crop failure. The results for the three assumptions are similar, suggesting that the performance of the system is limited by something other than information on the type of groundnut grown. In the second set of simulations the crop model is driven with observed weather up to the forecast date, followed by ECMWF system 3 seasonal forecasts until harvest. The variation of skill with forecast date

  18. Africa: Prosperous times

    SciTech Connect

    1996-08-01

    Political instability and corruption is the rule, rather than the exception, in Africa`s main producing regions, but exploration and production prospects there are bright and attractive to foreign operators. The paper discusses exploration, drilling, resource development, and production in Nigeria, Libya, Algeria, Egypt, Angola, Congo, Gabon, and Tunisia. The other countries of Africa are briefly mentioned, i.e., Cameroon, Cote D`Ivoire, South Africa, Sudan, Namibia, Equatorial Guinea, Eritrea, Zaire, Mozambique, Ghana, Niger, and Seychelles.

  19. Process-based assessment of an ensemble of climate projections for West Africa

    NASA Astrophysics Data System (ADS)

    James, Rachel; Washington, Richard; Jones, Richard

    2015-02-01

    Determining the level of confidence in regional climate model projections could be very useful for designing climate change adaptation, particularly for vulnerable regions. The majority of previous research to evaluate models has been based on the mean state, but for confidence in projections the plausibility of the mechanisms for change is just as, if not more, important. In this study we demonstrate a methodology for process-based assessment of projections, whereby circulation changes accompanying future responses are examined and then compared to atmospheric dynamics during historical years in models and reanalyses. We apply this methodology to an ensemble of five global and regional model experiments and focus on West Africa, where these models project a strong drying trend. The analysis reveals that this drying is associated with anomalous subsidence in the upper atmosphere, and large warming of the Saharan heat low region, with potential feedback effects via the African easterly jet and West African monsoon. This mode occurs during dry years in the historical period, and dominates in the future experiments. However, the same mode is not found in dry years in reanalysis data, which casts doubt on the reasons for strong drying in these models. The regional models show a very similar response to their driving global models, and are therefore no more trustworthy in this case. This result underlines the importance of assessing model credibility on a case-by-case basis and implies that process-based methodologies should be applied to other model projections before their outputs are used to inform decision making.

  20. Impact of land cover characterization on regional climate modeling over West Africa

    NASA Astrophysics Data System (ADS)

    Sylla, Mouhamadou Bamba; Pal, Jeremy S.; Wang, Guiling L.; Lawrence, Peter J.

    2016-01-01

    The impact of high resolution modern vegetation cover on the West African climate is examined using the International Centre for Theoretical Physics Regional Climate Model implementing the NCAR Community Land Model. Two high resolution 25 km long-term simulations driven by the output from a coarser 50-km resolution simulation are performed for the period 1998-2010. One high resolution simulation uses an earlier and coarser-resolution version of plant functional type distribution and leaf area index, while the other uses a more recent, higher-quality, and finer-resolution version of the data. The results indicate that the new land cover distribution substantially alters the distribution of temperature with warming in Central Nigeria, northern Gulf of Guinea and part of the Sahel due to the replacement of C4 grass with corn; and cooling along the coastlines of the Gulf of Guinea and in Central Africa due to the replacement of C4 grass with tropical broadleaf evergreen trees. Changes in latent heat flux appear to be largely responsible for these temperature changes with a net decrease (increase) in regions of warming (cooling). The improved land cover distribution also results in a wetter monsoon season. The presence of corn tends to favor larger precipitation amounts via more intense events, while the presence of tropical broadleaf evergreen trees tends to favor the occurrence of both more intense and more frequent events. The wetter conditions appear to be sustained via (1) an enhanced soil moisture feedback; and (2) elevated moisture transport due to increased low-level convergence in regions south of 10N where the most substantial land cover differences are present. Overall the changes induced by the improved vegetation cover improve, to some extent, the performance of the high resolution regional climate model in simulating the main West African summer monsoon features.

  1. Legume Diversity Patterns in West Central Africa: Influence of Species Biology on Distribution Models

    PubMed Central

    de la Estrella, Manuel; Mateo, Rubén G.; Wieringa, Jan J.; Mackinder, Barbara; Muñoz, Jesús

    2012-01-01

    Objectives Species Distribution Models (SDMs) are used to produce predictions of potential Leguminosae diversity in West Central Africa. Those predictions are evaluated subsequently using expert opinion. The established methodology of combining all SDMs is refined to assess species diversity within five defined vegetation types. Potential species diversity is thus predicted for each vegetation type respectively. The primary aim of the new methodology is to define, in more detail, areas of species richness for conservation planning. Methodology Using Maxent, SDMs based on a suite of 14 environmental predictors were generated for 185 West Central African Leguminosae species, each categorised according to one of five vegetation types: Afromontane, coastal, non-flooded forest, open formations, or riverine forest. The relative contribution of each environmental variable was compared between different vegetation types using a nonparametric Kruskal-Wallis analysis followed by a post-hoc Kruskal-Wallis Paired Comparison contrast. Legume species diversity patterns were explored initially using the typical method of stacking all SDMs. Subsequently, five different ensemble models were generated by partitioning SDMs according to vegetation category. Ecological modelers worked with legume specialists to improve data integrity and integrate expert opinion in the interpretation of individual species models and potential species richness predictions for different vegetation types. Results/Conclusions Of the 14 environmental predictors used, five showed no difference in their relative contribution to the different vegetation models. Of the nine discriminating variables, the majority were related to temperature variation. The set of variables that played a major role in the Afromontane species diversity model differed significantly from the sets of variables of greatest relative important in other vegetation categories. The traditional approach of stacking all SDMs indicated overall

  2. Effects of climate variability on savannah fire regimes in West Africa

    NASA Astrophysics Data System (ADS)

    N'Datchoh, E. T.; Konaré, A.; Diedhiou, A.; Diawara, A.; Quansah, E.; Assamoi, P.

    2015-04-01

    The main objective of this work is to investigate at regional scale the variability in burned areas over the savannahs of West Africa and their links with the rainfall and the large-scale climatic indexes such as the Southern Oscillation Index (SOI), Multivariate ENSO Index (MEI), North Atlantic Oscillation (NAO) and sea surface temperature gradient (SSTG). Daily satellite products (L3JRC) of burned areas from the SPOT Vegetation sensor at a moderate spatial resolution of 1 km x 1 km between 2000 and 2007 were analyzed over the West African savannah in this paper. Results from seasonal analysis revealed a large increase in burned areas from November to February, with consistent peaks in December at the regional scale. In addition, about 30% of the pixels are burned at least four times within the 7-year period. Positive correlations were found between burned areas and rainfall values obtained from the TRMM satellite over savannahs located above 8° N, meaning that a wet rainfall season over these regions was favorable to biomass availability in the next dry season and therefore may induce an increase in burned areas in this region. Moreover, our results showed a nonlinear relationship between the large-scale climatic indexes SOI, MEI, NAO and SSTG and burned-area anomalies. Positive (negative) correlations between burned areas and SOI (MEI) were consistent over the Sahel and Sudano-Sahelian areas. Negative correlations with Atlantic SSTG were significant over the Guinea subregion. Correlations between burned areas over Sudano-Guinean subregion and all the large-scale indexes were weak and may be explained by the fact that this subregion had a mean rainfall greater than 800 mm yr-1 with permanent biomass availability and an optimal amount of soil moisture favorable to fire practice irrespective of the climate conditions. The teleconnection with NAO was not clear and needed to be investigated further.

  3. Interplay of riparian forest and groundwater in the hillslope hydrology of Sudanian West Africa (northern Benin)

    NASA Astrophysics Data System (ADS)

    Richard, A.; Galle, S.; Descloitres, M.; Cohard, J.-M.; Vandervaere, J.-P.; Séguis, L.; Peugeot, C.

    2013-12-01

    Forests are thought to play an important role in the regional dynamics of the West African monsoon, through their capacity to extract water from a permanent and deep groundwater table to the atmosphere even during the dry season. It should be the case for riparian forests too, as these streambank forests are key landscape elements in Sudanian West Africa. The interplay of riparian forest and groundwater in the local hydrodynamics was investigated, by quantifying their contribution to the water balance. Field observations from a comprehensively instrumented hillslope in northern Benin were used. Particular attention was paid to measurements of actual evapotranspiration, soil water and deep groundwater levels. A vertical 2-D hydrological modelling approach using the Hydrus software was used as a testing tool to understand the interactions between the riparian area and the groundwater. The model was calibrated and evaluated using a multi-criteria approach (reference simulation). A virtual experiment, including three other simulations, was designed (no forest, no groundwater, neither forest nor groundwater). The model correctly simulated the hydrodynamics of the hillslope regarding vadose zone dynamics, deep groundwater fluctuation and actual evapotranspiration dynamics. The virtual experiment showed that the riparian forest transpiration depleted the deep groundwater table level and disconnected it from the river, which is consistent with the observations. The riparian forest and the deep groundwater table actually form an interacting transpiration system: the high transpiration rate in the riparian area was shown to be due to the existence of the water table, supplied by downslope lateral water flows within the hillslope soil layer. The simulated riparian transpiration rate was practically steady all year long, around 7.6 mm d-1. This rate lies within high-end values of similar study results. The riparian forest as simulated here contributes to 37% of the annual

  4. Onchocerciasis infection in children born during 14 years of Simulium control in West Africa.

    PubMed

    De Sole, G; Remme, J

    1991-01-01

    The incidence of onchocerciasis infection in children born since the start of vector control is one of the indicators used in the epidemiological evaluation of the Onchocerciasis Control Programme in West Africa (OCP). Though initially of littel value, after a decade of control it has become a sensitive indicator of residual transmission. The results of 14 years of control are reported. In 179 villages parasitological surveys were undertaken at intervals of 3-4 years. 15,286 children were examined and 110 were found to be infected, compared to an expected number of 2467 infected had there been no control. There was considerable geographical variation in the results. In the large central OCP area the results were excellent. Of 12,172 children examined in 127 villages, only 23 were found to be infected compared to an expected number of 1960 without control. This suggests that larviciding had achieved a 99% reduction in the incidence of infection in children. Additional surveys in 2 foci in the central OCP area where transmission had relapsed showed that these problems were very localized. Most villages with infected children were found in OCP border areas in the east and west, which had been reinvaded by infective vectors from elsewhere, and in the intermediate area between forest and savanna in Côte d'Ivoire where there had been partial control failures because of resistance. The incidence of infection in children was reduced by an estimated 68% in the eastern reinvaded area, by 87% in the western reinvaded area, and by 84% in the intermediate area. PMID:1949145

  5. Seasonal changes in groundwater storage estimated by absolute ground gravity and MRS surveys in West Africa

    NASA Astrophysics Data System (ADS)

    Favreau, G.; Boucher, M.; Luck, B.; Pfeffer, J.; Genthon, P.; Hinderer, J.

    2009-04-01

    Important and fast groundwater storage changes occur in tropical monsoon regions in response to seasonal rainfall and subsequent surface water redistribution. In West Africa, one main goal of the GHYRAF experiment (Gravity and Hydrology in Africa, 2008-2010) is to compare absolute gravimetric measurements with dense hydrological surveys to better estimate and model water storage changes at various time scales. Magnetic Resonance Sounding (MRS) is a non-invasive geophysical method having a signal directly related to groundwater quantity. In SW Niger, MRS surveys were performed concurrently with gravimetric (FG5) measurements for monitoring seasonal changes in groundwater storage. Water table levels were recorded on a 4-piezometers profile (~500 m) near a temporary pond (area ~2 ha) fed by sandy gullies. The volume of water drained from the pond to the phreatic aquifer was computed to be ~100,000 m3/yr. Large piezometric fluctuations (3-6 m) occurred in response to indirect recharge through the pond during the 2008 rainy season (July-Sept.), with stronger water table fluctuations recorded near the pond. Absolute gravimetric (FG5) measurements were performed at a distance of 150 m from the pond, in order to minimize the influence of 2D effects on gravimetric records. The increase in absolute gravity measured between two dates (July-Sept.) was 8.7 ± 2.6 µGal; for the same period, the measured water table rise was +3.0 m. Considering these values, a first estimate of the groundwater storage increase is 0.2 m, corresponding to a porosity filled up by the water table rise of ~7%. Repeated MRS surveys were performed at the same location for different dates (three soundings in Sept., one in Dec.). The MRS water content was 13%, with little variation in space (±3%) along the piezometric profile. In response to a 3 metres drop in the water table (Sept- Dec), there was no significant recorded change in the MRS water content and/or in the estimated MRS water table depth. MRS

  6. University-level nutrition training in West Africa: cost and financing issues

    PubMed Central

    Sodjinou, Roger; Bosu, William; Fanou, Nadia; Zagre, Noel; Tchibindat, Félicité; Baker, Shawn; Delisle, Helene

    2015-01-01

    Background There is a serious shortage of skilled nutrition professionals in West Africa. Investing in nutrition training is one of the strategies for strengthening the human resource base in nutrition. However, little is known about how nutrition training in the region is financed and the levels of tuition fees charged. The purpose of this study was to provide a comprehensive assessment about the levels of tuition fees charged for nutrition training in the West Africa region and to determine to what extent this is of reach to the average student. Methodology The data for this study were obtained from 74 nutrition degree programs operating in nine West African countries in 2013 through semi-structured interviews during on-site visits or through self-administered questionnaires. They included the age of the programs, school ownership, tuition fees, financial assistance, and main sources of funding. Tuition fees (in 2013 US$) were expressed per program to enable uniformity and comparability. Simple descriptive and bivariate analyses were performed. Results Results from 74 nutrition training programs in nine countries showed a wide variation in tuition fees within and between countries. The tuition fees for bachelor's, master's, and doctoral programs, respectively, ranged from 372 to 4,325 (mean: 2,353); 162 to 7,678 (mean: 2,232); and 369 to 5,600 (mean: 2,208). The tuition fees were significantly higher (p<0.05) in private institutions than in public institutions (mean: US$3,079 vs. US$2,029 for bachelor's programs; US$5,118 vs. US$1,820 for master's programs; and US$3,076 vs. US$1,815 for doctoral programs). The difference in the tuition fees between Francophone and Anglophone countries was not statistically significant (mean: US$2,570 vs. US$2,216 for bachelor's programs; US$2,417 vs. US$2,147 for master's programs; US$3,285 vs. US$2,055 for doctoral programs). In most countries, the tuition fees appeared to be out of reach of the average student. Recent master

  7. Financing Higher Education in Francophone West Africa. An EDI Policy Seminar Report, Number 12.

    ERIC Educational Resources Information Center

    Ransom, Angela

    Meetings were held in Senegal in 1985, in Cote d'Ivoire in 1986, and in Zimbabwe in 1987, concerning the current state of higher education finance in Africa, the structure of unit costs, and the role of development assistance agencies and other sources of financial support. Reports are presented concerning the macroeconomic perspective, internal…

  8. Effectiveness of Alternative Extension Methods through Radio Broadcasting in West Africa

    ERIC Educational Resources Information Center

    Moussa, Bokar; Otoo, Miriam; Fulton, Joan; Lowenberg-DeBoer, James

    2011-01-01

    There is an urgent need to quantify which extension methods are most effective in Africa. The objective of this study was to determine the impact of alternative extension methods on adoption of the triple bagging cowpea storage technology in Niger and Burkina Faso. This study was designed as a quasi-experiment with two alternative extension…

  9. Stabilization of large drainage basins over geological time scales: Cenozoic West Africa, hot spot swell growth, and the Niger River

    NASA Astrophysics Data System (ADS)

    Chardon, Dominique; Grimaud, Jean-Louis; Rouby, Delphine; Beauvais, Anicet; Christophoul, Frédéric

    2016-03-01

    Reconstructing the evolving geometry of large river catchments over geological time scales is crucial to constraining yields to sedimentary basins. In the case of Africa, it should further help deciphering the response of large cratonic sediment routing systems to Cenozoic growth of the basin-and-swell topography of the continent. Mapping of dated and regionally correlated lateritic paleolandscape remnants complemented by onshore sedimentological archives allows the reconstruction of two physiographic configurations of West Africa in the Paleogene. Those reconstructions show that the geometry of the drainage is stabilized by the late early Oligocene (29 Ma) and probably by the end of the Eocene (34 Ma), allowing to effectively link the inland morphoclimatic record to offshore sedimentation since that time, particularly in the case of the Niger catchment—delta system. Mid-Eocene paleogeography reveals the antiquity of the Senegambia catchment back to at least 45 Ma and suggests that a marginal upwarp forming a continental divide preexisted early Oligocene connection of the Niger and Volta catchments to the Equatorial Atlantic Ocean. Such a drainage rearrangement was primarily enhanced by the topographic growth of the Hoggar hot spot swell and caused a stratigraphic turnover along the Equatorial margin of West Africa.

  10. Precipitation recycling in West Africa - regional modeling, evaporation tagging and atmospheric water budget analysis

    NASA Astrophysics Data System (ADS)

    Arnault, Joel; Kunstmann, Harald; Knoche, Hans-Richard

    2015-04-01

    -atmospheric processes involved in the atmospheric branch of the water cycle in West Africa, based on our WRF simulation. We will particularly focus on the respective contribution of local and remote water vapor to atmospheric processes involved in local precipitation, and compare the results at the 100 and 1000 km2 scales. The potential impact of local land use change on local precipitation will finally be discussed based on this quantitative analysis.

  11. Interannual variability of vapor isotope in West Africa and its relation to ENSO

    NASA Astrophysics Data System (ADS)

    Okazaki, A.; Satoh, Y.; Tremoy, G.; Vimeux, F.; Yoshimura, K.

    2013-12-01

    This study presents the relationship between surface vapor isotope (δ18Ov) in West Africa in monsoon season (July to September) and ENSO activity using isotope enabled GCM (IsoGSM; Yoshimura et al., 2008). First we validated the model with observation data (Tremoy et al., 2012; T12). T12 conducted a 1-yr observation in Niamey (Niger) from 2010 to 2011, and found depletion of δ18Ov in monsoon season. Our model well captured the depletion. The result of a budget analysis for isotope flux using the model to clarify what made the decrease in δ18Ov shows that the main driver of the depletion is precipitation, and that is consistent with T12. Second, we extended our simulation to 34 years (1979-2012) to look into the relation further. We observed that the depletion in monsoon season does not always appear every year in the model. The major difference between the composite fields with and without depletion is the precipitation amount in the upper stream area of Niamey (10°W-10°E, 5°N-10°N; area A). This mechanism can be explained by the Rayleigh type distillation; the heavier precipitation in the area falls, the lighter moisture is brought into Niamey area. The depleted area stretches northward; 10°W-10°E, 7°N-15°N (area B) centering around Niamey. The correlation coefficient between monsoon season averaged δ18Ov in the area B and precipitation in the area A is -0.85 (N=34, α<0.01). Given the connection between West African monsoon and ENSO, the relation between δ18Ov and ENSO is expected. We therefore regressed monsoon season averaged δ18Ov from the model and annually averaged NINO3 index, and found a statistically significant correlation (R=0.53, N=34, α<0.01). This relation suggests that there is a possibility to reconstruct past West African Monsoon activity and ENSO using climate proxies.

  12. Real time black carbon measurements in West and Central Africa urban sites

    NASA Astrophysics Data System (ADS)

    Doumbia, El Hadji Thierno; Liousse, Catherine; Galy-Lacaux, Corinne; Ndiaye, Seydi Ababacar; Diop, Babacar; Ouafo, Marie; Assamoi, Eric Michel; Gardrat, Eric; Castera, Pierre; Rosset, Robert; Akpo, Aristide; Sigha, Luc

    2012-07-01

    Real time measurements of Black Carbon (BC) in PM2.5 aerosols were performed during AMMA and POLCA programs, between 2005 and 2010 in Cotonou (Benin), Dakar (Senegal), Bamako (Mali), and Yaounde (Cameroon). Indeed, BC was chosen as a metric because of its interest as an urban pollutant. The instrumented sites are representative of the traffic source. At Dakar, BC concentrations are high from November to April (13,000 ± 3500 ng m-3) and lower from May to September (8000 ± 3200 ng m-3). In dry season (November-April), high BC concentrations occurred as a result of northeasterly long-range transport of polluted air masses over West Africa, in addition to local emissions. However, during wet season (May-September) reduced traffic levels, school vacations and wet deposition processes contribute to lower BC concentration levels. Measured diurnal BC peak concentrations, at all sites, mainly occur during morning and evening rush-hour periods, indicating the paramount role of traffic. Highest values are observed between 5-9 a.m. and from 5 p.m. to 9 p.m. depending on the site, while lowest are occurred at night time and middle afternoon when activities of the population are reduced. BC source apportionment from absorption measurements also confirmed the relative importance of traffic (88%) versus biomass burning (12%). Also, BC measurements were functions of days of the week, with highest values occurring on Fridays and lowest ones on Sundays. Spatial variations associated to BC levels are very different from one site to another, revealing different types of sources with strong variations at the regional scale. It appears that mean BC concentrations in Dakar are lower by a factor of two, compared to those observed in Bamako, but remain higher than in some other West African sites (e.g. Cotonou, Yaounde). Overall, BC concentrations in our different sites are comparable to reported European and Asian megacity levels. Finally, using measured BC/PM2.5 ratios, we have

  13. From institutionalization of user fees to their abolition in West Africa: a story of pilot projects and public policies

    PubMed Central

    2015-01-01

    This article analyzes the historical background of the institutionalization of user fees and their subsequent abolition in West Africa. Based on a narrative review, we present the context that frames the different articles in this supplement. We first show that a general consensus has emerged internationally against user fees, which were imposed widely in Africa in the 1980s and 1990s; at that time, the institutionalization of user fees was supported by evidence from pilot projects funded by international aid agencies. Since then there have been other pilot projects studying the abolition of user fees in the 2000s, but these have not yet had any real influence on public policies, which are often still chaotic. This perplexing situation might be explained more by ideologies and political will than by insufficient financial capacity of states. PMID:26559564

  14. Parameter identification of the SWAT model on the BANI catchment (West Africa) under limited data condition

    NASA Astrophysics Data System (ADS)

    Chaibou Begou, Jamilatou; Jomaa, Seifeddine; Benabdallah, Sihem; Rode, Michael

    2015-04-01

    Due to the climate change, drier conditions have prevailed in West Africa, since the seventies, and the consequences are important on water resources. In order to identify and implement management strategies of adaptation to climate change in the sector of water, it is crucial to improve our physical understanding of water resources evolution in the region. To this end, hydrologic modelling is an appropriate tool for flow predictions under changing climate and land use conditions. In this study, the applicability and performance of the recent version of Soil and Water Assessment Tool (SWAT2012) model were tested on the Bani catchment in West Africa under limited data condition. Model parameters identification was also tested using one site and multisite calibration approaches. The Bani is located in the upper part of the Niger River and drains an area of about 101, 000 km2 at the outlet of Douna. The climate is tropical, humid to semi-arid from the South to the North with an average annual rainfall of 1050 mm (period 1981-2000). Global datasets were used for the model setup such as: USGS hydrosheds DEM, USGS LCI GlobCov2009 and the FAO Digital Soil Map of the World. Daily measured rainfall from nine rain gauges and maximum and minimum temperature from five weather stations covering the period 1981-1997 were used for model setup. Sensitivity analysis, calibration and validation are performed within SWATCUP using GLUE procedure at Douna station first (one site calibration), then at three additional internal stations, Bougouni, Pankourou and Kouoro1 (multi-site calibration). Model parameters were calibrated at daily time step for the period 1983-1992, then validated for the period 1993-1997. A period of two years (1981-1982) was used for model warming up. Results of one-site calibration showed that the model performance is evaluated by 0.76 and 0.79 for Nash-Sutcliffe (NS) and correlation coefficient (R2), respectively. While for the validation period the performance

  15. Precipitation chemistry and wet deposition in a remote wet savanna site in West Africa: Djougou (Benin)

    NASA Astrophysics Data System (ADS)

    Akpo, A. B.; Galy-Lacaux, C.; Laouali, D.; Delon, C.; Liousse, C.; Adon, M.; Gardrat, E.; Mariscal, A.; Darakpa, C.

    2015-08-01

    In the framework of the IDAF (IGAC/DEBITS/AFrica) international program, this study aims to study the chemical composition of precipitation and associated wet deposition at the rural site of Djougou in Benin, representative of a West and Central African wet savanna. Five hundred and thirty rainfall samples were collected at Djougou, Benin, from July 2005 to December 2009 to provide a unique database. The chemical composition of precipitation was analyzed for inorganic (Ca2+, Mg2+, Na+, NH4+, K+, NO3-, Cl-, SO42-) and organic (HCOO-, CH3COO-, C2H5COO-, C2O42-) ions, using ion chromatography. The 530 collected rain events represent a total of 5706.1 mm of rainfall compared to the measured pluviometry 6138.9 mm, indicating that the collection efficiency is about 93%. The order of total annual loading rates for soluble cations is NH4+ > Ca2+ > Mg2+ > K+. For soluble anions the order of loading is carbonates > HCOO- > NO3- > CH3COO- > SO4,SUP>2- > Cl- > C2O42- > C2H5COO-. In the wet savanna of Djougou, 86% of the measured pH values range between 4.7 and 5.7 with a median pH of 5.19, corresponding to a VWM (Volume Weighed Mean) H+ concentration of 6.46 μeq·L-1. This acidity results from a mixture of mineral and organic acids. The annual sea salt contribution was computed for K+, Mg2+, Ca2+ and SO42- and represents 4.2% of K+, 41% of Mg2+, 1.3% of Ca2+, and 7.4% of SO42-. These results show that K+, Ca2+, SO42-, and Mg2+ were mainly of non-marine origin. The marine contribution is estimated at 9%. The results of the chemical composition of rainwater of Djougou indicates that, except for the carbonates, ammonium has the highest VWM concentration (14.3 μeq·L-1) and nitrate concentration is 8.2 μeq·L-1. The distribution of monthly VWM concentration for all ions is computed and shows the highest values during the dry season, comparing to the wet season. Identified nitrogenous compound sources (NOx and NH3) are domestic animals, natural emissions from savanna soils

  16. Ecosystem properties of semiarid savanna grassland in West Africa and its relationship with environmental variability.

    PubMed

    Tagesson, Torbern; Fensholt, Rasmus; Guiro, Idrissa; Rasmussen, Mads Olander; Huber, Silvia; Mbow, Cheikh; Garcia, Monica; Horion, Stéphanie; Sandholt, Inge; Holm-Rasmussen, Bo; Göttsche, Frank M; Ridler, Marc-Etienne; Olén, Niklas; Lundegard Olsen, Jørgen; Ehammer, Andrea; Madsen, Mathias; Olesen, Folke S; Ardö, Jonas

    2015-01-01

    The Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ data. The studied variables include hydroclimatic variables, species composition, albedo, normalized difference vegetation index (NDVI), hyperspectral characteristics (350-1800 nm), surface reflectance anisotropy, brightness temperature, fraction of absorbed photosynthetic active radiation (FAPAR), biomass, vegetation water content, and land-atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable for investigating relationships between ecosystem properties and hydroclimatic variables for semiarid savanna ecosystems of the region. There were strong interannual, seasonal and diurnal dynamics in NEE, with high values of ~-7.5 g C m(-2)  day(-1) during the peak of the growing season. We found neither browning nor greening NDVI trends from 2002 to 2012. Interannual variation in species composition was strongly related to rainfall distribution. NDVI and FAPAR were strongly related to species composition, especially for years dominated by the species Zornia glochidiata. This influence was not observed in interannual variation in biomass and vegetation productivity, thus challenging dryland productivity models based on remote sensing. Surface reflectance anisotropy (350-1800 nm) at the peak of the growing season varied strongly depending on wavelength and viewing angle thereby having implications for the design of remotely sensed spectral vegetation indices covering different wavelength regions. The presented time series of in situ data have great potential for dryland dynamics

  17. The Impact of the West Africa Ebola Outbreak on Obstetric Health Care in Sierra Leone

    PubMed Central

    Brolin Ribacke, Kim J.; van Duinen, Alex J.; Nordenstedt, Helena; Höijer, Jonas; Molnes, Ragnhild; Froseth, Torunn Wigum; Koroma, AP; Darj, Elisabeth; Bolkan, Håkon Angel; Ekström, AnnaMia

    2016-01-01

    Background As Sierra Leone celebrates the end of the Ebola Virus Disease (EVD) outbreak, we can begin to fully grasp its impact on already weak health systems. The EVD outbreak in West Africa forced many hospitals to close down or reduce their activity, either to prevent nosocomial transmission or because of staff shortages. The aim of this study is to assess the potential impact of EVD on nationwide access to obstetric care in Sierra Leone. Methods and Findings Community health officers collected weekly data between January 2014—May 2015 on in-hospital deliveries and caesarean sections (C-sections) from all open facilities (public, private for-profit and private non-profit sectors) offering emergency obstetrics in Sierra Leone. This was compared to official data of EVD cases per district. Logistic and Poisson regression analyses were used to compute risk and rate estimates. Nationwide, the number of in-hospital deliveries and C-sections decreased by over 20% during the EVD outbreak. The decline occurred early on in the EVD outbreak and was mainly attributable to the closing of private not-for-profit hospitals rather than government facilities. Due to difficulties in collecting data in the midst of an epidemic, limitations of this study include some missing data points. Conclusions Both the number of in-hospital deliveries and C-sections substantially declined shortly after the onset of the EVD outbreak. Since access to emergency obstetric care, like C-sections, is associated with decreased maternal mortality, many women are likely to have died due to the reduced access to appropriate care during childbirth. Future research on indirect health effects of health system breakdown should ideally be nationwide and continue also into the recovery phase. It is also important to understand the mechanisms behind the deterioration so that important health services can be reestablished. PMID:26910462

  18. Petrology and chemistry of the basaltic shergottite North West Africa 480

    NASA Astrophysics Data System (ADS)

    Barrat, J. A.; Gillet, Ph.; Sautter, V.; Jambon, A.; Javoy, M.; Göpel, C.; Lesourd, M.; Keller, F.; Petit, E.

    2002-04-01

    North West Africa (NWA) 480 is a new martian meteorite of 28 g found in the Moroccan Sahara in November 2000. It consists mainly of large gray pyroxene crystals (the largest grains are up to 5 mm in length) and plagioclase converted to maskelynite. Excluding the melt pocket areas, modal analyses indicate the following mineral proportions: 72 vol% pyroxenes extensively zoned, 25% maskelynite, 1% phosphates (merrillite and chlorapatite), 1% opaque oxides (ilmenite, ulvospinel and chromite) and sulfides, and 1% others such as silica and fayalite. The compositional trend of NWA 480 pyroxenes is similar to that of Queen Alexandra Range (QUE) 94201 but in NWA 480 the pyroxene cores are more Mg-rich (En77-En65). Maskelynites display a limited zoning (An42-50Ab54-48Or2-4). Our observations suggest that NWA 480 formed from a melt with a low nuclei density at a slow cooling rate. The texture was achieved via a single-stage cooling where pyroxenes grew continuously. A similar model was previously proposed for QUE 94201 by McSween et al. (1996). NWA 480 is an Al-poor ferroan basaltic rock and resembles Zagami or Shergotty for major elements and compatible trace element abundances. The bulk rock analysis for oxygen isotopes yields V17O = +0.42%o, a value in agreement at the high margin, with those measured on other shergottites (Clayton and Mayeda, 1996; Romanek et al., 1998; Franchi et al., 1999). Its CI-normalized rare earth element pattern is similar to those of peridotitic shergottites such as Allan Hills (ALH)A77005, suggesting that these shergottites shared a similar parent liquid, or at least the same mantle source.

  19. An Analysis of the Environments of Intense Convective Systems in West Africa in 2003

    NASA Technical Reports Server (NTRS)

    Nicholls, Stephen D.; Mohr, Karen I.

    2010-01-01

    We investigated the local- and regional-scale thermodynamical and dynamical environments associated with intense convective systems in West Africa during 2003. We identified convective system cases from TRMM microwave imagery, classifying each case by the system minimum 85-GHz brightness temperature and by the estimated elapsed time of propagation from high terrain. The speed of the mid-level jet, the magnitude of the low-level shear, and the surface equivalent potential temperature (theta(sub e)) were greater for the intense cases compared to the non-intense cases, although the differences between the means tended to be small, less than 3K for surface theta(sub e). Hypothesis testing of a series of commonly used intensity prediction metrics resulted in significant results only for low-level metrics such as convective available potential energy and not for any of the mid- or upper-level metrics such as 700-hPa theta(sub e). None of the environmental variables or intensity metrics by themselves or in combination appeared to be reliable direct predictors of intensity. In the regional scale analysis, the majority of intense convective systems occurred in the surface baroclinic zone where surface theta(sub e) exceeded 344 K and the 700-hPa zonal wind speeds were less than -6/ms. Fewer intense cases compared to non-intense cases were associated with African easterly wave troughs. Fewer than 25% of our cases occurred in environments with detectable Saharan dust loads, and the results for intense and non-intense cases were similar. Our results for the regional analysis were consistent with the seasonal movement of the WAM and the intertropical front, regional differences in topography, and AEW energetics.

  20. Studies of 21st-Century Precipitation Trends Over West Africa

    NASA Technical Reports Server (NTRS)

    Druyan, Leonard M.

    2010-01-01

    West Africa includes a semi-arid zone between the Sahara Desert and the humid Gulf of Guinea coast, approximately between 10 N and 20 N, which is irrigated by summer monsoon rains. This article refers to the region as the Sahel. Rain-fed agriculture is the primary sustenance for Sahel populations, and severe droughts (in the 1970s and 1980s), therefore, have devastating negative societal impacts. The future frequency of Sahel droughts and the evolution of its hydrological balance are therefore of great interest. The article reviews 10 recent research studies that attempt to discover how climate changes will affect the hydrology of the Sahel throughout the 21st century. All 10 studies rely on atmosphere ocean global climate model (AOGCM) simulations based on a range of greenhouse gas emissions scenarios. Many of the simulations are contained in the Intergovernmental Panel on Climate Change archives for Assessment Reports #3 and #4. Two of the studies use AOGCM data to drive regional climate models. Seven studies make projections for the first half of the 21st century and eight studies make projections for the second half. Some studies make projections of wetter conditions and some predict more frequent droughts, and each describes the atmospheric processes associated with its prediction. Only one study projects more frequent droughts before 2050, and that is only for continent-wide degradation in vegetation cover. The challenge to correctly simulate Sahel rainfall decadal trends is particularly daunting because multiple physical mechanisms compete to drive the trend upwards or downwards. A variety of model deficiencies, regarding the simulation of one or more of these physical processes, taints models climate change projections. Consequently, no consensus emerges regarding the impact of anticipated greenhouse gas forcing on the hydrology of the Sahel in the second half of the 21st century.

  1. Ebola or Not? Evaluating the Ill Traveler From Ebola-Affected Countries in West Africa

    PubMed Central

    Fairley, Jessica K.; Kozarsky, Phyllis E.; Kraft, Colleen S.; Guarner, Jeannette; Steinberg, James P.; Anderson, Evan; Jacob, Jesse T.; Meloy, Patrick; Gillespie, Darria; Espinoza, Tamara R.; Isakov, Alexander; Vanairsdale, Sharon; Baker, Esther; Wu, Henry M.

    2016-01-01

    Background. The 2014–2015 Ebola epidemic in West Africa had global impact beyond the primarily affected countries of Guinea, Liberia, and Sierra Leone. Other countries, including the United States, encountered numerous patients who arrived from highly affected countries with fever or other signs or symptoms consistent with Ebola virus disease (EVD). Methods. We describe our experience evaluating 25 travelers who met the US Centers for Disease Control and Prevention case definition for a person under investigation (PUI) for EVD from July 20, 2014 to January 28, 2015. All patients were triaged and evaluated under the guidance of institutional protocols to the emergency department, outpatient tropical medicine clinic, or Emory's Ebola treatment unit. Strict attention to infection control and early involvement of public health authorities guided the safe evaluation of these patients. Results. None were diagnosed with EVD. Respiratory illnesses were common, and 8 (32%) PUI were confirmed to have influenza. Four patients (16%) were diagnosed with potentially life-threatening infections or conditions, including 3 with Plasmodium falciparum malaria and 1 with diabetic ketoacidosis. Conclusions. In addition to preparing for potential patients with EVD, Ebola assessment centers should consider other life-threatening conditions requiring urgent treatment, and travelers to affected countries should be strongly advised to seek pretravel counseling. Furthermore, attention to infection control in all aspects of PUI evaluation is paramount and has presented unique challenges. Lessons learned from our evaluation of potential patients with EVD can help inform preparations for future outbreaks of highly pathogenic communicable diseases. PMID:26925428

  2. Dictating participation? Rethinking the adaptive co-management of socio-ecological systems in West Africa

    NASA Astrophysics Data System (ADS)

    El Vilaly, Audra; Abd salam El Vilaly, Mohamed

    2015-04-01

    In the face of environmental change, enhancing adaptive capacity relies on stakeholder engagement. But the participatory process, while critical to the translation, transfer, and application of scientific knowledge to society, is not without its own contradictions. These include the asymmetrical relations of power that prevail between environmental scientists, managers, and local users; discrepant understandings of knowledge and its appropriate uses; and conflicting social, economic, and ecological values, to name only a few. Our research examines five major transboundary river basin organizations in West Africa and their efforts to improve adaptive basin management via stakeholder collaboration. In particular, we evaluate the participatory strategies of these organizations to measure non-linear, multi-directional feedbacks between the social and biophysical factors of land use/land cover change, as well as the impacts of this change on basins and their dependent populations. Our research suggests that oftentimes, these methods paradoxically produce a hierarchical and marginalizing effect on local stakeholders in relation to the scientists that study them. In seeking to address these limitations, we assess the potential costs and benefits of integrating select components of a Participatory Action Research (PAR) framework (see, for example, Reason & Bradbury-Huang, 2007) into studies of complex socio-ecological problems. This approach, used widely in the social sciences, promotes critical reflection on and minimization of the power inequities inherent in science-society collaborations. It instead favors more horizontal forms of knowledge co-production that support and foster the expansion of local, existing movements for social and environmental justice. A PAR framework may therefore improve the efficiency, sustainability, and equitability of land-based adaptation to environmental change; further research is thus recommended to test this hypothesis. References

  3. Analysis of Hydrological Processes In A Small Catchment In Benin (west Africa)

    NASA Astrophysics Data System (ADS)

    Giertz, S.; Diekkrüger, B.

    The presented study is integrated in the GLOWA IMPETUS project (an integrated ap- proach to the efficient management of scarce water resources in West Africa) which analyses the effects of global change conditions on regional hydrological processes and on the water availability in Benin and Morocco. To examine the hydrological cy- cle and its change at the regional scale, detailed knowledge about the dominant hydro- logical processes dependent on the environmental conditions is necessary. This study provides the analysis of the hydrological processes as well as their simulation at the local scale serving as a basis for the subsequent regionalisation of processes and model parameters. The investigated area is a 30 km2 sized catchment in the sub-humid region of Benin which has been selected as research area for several participating disciplines of the IMPETUS-Project (hydrology, soil degradation, dynamics of vegetation, phys- iological plant ecology). The catchment is characterized by a high spatial variability of the land cover and a high temporal variablility due to land cover changes. Con- sequently all hydrologic measurements are performed on different land use types to analyse their influence on the hydrological processes. The measurements of soil water dynamics, runoff, infiltration and soil physical properties provide detailed information on the generation of model input parameters. A validation of the model output is car- ried out by comparing simulated and measured dynamics of state variables as well as water balance terms. By testing and validating the TOPLATS-model at the local scale in different-sized sub-catchments an evaluation of its applicability to the regional scale and the assessment of the related uncertainties is performed.

  4. Regional Climate Change Impact on Agricultural Land Use in West Africa

    NASA Astrophysics Data System (ADS)

    Ahmed, K. F.; Wang, G.; You, L.

    2014-12-01

    Agriculture is a key element of the human-induced land use land cover change (LULCC) that is influenced by climate and can potentially influence regional climate. Temperature and precipitation directly impact the crop yield (by controlling photosynthesis, respiration and other physiological processes) that then affects agricultural land use pattern. In feedback, the resulting changes in land use and land cover play an important role to determine the direction and magnitude of global, regional and local climate change by altering Earth's radiative equilibrium. The assessment of future agricultural land use is, therefore, of great importance in climate change study. In this study, we develop a prototype land use projection model and, using this model, project the changes to land use pattern and future land cover map accounting for climate-induced yield changes for major crops in West Africa. Among the inputs to the land use projection model are crop yield changes simulated by the crop model DSSAT, driven with the climate forcing data from the regional climate model RegCM4.3.4-CLM4.5, which features a projected decrease of future mean crop yield and increase of inter-annual variability. Another input to the land use projection model is the projected changes of food demand in the future. In a so-called "dumb-farmer scenario" without any adaptation, the combined effect of decrease in crop yield and increase in food demand will lead to a significant increase in agricultural land use in future years accompanied by a decrease in forest and grass area. Human adaptation through land use optimization in an effort to minimize agricultural expansion is found to have little impact on the overall areas of agricultural land use. While the choice of the General Circulation Model (GCM) to derive initial and boundary conditions for the regional climate model can be a source of uncertainty in projecting the future LULCC, results from sensitivity experiments indicate that the changes

  5. How model and input uncertainty impact maize yield simulations in West Africa

    NASA Astrophysics Data System (ADS)

    Waha, Katharina; Huth, Neil; Carberry, Peter; Wang, Enli

    2015-02-01

    Crop models are common tools for simulating crop yields and crop production in studies on food security and global change. Various uncertainties however exist, not only in the model design and model parameters, but also and maybe even more important in soil, climate and management input data. We analyze the performance of the point-scale crop model APSIM and the global scale crop model LPJmL with different climate and soil conditions under different agricultural management in the low-input maize-growing areas of Burkina Faso, West Africa. We test the models’ response to different levels of input information from little to detailed information on soil, climate (1961-2000) and agricultural management and compare the models’ ability to represent the observed spatial (between locations) and temporal variability (between years) in crop yields. We found that the resolution of different soil, climate and management information influences the simulated crop yields in both models. However, the difference between models is larger than between input data and larger between simulations with different climate and management information than between simulations with different soil information. The observed spatial variability can be represented well from both models even with little information on soils and management but APSIM simulates a higher variation between single locations than LPJmL. The agreement of simulated and observed temporal variability is lower due to non-climatic factors e.g. investment in agricultural research and development between 1987 and 1991 in Burkina Faso which resulted in a doubling of maize yields. The findings of our study highlight the importance of scale and model choice and show that the most detailed input data does not necessarily improve model performance.

  6. Ebola or Not? Evaluating the Ill Traveler From Ebola-Affected Countries in West Africa.

    PubMed

    Fairley, Jessica K; Kozarsky, Phyllis E; Kraft, Colleen S; Guarner, Jeannette; Steinberg, James P; Anderson, Evan; Jacob, Jesse T; Meloy, Patrick; Gillespie, Darria; Espinoza, Tamara R; Isakov, Alexander; Vanairsdale, Sharon; Baker, Esther; Wu, Henry M

    2016-01-01

    Background.  The 2014-2015 Ebola epidemic in West Africa had global impact beyond the primarily affected countries of Guinea, Liberia, and Sierra Leone. Other countries, including the United States, encountered numerous patients who arrived from highly affected countries with fever or other signs or symptoms consistent with Ebola virus disease (EVD). Methods.  We describe our experience evaluating 25 travelers who met the US Centers for Disease Control and Prevention case definition for a person under investigation (PUI) for EVD from July 20, 2014 to January 28, 2015. All patients were triaged and evaluated under the guidance of institutional protocols to the emergency department, outpatient tropical medicine clinic, or Emory's Ebola treatment unit. Strict attention to infection control and early involvement of public health authorities guided the safe evaluation of these patients. Results.  None were diagnosed with EVD. Respiratory illnesses were common, and 8 (32%) PUI were confirmed to have influenza. Four patients (16%) were diagnosed with potentially life-threatening infections or conditions, including 3 with Plasmodium falciparum malaria and 1 with diabetic ketoacidosis. Conclusions.  In addition to preparing for potential patients with EVD, Ebola assessment centers should consider other life-threatening conditions requiring urgent treatment, and travelers to affected countries should be strongly advised to seek pretravel counseling. Furthermore, attention to infection control in all aspects of PUI evaluation is paramount and has presented unique challenges. Lessons learned from our evaluation of potential patients with EVD can help inform preparations for future outbreaks of highly pathogenic communicable diseases. PMID:26925428

  7. The contribution of occult precipitation to nutrient deposition on the west coast of South Africa.

    PubMed

    Nyaga, Justine M; Neff, Jason C; Cramer, Michael D

    2015-01-01

    The Strandveld mediterranean-ecosystem of the west coast of South Africa supports floristically diverse vegetation growing on mostly nutrient-poor aeolian sands and extending from the Atlantic Ocean tens of kilometers inland. The cold Benguela current upwelling interacts with warm onshore southerly winds in summer causing coastal fogs in this region. We hypothesized that fog and other forms of occult precipitation contribute moisture and nutrients to the vegetation. We measured occult precipitation over one year along a transect running inland in the direction of the prevailing wind and compared the nutrient concentrations with those in rainwater. Occult deposition rates of P, N, K, Mg, Ca, Na, Al and Fe all decreased with distance from the ocean. Furthermore, ratios of cations to Na were similar to those of seawater, suggesting a marine origin for these. In contrast, N and P ratios in occult precipitation were higher than in seawater. We speculate that this is due to marine foam contributing to occult precipitation. Nutrient loss in leaf litter from dominant shrub species was measured to indicate nutrient demand. We estimated that occult precipitation could meet the demand of the dominant shrubby species for annual N, P, K and Ca. Of these species, those with small leaves intercepted more moisture and nutrients than those with larger leaves and could take up foliar deposits of glycine, NO3(-), NH4(+) and Li (as tracer for K) through leaf surfaces. We conclude that occult deposition together with rainfall deposition are potentially important nutrient and moisture sources for the Strandveld vegetation that contribute to this vegetation being floristically distinct from neighbouring nutrient-poor Fynbos vegetation. PMID:26017747

  8. Interactive Land Use-Climate Change Predictions in West Africa: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Wang, G.; Ahmed, K. F.; You, L.; Koo, J.

    2013-12-01

    Land use changes constitute an important regional climate change forcing that modifies the greenhouse gas induced future climate changes. At the same time, climate change is an important driver for land use changes, although it is unclear how important this impact might be relative to the impact of socio-economic factors on future land use. Using West Africa as an example, this study examines the importance of considering land use-climate change interactions in decadal predictions for future land use and climate changes, and thus assess whether there is a strong need to incorporate land use modeling into earth system models. Specifically, we evaluate the impact of projected climate changes from a regional climate model (RegCM4-CLM4) on crop yields using the crop model DSSAT, and assess the need for future land use changes by combining crop yield changes with demand for local productions predicted based on socio-economic drivers using an economic model (IFPRI's IMPACT model). For this preliminary assessment, a simple land use allocation approach is used, which favors agricultural expansion over intensification in order to provide an upper limit for land use changes. As a first test, the RCP8.5 mid-century climate projected by the NCAR CESM model is used as the future climate boundary conditions to drive the regional climate model. The impact of considering the land use-climate change interactions will be evaluated based on the differences in projected climate changes between two types of simulations: one that considers land use changes driven by both climate-induced crop yield changes and socioeconomic factors, and one that considers land use changes driven solely by socioeconomic factors.

  9. Sediment budget of cratons: insights from West Africa over the Cenozoic

    NASA Astrophysics Data System (ADS)

    Jean-Louis, G.; Chardon, D.; Rouby, D.; Beauvais, A.

    2015-12-01

    The sediment load of rivers constitutes the material that builds the stratigraphic successions found from continental margins to the deep ocean. Measure of this flux is relevant to understanding continental controls on denudation, riverine transport and basin filling. An increasing number of sediment yield measures is available but whether these modern values can be extrapolated at geological timescales for large watersheds is still questioned. One reason is the lack of long-term data. Here, we present a sediment budget for Sub-Saharan West Africa over the Cenozoic to compare with the modern rates. The denudation of this cratonic area is constrained using three regional lateritic paleo-landsurfaces that formed during periods of enhanced weathering since the Paleocene-Eocene greenhouse peak. The 3D interpolation of these surfaces allowed building three successive denudation maps for the 45-24, 24-11 and 11-0 Ma intervals together with reconstructions of the paleo-drainage. The regional distribution of erosion suggests the influence of lithospheric deformation, concentrated around a southern marginal upwarp and eastern hotspot swells. The export of large-scale drainages was calculated by converting denudated volumes into sediment fluxes using the porosity and density of lateritic regolith. Exported volumes calculated for the Niger watershed fall within the same range as the Cenozoic clastic accumulations of the Niger delta. Comparisons also show that modern fluxes can be an order of magnitude above the long-term fluxes for moderately large watersheds but that modern and long-term yields are similar for the largest watersheds (e.g. Niger, Volta, Senegal). These results suggest that the export of very large cratonic watersheds is independent of the measurement timescale and that their modern yields can be extrapolated at long-timescale. Finally, it allows assessing the relative contribution of cratons, i.e. non-active orogenic areas, to the global sediment budgets at

  10. Monthly streamflow prediction in the Volta Basin of West Africa: A SISO NARMAX polynomial modelling

    NASA Astrophysics Data System (ADS)

    Amisigo, B. A.; van de Giesen, N.; Rogers, C.; Andah, W. E. I.; Friesen, J.

    Single-input-single-output (SISO) non-linear system identification techniques were employed to model monthly catchment runoff at selected gauging sites in the Volta Basin of West Africa. NARMAX (Non-linear Autoregressive Moving Average with eXogenous Input) polynomial models were fitted to basin monthly rainfall and gauging station runoff data for each of the selected sites and used to predict monthly runoff at the sites. An error reduction ratio (ERR) algorithm was used to order regressors for various combinations of input, output and noise lags (various model structures) and the significant regressors for each model selected by applying an Akaike Information Criterion (AIC) to independent rainfall-runoff validation series. Model parameters were estimated from the Matlab REGRESS function (an orthogonal least squares method). In each case, the sub-model without noise terms was fitted first followed by a fitting of the noise model. The coefficient of determination ( R-squared), the Nash-Sutcliffe Efficiency criterion (NSE) and the F statistic for the estimation (training) series were used to evaluate the significance of fit of each model to this series while model selection from the range of models fitted for each gauging site was done by examining the NSEs and the AICs of the validation series. Monthly runoff predictions from the selected models were very good, and the polynomial models appeared to have captured a good part of the rainfall-runoff non-linearity. The results indicate that the NARMAX modelling framework is suitable for monthly river runoff prediction in the Volta Basin. The several good models made available by the NARMAX modelling framework could be useful in the selection of model structures that also provide insights into the physical behaviour of the catchment rainfall-runoff system.

  11. Impact of future climate change on streamflow in the White Volta river basin, West Africa

    NASA Astrophysics Data System (ADS)

    Obuobie, E.; Diekkrüger, B.; Liebe, J.

    2009-04-01

    The Soil and Water Assessment Tool (SWAT) model was applied in the White Volta river basin, West Africa, to simulate the streamflow and to estimate the impact of future climate change on the streamflow. The White Volta river basin is one of the three major sub-basins of the Volta river basin, and drains an area of about 106,000 km2 mainly shared by the riparian countries, Burkina Faso and Ghana. The model was calibrated and validated using daily measured streamflow data from the stream gage at Nawuni, for the period 1980-2000. Impact of future climate change on streamflow was estimated by simulating streamflow of two time slices, the present (1990-2000) and future (2030-2039), using the calibrated SWAT model and stochastically generated daily climate series and comparing their mean annual values. The generated future climate series reflected monthly changes in precipitation and temperature forecasted by the meso-scale climate model MM5, which was downscaled from ECHAM4 scenario IS92a. The results show that SWAT is able to accurately reproduce the streamflow in the White Volta Basin. The coefficient of determination and Nash-Sutcliffe model efficiency were found to be, respectively, higher than 0.8 and 0.7, for both the calibration and validation periods. Compared to the present, the future mean annual streamflow and the annual coefficient of variation of the streamflow in the basin are expected to increase by 33% and 52%, respectively, as a result of future climate change.

  12. The climatic imprint of bimodal distributions in vegetation cover for West Africa

    NASA Astrophysics Data System (ADS)

    Yin, Z.; Dekker, S. C.; van den Hurk, B. J. J. M.; Dijkstra, H. A.

    2015-11-01

    Observed bimodal distributions of woody cover in West Africa provide evidence that alternative ecosystem states may exist under the same precipitation regimes. Understanding the explicit climate conditions where the woody cover bimodality can exist is important to predict crucial transitions of ecosystems due to climate change. In this study, we show that bimodality can also be observed in mean annual shortwave radiation and above ground biomass. Through conditional histogram analysis, we find that the bimodality of woody cover can only exist under low mean annual shortwave radiation and low above ground biomass. Based on a land cover map, in which anthropogenic land use was removed, six climatic indicators that represent water, energy, climate seasonality and water-radiation coupling are analyzed to investigate the coexistence of these indicators with specific land cover types. From this analysis we find that the mean annual precipitation is not a sufficient predictor of a potential land cover change. Indicators of climate seasonality are strongly related to the observed land cover type. However, these indicators can only demonstrate the potential occurrence of bimodality but cannot exclude the probability of bimodal vegetation distributions. A new indicator: the normalized difference of precipitation, successfully expresses the stability of the precipitation regime and can improve the accuracy of predictions of forest states. We evaluate the land cover predictions based on different combinations of climatic indicators. Regions with high potential of land cover transitions are displayed. The results suggest that the tropical forest in the Congo basin may be unstable and shows the possibility to significantly decrease. An increase in the area covered by savanna and grass is possible, which coincides with an observed re-greening of the Sahara.

  13. The Contribution of Occult Precipitation to Nutrient Deposition on the West Coast of South Africa

    PubMed Central

    2015-01-01

    The Strandveld mediterranean-ecosystem of the west coast of South Africa supports floristically diverse vegetation growing on mostly nutrient-poor aeolian sands and extending from the Atlantic Ocean tens of kilometers inland. The cold Benguela current upwelling interacts with warm onshore southerly winds in summer causing coastal fogs in this region. We hypothesized that fog and other forms of occult precipitation contribute moisture and nutrients to the vegetation. We measured occult precipitation over one year along a transect running inland in the direction of the prevailing wind and compared the nutrient concentrations with those in rainwater. Occult deposition rates of P, N, K, Mg, Ca, Na, Al and Fe all decreased with distance from the ocean. Furthermore, ratios of cations to Na were similar to those of seawater, suggesting a marine origin for these. In contrast, N and P ratios in occult precipitation were higher than in seawater. We speculate that this is due to marine foam contributing to occult precipitation. Nutrient loss in leaf litter from dominant shrub species was measured to indicate nutrient demand. We estimated that occult precipitation could meet the demand of the dominant shrubby species for annual N, P, K and Ca. Of these species, those with small leaves intercepted more moisture and nutrients than those with larger leaves and could take up foliar deposits of glycine, NO3-, NH4+ and Li (as tracer for K) through leaf surfaces. We conclude that occult deposition together with rainfall deposition are potentially important nutrient and moisture sources for the Strandveld vegetation that contribute to this vegetation being floristically distinct from neighbouring nutrient-poor Fynbos vegetation. PMID:26017747

  14. Calculating crop water requirement satisfaction in the West Africa Sahel with remotely sensed soil moisture

    USGS Publications Warehouse

    McNally, Amy; Gregory J. Husak; Molly Brown; Mark Carroll; Funk, Christopher C.; Soni Yatheendradas; Kristi Arsenault; Christa Peters-Lidard; Verdin, James

    2015-01-01

    The Soil Moisture Active Passive (SMAP) mission will provide soil moisture data with unprecedented accuracy, resolution, and coverage, enabling models to better track agricultural drought and estimate yields. In turn, this information can be used to shape policy related to food and water from commodity markets to humanitarian relief efforts. New data alone, however, do not translate to improvements in drought and yield forecasts. New tools will be needed to transform SMAP data into agriculturally meaningful products. The objective of this study is to evaluate the possibility and efficiency of replacing the rainfall-derived soil moisture component of a crop water stress index with SMAP data. The approach is demonstrated with 0.1°-resolution, ~10-day microwave soil moisture from the European Space Agency and simulated soil moisture from the Famine Early Warning Systems Network Land Data Assimilation System. Over a West Africa domain, the approach is evaluated by comparing the different soil moisture estimates and their resulting Water Requirement Satisfaction Index values from 2000 to 2010. This study highlights how the ensemble of indices performs during wet versus dry years, over different land-cover types, and the correlation with national-level millet yields. The new approach is a feasible and useful way to quantitatively assess how satellite-derived rainfall and soil moisture track agricultural water deficits. Given the importance of soil moisture in many applications, ranging from agriculture to public health to fire, this study should inspire other modeling communities to reformulate existing tools to take advantage of SMAP data.

  15. Participatory planning in river catchments, an innovative toolkit tested in Southern Africa and North West England.

    PubMed

    Tippett, J

    2005-01-01

    The European Union Water Framework Directive (WFD) offers an unparalleled opportunity for improving river basin management. Active participation is essential for its delivery. "End-of-pipe" solutions will not deliver the improvements needed to achieve its ambitious goals. This research tested DesignWays, a toolkit for participatory planning, as a mechanism for maximizing the long-term social and environmental benefits of such stakeholder and community participation. It examined the emerging role of "planning for sustainability" in the context of river catchments. Sustainable management of water requires integration, and recognition of interconnections between systems at different levels of scale. This is an endeavour in which systems thinking provides useful tools. The development of DesignWays was a conscious attempt to embed 'new paradigm' living systems metaphors into a practical planning tool. This paper begins with a description of DesignWays and its development in Southern Africa. An outline of the context of the action research in North-West England is followed by a description of the stages of the process, with highlights of the outcomes. This research had two major outcomes: a contribution to theory through an in-depth exploration of the theoretical basis of participatory, ecologically informed design; and a contribution to practice through investigating DesignWays' potential to meet key challenges of the WFD. This research points to the importance of understanding participatory planning as a societal process, aiming to make the process engaging and meaningful. It has pointed to the need to see participatory planning and education for sustainability as an integrated process. It demonstrated the benefits of an iterative process in which planning at the landscape level of scale informs, and is informed by, work at the site level. It has shown that an approach consistent with a living systems paradigm can contribute to the development of more integrated

  16. Overview of main challenges for Early Warning Systems for Food Security in West Africa

    NASA Astrophysics Data System (ADS)

    Genesio, Lorenzo; Bacci, Maurizio; Baron, Christian; Diarra, Birama; di Vecchia, Andrea; Traoré, Seydou; Hassane, Idrissa; Ndiaye, Mamadou; Philippon, Nathalie; Tarchiani, Vieri

    2010-05-01

    In West Africa Early Warning Systems (EWSs) for food security have been widely recognized to have contributed in the last twenty years to better face famine emergencies. The improved understanding of the environmental and socio-economic dynamics of the region, a change in the causes for food insecurity and the evolution of Information and Communication Technologies (ICT) have favored the introduction of new approaches and the involvement of a network of stakeholders. In recent years the improvement of EWS has been concentrated in the adaptation and the transfer of existing tools rather than the development of the overall design of EWS in function of users needs, at the same time key scientific areas to be improved to provide major operational advancements needs to be better identified. This partially due to a difficulty of the research community to be in direct connection with operational processes and on the other side by an evident limit in following a demand driven approach due to the difficulties in modelling bio and social phenomena in a unique environment. In this context AMMA project had the ambitious objective of bridging the gap between state of the art research in the domains of geo-science and human related disciplines, and the operational EWS. The work carried out in AMMA, while improving the understanding of monsoon system, allowed to better orient research challenges in order to provide EWS with improved products effectively meeting the needs of end-users at different levels. In this work, advancements in providing appropriate information for the identification of agricultural risk zones by using short to long time forecasts are illustrated highlighting critical aspects still demanding scientific improvements.

  17. Temporal and spatial analysis of the 2014-2015 Ebola virus outbreak in West Africa.

    PubMed

    Carroll, Miles W; Matthews, David A; Hiscox, Julian A; Elmore, Michael J; Pollakis, Georgios; Rambaut, Andrew; Hewson, Roger; García-Dorival, Isabel; Bore, Joseph Akoi; Koundouno, Raymond; Abdellati, Saïd; Afrough, Babak; Aiyepada, John; Akhilomen, Patience; Asogun, Danny; Atkinson, Barry; Badusche, Marlis; Bah, Amadou; Bate, Simon; Baumann, Jan; Becker, Dirk; Becker-Ziaja, Beate; Bocquin, Anne; Borremans, Benny; Bosworth, Andrew; Boettcher, Jan Peter; Cannas, Angela; Carletti, Fabrizio; Castilletti, Concetta; Clark, Simon; Colavita, Francesca; Diederich, Sandra; Donatus, Adomeh; Duraffour, Sophie; Ehichioya, Deborah; Ellerbrok, Heinz; Fernandez-Garcia, Maria Dolores; Fizet, Alexandra; Fleischmann, Erna; Gryseels, Sophie; Hermelink, Antje; Hinzmann, Julia; Hopf-Guevara, Ute; Ighodalo, Yemisi; Jameson, Lisa; Kelterbaum, Anne; Kis, Zoltan; Kloth, Stefan; Kohl, Claudia; Korva, Miša; Kraus, Annette; Kuisma, Eeva; Kurth, Andreas; Liedigk, Britta; Logue, Christopher H; Lüdtke, Anja; Maes, Piet; McCowen, James; Mély, Stéphane; Mertens, Marc; Meschi, Silvia; Meyer, Benjamin; Michel, Janine; Molkenthin, Peter; Muñoz-Fontela, César; Muth, Doreen; Newman, Edmund N C; Ngabo, Didier; Oestereich, Lisa; Okosun, Jennifer; Olokor, Thomas; Omiunu, Racheal; Omomoh, Emmanuel; Pallasch, Elisa; Pályi, Bernadett; Portmann, Jasmine; Pottage, Thomas; Pratt, Catherine; Priesnitz, Simone; Quartu, Serena; Rappe, Julie; Repits, Johanna; Richter, Martin; Rudolf, Martin; Sachse, Andreas; Schmidt, Kristina Maria; Schudt, Gordian; Strecker, Thomas; Thom, Ruth; Thomas, Stephen; Tobin, Ekaete; Tolley, Howard; Trautner, Jochen; Vermoesen, Tine; Vitoriano, Inês; Wagner, Matthias; Wolff, Svenja; Yue, Constanze; Capobianchi, Maria Rosaria; Kretschmer, Birte; Hall, Yper; Kenny, John G; Rickett, Natasha Y; Dudas, Gytis; Coltart, Cordelia E M; Kerber, Romy; Steer, Damien; Wright, Callum; Senyah, Francis; Keita, Sakoba; Drury, Patrick; Diallo, Boubacar; de Clerck, Hilde; Van Herp, Michel; Sprecher, Armand; Traore, Alexis; Diakite, Mandiou; Konde, Mandy Kader; Koivogui, Lamine; Magassouba, N'Faly; Avšič-Županc, Tatjana; Nitsche, Andreas; Strasser, Marc; Ippolito, Giuseppe; Becker, Stephan; Stoecker, Kilian; Gabriel, Martin; Raoul, Hervé; Di Caro, Antonino; Wölfel, Roman; Formenty, Pierre; Günther, Stephan

    2015-08-01

    West Africa is currently witnessing the most extensive Ebola virus (EBOV) outbreak so far recorded. Until now, there have been 27,013 reported cases and 11,134 deaths. The origin of the virus is thought to have been a zoonotic transmission from a bat to a two-year-old boy in December 2013 (ref. 2). From this index case the virus was spread by human-to-human contact throughout Guinea, Sierra Leone and Liberia. However, the origin of the particular virus in each country and time of transmission is not known and currently relies on epidemiological analysis, which may be unreliable owing to the difficulties of obtaining patient information. Here we trace the genetic evolution of EBOV in the current outbreak that has resulted in multiple lineages. Deep sequencing of 179 patient samples processed by the European Mobile Laboratory, the first diagnostics unit to be deployed to the epicentre of the outbreak in Guinea, reveals an epidemiological and evolutionary history of the epidemic from March 2014 to January 2015. Analysis of EBOV genome evolution has also benefited from a similar sequencing effort of patient samples from Sierra Leone. Our results confirm that the EBOV from Guinea moved into Sierra Leone, most likely in April or early May. The viruses of the Guinea/Sierra Leone lineage mixed around June/July 2014. Viral sequences covering August, September and October 2014 indicate that this lineage evolved independently within Guinea. These data can be used in conjunction with epidemiological information to test retrospectively the effectiveness of control measures, and provides an unprecedented window into the evolution of an ongoing viral haemorrhagic fever outbreak. PMID:26083749

  18. The influence of woody thickening on SOM dynamics along a precipitation gradient in West Africa

    NASA Astrophysics Data System (ADS)

    Saiz, Gustavo; Bird, Michael; Wurster, Christopher; Ascough, Philippa; Veenendaal, Elmar; Butterbach-Bahl, Klaus; Schrodt, Franziska; Domingues, Tomas; Feldpausch, Ted; Braojos, Victor; Lloyd, Jonathan

    2014-05-01

    We made use of the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples to assess the influence of C3/C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. The non-linear nature of the relationship between δ13C and SOC content observed across the latitudinal gradient strongly suggests that in addition to the inherent differences in the input rates and turnover times of tree and grass-derived carbon, the broad range of edaphic characteristics may have a major effect in both the physical protection of particulate organic carbon and the chemical stabilization of 13C enriched microbial metabolites. The stable carbon isotopic composition of SOM with depth indicated that there was a larger proliferation in woody vegetation with increasing precipitation, with such trend being also heavily dependent on the characteristics of the soils. An unbiased assessment of the potential impact of tropical vegetation thickening on SOM dynamics is characteristically difficult given the confounding effects posed by the interaction of varying climatic and edaphic factors. Therefore, in order to minimize the impact of those factors, we selected two neighboring transitional ecosystems (a closed savanna woodland and a semideciduous dry forest) occurring in soils of comparable characteristics. Both sites showed varying degrees of δ13C enrichment with depth in bulk and fractionated SOM. Moreover, radiocarbon analyses of sand-size aggregates (>53 μm HF) yielded relatively short MRT, which shows highly dynamic SOM processes even in fairly deep locations. Interestingly, the most stable SOM fraction associated to silt and clay (

  19. [Organisation of Veterinary Services in the developing countries of West Africa].

    PubMed

    Coulibaly, H

    2004-04-01

    The Veterinary Services in West Africa focused on animal health and production activities, which up until the beginning of the 1990s, were exclusively their responsibility. They were supported by many projects, conducted with notable successes. Veterinary public health activities were considered to be less of a priority because the major objective was improving productivity and because the concept of food safety was perceived by stakeholders to be much less important. The major challenges and issues that the weakened Veterinary Services will have to face are complying with the requirements of the World Trade Organization, negotiating new economic partnership agreements and dealing with the consequences of the implementation of structural adjustment programmes in the agricultural sector. The reorganisation of these Services is therefore taking place in the context of the globalisation of health problems, and in a trading framework that requires the application of the current international standards and regulations. Veterinary Services and their governments will have to meet these challenges by initiating discussions that lead to effective operational structures that can implement public health measures, satisfy the expectations of consumers and partner countries and withstand assessment by other countries. However, such reform depends upon several factors, such as a demonstration of political will, the development of an approach based on regional economic unions, and the indispensable support of financial backers. To add to the debate, the author offers recommendations and guidelines on the institutional framework, veterinary personnel and equipment and material needs. Creating effective Veterinary Services that have efficient operational structures and procedures is an ongoing process; how long this process takes depends on the ability of Veterinary Services to respond to the various challenges. Underlying these challenges and issues, in this region of the world as

  20. Water balance estimation with the Budyko method to assess the hydropower potential of rivers in West Africa

    NASA Astrophysics Data System (ADS)

    Kling, Harald; Stanzel, Philipp; Fuchs, Martin

    2015-04-01

    Small and medium hydropower has a large potential for future development in West Africa, a region that is facing a constant shortage of energy supply and thereby limiting economic growth. The river reaches suitable for small and medium hydropower development are usually located in headwater areas. Mean annual discharge (along with slope) is a key variable for assessing the hydropower potential of a river reach. As discharge gauges are typically located at larger, downstream rivers a regionalization of flow is required. In this study we use the Budyko method to establish the spatially distributed mean annual water balance for whole West Africa (appr. 5 Mio km²), including the basins of e.g. Niger, Volta, and Senegal rivers. The spatially distributed inputs of mean annual precipitation and potential evapotranspiration are used to compute actual evapotranspiration and thus runoff. Runoff is aggregated along the river network to compute discharge. Due to the impact of different soils and vegetation cover the Budyko curve is calibrated with observed discharge data of about 100 basins covering a wide range of humid to semi-arid conditions. A framework is developed to properly account for the distinctive decadal variations of rainfall (and discharge) in West Africa. Specific challenges are (a) apparently biased discharge measurements at some gauges and (b) uncertainties in the precipitation data (station-based and satellite-based). The results of this study will give (1) an overview about the hydropower potential in each West African country and (2) the theoretical hydropower potential of about 100,000 river reaches. The results will be published on a website with interactive maps to enable the selection of regions of interest for further, detailed assessment of small and medium hydropower development.

  1. The relationship between African easterly waves and daily rainfall over West Africa: observations and regional climate simulations

    NASA Astrophysics Data System (ADS)

    Crétat, Julien; Vizy, Edward K.; Cook, Kerry H.

    2015-01-01

    The relationship between summer African easterly waves (AEWs) and daily rainfall is assessed in West Africa for 1998-2008 using various reanalyses, satellite-derived rainfall products, and a regional climate model (RCM) run at 90- and 30-km resolutions. 3-5 and 6-9 day AEWs are extracted by filtering daily 700 hPa meridional wind time series at 1°W and 11.5°N, and 1°W and 17.5°N, respectively. Both observed and simulated rainfall anomalies are of larger magnitude over West Africa during 3-5-d than 6-9-d AEWs. The RCM simulates larger rainfall rates in phase with the 3-5-d wave trough instead of ahead, unlike the observations, and overestimates the intensity and spatial coverage of rainfall associated with 6-9-d AEWs. The observed and simulated co-variability between 3-5-d (6-9-d) AEW activity and daily rainfall is strong (weak) and mostly located south (north) of 15°N. However, the RCM overestimates the spatial coverage of the AEW-rainfall relationship in the longitudinal (latitudinal) direction in the case of 3-5-d (6-9-d) AEWs. Observed and simulated daily intense rainfall events, extracted using a percentile threshold approach, are mostly located south of 15°N during summer. The observed relationship between their frequency of occurrence and active 3-5-d AEWs is maximal west of 8°E, while extends up to southern Chad in both RCM simulations. Their magnitude is also largely overestimated by the RCM, indicating an exaggerated coupling between the wave activity and the convection. Finally, observed and simulated 3-5-d AEWs establish the most favorable synoptic conditions for the development of intense rainfall events over West Africa.

  2. Predicting The Rainy Season Over Southern West Africa From Global Predictors and Climate Model Output: A Mos Approach

    NASA Astrophysics Data System (ADS)

    Paeth, H.; Born, K.; Hense, A.

    As 75 % of annual precipitation over the Sahel and Guinea Coast region are confined to the rainy season between June and September, prediction of this season is largely rel- evant in terms of fresh water availability for vegetation and human activity. Therefore, we present various global near-surface predictors of summertime rainfall for different regions of West Africa. The most important predictability arises from more regional information such as the SST in the tropical and subtropical Atlantic or the large-scale surface pressure field over the West African subcontinent. However, there are some teleconnections to the tropical Pacific, involving ENSO and the Walker circulation. The extratropical circulation modes such as the NAO play a minor role over the north- western part of West Africa. Based on the whole 20th century validation period the impact of increasing GHG is barely apparent. The same goes for all India rainfall and the QBO. Using multiple regression and cross validation a forecast model for the rainy season is developped by which we gain insight into the optimal number of relevant predictors. Thus, predictors which result from statistical correlation rather than physical rela- tionship are discarded. The remaining predictors, partly derived from the EOF space, account for around 55 % of the simulated interannual variability. In terms of the ob- servations, the forecast model is composed of the global predictors mentioned above and the simulated seasonal rainfall from different global climate models. Then, the method reveals a forecast potential of slightly more than 50 % for the observed inter- annual variations in summertime rainfall over southern West Africa. Given the strong autocorrelation of tropical SST, our approach could be used for operational seasonal forecasting with reasonable computing time.

  3. Zika Virus Outside Africa

    PubMed Central

    2009-01-01

    Zika virus (ZIKV) is a flavivirus related to yellow fever, dengue, West Nile, and Japanese encephalitis viruses. In 2007 ZIKV caused an outbreak of relatively mild disease characterized by rash, arthralgia, and conjunctivitis on Yap Island in the southwestern Pacific Ocean. This was the first time that ZIKV was detected outside of Africa and Asia. The history, transmission dynamics, virology, and clinical manifestations of ZIKV disease are discussed, along with the possibility for diagnostic confusion between ZIKV illness and dengue.The emergence of ZIKV outside of its previously known geographic range should prompt awareness of the potential for ZIKV to spread to other Pacific islands and the Americas. PMID:19788800

  4. Evaluation of WindSat Land Surface Data over West Africa

    NASA Astrophysics Data System (ADS)

    Steele-Dunne, S. C.; Li, L.; Gaiser, P.; van de Giesen, N.

    2009-12-01

    The WindSat instrument is a spaceborne polarimetric microwave radiometer, data from which has been used in a wide range of ocean and land-based applications. Li et al. (2009) developed a physically based algorithm, based on maximum likelihood estimation, which uses vertical and horizontal polarization data at 10, 18.7 and 37 GHz to simultaneously retrieve soil moisture, vegetation water content and land surface temperature. In this research, the performance of these Windsat land products is evaluated over West Africa, from February 2003 to May 2006, through comparison with both in-situ and remote-sensing data. Though the in-situ data and WindSat soil moisture produce showed the same general temporal pattern, it is important to note that the in-situ observations were collected at a single point while the WindSat soil moisture is a 25km gridded product. For a more complete view, WindSat soil moisture and vegetation water content products were also analyzed alongside precipitation data (TRMM), vegetation indices (e.g. NDVI) and other soil moisture products (e.g. ERS) from remote-sensing to determine how well the WindSat data could capture the soil moisture and vegetation response to observed precipitation. Our analysis shows that WindSat clearly detects the north-south gradient in soil moisture due to the West African monsoon. The difference in regime between tropical forest, savanna and desert is plainly discernible in both the soil moisture and vegetation water content data. The soil moisture dynamics of the Niger Inland Delta can also be seen in the WindSat data. The modest impact of local rainfall is seen during the rainy season, while a significant rise in soil moisture is detected in October when rainfall from the Niger and Bani headwaters reaches the inland delta. The main growing season follows, and the soil moisture is seen to decrease slowly due to infiltration and evapotranspiration. These results support those of the global WindSat validation, and

  5. Assessments for the impact of mineral dust on the meningitis incidence in West Africa

    NASA Astrophysics Data System (ADS)

    Martiny, Nadège; Chiapello, Isabelle

    2013-05-01

    Recently, mineral dust has been suspected to be one of the important environmental risk factor for meningitis epidemics in West Africa. The current study is one of the first which relies on long-term robust aerosol measurements in the Sahel region to investigate the possible impact of mineral dust on meningitis cases (incidence). Sunphotometer measurements, which allow to derive aerosol and humidity parameters, i.e., aerosol optical thickness, Angström coefficient, and precipitable water, are combined with quantitative epidemiological data in Niger and Mali over the 2004-2009 AMMA (African Monsoon Multidisciplinary Analysis) program period. We analyse how the extremely high aerosol loads in this region may influence both the calendar (onset, peaks, end) and the intensity of meningitis. We highlight three distinct periods: (i) from November to December, beginning of the dry season, humidity is weak, there is no dust and no meningitis cases; (ii) from January to April, humidity is still weak, but high dust loads occur in the atmosphere and this is the meningitis season; (iii) from May to October, humidity is high and there is no meningitis anymore, in presence of dust or not, which flow anyway in higher altitudes. More specifically, the onset of the meningitis season is tightly related to mineral dust flowing close to the surface at the very beginning of the year. During the dry, and the most dusty season period, from February to April, each meningitis peak is preceded by a dust peak, with a 0-2 week lead-time. The importance (duration, intensity) of these meningitis peaks seems to be related to that of dust, suggesting that a cumulative effect in dust events may be important for the meningitis incidence. This is not the case for humidity, confirming the special contribution of dust at this period of the year. The end of the meningitis season, in May, coincides with a change in humidity conditions related to the West African Monsoon. These results, which are

  6. The Foraging Ecology of the Endangered Cape Verde Shearwater, a Sentinel Species for Marine Conservation off West Africa.

    PubMed

    Paiva, Vitor H; Geraldes, Pedro; Rodrigues, Isabel; Melo, Tommy; Melo, José; Ramos, Jaime A

    2015-01-01

    Large Marine Ecosystems such as the Canary Current system off West Africa sustains high abundance of small pelagic prey, which attracts marine predators. Seabirds are top predators often used as biodiversity surrogates and sentinel species of the marine ecosystem health, thus frequently informing marine conservation planning. This study presents the first data on the spatial (GPS-loggers) and trophic (stable isotope analysis) ecology of a tropical seabird-the endangered Cape Verde shearwater Calonectris edwardsii-during both the incubation and the chick-rearing periods of two consecutive years. This information was related with marine environmental predictors (species distribution models), existent areas of conservation concern for seabirds (i.e. marine Important Bird Areas; marine IBAs) and threats to the marine environment in the West African areas heavily used by the shearwaters. There was an apparent inter-annual consistency on the spatial, foraging and trophic ecology of Cape Verde shearwater, but a strong alteration on the foraging strategies of adult breeders among breeding phases (i.e. from incubation to chick-rearing). During incubation, birds mostly targeted a discrete region off West Africa, known by its enhanced productivity profile and thus also highly exploited by international industrial fishery fleets. When chick-rearing, adults exploited the comparatively less productive tropical environment within the islands of Cape Verde, at relatively close distance from their breeding colony. The species enlarged its trophic niche and increased the trophic level of their prey from incubation to chick-rearing, likely to provision their chicks with a more diversified and better quality diet. There was a high overlap between the Cape Verde shearwaters foraging areas with those of European shearwater species that overwinter in this area and known areas of megafauna bycatch off West Africa, but very little overlap with existing Marine Important Bird Areas. Further

  7. The Foraging Ecology of the Endangered Cape Verde Shearwater, a Sentinel Species for Marine Conservation off West Africa

    PubMed Central

    Paiva, Vitor H.; Geraldes, Pedro; Rodrigues, Isabel; Melo, Tommy; Melo, José; Ramos, Jaime A.

    2015-01-01

    Large Marine Ecosystems such as the Canary Current system off West Africa sustains high abundance of small pelagic prey, which attracts marine predators. Seabirds are top predators often used as biodiversity surrogates and sentinel species of the marine ecosystem health, thus frequently informing marine conservation planning. This study presents the first data on the spatial (GPS-loggers) and trophic (stable isotope analysis) ecology of a tropical seabird—the endangered Cape Verde shearwater Calonectris edwardsii–during both the incubation and the chick-rearing periods of two consecutive years. This information was related with marine environmental predictors (species distribution models), existent areas of conservation concern for seabirds (i.e. marine Important Bird Areas; marine IBAs) and threats to the marine environment in the West African areas heavily used by the shearwaters. There was an apparent inter-annual consistency on the spatial, foraging and trophic ecology of Cape Verde shearwater, but a strong alteration on the foraging strategies of adult breeders among breeding phases (i.e. from incubation to chick-rearing). During incubation, birds mostly targeted a discrete region off West Africa, known by its enhanced productivity profile and thus also highly exploited by international industrial fishery fleets. When chick-rearing, adults exploited the comparatively less productive tropical environment within the islands of Cape Verde, at relatively close distance from their breeding colony. The species enlarged its trophic niche and increased the trophic level of their prey from incubation to chick-rearing, likely to provision their chicks with a more diversified and better quality diet. There was a high overlap between the Cape Verde shearwaters foraging areas with those of European shearwater species that overwinter in this area and known areas of megafauna bycatch off West Africa, but very little overlap with existing Marine Important Bird Areas

  8. Full-Genome Sequence of a Neuroinvasive West Nile Virus Lineage 2 Strain from a Fatal Horse Infection in South Africa

    PubMed Central

    Mentoor, Juliet L. D.; Lubisi, Alison B.; Gerdes, Truuska; Human, Stacey; Williams, June H.

    2016-01-01

    We report here the complete genome sequence of a lineage 2 West Nile virus (WNV) strain that resulted in fatal neurological disease in a horse in South Africa. Several recent reports exist of neurological disease associated with lineage 2 WNV in humans and horses in South Africa and Europe; however, there are a lack of sequencing data from recent fatal cases in Southern Africa, where these strains likely originate. A better understanding of the genetic composition of highly neuroinvasive lineage 2 strains may facilitate the identification of putative genetic factors associated with increased virulence. PMID:27469963

  9. Full-Genome Sequence of a Neuroinvasive West Nile Virus Lineage 2 Strain from a Fatal Horse Infection in South Africa.

    PubMed

    Mentoor, Juliet L D; Lubisi, Alison B; Gerdes, Truuska; Human, Stacey; Williams, June H; Venter, Marietjie

    2016-01-01

    We report here the complete genome sequence of a lineage 2 West Nile virus (WNV) strain that resulted in fatal neurological disease in a horse in South Africa. Several recent reports exist of neurological disease associated with lineage 2 WNV in humans and horses in South Africa and Europe; however, there are a lack of sequencing data from recent fatal cases in Southern Africa, where these strains likely originate. A better understanding of the genetic composition of highly neuroinvasive lineage 2 strains may facilitate the identification of putative genetic factors associated with increased virulence. PMID:27469963

  10. An updated Bouguer anomaly map of south-central West Africa

    USGS Publications Warehouse

    Hastings, David A.

    1983-01-01

    A new Bouguer gravity anomaly map compiled for western Africa adds data for Ghana, Guinea, and Liberia.The new data add detail to a key part of the Eburnean shield and assist in the development of a model of rifting at the time of the Eburnean orogeny, 2000 million years ago. This model includes a framework for the deposition of the region's mineral deposits. The model and existing field data can be used to guide future minerals exploration in the region.

  11. Marine communities on oil platforms in Gabon, West Africa: high biodiversity oases in a low biodiversity environment.

    PubMed

    Friedlander, Alan M; Ballesteros, Enric; Fay, Michael; Sala, Enric

    2014-01-01

    The marine biodiversity of Gabon, West Africa has not been well studied and is largely unknown. Our examination of marine communities associated with oil platforms in Gabon is the first scientific investigation of these structures and highlights the unique ecosystems associated with them. A number of species previously unknown to Gabonese waters were recorded during our surveys on these platforms. Clear distinctions in benthic communities were observed between older, larger platforms in the north and newer platforms to the south or closer to shore. The former were dominated by a solitary cup coral, Tubastraea sp., whereas the latter were dominated by the barnacle Megabalanus tintinnabulum, but with more diverse benthic assemblages compared to the northerly platforms. Previous work documented the presence of limited zooxanthellated scleractinian corals on natural rocky substrate in Gabon but none were recorded on platforms. Total estimated fish biomass on these platforms exceeded one ton at some locations and was dominated by barracuda (Sphyraena spp.), jacks (Carangids), and rainbow runner (Elagatis bipinnulata). Thirty-four percent of fish species observed on these platforms are new records for Gabon and 6% are new to tropical West Africa. Fish assemblages closely associated with platforms had distinct amphi-Atlantic affinities and platforms likely extend the distribution of these species into coastal West Africa. At least one potential invasive species, the snowflake coral (Carijoa riisei), was observed on the platforms. Oil platforms may act as stepping stones, increasing regional biodiversity and production but they may also be vectors for invasive species. Gabon is a world leader in terrestrial conservation with a network of protected areas covering >10% of the country. Oil exploration and biodiversity conservation currently co-exist in terrestrial and freshwater ecosystems in Gabon. Efforts to increase marine protection in Gabon may benefit by including oil

  12. Marine Communities on Oil Platforms in Gabon, West Africa: High Biodiversity Oases in a Low Biodiversity Environment

    PubMed Central

    Friedlander, Alan M.; Ballesteros, Enric; Fay, Michael; Sala, Enric

    2014-01-01

    The marine biodiversity of Gabon, West Africa has not been well studied and is largely unknown. Our examination of marine communities associated with oil platforms in Gabon is the first scientific investigation of these structures and highlights the unique ecosystems associated with them. A number of species previously unknown to Gabonese waters were recorded during our surveys on these platforms. Clear distinctions in benthic communities were observed between older, larger platforms in the north and newer platforms to the south or closer to shore. The former were dominated by a solitary cup coral, Tubastraea sp., whereas the latter were dominated by the barnacle Megabalanus tintinnabulum, but with more diverse benthic assemblages compared to the northerly platforms. Previous work documented the presence of limited zooxanthellated scleractinian corals on natural rocky substrate in Gabon but none were recorded on platforms. Total estimated fish biomass on these platforms exceeded one ton at some locations and was dominated by barracuda (Sphyraena spp.), jacks (Carangids), and rainbow runner (Elagatis bipinnulata). Thirty-four percent of fish species observed on these platforms are new records for Gabon and 6% are new to tropical West Africa. Fish assemblages closely associated with platforms had distinct amphi-Atlantic affinities and platforms likely extend the distribution of these species into coastal West Africa. At least one potential invasive species, the snowflake coral (Carijoa riisei), was observed on the platforms. Oil platforms may act as stepping stones, increasing regional biodiversity and production but they may also be vectors for invasive species. Gabon is a world leader in terrestrial conservation with a network of protected areas covering >10% of the country. Oil exploration and biodiversity conservation currently co-exist in terrestrial and freshwater ecosystems in Gabon. Efforts to increase marine protection in Gabon may benefit by including oil

  13. Phylogeography of West Nile Virus: from the Cradle of Evolution in Africa to Eurasia, Australia, and the Americas▿ †

    PubMed Central

    May, Fiona J.; Davis, C. Todd; Tesh, Robert B.; Barrett, Alan D. T.

    2011-01-01

    West Nile virus (WNV) is the most widely distributed of the encephalitic flaviviruses and is a major cause of encephalitis, with isolates obtained from all continents, apart from Antarctica. Subsequent to its divergence from the other members of the Japanese encephalitis virus complex, presumably in Africa, WNV has diverged into individual lineages that mostly correspond with geographic distribution. Here we elucidate the phylogeography and evolutionary history of isolates from lineage 1 of WNV. Interestingly, there are many examples of the same amino acid having evolved independently on multiple occasions. In Africa, WNV exists in an endemic cycle, whereas it is epidemic in Europe, being reintroduced regularly from Africa either directly (in western Europe) or via the Middle East (in eastern Europe). Significantly, introduction into other geographic areas has occurred on one occasion only in each region, leading to subsequent establishment and expansion of the virus in these areas. Only one endemic genotype each is present in India and Australia, suggesting that WNV was successfully introduced into these locations once only. Each introduction occurred many centuries ago, probably due to trade and exploration during the 19th century. Likewise, in the Americas, WNV was successfully introduced in 1999 and subsequently became endemic across most temperate regions of North America (NA). In contrast to previous suggestions, an isolate from the epidemic in Israel in 1998 was not the direct progenitor of the NA epidemic; rather, both epidemics originated from the same (unknown) location. PMID:21159871

  14. Development of a new version of the Liverpool Malaria Model. II. Calibration and validation for West Africa

    PubMed Central

    2011-01-01

    Background In the first part of this study, an extensive literature survey led to the construction of a new version of the Liverpool Malaria Model (LMM). A new set of parameter settings was provided and a new development of the mathematical formulation of important processes related to the vector population was performed within the LMM. In this part of the study, so far undetermined model parameters are calibrated through the use of data from field studies. The latter are also used to validate the new LMM version, which is furthermore compared against the original LMM version. Methods For the calibration and validation of the LMM, numerous entomological and parasitological field observations were gathered for West Africa. Continuous and quality-controlled temperature and precipitation time series were constructed using intermittent raw data from 34 weather stations across West Africa. The meteorological time series served as the LMM data input. The skill of LMM simulations was tested for 830 different sets of parameter settings of the undetermined LMM parameters. The model version with the highest skill score in terms of entomological malaria variables was taken as the final setting of the new LMM version. Results Validation of the new LMM version in West Africa revealed that the simulations compare well with entomological field observations. The new version reproduces realistic transmission rates and simulated malaria seasons are comparable to field observations. Overall the new model version performs much better than the original model. The new model version enables the detection of the epidemic malaria potential at fringes of endemic areas and, more importantly, it is now applicable to the vast area of malaria endemicity in the humid African tropics. Conclusions A review of entomological and parasitological data from West Africa enabled the construction of a new LMM version. This model version represents a significant step forward in the modelling of a weather

  15. Improving Brain Tumor Research in Resource-Limited Countries: A Review of the Literature Focusing on West Africa

    PubMed Central

    Fezeu, Francis; Ramesh, Arjun; Moosa, Shayan; Purow, Benjamin; Lopez, Beatrice; Schiff, David; Hussaini, Isa M; Sandabe, Umar K

    2015-01-01

    Neoplasms of the brain are often overlooked in resource-limited countries. Our literature search via AJOL and PubMed demonstrated that brain tumor research is still a rarity in these regions. We highlight the current status, importance, challenges, and methods of improving brain tumor research in West Africa. We suggest that more attention be given to basic, clinical, and epidemiological brain tumor research by national governments, private organizations, international organizations, non-governmental organizations (NGOs), and individuals in this region. PMID:26677422

  16. Region-wide assessment of the capacity for human nutrition training in West Africa: current situation, challenges, and way forward

    PubMed Central

    Sodjinou, Roger; Fanou, Nadia; Deart, Lucie; Tchibindat, Félicité; Baker, Shawn; Bosu, William; Pepping, Fré; Delisle, Hélène

    2014-01-01

    Background There is a dearth of information on existing nutrition training programs in West Africa. A preliminary step in the process of developing a comprehensive framework to strengthen human capacity for nutrition is to conduct an inventory of existing training programs. Objective This study was conducted to provide baseline data on university-level nutrition training programs that exist in the 16 countries in West Africa. It also aimed to identify existing gaps in nutrition training and propose solutions to address them. Design Participating institutions were identified based on information provided by in-country key informants, UNICEF offices or through internet searches. Data were collected through semi-structured interviews during on-site visits or through self-administered questionnaires. Simple descriptive and bivariate analyses were performed. Results In total, 83 nutrition degree programs comprising 32 B.Sc. programs, 34 M.Sc. programs, and 17 Ph.D. programs were identified in the region. More than half of these programs were in Nigeria. Six countries (Cape Verde, Guinea-Bissau, Liberia, Mali, The Gambia, and Togo) offered no nutrition degree program. The programs in francophone countries were generally established more recently than those in anglophone countries (age: 3.5 years vs. 21.4 years). Programs were predominantly (78%) run by government-supported institutions. They did not provide a comprehensive coverage of all essential aspects of human nutrition. They were heavily oriented to food science (46%), with little emphasis on public health nutrition (24%) or overnutrition (2%). Annual student intakes per program in 2013 ranged from 3 to 262; 7 to 40; and 3 to 10, respectively, for bachelor's, master's, and doctoral programs while the number of graduates produced annually per country ranged from 6 to 271; 3 to 64; and 1 to 18, respectively. External collaboration only existed in 15% of the programs. In-service training programs on nutrition existed

  17. Desertification control and renewable-resource management in the Sahelian and Sudanian zones of west africa. Technical paper

    SciTech Connect

    Falloux, F.; Mukendi, A.

    1987-01-01

    This volume is a compendium of papers presented at the 'Workshop on Desertification Control and Renewable Resource Management' held in Oslo, Norway in June 1986, and sponsored by the Norwegian Ministry of Development Cooperation, the Canadian International Development Agency and the World Bank. The main objective of the workshop was to develop workable guidelines for addressing the problem of resource depletion in the Sahelian and Sudanian zones of West Africa. Major policy areas covered include land tenure, water management, household energy use, production systems, and migration.

  18. U.S. Public Health Service Response to the 2014-2015 Ebola Epidemic in West Africa: A Nursing Perspective.

    PubMed

    Mosquera, Alexis; Braun, Michelle; Hulett, Melissa; Ryszka, Lauren

    2015-01-01

    The 2014-2015 Ebola epidemic in West Africa has been the deadliest Ebola epidemic to date. In response to this deadly epidemic, the U.S. government declared this a top national security priority and members of the Commissioned Corps of the United States Public Health Service were tasked to provide direct patient care to Ebola virus disease patients. Commissioned Corps nurses provided the highest level of care under the most austere conditions. This article discusses the training, ethical dilemmas, and constant risk for potential exposure while working in an Ebola Treatment Unit. PMID:26207646

  19. The prevalence of helminth and arthropod parasites of warthog, Phacochoerus aethiopicus, in South West Africa/Namibia.

    PubMed

    Horak, I G; Biggs, H C; Hanssen, T S; Hanssen, R E

    1983-06-01

    A total of 38 warthog, Phacochoerus aethiopicus, shot on a farm in northern South West Africa/Namibia were examined for internal and external parasites at monthly intervals over a period of 13 months. They harboured cestodes, 9 nematode species, 6 ixodid tick species and 1 species each of an argasid tick, a flea, a louse and larvae of a dipteran fly. Clear patterns of seasonal abundance could be determined only for the spirurid stomach worm, Physocephalus sexalatus, and the sucking louse, Haematopinus phachoeri. PMID:6634088

  20. Seismic architecture and morphology of Neogenic sediment waves and drifts, offshore West Africa

    NASA Astrophysics Data System (ADS)

    Baglioni, Luca; Bonamini, Enrico

    2013-04-01

    fill SW troughs. The positive relief of wave crests guided sediment gravity flows, inducing erosion and deposition focused along wave troughs. The shallower interval is fully dominated by bottom current deposits. A succession of SW around 300 ms thick covers the central-eastern sector of the study area. The described SW field is about 5 km wide and continuous over a distance of 30 km, and the average wavelength between two crests is 2 km. It is connected updip with a time equivalent rectilinear canyon-shaped erosive feature, whose genetic relation with the SW is now matter of discussion. The presence of upslope migrating SW indicates deposition by bottom current flowing upslope, under the influence of the Coriolis force. Such landwards-directed bottom currents on the slope probably represent the still active South-East Atlantic Upwelling, which has been present along the West Africa margin throughout the Neogene.

  1. Implications of land use change in tropical West Africa under global warming

    NASA Astrophysics Data System (ADS)

    Brücher, Tim; Claussen, Martin

    2015-04-01

    Northern Africa, and the Sahel in particular, are highly vulnerable to climate change, due to strong exposure to increasing temperature, precipitation variability, and population growth. A major link between climate and humans in this region is land use and associated land cover change, mainly where subsistence farming prevails. But how strongly does climate change affect land use and how strongly does land use feeds back into climate change? To which extent may climate-induced water, food and wood shortages exacerbate conflict potential and lead changes in land use and to migration? Estimates of possible changes in African climate vary among the Earth System Models participating in the recent Coupled Model Intercomparison (CMIP5) exercise, except for the region adjacent to the Mediterranean Sea, where a significant decrease of precipitation emerges. While all models agree in a strong temperature increase, rainfall uncertainties for most parts of the Sahara, Sahel, and Sudan are higher. Here we present results of complementary experiments based on extreme and idealized land use change scenarios within a future climate.. We use the MPI-ESM forced with a strong green house gas scenario (RCP8.5) and apply an additional land use forcing by varying largely the intensity and kind of agricultural practice. By these transient experiments (until 2100) we elaborate the additional impact on climate due to strong land use forcing. However, the differences are mostly insignificant. The greenhouse gas caused temperature increase and the high variability in the West African Monsoon rainfall superposes the minor changes in climate due to land use. While simulated climate key variables like precipitation and temperature are not distinguishable from the CMIP5 RCP8.5 results, an additional greening is simulated, when crops are demanded. Crops have lower water usage than pastureland has. This benefits available soil water, which is taken up by the natural vegetation and makes it more

  2. Investigating an Automated Method to Explore Mesoscale Convective Complexes in West Africa

    NASA Astrophysics Data System (ADS)

    Whitehall, Kim Dionne

    Mesoscale convective complexes are convectively driven, high impact weather systems with durations of approximately 10-12 hours, and are large contributors to daily and monthly rainfall totals. In West Africa, approximately 40 mesoscale convective complexes contribute an estimated one-quarter of the total rainfall amounts between July and September annually. As such, an understanding of the lifecycle, characteristics, frequency, and seasonality of these weather features is important for climate studies, agricultural and hydrological studies, and disaster management. Identification criteria of mesoscale convective complexes exist for infrared satellite data, but the spatial expanse and the spatio-temporal variability of the convective characteristics of these mesoscale convective complexes make rainfall characterization difficult, even in dense networks of radars and / or surface gauges. Hence, fully automated methods are required to explore mesoscale convective complexes in long-term infrared satellite data, and to determine their characteristics from other datasets, such as precipitation rate satellite datasets. Automated identification methods of mesoscale convective complexes are based on forward- and / or backward-in-time spatial-temporal analyses of infrared satellite data, and usually incorporate a manual component to verify the features and / or characterize the associated precipitation. These existing identification and precipitation characterization methods are not readily transferable to voluminous data or other satellite-derived datasets, thus hindering comprehensive studies of these features, both at weather and climate timescales. In recognizing these limitations and the growing volume of satellite data, this study explores the applicability of graph theory to creating a fully automated method for identifying mesoscale convective systems in satellite datasets. The framework for such a method is provided in this work. The results indicate that applying

  3. The Behavior of Gust Fronts in West Africa Based on Radar and Satellite Observations

    NASA Astrophysics Data System (ADS)

    McGraw-Herdeg, M.; Williams, E.

    2009-12-01

    M. McGraw-Herdeg, E. Williams. If we are to understand the global influence of dust storms in the tropical Sahelian region of West Africa, we must first understand what factors affect how these large storms develop, how far they travel, how fast they travel, and how much particulate matter they carry. Observations link the gust fronts of these large, dusty storms to new moist convection. As a first step, we test available theories against measured data by comparing the density current model's predictions of gust front speed (measured at using temperature-drop data measured by the ARM Mobile Facility and speed measurements derived from the MIT C-band radar site, both in Niamey, Niger for the AMMA (African Monsoon and Multidisciplinary Analysis) in 2006. We track intersections of CALIPSO satellite images with the front, as seen by the MIT radar. With speed information for 20 gust fronts tracked by the MIT radar site, we can show how a gust front's speed declines over time as it mixes with its dry environment. By interpreting these data alongside Meteosat satellite dust information (SEVIRI), we describe the average "lifespan" of these gust fronts and their maximum distance of propagation, which may range from 24-36 hours or 1000-1500 km. This analysis contributes precise speed data for a large number of gust fronts measured by the MIT radar. We have measured speeds for 20 gust fronts with 10-minute speeds calculated across a 150-km or 250-km radar circle. The average speed was 14.8 m/s; the average 10-minute speed as the fronts crossed the radar circle was 15.6 m/s. SEVIRI imagery indicates that nearly all the events which crossed the radar site originated at about the same place, and most started within two hours of 15:00, suggesting that local geography and the diurnal cycle plays significant roles in formation of gust fronts. Surface temperature drops as the gust front crosses the radar site were found to be weakly linearly correlated with velocity at crossing

  4. Evaluation of a Soil Moisture Data Assimilation System Over West Africa

    NASA Astrophysics Data System (ADS)

    Bolten, J. D.; Crow, W.; Zhan, X.; Jackson, T.; Reynolds, C.

    2009-05-01

    A crucial requirement of global crop yield forecasts by the U.S. Department of Agriculture (USDA) International Production Assessment Division (IPAD) is the regional characterization of surface and sub-surface soil moisture. However, due to the spatial heterogeneity and dynamic nature of precipitation events and resulting soil moisture, accurate estimation of regional land surface-atmosphere interactions based sparse ground measurements is difficult. IPAD estimates global soil moisture using daily estimates of minimum and maximum temperature and precipitation applied to a modified Palmer two-layer soil moisture model which calculates the daily amount of soil moisture withdrawn by evapotranspiration and replenished by precipitation. We attempt to improve upon the existing system by applying an Ensemble Kalman filter (EnKF) data assimilation system to integrate surface soil moisture retrievals from the NASA Advanced Microwave Scanning Radiometer (AMSR-E) into the USDA soil moisture model. This work aims at evaluating the utility of merging satellite-retrieved soil moisture estimates with the IPAD two-layer soil moisture model used within the DBMS. We present a quantitative analysis of the assimilated soil moisture product over West Africa (9°N- 20°N; 20°W-20°E). This region contains many key agricultural areas and has a high agro- meteorological gradient from desert and semi-arid vegetation in the North, to grassland, trees and crops in the South, thus providing an ideal location for evaluating the assimilated soil moisture product over multiple land cover types and conditions. A data denial experimental approach is utilized to isolate the added utility of integrating remotely-sensed soil moisture by comparing assimilated soil moisture results obtained using (relatively) low-quality precipitation products obtained from real-time satellite imagery to baseline model runs forced with higher quality rainfall. An analysis of root-zone anomalies for each model

  5. Integrated assessment of groundwater resources in the Ouémé basin, Benin, West Africa

    NASA Astrophysics Data System (ADS)

    Barthel, R.; Sonneveld, B. G. J. S.; Götzinger, J.; Keyzer, M. A.; Pande, S.; Printz, A.; Gaiser, T.

    An integrated assessment of groundwater resources in Benin, West Africa was performed within the framework of the EC-funded research project RIVERTWIN ( www.rivertwin.org). The assessment included a spatial analysis of groundwater relevant parameters taken from more than 4000 wells stored in a countrywide water database (BDI - Banque des Données Intégrée) and an estimation of the spatial and temporal distribution of groundwater recharge using a modified version of the hydrological model HBV. Additionally, a socio-economic assessment of the impacts of groundwater availability and accessibility on national health issues as well as an assessment of groundwater development costs was carried out. The analysis revealed particularly unfavourable conditions for groundwater use in the northern part of the country where groundwater recharge during the wet season does not lead to the formation of persistent groundwater storage in its shallow, unconfined aquifers. Poor storage capacity and hydraulic properties of the deeper fractured aquifers additionally limit the capacity of individual wells to capture groundwater recharge. Including climate change scenarios forecasting less precipitation (generated from global climate models (GCM) based on IPCC scenarios) indicates that the situation in water scarce regions will worsen, as recharge volumes lessen and occur over a shorter time period. Drilling more wells may be a limited option to capture larger portions of the recharge, since the capture zone and therefore the regional influence of existing wells is rather small. In the south, deeper confined aquifers guarantee better and more reliable yields, yet the lack of long-term monitoring and groundwater age data does not allow an appraisal of the limits of the sustainable use of these aquifers. Finally, it has been shown that access to suitable aquifers and diarrhea prevalence are spatially correlated. Access to groundwater is thereby not only a function of aquifer suitability

  6. Assessment of Groundwater Potential in Fractured Crystalline rocks of the North West Province, South Africa

    NASA Astrophysics Data System (ADS)

    Tessema, A.

    2014-12-01

    Investigation of groundwater potential in crystalline rocks of the North West Province was carried out. The area is located close to the boundary between South Africa and Botswana. The main objective of the study is to investigate groundwater potential using multi-data integration approach. Geologically, the area comprises of volcano-sedimentary rocks of the Ventersdorp Supergroup, carbonates, arenaceous and argillaceous sedimentary rocks of the Transvaal Supergroup. The youngest rocks are the Karoo Supergroup and the Quaternary sedimentary cover. Multivariate statistical modelling was carried out to produce groundwater prospectivity map of the area. In addition, groundwater quality was assessed using hydrochemical and environmental isotopes. The statistical modelling includes data-driven and knowledge-based approaches. The data-driven approach includes artificial neural networks (ANNs), weights of evidence (WoE) and logistic regression (LG), while the knowledge-based approach involves the use of fuzzy logic. The two statistical modellings were applied to five evidential themes that include geology, structures, geomorphology, land-use and soil types. The data-driven approach provided nearly similar results showing lithologic units and fracture connectivity play a key role in controlling groundwater occurrence. The influence of lithology is significant in the southern part of the area, while fracture connectivity play important role in controlling groundwater occurrence within the crystalline rocks that are situated in the central and northern parts of the area. In general, the results of multivariate statistical modelling show number of groundwater potential zones varying from very good to very poo. The zone shown as very good and goodgroundwater potential covers ~17% and ~22% of the study area, respectively. These zones correspond to carbonate rocks located in the southern part of the area where percolating rainwater developed large cavities that can store and

  7. Structure of the crust beneath Cameroon (West Africa) revealed by ambient noise tomography

    NASA Astrophysics Data System (ADS)

    Guidarelli, M.; Zandomeneghi, D.; Aoudia, A.

    2011-12-01

    As Cameroon is characterized by moderate seismicity, mainly restricted to Mt. Cameroon, the study of crust and uppermost mantle with traditional seismic tomography methods can be very limited. We use the ambient noise surface wave tomography to overcome the limitations of traditional methods and fully exploit the Cameroon network data. By cross-correlating six months of continuous seismic noise records from 32 broadband stations distributed across Cameroon, we have been able to measure Rayleigh wave group velocity in the period range 5-35 s, sensitive to approximately the upper 40 km of the crust, for about 300 station-to-station paths. We first apply a dispersion analysis using the frequency-time analysis to obtain the group velocity of the fundamental mode of Rayleigh waves for periods ranging from 5 to 35 sec. We then invert path-averaged dispersion curves to obtain 2D maps, on a 0.5 ° x0.5 ° nodal grid, of group velocity for discrete periods using a method that is the generalization to two dimensions of the Backus and Gilbert method. We obtain tomographic group velocity maps of the Cameroon crust that image the main tectonic features of the Cameroon crust, with an unprecedented detail on the major West Africa tectonic feature, known as Cameroon Volcanic Line. Through Cameroon, the anomaly maps clearly show both higher- and slower-than-average velocities, marking a variety of geological/tectonic features. In the period range 10-20 s, which corresponds to crustal depths, the most evident features are: the high velocity region, wide and composite, in southern Cameroon in clear spatial correspondence with the Congo Craton; the low velocity in the central-eastern part of the country corresponding to the Adamawa Plateau; a strong low velocity anomaly beneath Mt. Cameroon that persists up to 25 s period; and low group velocities along the border with Nigeria. Based on our new results and integrated with precedent studies we discuss the origin of the Cameroon

  8. The development and state of health and safety in the workplace in west Africa: perspectives from Nigeria.

    PubMed

    Asuzu, M C

    1996-01-01

    Occupational health practice originated in Europe following the systematic work of Bernadino Ramazzini in Italy at the turn of the 17th century. It grew mostly under the notion of Industrial health, concentrating on the chemical, mechanical and social conditions of labourers as well as the work of the arts and trades, until the work of Charles Turner Thackrah in Britain broadened its understanding to include the professions and certain civic ways of living. In West Africa, as in most of the developing world, occupational health and safety practice came to us mostly as side products of the colonial company health work, in their attempt to fulfil the requirements of their national health laws to their citizens here. The first organised effort to boost occupational health and practice for the Africans among the Africans, and involving mainly Africans, came in the 1960s with the first African Conference on Occupational health in Africa in Lagos in 1968. This process has gone on now, albeit rather slowly, until the citing of a Chair of Occupational health at the University of Ibadan by the Society of Occupational Health Physicians of Nigeria in the 1992/93 academic year. The health and safety in industries in Nigeria have however not been in anyway adequate from studies in that area, especially among the indigenous small and medium sized companies. This paper reviews these developments and proposes some suggestions on how to improve on the speed and accuracy of these developments, specifically in Nigeria; and by extrapolation, for the West Africa sub-region as well. PMID:8652439

  9. Hydro-gravimetry in West-Africa: First results from the Djougou (Benin) superconducting gravimeter

    NASA Astrophysics Data System (ADS)

    Hector, Basile; Hinderer, Jacques; Séguis, Luc; Boy, Jean-Paul; Calvo, Marta; Descloitres, Marc; Rosat, Séverine; Galle, Sylvie; Riccardi, Umberto

    2014-10-01

    The increasing number of hydro-gravimetry studies proves the rising interest of the hydrology community toward this monitoring method. The accuracy of superconducting gravimeters (SG) potentially allows the retrieval of small water storage changes (WSC) down to a few millimeters of equivalent water thickness. However, the importance of corrections applied to SG data to achieve such a precision in gravity residuals should be recalled. The Djougou permanent gravity station presented in this paper and located in northern Benin, West-Africa, provides a good opportunity to review these considerations. This station is equipped since July 2010 with the superconducting gravimeter SG-060 aimed at deriving WSC at different time-scales, daily to inter-annual. In this area, WSC are (1) part of the control system for evapotranspiration (ET) process, a key variable of the West-African monsoon cycle and (2) the state variable for resource management, a critical issue in storage-poor hard rock basement contexts such as in northern Benin. The potential for deriving WSC from time-lapse gravity data partly depends on environmental features such as topography and the instrument shelter. Therefore, this issue is addressed first, with the background idea that such sensitivity analysis should be undertaken before setting up any new instrument. In Djougou, local topography is quite flat leading to a theoretical straightforward relationship between gravity changes and WSC, close to the standard Bouguer value. However, the shelter plays a significant masking role, which is the principal limitation to the retrieval of fast hydrological processes such as ET following a rain event. Several issues concerning classical gravity corrections are also addressed in the paper. These include gap-filling procedures during rain-events and drift estimates for short time series. Special attention is provided to atmospheric corrections, and different approaches are tested: a simple scalar admittance, a

  10. The monetary value of human milk in Francophone west Africa: a PROFILES analysis for nutrition policy communication.

    PubMed

    Aguayo, Víctor M; Ross, Jay

    2002-06-01

    Using a simple and conservative methodology, we estimated the volume and monetary value of the human milk produced by lactating women in Francophone West Africa. In that region, children zero to 35.9 months old consume over 1.1 billion liters of human milk per year. However, suboptimal breastfeeding practices account for the loss of 175 million liters of human milk annually. If the human milk consumed by children zero to 35.9 months old were to be adequately replaced using commercial breastmilk substitutes, an annual expenditure of about 2 billion US dollars would be needed. At the household level, the annual replacement cost of human milk would amount to US$412 per infant. This is beyond the reach of most families in West Africa, where as many as 61% of families in some countries live on less than one US dollar per day. Appropriate policies to foster breastfeeding need to be developed and adequately implemented. Such policy action is more likely to occur if decision makers fully appreciate the monetary value of human milk. PMID:12094665

  11. Simulating and Tracking a Heavily Rainy Wave over West Africa Using a Modeling Strategy with WRF Model

    NASA Astrophysics Data System (ADS)

    Sarr, A.

    2014-12-01

    The last decades, over Sahel, are characterized by a relative recovery in rainfall compared to the long drought, which affected this part of West Africa in the 70s, 80s and early 90s. It is also noted an increase of extreme events, mainly excess of rainfall causing damages to many parts of the Sahel area. In this study, we are focusing on an extreme case, which occurred during September 2009. A deep African Easterly Wave (AEW) crossed the region from Niger to Senegal giving heavy rains along its path with a maximum of more than 260mm in Ouagadougou, Burkina Faso. While continuing its trajectory other strong winds associated with the systems caused other kind of damages. A modeling strategy, based on a moving nest with the Weather Research and Forecast model (WRF-ARW), is used to simulate the system. The model is run at 27 and 9km respectively for the outer and inner domains. Key parameters are investigated in order to assess the ability of WRF model in simulating the even. The study has shown good performance of WRF in simulating tropical systems. Noted weaknesses are also highlighted in the study, which showed promising results in simulating extremes, hours to days head, in support to early warning systems (EWS) to mitigate the adverse effects of extremes. This is a key responsibility of National Meteorological Services lacking this capacity in developing countries of West Africa.

  12. Evaluating climate change impacts and adaptation options for agriculture in West Africa: a multi-model comparison

    NASA Astrophysics Data System (ADS)

    Sultan, B.; Lobell, D. B.; Biasutti, M.; Guan, K.; Roudier, P.; Piani, C.

    2013-12-01

    Climate change is likely to stress food production in many parts of the developing world over the next few decades. In areas such as West Africa, where poor communities are highly dependent on the direct use of local natural resources, the effects of climate change on food security could be particularly devastating. Given these concerns, there is great interest in identifying and investing in technologies or practices that could help farmers adapt to climate variability and change. Recent studies found a robust agreement across the various climate models of the IPCC Coupled Models Inter-comparison Program ensemble on the seasonal distribution of Sahel rainfall changes (with a drying of the early season and positive rainfall anomaly at the end) in contrast with a large uncertainty for summertime rainfall totals. These changes will therefore certainly impact agriculture strategy (selection of new cultivars, later sowing) and output. This study estimates such impacts by using a series of climate scenarios as input for two crop models for multiple locations within West Africa. Simulations are run for the two major crops in the region - sorghum and millets. Building on the above simulations, we then simulate different scenarios of adaptation that could be used to cope with climate changes.

  13. Public health challenges and legacies of Japan's response to the Ebola virus disease outbreak in West Africa 2014 to 2015.

    PubMed

    Saito, Tomoya

    2015-01-01

    The largest outbreak of Ebola virus disease occurred in West Africa in 2014 and resulted in unprecedented transmission even in distant countries. In Japan, only nine individuals were screened for Ebola and there was no confirmed case. However, the government promoted the reinforcement of response measures and interagency collaboration, with training and simulation exercises conducted country-wide. The legacies included: publication of a communication policy on case disclosure, a protocol for collaboration between public health and other agencies, and establishing an expert committee to assemble the limited available expertise. There were challenges in taking proportionate and flexible measures in the management of people identified to be at high risk at entry points to Japan, in the decentralised medical response strategy, and in the medical countermeasures preparedness. The Ebola outbreak in West Africa provided a crucial opportunity to reveal the challenges and improve the preparedness for rare but high impact emerging diseases that are prone to be neglected. Efforts to uphold the lessons learnt and maintain public health preparedness should help prepare for future emerging diseases, including bioterrorist acts and pandemics. PMID:26559148

  14. Assessment of Regional Climate Models over Côte d'Ivoire and Analysis of Future Projections over West Africa

    NASA Astrophysics Data System (ADS)

    Kouadio, K.; Konare, A.; Diawara, A.; Dje, B. K.; Ajayi, V. O.; Diedhiou, A.

    2015-12-01

    The ability of six Regional Climate Models (RCMs) used in AMMA-ENSEMBLES project is assessed over six meteorological stations in Côte d'Ivoire. The ensemble mean of the models is also used for the prediction of climate change over West Africa. The study focused on two periods: the period 1995-2005, the present-day simulations, is used to evaluate the skills of the models over the country and the years 2010-2013, for assessment of the future climate change scenario used. The results show that the skills of the models vary from one station to another and from one season to another. None of the models considered, presents an excellent performance over the entire country and in all the seasons. Generally, the ensemble mean of all the models presents better results when compared with the observation. These results suggest that the choice of any model for study over the country may depend on the focus of interest: intensity or variability of the rain and also on area of interest. The projection for 2020-2040, future climate change over West Africa shows that the Sahel exhibits a tendency to be drier while wetter Guinean coast is observed

  15. Characteristics of HIV-2 and HIV-1/HIV-2 Dually Seropositive Adults in West Africa Presenting for Care and Antiretroviral Therapy: The IeDEA-West Africa HIV-2 Cohort Study

    PubMed Central

    Ekouevi, Didier K.; Balestre, Eric; Coffie, Patrick A.; Minta, Daouda; Messou, Eugene; Sawadogo, Adrien; Minga, Albert; Sow, Papa Salif; Bissagnene, Emmanuel; Eholie, Serge P.; Gottlieb, Geoffrey S.; Dabis, François; Zannou, Djimon Marcel; Ahouada, Carin; Akakpo, Jocelyn; Ahomadegbé, Christelle; Bashi, Jules; Gougounon-Houéto, Alice; Azon-Kouanou, Angèle; Houngbé, Fabien; Koumakpaï, Sikiratou; Alihonou, Florence; d’Almeida, Marcelline; Hodonou, Irvine; Hounhoui, Ghislaine; Sagbo, Gracien; Tossa-Bagnan, Leïla; Adjide, Herman; Drabo, Joseph; Bognounou, René; Dienderé, Arnaud; Traore, Eliezer; Zoungrana, Lassane; Zerbo, Béatrice; Sawadogo, Adrien Bruno; Zoungrana, Jacques; Héma, Arsène; Soré, Ibrahim; Bado, Guillaume; Tapsoba, Achille; Yé, Diarra; Kouéta, Fla; Ouedraogo, Sylvie; Ouédraogo, Rasmata; Hiembo, William; Gansonré, Mady; Messou, Eugène; Gnokoro, Joachim Charles; Koné, Mamadou; Kouakou, Guillaume Martial; Bosse, Clarisse Amani; Brou, Kouakou; Assi, Achi Isidore; Chenal, Henri; Hawerlander, Denise; Soppi, Franck; Minga, Albert; Abo, Yao; Bomisso, Germain; Eholié, Serge Paul; Amego, Mensah Deborah Noelly; Andavi, Viviane; Diallo, Zelica; Ello, Frédéric; Tanon, Aristophane Koffi; Koule, Serge Olivier; Anzan, Koffi Charles; Guehi, Calixte; Aka, Edmond Addi; Issouf, Koffi Ladji; Kouakou, Jean-Claude; N’Gbeche, Marie-Sylvie; Touré, Pety; Avit-Edi, Divine; Kouakou, Kouadio; Moh, Magloire; Yao, Valérie Andoblé; Folquet, Madeleine Amorissani; Dainguy, Marie-Evelyne; Kouakou, Cyrille; Méa-Assande, Véronique Tanoh; Oka-Berete, Gladys; Zobo, Nathalie; Acquah, Patrick; Kokora, Marie-Berthe; Eboua, Tanoh François; Timité-Konan, Marguerite; Ahoussou, Lucrèce Diecket; Assouan, Julie Kebé; Sami, Mabéa Flora; Kouadio, Clémence; Renner, Lorna; Goka, Bamenla; Welbeck, Jennifer; Sackey, Adziri; Owiafe, Seth Ntiri; Wejse, Christian; Silva, Zacarias José Da; Paulo, Joao; Rodrigues, Amabelia; da Silva, David; Medina, Candida; Oliviera-Souto, Ines; Østergaard, Lars; Laursen, Alex; Sodemann, Morten; Aaby, Peter; Fomsgaard, Anders; Erikstrup, Christian; Eugen-Olsen, Jesper; Maïga, Moussa Y; Diakité, Fatoumata Fofana; Kalle, Abdoulaye; Katile, Drissa; Traore, Hamar Alassane; Minta, Daouda; Cissé, Tidiani; Dembelé, Mamadou; Doumbia, Mohammed; Fomba, Mahamadou; Kaya, Assétou Soukho; Traoré, Abdoulaye M; Traoré, Hamady; Toure, Amadou Abathina; Dicko, Fatoumata; Sylla, Mariam; Berthé, Alima; Traoré, Hadizatou Coulibaly; Koïta, Anta; Koné, Niaboula; N'Diaye, Clémentine; Coulibaly, Safiatou Touré; Traoré, Mamadou; Traoré, Naïchata; Charurat, Man; Ajayi, Samuel; Dapiap, Stephen; Otu; Igbinoba, Festus; Benson, Okwara; Adebamowo, Clément; James, Jesse; Obaseki; Osakede, Philip; Olasode, John; Sow, Papa Salif; Diop, Bernard; Manga, Noël Magloire; Tine, Judicael Malick; Signate Sy, Haby; Ba, Abou; Diagne, Aida; Dior, Hélène; Faye, Malick; Gueye, Ramatoulaye Diagne; Mbaye, Aminata Diack; Patassi, Akessiwe; Kotosso, Awèrou; Kariyare, Benjamin Goilibe; Gbadamassi, Gafarou; Komi, Agbo; Mensah-Zukong, Kankoé Edem; Pakpame, Pinuwe; Lawson-Evi, Annette Koko; Atakouma, Yawo; Takassi, Elom; Djeha, Améyo; Ephoévi-gah, Ayoko; Djibril, Sherifa El-Hadj; Dabis, François; Bissagnene, Emmanuel; Arrivé, Elise; Coffie, Patrick; Ekouevi, Didier; Jaquet, Antoine; Leroy, Valériane; Lewden, Charlotte; Sasco, Annie; Azani, Jean-Claude; Allou, Gérard; Balestre, Eric; Bohossou, Franck; Karcher, Sophie; Gonsan, Jules Mahan; Carrou, Jérôme Le; Lenaud, Séverin; Nchot, Célestin; Malateste, Karen; Yao, Amon Roseamonde; Siloué, Bertine; Clouet, Gwenaelle; Djetouan, Hugues; Doring, Alexandra; Kouakou, Adrienne; Rabourdin, Elodie; Rivenc, Jean; Anglaret, Xavier; Ba, Boubacar; Essanin, Jean Bosco; Ciaranello, Andrea; Datté, Sébastien; Desmonde, Sophie; Diby, Jean-Serge Elvis; Gottlieb, Geoffrey S.; Horo, Apollinaire Gninlgninrin; Kangah, Serge N'zoré; Malvy, Denis; Meless, David; Mounkaila-Harouna, Aida; Ndondoki, Camille; Shiboski, Caroline; Thiébaut, Rodolphe; PAC-CI; Abidjan

    2013-01-01

    Background HIV-2 is endemic in West Africa. There is a lack of evidence-based guidelines on the diagnosis, management and antiretroviral therapy (ART) for HIV-2 or HIV-1/HIV-2 dual infections. Because of these issues, we designed a West African collaborative cohort for HIV-2 infection within the framework of the International epidemiological Databases to Evaluate AIDS (IeDEA). Methods We collected data on all HIV-2 and HIV-1/HIV-2 dually seropositive patients (both ARV-naive and starting ART) and followed-up in clinical centres in the IeDEA-WA network including a total of 13 clinics in five countries: Benin, Burkina-Faso Côte d’Ivoire, Mali, and Senegal, in the West Africa region. Results Data was merged for 1,754 patients (56% female), including 1,021 HIV-2 infected patients (551 on ART) and 733 dually seropositive for both HIV-1 and HIV 2 (463 on ART). At ART initiation, the median age of HIV-2 patients was 45.3 years, IQR: (38.3–51.7) and 42.4 years, IQR (37.0–47.3) for dually seropositive patients (p = 0.048). Overall, 16.7% of HIV-2 patients on ART had an advanced clinical stage (WHO IV or CDC-C). The median CD4 count at the ART initiation is 166 cells/mm3, IQR (83–247) among HIV-2 infected patients and 146 cells/mm3, IQR (55–249) among dually seropositive patients. Overall, in ART-treated patients, the CD4 count increased 126 cells/mm3 after 24 months on ART for HIV-2 patients and 169 cells/mm3 for dually seropositive patients. Of 551 HIV-2 patients on ART, 5.8% died and 10.2% were lost to follow-up during the median time on ART of 2.4 years, IQR (0.7–4.3). Conclusions This large multi-country study of HIV-2 and HIV-1/HIV-2 dual infection in West Africa suggests that routine clinical care is less than optimal and that management and treatment of HIV-2 could be further informed by ongoing studies and randomized clinical trials in this population. PMID:23824279

  16. The geological significance of kelp-rafted rock along the west coast of South Africa

    NASA Astrophysics Data System (ADS)

    Woodborne, M. W.; Rogers, J.; Jarman, N.

    1989-06-01

    Angular to well-rounded pebbles and cobbles have been observed along the southwest coast of South Africa, attached to holdfasts of three species of kelp: Ecklonia maxima, Laminaria pallida, and Laminaria schinzii. A kelp-rafted clast has been dredged from the outer shelf and other clasts have been observed in situ in up to 5 m of water near Cape Town. The clasts have been found on both rocky and sandy shores as well as in a large backshore lagoon on the exposed Atlantic coast of the Cape Peninsula. Isolated clasts in a mid-Holocene lagoon were probably rafted ashore during winter storms in the mid-Holocene.

  17. Language in South Africa.

    ERIC Educational Resources Information Center

    Mesthrie, Rajend, Ed.

    This collection of 24 papers focuses on language and society in South Africa. Part 1, "The Main Language Groupings," includes (1) "South Africa: A Sociolinguistic Overview" (R. Mesthrie); (2) "The Khoesan Languages" (A. Traill); (3) "The Bantu Languages: Sociohistorical Perspectives" (Robert K. Herbert and Richard Bailey); (4) "Afrikaans:…

  18. Generation 2030/Africa

    ERIC Educational Resources Information Center

    You, Danzhen; Hug, Lucia; Anthony, David

    2014-01-01

    Until relatively recently, much of Africa has been among the economically least developed and least densely populated places on earth, replete with villages and rural communities. Africa is changing rapidly, in its economy, trade and investment; in climate change; in conflict and stability; in urbanization, migration patterns, and most of all in…

  19. A systematic assessment of the current capacity to act in nutrition in West Africa: cross-country similarities and differences

    PubMed Central

    Sodjinou, Roger; Bosu, William K.; Fanou, Nadia; Déart, Lucie; Kupka, Roland; Tchibindat, Félicité; Baker, Shawn

    2014-01-01

    Background Although it is widely accepted that lack of capacity is one of the barriers to scaling up nutrition in West Africa, there is a paucity of information about what capacities exist and the capacities that need to be developed to accelerate progress toward improved nutrition outcomes in the region. Objective To systematically assess the current capacity to act in nutrition in the West Africa region and explore cross-country similarities and differences. Design Data were collected from 13 West African countries through interviews with government officials, key development partners, tertiary-level training institutions, and health professional schools. The assessment was based on a conceptual framework of four interdependent levels (tools; skills; staff and infrastructure; and structures, systems and roles). In each of the surveyed countries, we assessed capacity assets and gaps at individual, organizational, and systemic levels. Results Important similarities and differences in capacity assets and gaps emerged across all the surveyed countries. There was strong momentum to improve nutrition in nearly all the surveyed countries. Most of the countries had a set of policies on nutrition in place and had set up multisectoral, multi-stakeholder platforms to coordinate nutrition activities, although much remained to be done to improve the effectiveness of these platforms. Many initiatives aimed to reduce undernutrition were ongoing in the region, but there did not seem to be clear coordination between them. Insufficient financial resources to implement nutrition activities were a major problem in all countries. The bulk of financial allocations for nutrition was provided by development partners, even though some countries, such as Niger, Nigeria, and Senegal, had a national budget line for nutrition. Sporadic stock-outs of nutrition supplies were reported in most of the countries as a result of a weak logistic and supply chain system. They also had a critical

  20. Water availability and demand in West Africa in the 21st century: impacts of climate change and population growth

    NASA Astrophysics Data System (ADS)

    Wisser, Dominik; Oyerinde, Ganiyu; Ibrahim, Moussa; Ibrahim, Boubacar

    2014-05-01

    The countries in West Africa are highly dependent on rainfed agriculture. Changes in the magnitude and timing of precipitation will affect the agricultural output and the economies as a whole. Irrigation is increasingly being considered an important adaptation option to help improve food security of the population that is expected to double in less than 50 years. West Africa is one of the regions where general circulation models (GCM) show the highest disagreements in the direction of future trends of precipitation, making assessments of water availability and the potential for irrigation a difficult task. We use output from a set of dynamically downscaled climate data sets from regional climate modes (RCM) from the CORDEX CMIP5 collection to drive WBMplus, a macroscale hydrological model and simultaneously calculate water demand (livestock, domestic, and irrigation) and availability for a set of land use, and socio economic scenarios around the 2050's for river basins in the ten countries participating in the West African Science Service Center on Climate Change and Adapted Land Use (WASCAL) project. Contrary to earlier results from GCMs, the set of RCMs suggest a consistent increase (~5-10%) in annual precipitation for a majority of the land area in West Africa that translates to slight increases in river flow under natural conditions for most river basins and a opportunities for increasing irrigation during the dry season. However, water demand is projected to more than double for livestock and domestic needs as a result of population growth. Demand for irrigation will rise sharply if irrigation is expanded from the current area (representing less than 3% of all croplands in the region), closer to its potential which is multiple times higher than the existing area. The pressures on water resources in the region will therefore be dominated by pressures arising from increased demand rather than changes in the availability of water and can potentially lead to

  1. The UNEP Shelf Programme: Highlighting efforts in West Africa and the Pacific Islands

    NASA Astrophysics Data System (ADS)

    Baker, E.; Beaudoin, Y. C.; Brekke, H.; Fabres, J.; Halvorsen, O.; Harris, P. T.; Lonne, O.; Nilsen, R.; Sorensen, M.; Thygesen, K.

    2013-12-01

    The UNEP Shelf Programme, coordinated by GRID-Arendal (a center collaborating with UNEP) was established in 2003 in response to Article 76 of the UN Convention on the Law of the Sea (UNCLOS) and UN General Assembly resolution 57/141. The Programme provides scientific and technical support to developing countries to assist in making timely submissions under the Convention to establish the outer limits of their continental shelf. The deadline for most states was midnight on 12 May 2009. All states that were expected to submit, managed to meet the deadline, and almost all developing states received support from the UNEP Shelf Programme. The support ranged from comprehensive capacity building and tailor-made training, to access to data from GRID-Arendal's One Stop Data Shop (OSDS). Two case studies will be presented and discussed: In the period from 8 December 2011 to 20 June 2012, the ship 'Sea Surveyor' of Gardline Hydro carried out a regional marine acquisition program off West Africa. The acquisition program was part of a joint project between seven African states (Mauretania, Senegal, the Gambia, Cape Verde, Guinea Bissau, Guinea and Sierra Leone) in cooperation with the Government of Norway. The data were acquired for the purpose of delineating and documenting the outer limits of the continental shelf of the seven states in accordance with article 76 of UNCLOS. Multibeam bathymetry (40 000 km) was acquired for the identification of the base of slope (BOS) and for the detailed foot of slope (FOS) analyses. Single channel reflection seismic (36 000 km) and sub bottom profiler data (40 000 km) were acquired for the interpretation of the general geology (including basement characteristics and sediment thickness) and recent sedimentary processes, respectively, as supportive evidence in the establishment of the BOS. In two areas, multi channel reflection seismic (4 000 km) data were acquired for the purpose of detailed sediment thickness analyses. Wide-angle reflection

  2. The Use of Lactic Acid Bacteria Starter Cultures during the Processing of Fermented Cereal-based Foods in West Africa: A Review

    PubMed Central

    Soro-Yao, Amenan Anastasie; Brou, Kouakou; Amani, Georges; Thonart, Philippe; Djè, Koffi Marcelin

    2014-01-01

    Lactic acid bacteria (LAB) are the primary microorganisms used to ferment maize-, sorghum- or millet-based foods that are processed in West Africa. Fermentation contributes to desirable changes in taste, flavour, acidity, digestibility and texture in gruels (ogi, baca, dalaki), doughs (agidi, banku, komé) or steam-cooked granulated products (arraw, ciacry, dégué). Similar to other fermented cereal foods that are available in Africa, these products suffer from inconsistent quality. The use of LAB starter cultures during cereal dough fermentation is a subject of increasing interest in efforts to standardise this step and guaranty product uniformity. However, their use by small-scale processing units or small agro-food industrial enterprises is still limited. This review aims to illustrate and discuss major issues that influence the use of LAB starter cultures during the processing of fermented cereal foods in West Africa. PMID:27073601

  3. Resisting Conformity: Anglican Mission Women and the Schooling of Girls in Early Nineteenth-Century West Africa

    ERIC Educational Resources Information Center

    Leach, Fiona

    2012-01-01

    The origins of modern schooling in early nineteenth-century Africa have been poorly researched. Moreover, histories of education in Africa have focused largely on the education of boys. Little attention has been paid to girls' schooling or to the missionary women who sought to construct a new feminine Christian identity for African girls. In the…

  4. The Epidemiology and Geographic Distribution of Relapsing Fever Borreliosis in West and North Africa, with a Review of the Ornithodoros erraticus Complex (Acari: Ixodida)

    PubMed Central

    Trape, Jean-François; Diatta, Georges; Arnathau, Céline; Bitam, Idir; Sarih, M’hammed; Belghyti, Driss; Bouattour, Ali; Elguero, Eric; Vial, Laurence; Mané, Youssouph; Baldé, Cellou; Pugnolle, Franck; Chauvancy, Gilles; Mahé, Gil; Granjon, Laurent; Duplantier, Jean-Marc

    2013-01-01

    Background Relapsing fever is the most frequent bacterial disease in Africa. Four main vector / pathogen complexes are classically recognized, with the louse Pediculus humanus acting as vector for B. recurrentis and the soft ticks Ornithodoros sonrai, O. erraticus and O. moubata acting as vectors for Borrelia crocidurae, B. hispanica and B. duttonii, respectively. Our aim was to investigate the epidemiology of the disease in West, North and Central Africa. Methods And Findings From 2002 to 2012, we conducted field surveys in 17 African countries and in Spain. We investigated the occurrence of Ornithodoros ticks in rodent burrows in 282 study sites. We collected 1,629 small mammals that may act as reservoir for Borrelia infections. Using molecular methods we studied genetic diversity among Ornithodoros ticks and Borrelia infections in ticks and small mammals. Of 9,870 burrows investigated, 1,196 (12.1%) were inhabited by Ornithodoros ticks. In West Africa, the southern and eastern limits of the vectors and Borrelia infections in ticks and small mammals were 13°N and 01°E, respectively. Molecular studies revealed the occurrence of nine different Ornithodoros species, including five species new for science, with six of them harboring Borrelia infections. Only B. crocidurae was found in West Africa and three Borrelia species were identified in North Africa: B. crocidurae, B. hispanica, and B. merionesi. Conclusions Borrelia Spirochetes responsible for relapsing fever in humans are highly prevalent both in Ornithodoros ticks and small mammals in North and West Africa but Ornithodoros ticks seem absent south of 13°N and small mammals are not infected in these regions. The number of Ornithodoros species acting as vector of relapsing fever is much higher than previously known. PMID:24223812

  5. Non-conventional humanitarian interventions on Ebola outbreak crisis in West Africa: health, ethics and legal implications.

    PubMed

    Tambo, Ernest

    2014-01-01

    Due to the lack of Ebola outbreak early warning alert, preparedness, surveillance and response systems, the most deadly, complex and largest ever seen Ebola war has been devastating West African communities. The unparalleled Ebola tsunami has prompted interrogations into, and uncertainties about, the effectiveness and efficiency of national, regional and international community's illed- responses using conventional humanitarian control and containment approaches and methods. The late humanitarian and local non-government organisations emergency responses and challenges to curb transmission dynamics and stop the ongoing spread in the Ebola outbreak in West Africa have led to an unprecedented toll of 14,413 reported Ebola cases in eight countries since the outbreak began, with 5,177 reported deaths including 571 health-care workers and 325 died as 14 November 2014. These indications the need of further evaluation of monitoring as substantial proportion of infections outside the context of Ebola epicentres, Ebola health centres treatment and care, infection prevention and control quality assurance checks in these countries. At the same time, exhaustive efforts should target ensuring an sufficient supply of optimal personal protective equipment (PPE) to all Ebola treatment facilities, along with the provision of training and relevant guidelines to limit to the minimum possible level of risk. The continent hosts a big proportion of the world's wealth, yet its people live in abject poverty, with governments unable to feed and govern them effectively, and who are condemned to endure even darker moments with the Ebola outbreak in West Africa. Institutionalisation of practical and operational non-conventional emergency response models efficient health systems, and tailored programmes can clearly support to prevent, control and eventually stamp out Ebola geo-distribution in addition to population mental health services that are requisite to address the massive range of the

  6. AMMA-CATCH a Hydrological, Meteorological and Ecological Long Term Observatory on West Africa : Some Recent Results

    NASA Astrophysics Data System (ADS)

    Galle, S.; Grippa, M.; Peugeot, C.; Bouzou Moussa, I.; Cappelaere, B.; Demarty, J.; Mougin, E.; Lebel, T.; Chaffard, V.

    2015-12-01

    AMMA-CATCH is a multi-scale observation system dedicated to long-term monitoring of the water cycle, the vegetation dynamics and their interaction with climate and water resources in West Africa. In the context of the global change, long-term observations are required to i) gain understanding in eco-hydrological processes over this highly contrasted region, ii) help their representation in Earth System Models, and iii) detect trends and infer their impacts on water resources and living conditions. It is made of three meso-scale sites (~ 1°x1°) in Mali, Niger and Benin, extending along the West African eco-climatic gradient. Within this regional window (5° by 9°), each of the three sites comprises a multi-scale set-up which helps documenting the components of the hydrologic budget and the evolutions of the surface conditions over a range of time scales: raingages, piezometers, river discharge stations, soil moisture and temperature profiles, turbulent fluxes measurements, LAI/biomass monitoring. This observation system has been continuously generating coherent datasets for 10 to 25 years depending on the datasets. It is jointly operated by French and African (Mali, Niger and Benin) research institutions. The data-base is available to the community through the website (www.amma-catch.org). AMMA-CATCH is a member of the French critical zone observatory network "Réseau des Bassins Versants", (RBV). AMMA-CATH participates to several global or regional observation networks, such as FluxNet, CarboAfrica, International Soil Moisture Networks (ISMN) and to calibration/validation campaigns for satellite missions such as SMOS (CNES, ESA), MEGHA-TROPIQUES (France/India) or SWAP(NASA). AMMA-CATCH fills a gap over a region, West Africa, where environmental data are largely lacking, and thus, it can usefully contribute to the international networking effort for environmental monitoring and research. Recent results on regional evolution of land cover, rainfall intensity and

  7. Ebola Virus Disease Epidemic: What Can the World Learn and Not Learn from West Africa?

    PubMed Central

    Azuine, Romuladus E.; Ekejiuba, Sussan E.; Singh, Gopal K.; Azuine, Magnus A.

    2015-01-01

    With over 4,500 deaths and counting, and new cases identified in two developed countries that are struggling and faltering in their handling of the epidemic, the 2014 Ebola Virus Disease (EVD) epidemic is unlike any of its kind ever encountered. The ability of some poor, resource-limited, developing countries in sub-Saharan Africa to efficiently handle the epidemic within their shores provides some lessons learned for the global health community. Among others, the 2014 EVD epidemic teaches us that it is time to put the “P” back in public and population health around the world. The global health community must support a sustainable strategy to mitigate Ebola virus and other epidemics both within and outside their shores, even after the cameras are gone. Ebola virus must not be called the disease of the poor and developing world.

  8. Soil carbon and plant diversity distribution at the farm level in the savannah region of Northern Togo (West Africa)

    NASA Astrophysics Data System (ADS)

    Sebastiã, M.-T.; Marks, E.; Poch, R. M.

    2008-10-01

    In western Africa, soil organic matter is a source of fertility for food provision and a tool for climate mitigation. In the Savannah region, strong soil degradation linked to an increase in population threatens organic matter conservation and agricultural yield. Soil degradation is also expected to impact biodiversity and, with it, increase the vulnerability of ecosystem goods and services, including the storage of soil organic carbon. Studies of land use, plant species composition and soil fertility were conducted for a conservation project at a demonstration farm in Northern Togo (West Africa), host to various management regimes. Results showed a low organic matter content of the surface soil horizons, often around 0.5%. The highest values were found in a sacred forest within the farm (2.2%). Among crops, rice had the highest soil organic matter, around 1%. In a survey of grasslands, pastures showed the highest organic matter content, with vegetation composition differing from grazed fallows and abandoned grasslands. Plant species richness showed a positive relationship with soil organic matter (R2adj=41.2%), but only by the end of the wet season, when species richness was also highest. Sampling date had a strong effect on vegetation composition. Results showed a strong influence of human activity on soil formation and distribution, and also on plant diversity. The soil characteristics found under the permanent forest suggest a high potential of the soils of the region for improvement of both agricultural yields and as a potential carbon sink relevant to global change policies.

  9. The genus Lactarius s. str. (Basidiomycota, Russulales) in Togo (West Africa): phylogeny and a new species described.

    PubMed

    Maba, Dao Lamèga; Guelly, Atsu K; Yorou, Nourou S; De Kesel, André; Verbeken, Annemieke; Agerer, Reinhard

    2014-06-01

    Lactarius s. str. represents a monophyletic group of about 40 species in tropical Africa, although the delimitation of the genus from Lactifluus is still in progress. Recent molecular phylogenetic and taxonomic revisions have led to numerous changes in names of tropical species formerly referred to Lactarius. To better circumscribe the genus Lactarius in Togo, we combined morphological data with sequence analyses and phylogeny inference of rDNA ITS sequences. Morphological and molecular data were generated from specimens sampled in various native woodlands and riverside forests; Lactarioid- and Russula sequences from public GenBank NCBI, and UNITE are included for phylogenetic analysis. The Maximum likelihood phylogeny tree inferred from aligned sequences supports the phylogenetic position of the studied samples from Togo within the subgenera Piperites, and Plinthogali. Lactarius s. str. includes about 13 species described from West Africa, of which eight were not previously known from Togo, including one new species: Lactarius subbaliophaeus identifiable by the presence of winged basidiospores, a pallisadic pileipellis with a uprapellis composed of cylindrical cells, inconspicuous pleurocystidia, and fusiform or tortuous, often tapering apex marginal cells. It can also be recognised by a transparent white latex that turns pinkish and then blackish, and a bluish reaction of the flesh context with FeSO4. These features mentioned do not match any of the morpho-anatomically most similar species, notably L. baliophaeus and L. griseogalus. PMID:25083405

  10. Cryptomyrus: a new genus of Mormyridae (Teleostei, Osteoglossomorpha) with two new species from Gabon, West-Central Africa.

    PubMed

    Sullivan, John P; Lavoué, Sébastien; Hopkins, Carl D

    2016-01-01

    We use mitochondrial and nuclear sequence data to show that three weakly electric mormyrid fish specimens collected at three widely separated localities in Gabon, Africa over a 13-year period represent an unrecognized lineage within the subfamily Mormyrinae and determine its phylogenetic position with respect to other taxa. We describe these three specimens as a new genus containing two new species. Cryptomyrus, new genus, is readily distinguished from all other mormyrid genera by a combination of features of squamation, morphometrics, and dental attributes. Cryptomyrus ogoouensis, new species, is differentiated from its single congener, Cryptomyrus ona, new species, by the possession of an anal-fin origin located well in advance of the dorsal fin, a narrow caudal peduncle and caudal-fin lobes nearly as long as the peduncle. In Cryptomyrus ona, the anal-fin origin is located only slightly in advance of the dorsal fin, the caudal peduncle is deep and the caudal-fin lobes considerably shorter than the peduncle. Continued discovery of new taxa within the "Lower Guinea Clade" of Mormyridae highlights the incompleteness of our knowledge of fish diversity in West-Central Africa. We present a revised key to the mormyrid genera of Lower Guinea. PMID:27006619

  11. The Impact of Human Conflict on the Genetics of Mastomys natalensis and Lassa Virus in West Africa

    PubMed Central

    Denys, Christiane; ter Meulen, Jan; Wirth, Thierry

    2012-01-01

    Environmental changes have been shown to play an important role in the emergence of new human diseases of zoonotic origin. The contribution of social factors to their spread, especially conflicts followed by mass movement of populations, has not been extensively investigated. Here we reveal the effects of civil war on the phylogeography of a zoonotic emerging infectious disease by concomitantly studying the population structure, evolution and demography of Lassa virus and its natural reservoir, the rodent Mastomys natalensis, in Guinea, West Africa. Analysis of nucleoprotein gene sequences enabled us to reconstruct the evolutionary history of Lassa virus, which appeared 750 to 900 years ago in Nigeria and only recently spread across western Africa (170 years ago). Bayesian demographic inferences revealed that both the host and the virus populations have gone recently through severe genetic bottlenecks. The timing of these events matches civil war-related mass movements of refugees and accompanying environmental degradation. Forest and habitat destruction and human predation of the natural reservoir are likely explanations for the sharp decline observed in the rodent populations, the consequent virus population decline, and the coincident increased incidence of Lassa fever in these regions. Interestingly, we were also able to detect a similar pattern in Nigeria coinciding with the Biafra war. Our findings show that anthropogenic factors may profoundly impact the population genetics of a virus and its reservoir within the context of an emerging infectious disease. PMID:22615894

  12. Cryptomyrus: a new genus of Mormyridae (Teleostei, Osteoglossomorpha) with two new species from Gabon, West-Central Africa

    PubMed Central

    Sullivan, John P.; Lavoué, Sébastien; Hopkins, Carl D.

    2016-01-01

    Abstract We use mitochondrial and nuclear sequence data to show that three weakly electric mormyrid fish specimens collected at three widely separated localities in Gabon, Africa over a 13-year period represent an unrecognized lineage within the subfamily Mormyrinae and determine its phylogenetic position with respect to other taxa. We describe these three specimens as a new genus containing two new species. Cryptomyrus, new genus, is readily distinguished from all other mormyrid genera by a combination of features of squamation, morphometrics, and dental attributes. Cryptomyrus ogoouensis, new species, is differentiated from its single congener, Cryptomyrus ona, new species, by the possession of an anal-fin origin located well in advance of the dorsal fin, a narrow caudal peduncle and caudal-fin lobes nearly as long as the peduncle. In Cryptomyrus ona, the anal-fin origin is located only slightly in advance of the dorsal fin, the caudal peduncle is deep and the caudal-fin lobes considerably shorter than the peduncle. Continued discovery of new taxa within the “Lower Guinea Clade” of Mormyridae highlights the incompleteness of our knowledge of fish diversity in West-Central Africa. We present a revised key to the mormyrid genera of Lower Guinea. PMID:27006619

  13. The impact of human conflict on the genetics of Mastomys natalensis and Lassa virus in West Africa.

    PubMed

    Lalis, Aude; Leblois, Raphaël; Lecompte, Emilie; Denys, Christiane; Ter Meulen, Jan; Wirth, Thierry

    2012-01-01

    Environmental changes have been shown to play an important role in the emergence of new human diseases of zoonotic origin. The contribution of social factors to their spread, especially conflicts followed by mass movement of populations, has not been extensively investigated. Here we reveal the effects of civil war on the phylogeography of a zoonotic emerging infectious disease by concomitantly studying the population structure, evolution and demography of Lassa virus and its natural reservoir, the rodent Mastomys natalensis, in Guinea, West Africa. Analysis of nucleoprotein gene sequences enabled us to reconstruct the evolutionary history of Lassa virus, which appeared 750 to 900 years ago in Nigeria and only recently spread across western Africa (170 years ago). Bayesian demographic inferences revealed that both the host and the virus populations have gone recently through severe genetic bottlenecks. The timing of these events matches civil war-related mass movements of refugees and accompanying environmental degradation. Forest and habitat destruction and human predation of the natural reservoir are likely explanations for the sharp decline observed in the rodent populations, the consequent virus population decline, and the coincident increased incidence of Lassa fever in these regions. Interestingly, we were also able to detect a similar pattern in Nigeria coinciding with the Biafra war. Our findings show that anthropogenic factors may profoundly impact the population genetics of a virus and its reservoir within the context of an emerging infectious disease. PMID:22615894

  14. High Resolution Simulations of Future Climate in West Africa Using a Variable-Resolution Atmospheric Model

    NASA Astrophysics Data System (ADS)

    Adegoke, J. O.; Engelbrecht, F.; Vezhapparambu, S.

    2013-12-01

    In previous work demonstrated the application of a var¬iable-resolution global atmospheric model, the conformal-cubic atmospheric model (CCAM), across a wide range of spatial and time scales to investigate the ability of the model to provide realistic simulations of present-day climate and plausible projections of future climate change over sub-Saharan Africa. By applying the model in stretched-grid mode the versatility of the model dynamics, numerical formulation and physical parameterizations to function across a range of length scales over the region of interest, was also explored. We primarily used CCAM to illustrate the capability of the model to function as a flexible downscaling tool at the climate-change time scale. Here we report on additional long term climate projection studies performed by downscaling at much higher resolutions (8 Km) over an area that stretches from just south of Sahara desert to the southern coast of the Niger Delta and into the Gulf of Guinea. To perform these simulations, CCAM was provided with synoptic-scale forcing of atmospheric circulation from 2.5 deg resolution NCEP reanalysis at 6-hourly interval and SSTs from NCEP reanalysis data uses as lower boundary forcing. CCAM 60 Km resolution downscaled to 8 Km (Schmidt factor 24.75) then 8 Km resolution simulation downscaled to 1 Km (Schmidt factor 200) over an area approximately 50 Km x 50 Km in the southern Lake Chad Basin (LCB). Our intent in conducting these high resolution model runs was to obtain a deeper understanding of linkages between the projected future climate and the hydrological processes that control the surface water regime in this part of sub-Saharan Africa.

  15. Development of reference transcriptomes for the major insect pests of cowpea: a toolbox for insect pest management approaches in West Africa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cowpea crops are widely cultivated and a major nutritional source of protein for indigenous human populations in West Africa. Annual yields and longevity of grain storage is greatly reduced by feeding damage caused by a complex of insect pests that include Anoplocnemis curvipes, Aphis craccivora, Cl...

  16. Poverty reduction in Africa

    PubMed Central

    Collier, Paul

    2007-01-01

    Poverty in Africa has been rising for the last quarter-century, while it has been falling in the rest of the developing world. Africa's distinctive problem is that its economies have not been growing. This article attempts to synthesize a range of recent research to account for this failure of the growth process. I argue that the reasons lie not in African peculiarities but rather in geographic features that globally cause problems but that are disproportionately pronounced in Africa. These features interact to create three distinct challenges that are likely to require international interventions beyond the conventional reliance on aid. PMID:17942702

  17. Effects of Response to 2014–2015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa

    PubMed Central

    Parpia, Alyssa S.; Wenzel, Natasha S.; Galvani, Alison P.

    2016-01-01

    Response to the 2014–2015 Ebola outbreak in West Africa overwhelmed the healthcare systems of Guinea, Liberia, and Sierra Leone, reducing access to health services for diagnosis and treatment for the major diseases that are endemic to the region: malaria, HIV/AIDS, and tuberculosis. To estimate the repercussions of the Ebola outbreak on the populations at risk for these diseases, we developed computational models for disease transmission and infection progression. We estimated that a 50% reduction in access to healthcare services during the Ebola outbreak exacerbated malaria, HIV/AIDS, and tuberculosis mortality rates by additional death counts of 6,269 (2,564–12,407) in Guinea; 1,535 (522–2,8780) in Liberia; and 2,819 (844–4,844) in Sierra Leone. The 2014–2015 Ebola outbreak was catastrophic in these countries, and its indirect impact of increasing the mortality rates of other diseases was also substantial. PMID:26886846

  18. High seroprevalence of chikungunya virus antibodies among pregnant women living in an urban area in Benin, West Africa.

    PubMed

    Bacci, Anastasia; Marchi, Serena; Fievet, Nadine; Massougbodji, Achille; Perrin, Renè Xavier; Chippaux, Jean-Philippe; Sambri, Vittorio; Landini, Maria Paola; Varani, Stefania; Rossini, Giada

    2015-06-01

    The aim of this study was to investigate the seroprevalence of antichikungunya virus (anti-CHIKV) antibodies in pregnant women living in an urban area of Benin (West Africa). Results were obtained by screening sera collected in 2006 and 2007 with enzyme-linked immunosorbent assay (ELISA) for anti-CHIKV immunoglobulin G (IgG) and IgM. Positive results were confirmed by indirect immunofluorescence test and microneutralization assay. We found that a large proportion (36.1%) of pregnant women living in Cotonou had specific IgG against CHIKV, indicating a high seroprevalence of the infection in urban southern Benin, whereas no active cases of CHIKV infection were detected. PMID:25940198

  19. Genetic Regulation of Acquired Immune Responses to Antigens of Mycobacterium tuberculosis: a Study of Twins in West Africa

    PubMed Central

    Jepson, Annette; Fowler, Amanda; Banya, Winston; Singh, Mahavir; Bennett, Steve; Whittle, Hilton; Hill, Adrian V. S.

    2001-01-01

    The role of genetic factors in clinical tuberculosis is increasingly recognized; how such factors regulate the immune response to Mycobacterium tuberculosis in healthy individuals is unclear. In this study of 255 adult twin pairs residing in The Gambia, West Africa, it is apparent that memory T-cell responses to secreted mycobacterial antigens (85-kDa antigen complex, “short-term culture filtrate,” and peptides from the ESAT-6 protein), as well as to the 65-kDa heat shock protein, are subject to effective genetic regulation. The delayed hypersensitivity response to intradermal tuberculin also demonstrates significant genetic variance, while quantitative T-cell and antibody responses to the 38-kDa cell membrane protein appear to be determined largely by environmental factors. Such findings have implications for vaccine development. PMID:11349068

  20. Effects of Response to 2014-2015 Ebola Outbreak on Deaths from Malaria, HIV/AIDS, and Tuberculosis, West Africa.

    PubMed

    Parpia, Alyssa S; Ndeffo-Mbah, Martial L; Wenzel, Natasha S; Galvani, Alison P

    2016-03-01

    Response to the 2014-2015 Ebola outbreak in West Africa overwhelmed the healthcare systems of Guinea, Liberia, and Sierra Leone, reducing access to health services for diagnosis and treatment for the major diseases that are endemic to the region: malaria, HIV/AIDS, and tuberculosis. To estimate the repercussions of the Ebola outbreak on the populations at risk for these diseases, we developed computational models for disease transmission and infection progression. We estimated that a 50% reduction in access to healthcare services during the Ebola outbreak exacerbated malaria, HIV/AIDS, and tuberculosis mortality rates by additional death counts of 6,269 (2,564-12,407) in Guinea; 1,535 (522-2,8780) in Liberia; and 2,819 (844-4,844) in Sierra Leone. The 2014-2015 Ebola outbreak was catastrophic in these countries, and its indirect impact of increasing the mortality rates of other diseases was also substantial. PMID:26886846

  1. Phylogenetic and microscopic studies in the genus Lactifluus (Basidiomycota, Russulales) in West Africa, including the description of four new species.

    PubMed

    Maba, Dao Lamèga; Guelly, Atsu K; Yorou, Nourou S; Verbeken, Annemieke; Agerer, Reinhard

    2015-06-01

    Despite the crucial ecological role of lactarioid taxa (Lactifluus, Lactarius) as common ectomycorrhiza formers in tropical African seasonal forests, their current diversity is not yet adequately assessed. During the last few years, numerous lactarioid specimens have been sampled in various ecosystems from Togo (West Africa). We generated 48 ITS sequences and aligned them against lactarioid taxa from other tropical African ecozones (Guineo-Congolean evergreen forests, Zambezian miombo). A Maximum Likelihood phylogenetic tree was inferred from a dataset of 109 sequences. The phylogenetic placement of the specimens, combined with morpho-anatomical data, supported the description of four new species from Togo within the monophyletic genus Lactifluus: within subgen. Lactifluus (L. flavellus), subgen. Russulopsis (L. longibasidius and L. pectinatus), and subgen. Edules (L. melleus). This demonstrates that the current species richness of the genus is considerably higher than hitherto estimated for African species and, in addition, a need to redefine the subgenera and sections within it. PMID:26203413

  2. Deforestation and the limited contribution of forests to rural livelihoods in West Africa: evidence from Burkina Faso and Ghana.

    PubMed

    Pouliot, Mariève; Treue, Thorsten; Obiri, Beatrice Darko; Ouedraogo, Boureima

    2012-11-01

    Forest degradation in West Africa is generally thought to have negative consequences on rural livelihoods but there is little overview of its effects in the region because the importance of forests to rural livelihoods has never been adequately quantified. Based on data from 1014 rural households across Burkina Faso and Ghana this paper attempts to fill this knowledge gap. We demonstrate that agricultural lands and the non-forest environment including parklands are considerably more valuable to poor as well as more well-off rural households than forests. Furthermore, product types supplied by the non-forest environment are almost identical with those from forests. Accordingly, forest clearance/degradation is profitable for and, hence, probably performed by rural people at large. We attribute rural people's high reliance on non-forest versus forest resources to the two countries' restrictive and inequitable forest policies which must be reformed to promote effective forest conservation, e.g., to mitigate climate change. PMID:22669685

  3. Potential Impacts of Projected Mid-twenty-first Century Climate Change on the Hydrology of the Nasia Catchment, West Africa

    NASA Astrophysics Data System (ADS)

    Alo, C. A.; Oteng, F. M.; Bitew, M. M.; Ahmed, K. F.; Wang, G.

    2014-12-01

    In this study, the coupled surface water-groundwater model, MIKE-SHE has been calibrated to observed streamflow and groundwater heads spanning 2000-2009 for the Nasia sub-catchment in the White Volta Basin, West Africa. The calibrated model has been used to project the mid-twenty-first century hydrology of the region. Bias-correction has also been applied to daily precipitation and monthly average temperature projections for the period 2010-2050 to derive the meteorological forcing data required to drive the model. The climate projections have been drawn from ten Coupled Model Intercomparison Project phase 5 (CMIP5) relatively high resolution (less than two degrees latitude/longitude) climate models under the representative concentration pathway, RCP8.5. Here, we present simulated mid-twenty-first century hydrologic (streamflow and groundwater) changes over the Nasia sub-catchment with MIKE-SHE forced with the bias-corrected CMIP5 climate projections.

  4. Microsatellite analysis supports clonal propagation and reduced divergence of Trypanosoma vivax from asymptomatic to fatally infected livestock in South America compared to West Africa

    PubMed Central

    2014-01-01

    Background Mechanical transmission of the major livestock pathogen Trypanosoma vivax by other biting flies than tsetse allows its spread from Africa to the New World. Genetic studies are restricted to a small number of isolates and based on molecular markers that evolve too slowly to resolve the relationships between American and West African populations and, thus, unable us to uncover the recent history of T. vivax in the New World. Methods T. vivax genetic diversity, population structure and the source of outbreaks was investigated through the microsatellite multiloci (7 loci) genotype (MLGs) analysis in South America (47isolates from Brazil, Venezuela and French Guiana) and West Africa (12 isolates from The Gambia, Burkina Faso, Ghana, Benin and Nigeria). Relationships among MLGs were explored using phylogenetic, principal component and STRUCTURE analyses. Results Although closely phylogenetically related, for the first time, genetic differences were detected between T. vivax isolates from South America (11 genotypes/47 isolates) and West Africa (12 genotypes/12 isolates) with no MLGs in common. Diversity was far greater across West Africa than in South America, where genotypes from Brazil (MLG1-6), Venezuela (MLG7-10) and French Guiana (MLG11) shared similar but not identical allele composition. No MLG was exclusive to asymptomatic (endemic areas) or sick (outbreaks in non-endemic areas) animals, but only MLGs1, 2 and 3 were responsible for severe haematological and neurological disorders. Conclusions Our results revealed closely related genotypes of T. vivax in Brazil and Venezuela, regardless of endemicity and clinical conditions of the infected livestock. The MLGs analysis from T. vivax across SA and WA support clonal propagation, and is consistent with the hypothesis that the SA populations examined here derived from common ancestors recently introduced from West Africa. The molecular markers defined here are valuable to assess the genetic diversity, to

  5. Women in Africa

    ERIC Educational Resources Information Center

    Spitzer, Manon

    1975-01-01

    The role and status of women in Africa has changed profoundly since the end of the colonial period. Many differences in women's status and role are based on geography, history, nationality, political and socioeconomic systems, culture, and religion. (JR)

  6. Embargo on Lion Hunting Trophies from West Africa: An Effective Measure or a Threat to Lion Conservation?

    PubMed Central

    Bouché, Philippe; Crosmary, William; Kafando, Pierre; Doamba, Benoit; Kidjo, Ferdinand Claude; Vermeulen, Cédric; Chardonnet, Philippe

    2016-01-01

    The W-Arly-Pendjari (WAP) ecosystem, shared among Benin, Burkina Faso and Niger, represents the last lion stronghold of West Africa. To assess the impact of trophy hunting on lion populations in hunting areas of the WAP, we analyzed trends in harvest rates from 1999 to 2014. We also investigated whether the hunting areas with higher initial hunting intensity experienced steeper declines in lion harvest between 1999 and 2014, and whether lion densities in hunting areas were lower than in national parks. Lion harvest rate remained overall constant in the WAP. At initial hunting intensities below 1.5 lions/1000km2, most hunting areas experienced an increase in lion harvest rate, although that increase was of lower magnitude for hunting areas with higher initial hunting intensity. The proportion of hunting areas that experienced a decline in lion harvest rate increased at initial hunting intensities above 1.5 lions/1000km2. In 2014, the lion population of the WAP was estimated with a spoor count at 418 (230–648) adults and sub-adult individuals, comparable to the 311 (123–498) individuals estimated in the previous 2012 spoor survey. We found no significant lion spoor density differences between national parks and hunting areas. Hunting areas with higher mean harvest rates did not have lower lion densities. The ratio of large adult males, females and sub-adults was similar between the national parks and the hunting areas. These results suggested that the lion population was not significantly affected by hunting in the WAP. We concluded that a quota of 1 lion/1000km2 would be sustainable for the WAP. Based on our results, an import embargo on lion trophies from the WAP would not be justified. It could ruin the incentive of local actors to conserve lions in hunting areas, and lead to a drastic reduction of lion range in West Africa. PMID:27182985

  7. Ozone production in the upper troposphere over West Africa: sensitivity to non-methane hydrocarbons under convective conditions

    NASA Astrophysics Data System (ADS)

    Bechara, Joelle; Borbon, Agnès.; Aumont, Bernard; Jambert, Corinne; Perros, Pascal

    2010-05-01

    Tropical deep convection is an efficient pathway of transporting up to the upper troposphere (UT) trace gas species such as volatile organic compounds (VOC). However, the impact of convective transport on UT composition and chemistry is still poorly characterized. The chemical impact of convection on the tropical UT over West Africa was studied during the AMMA Special Observation Period in August 2006 (SOP 2a2). Experimental strategy consisted in sampling at altitudes between 0 and 12 km downwind of Mesoscale Convective Systems (MCS) and at cloud base on-board the two French aircrafts, the ATR-42 and the French Falcon-20. Previous work pointed out that tropical deep convection in West Africa is efficient and is responsible with fast transport of VOC into the UT even the most reactive (isoprene) in less than one hour (Bechara et al., 2009). Here, we have investigated the impact of VOC precursors on ozone production. For that purpose, box modelling was implemented with the Master Chemical Mechanism scheme to simulate ozone variability in the upper troposphere downwind convection. The model is initialized with observed trace gases concentrations (NMHC, NOx, NOy, CO...) collected during the AMMA SOP 2a2 airborne campaign. Results show a positive ozone production several days downwind convective clouds at an average rate of 4 ppb/day. They confirm that UT ozone production is sensitive to NOx. Surprisingly, the sensitivity of NMHC initial concentrations on ozone production is negative. Indeed, an increase in NMHC favours PAN (peroxyacetyl nitrate) formation and thus decreases ozone production. The implication on ozone budget in the upper troposphere is crucial.

  8. Consistent rainy season changes predicted from Regional Climate Models ensembles indicate threats to crop production in West Africa

    NASA Astrophysics Data System (ADS)

    Wisser, D.; Sylla, M. B.; Ibrahim, B.

    2014-12-01

    Agricultural production in West Africa is extremely vulnerable to precipitation change and variability. Designing adaptation options to anticipate these changes in precipitation requires robust predicting future climate conditions. Output from Global Circulation Models (GCMs) is too coarse to be used directly to assess regional and high order statistics changes. We use output from a set of Regional Climate Models that dynamically downscale CMIP5 GCMs and analyze mid-century changes in the characteristics of precipitation in West Africa over cropland areas. For each RCM/GCM combinations, we compared predicted precipitation for the period 2035-2065 under the RCP 8.5 scenario with its historical reconstruction of 1975-2005. The mean changes emerging from an analysis of the ensemble of 15 RCM/GCM combinations suggest moderate (~3%) increases in annual precipitation,a very consistent delay in the onset of the rainy season (1 to 4 days from South to North) and no consistent change in the ending of the rainy season. This illustrates a general shortening of the rainy season. An analysis of dry spells (periods of consecutive days with less than 5 mm) for a durations of between 5 and 15 days revealed an increased probability of experiencing longer dry spells during the rainy season in the future climate, coupled with a general intensification of precipitation. This finding was consistent across all models. Our analysis promotes regional prioritization of adaptation measures to the changes in precipitation characteristics that could potentially have detrimental effects on crop yields while also affecting water resources management, species distribution, and others sectors. Increased storage of water, in combination with supplemental irrigation can be an important mechanism for adapting to the effects for regional precipitation changes on crop yield.

  9. Heterogeneity in District-Level Transmission of Ebola Virus Disease during the 2013-2015 Epidemic in West Africa.

    PubMed

    Krauer, Fabienne; Gsteiger, Sandro; Low, Nicola; Hansen, Christian H; Althaus, Christian L

    2016-07-01

    The Ebola virus disease (EVD) epidemic in West Africa in 2013-2015 spread heterogeneously across the three hardest-hit countries Guinea, Liberia and Sierra Leone and the estimation of national transmission of EVD provides little information about local dynamics. To investigate district-level transmissibility of EVD, we applied a statistical modelling approach to estimate the basic reproduction number (R0) for each affected district and each country using weekly incident case numbers. We estimated growth rates during the early exponential phase of the outbreak using exponential regression of the case counts on the first eight weeks since onset. To take into account the heterogeneity between and within countries, we fitted a mixed effects model and calculated R0 based on the predicted individual growth rates and the reported serial interval distribution. At district level, R0 ranged from 0.36 (Dubréka) to 1.72 (Beyla) in Guinea, from 0.53 (Maryland) to 3.37 (Margibi) in Liberia and from 1.14 (Koinadugu) to 2.73 (Western Rural) in Sierra Leone. At national level, we estimated an R0 of 0.97 (95% CI 0.77-1.18) for Guinea, 1.26 (95% CI 0.98-1.55) for Liberia and 1.66 (95% CI 1.32-2.00) for Sierra Leone. Socio-demographic variables related to urbanisation such as high population density and high wealth index were found positively associated with R0 suggesting that the consequences of fast urban growth in West Africa may have contributed to the increased spread of EVD. PMID:27434164

  10. Embargo on Lion Hunting Trophies from West Africa: An Effective Measure or a Threat to Lion Conservation?

    PubMed

    Bouché, Philippe; Crosmary, William; Kafando, Pierre; Doamba, Benoit; Kidjo, Ferdinand Claude; Vermeulen, Cédric; Chardonnet, Philippe

    2016-01-01

    The W-Arly-Pendjari (WAP) ecosystem, shared among Benin, Burkina Faso and Niger, represents the last lion stronghold of West Africa. To assess the impact of trophy hunting on lion populations in hunting areas of the WAP, we analyzed trends in harvest rates from 1999 to 2014. We also investigated whether the hunting areas with higher initial hunting intensity experienced steeper declines in lion harvest between 1999 and 2014, and whether lion densities in hunting areas were lower than in national parks. Lion harvest rate remained overall constant in the WAP. At initial hunting intensities below 1.5 lions/1000km2, most hunting areas experienced an increase in lion harvest rate, although that increase was of lower magnitude for hunting areas with higher initial hunting intensity. The proportion of hunting areas that experienced a decline in lion harvest rate increased at initial hunting intensities above 1.5 lions/1000km2. In 2014, the lion population of the WAP was estimated with a spoor count at 418 (230-648) adults and sub-adult individuals, comparable to the 311 (123-498) individuals estimated in the previous 2012 spoor survey. We found no significant lion spoor density differences between national parks and hunting areas. Hunting areas with higher mean harvest rates did not have lower lion densities. The ratio of large adult males, females and sub-adults was similar between the national parks and the hunting areas. These results suggested that the lion population was not significantly affected by hunting in the WAP. We concluded that a quota of 1 lion/1000km2 would be sustainable for the WAP. Based on our results, an import embargo on lion trophies from the WAP would not be justified. It could ruin the incentive of local actors to conserve lions in hunting areas, and lead to a drastic reduction of lion range in West Africa. PMID:27182985

  11. Heterogeneity in District-Level Transmission of Ebola Virus Disease during the 2013-2015 Epidemic in West Africa

    PubMed Central

    Gsteiger, Sandro; Low, Nicola; Hansen, Christian H.; Althaus, Christian L.

    2016-01-01

    The Ebola virus disease (EVD) epidemic in West Africa in 2013–2015 spread heterogeneously across the three hardest-hit countries Guinea, Liberia and Sierra Leone and the estimation of national transmission of EVD provides little information about local dynamics. To investigate district-level transmissibility of EVD, we applied a statistical modelling approach to estimate the basic reproduction number (R0) for each affected district and each country using weekly incident case numbers. We estimated growth rates during the early exponential phase of the outbreak using exponential regression of the case counts on the first eight weeks since onset. To take into account the heterogeneity between and within countries, we fitted a mixed effects model and calculated R0 based on the predicted individual growth rates and the reported serial interval distribution. At district level, R0 ranged from 0.36 (Dubréka) to 1.72 (Beyla) in Guinea, from 0.53 (Maryland) to 3.37 (Margibi) in Liberia and from 1.14 (Koinadugu) to 2.73 (Western Rural) in Sierra Leone. At national level, we estimated an R0 of 0.97 (95% CI 0.77–1.18) for Guinea, 1.26 (95% CI 0.98–1.55) for Liberia and 1.66 (95% CI 1.32–2.00) for Sierra Leone. Socio-demographic variables related to urbanisation such as high population density and high wealth index were found positively associated with R0 suggesting that the consequences of fast urban growth in West Africa may have contributed to the increased spread of EVD. PMID:27434164

  12. Projecting Future Land Use Changes in West Africa Driven by Climate and Socioeconomic Factors: Uncertainties and Implications for Adaptation

    NASA Astrophysics Data System (ADS)

    Wang, G.; Ahmed, K. F.; You, L.

    2015-12-01

    Land use changes constitute an important regional climate change forcing in West Africa, a region of strong land-atmosphere coupling. At the same time, climate change can be an important driver for land use, although its importance relative to the impact of socio-economic factors may vary significant from region to region. This study compares the contributions of climate change and socioeconomic development to potential future changes of agricultural land use in West Africa and examines various sources of uncertainty using a land use projection model (LandPro) that accounts for the impact of socioeconomic drivers on the demand side and the impact of climate-induced crop yield changes on the supply side. Future crop yield changes were simulated by a process-based crop model driven with future climate projections from a regional climate model, and future changes of food demand is projected using a model for policy analysis of agricultural commodities and trade. The impact of human decision-making on land use was explicitly considered through multiple "what-if" scenarios to examine the range of uncertainties in projecting future land use. Without agricultural intensification, the climate-induced decrease of crop yield together with increase of food demand are found to cause a significant increase in agricultural land use at the expense of forest and grassland by the mid-century, and the resulting land use land cover changes are found to feed back to the regional climate in a way that exacerbates the negative impact of climate on crop yield. Analysis of results from multiple decision-making scenarios suggests that human adaptation characterized by science-informed decision making to minimize land use could be very effective in many parts of the region.

  13. Forest-Savanna Transitions in West-Africa: The climatic imprint of bimodal distributions in vegetation cover

    NASA Astrophysics Data System (ADS)

    Dekker, Stefan; Yin, Zun; Baudena, Mara; van den Hurk, Bart; Dijkstra, Henk

    2015-04-01

    Positive land-climate feedbacks can suddenly shift the vegetation state. Observed bimodal distributions of woody cover in West Africa provide evidence that alternative ecosystem states may exist under the same precipitation regimes. Understanding the explicit climate conditions where the woody cover bimodality can exist is important to predict crucial transitions of ecosystems due to climate change. This also helps in understanding the complexity of land-climate interactions. In this study, we show that bimodality can also be observed in mean annual shortwave radiation and above ground biomass. Through conditional histogram analysis, we find that the bimodality of woody cover in West-Africa can only exist under low mean annual shortwave radiation and low above ground biomass. From our analysis we find that the mean annual precipitation is not a sufficient predictor of a potential land cover change. Indicators of climate seasonality are strongly related to the observed land cover type. However, these indicators can only demonstrate the potential occurrence of bimodality but cannot exclude the probability of bimodal vegetation distributions. Regions with high potential of land cover transitions are displayed. The result suggests for instance that the tropical forest in the Congo basin, may be unstable and shows the possibility to significantly decrease. An increase in the area covered by savanna and grass is possible, which coincides with an observed re-greening of the Sahara These findings derived from observations only, are compared with three different Dynamic Global Vegetation Models (JSBACH, LPJ-GUESSSPITFIRE and aDGVM) describing the forest, savanna, and grassland transitions. Through these comparisons we improve the understanding of the bistable behavior of savanna systems due to two main mechanisms, 1) water limitation to tree growth, and tree-grass competition for water, 2) a grass-fire feedback, which maintains both forest and savanna occurrences in mesic

  14. Quantification of uncertainties related to the regional application of a conceptual hydrological model in Benin (West Africa)

    NASA Astrophysics Data System (ADS)

    Bormann, H.; Diekkrüger, B.

    2003-04-01

    A conceptual model is presented to simulate the water fluxes of regional catchments in Benin (West Africa). The model is applied in the framework of the IMPETUS project (an integrated approach to the efficient management of scarce water resources in West Africa) which aims to assess the effects of environmental and anthropogenic changes on the regional hydrological processes and on the water availability in Benin. In order to assess the effects of decreasing precipitation and increasing human activities on the hydrological processes in the upper Ouémé valley, a scenario analysis is performed to predict possible changes. Therefore a regional hydrological model is proposed which reproduces the recent hydrological processes, and which is able to consider the changes of landscape properties.The study presented aims to check the validity of the conceptual and lumped model under the conditions of the subhumid tree savannah and therefore analyses the importance of possible sources of uncertainty. Main focus is set on the uncertainties caused by input data, model parameters and model structure. As the model simulates the water fluxes at the catchment outlet of the Térou river (3133 km2) in a sufficient quality, first results of a scenario analysis are presented. Changes of interest are the expected future decrease in amount and temporal structure of the precipitation (e.g. minus X percent precipitation during the whole season versus minus X percent precipitation in the end of the rainy season, alternatively), the decrease in soil water storage capacity which is caused by erosion, and the increasing consumption of ground water for drinking water and agricultural purposes. Resuming from the results obtained, the perspectives of lumped and conceptual models are discussed with special regard to available management options of this kind of models. Advantages and disadvantages compared to alternative model approaches (process based, physics based) are discussed.

  15. Profile of South Africa

    SciTech Connect

    Fox, G.J.; Tonneson, L.C.

    1996-08-01

    A broad overview of the Republic of South Africa`s nuclear energy program is presented. Economic aspects are the main focus of the article, and numerical data is provided for electricity generation and use and uranium production. The role of the molecular laser isotope process for enrichment is discussed. The research reactor program, waste disposal and decommissioning, mining history, uranium production, and nonproliferation policy are other highlighted topics.

  16. Astronomy Landscape in Africa

    NASA Astrophysics Data System (ADS)

    Nemaungani, Takalani

    2015-01-01

    The vision for astronomy in Africa is embedded in the African Space Policy of the African Union in early 2014. The vision is about positioning Africa as an emerging hub for astronomy sciences and facilities. Africa recognized the need to take advantage of its natural resource, the geographical advantage of the clear southern skies and pristine sites for astronomy. The Pan African University (PAU) initiative also presents an opportunity as a post-graduate training and research network of university nodes in five regions of Africa and supported by the African Union. The Southern African node based in South Africa concentrates on space sciences which also includes astronomy. The PAU aims to provide the opportunity for advanced graduate training and postgraduate research to high-performing African students. Objectives also include promoting mobility of students and teachers and harmonizing programs and degrees.A number of astronomy initiatives have burgeoned in the Southern African region and these include the Southern Africa Largest Optical Telescope (SALT), HESS (High Energy Stereoscopic System), the SKA (Square Kilometre Array) and the AVN (African Very Long Baseline Interferometer Network). There is a growing appetite for astronomy sciences in Africa. In East Africa, the astronomy community is well organized and is growing - the East African Astronomical society (EAAS) held its successful fourth annual conference since 2010 on 30 June to 04 July 2014 at the University of Rwanda. Centred around the 'Role of Astronomy in Socio-Economic Transformation,' this conference aimed at strengthening capacity building in Astronomy, Astrophysics and Space Science in general, while providing a forum for astronomers from the region to train young and upcoming scientists.

  17. Usutu virus in Africa.

    PubMed

    Nikolay, Birgit; Diallo, Mawlouth; Boye, Cheikh Saad Bouh; Sall, Amadou Alpha

    2011-11-01

    Usutu virus (USUV) was discovered in South Africa in 1959. Since then, it has been reported in several African countries including Senegal, Central African Republic, Nigeria, Uganda, Burkina Faso, Cote d'Ivoire, and Morocco. In 2001, USUV has been identified for the first time outside of Africa, namely in Europe, where it caused a significant mortality among blackbirds in Vienna, Austria. In 2009, the first two human cases of USUV infection in Europe have been reported in Italy, causing encephalitis in immunocompromised patients. The host range in Africa includes mainly Culex mosquitoes, birds, and also humans with one benign and one severe case. Given its role as a potential human pathogen and the similar appearance compared with other emerging arboviruses, it is essential to investigate the natural history and ecology of USUV in Africa. In this regard, we review the emergence of USUV in Africa, summarizing data about isolations, host range, and potential vectors, which should help to improve our understanding of the factors underlying the circulation of USUV in Europe and Africa. PMID:21767160

  18. Seroprevalence of HHV-8, CMV, and EBV among the general population in Ghana, West Africa

    PubMed Central

    Adjei, Andrew A; Armah, Henry B; Gbagbo, Foster; Boamah, Isaac; Adu-Gyamfi, Clement; Asare, Isaac

    2008-01-01

    Background Human herpesvirus 8 (HHV-8), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are prevalent in Africa, but less common elsewhere and the modes of transmission are still subject to debate. Generally, they rarely cause disease in the immunocompetent host but are highly oncogenic when associated with immunosuppression. Although the high prevalence of HHV-8, CMV and EBV has been well documented in Africa, such data are sparse from Ghana. Methods Serum samples from 3275 HIV-seronegative healthy blood donors and 250 HIV-AIDS patients were tested for antibodies specific for HHV-8, CMV and EBV by IgG ELISA assays. Differences in seropositivity rates by gender and age were evaluated using the Chi-square test with Yates correction. Results Of the 3275 HIV-seronegative healthy blood donors tested, 2573 (78.6%) were males and 702 (21.4%) were females, with ages ranging from 18 to 65 years (median 32.6; mean 31.2; mode 30). Of the 250 HIV-AIDS patients tested, 140 (56%) were males and 110 (44%) were females, with ages ranging from 17 to 64 years (median 30.8; mean 30.3; mode 28). Among the HIV-seronegative healthy blood donors, overall seroprevalence of HHV-8, CMV and EBV was 23.7%, 77.6% and 20.0%, respectively. Among the HIV-AIDS patients, overall seroprevalence of HHV-8, CMV and EBV was 65.6%, 59.2% and 87.2%, respectively. The seroprevalence of HHV-8 (p < 0.005) and EBV (p < 0.001) was statistically significantly higher in HIV-AIDS patients compared to HIV-seronegative healthy blood donors. There was no statistically significant difference (p = 0.24) between CMV seroprevalence in HIV-AIDS patients and HIV-seronegative healthy blood donors. Age and gender were not independent determinants (p > 0.05) for all three infections among HIV-seronegative healthy blood donors and HIV-AIDS patients in Ghana. Conclusion The results presented herein indicate that HHV-8, CMV and EBV infections are hyperendemic in both HIV-seronegative and HIV-seropositive Ghanaians, and

  19. Mesoscale convective complexes in Africa

    SciTech Connect

    Laing, A.G.; Fritsch, J.M. )

    1993-08-01

    Digitized full-disk infrared satellite imagery from the European geostationary satellite (Meteosat) for 1986 and 1987 was used to construct a climatology of mesoscale convective complexes (MCCs) in Africa. One hundred ninety-five systems formed over Africa and its near vicinity during the two-year study period. From this database, characteristics of Africa MCCs were calculated. The results indicate that these MCCs display many of the same characteristics as those found in the Americas, the Indian subcontinent, and the western Pacific region. The systems are predominantly nocturnal and tend to form over or in the immediate vicinity of land. The average lifetime of African MCCs is about 11.5 h. The size distributions of the African systems are also extremely similar to those of the Americas, the Indian subcontinent, and the western Pacific region with most systems exhibiting areas between 2 [times] 10[sup 5] and 3 [times] 10[sup 5] km[sup 2]. The monthly frequency distribution of African systems indicates that peak activity tends to occur during the period of most intense insolation. Like the MCCs in the western Pacific region and the Americas, the African MCCs tend to propagate toward the low-level high-[theta][sub e] air that feeds the convective systems. Systems over northern Africa moved toward the west-southwest, with a few developing into tropical cyclones over the Atlantic. Systems over southeastern Africa generally moved toward the northeast and east. It is concluded that the satellite-observed systems over Africa are essentially the same phenomena as the MCC populations observed over the Americas, the Indian monsoon region, and the western Pacific region. In addition, the large number of MCCs found worldwide (approximately 300-400 per year) indicate that they may be significant contributors to the global tropospheric energy budget and hydrological cycle. 46 refs., 9 figs., 1 tab.

  20. An investigation of MAGSAT and complementary data emphasizing precambrian shields and adjacent areas of West Africa and South America

    NASA Technical Reports Server (NTRS)

    Hastings, D. A. (Principal Investigator)

    1981-01-01

    Accomplishments with regard to the mapping and analysis of MAGSAT data for the investigation of correlations between the magnetic field characteristics of South American and African shields are reported. Significant results in the interpretation of the global total-field anomalies and the anomaly patterns of Africa and South America are discussed. The central position of the Brazilian shield tends to form a negative total-field anomaly, consistent with findings for shields in equatorial Africa. Sedimentary sequences in the Amazon basin and in the Rio de Janeiro-Sao Paolo areas exhibit positive anomalies, also consistent with equatorial Africa. Results for the Caribbean Sea and Guyana regions are also described.

  1. An investigation of MAGSAT and complementary data emphasizing precambrian shields and adjacent areas of West Africa and South America

    NASA Technical Reports Server (NTRS)

    Hastings, D. A. (Principal Investigator)

    1982-01-01

    The problems associated with the use of an interactive magnetic modeling program are reported and a publication summarizing the MAGSAT anomaly results for Africa and the possible tectonic associations of these anomalies is provided. An overview of the MAGSAT scalar anomaly map for Africa suggested a correlation of MAGSAT anomalies with major crustal blocks of uplift or depression and different degrees of regional metamorphism. The strongest MAGSAT anomalies in Africa are closely correlated spatially with major tectonic features. Results indicate that the Bangui anomaly may be caused by a central old Precambrian shield, flanked to the north and south by two relatively young sedimentary basins.

  2. Assessment of the Contamination of Some Foodstuffs by Escherichia coli O157 in Benin, West Africa

    PubMed Central

    Bankole, Honoré Sourou; Dougnon, Victorien Tamègnon; Johnson, Roch Christian; Dougnon, T. J.; Yehouenou, Boniface; Kougblenou, Sylvain; Agonsa, Maxime; Legonou, Magloire; Dadie, Thomas

    2014-01-01

    Escherichia coli O157 is a pathogenic bacterium causing haemorrhagic colitis. It represents a serious public health problem in Northern America and Europe, which can plague Africa. Most cases of mentioned poisoning were related to contaminated meat products and vegetables. The present work aimed to estimate the prevalence of E. coli O157 in meat and vegetables in Benin. For this purpose, 6 lots of faeces samples from pigs and 8 from cattle were collected at the farms on the outskirts of Cotonou. Similarly, 20 samples of carcasses, 20 samples of intestines and stomach, and 20 surfaces samples of slaughtering equipment were taken. Vegetables and environment materials in gardens have also been sampled for 84 samples. Bacteriological analyses revealed a percentage of contamination of 50% for pig faeces and 25% for cattle ones. All the meats from stalling parks have been contaminated by this bacterium. For vegetables, 14.6% of samples were contaminated by E. coli O157. The presence of this pathovar in animal breeding and slaughtering environment and in the gardens shows that Benin is not aware of the risks of foodborne illness associated with the consumption of contaminated products. Therefore, it urges including that germ in a systematic search during safety control of food products in Benin. PMID:25506362

  3. Genome-wide and fine-resolution association analysis of malaria in West Africa

    PubMed Central

    Jallow, Muminatou; Teo, Yik Ying; Small, Kerrin S; Rockett, Kirk A; Deloukas, Panos; Clark, Taane G; Kivinen, Katja; Bojang, Kalifa A; Conway, David J; Pinder, Margaret; Sirugo, Giorgio; Sisay-Joof, Fatou; Usen, Stanley; Auburn, Sarah; Bumpstead, Suzannah J; Campino, Susana; Coffey, Alison; Dunham, Andrew; Fry, Andrew E; Green, Angela; Gwilliam, Rhian; Hunt, Sarah E; Inouye, Michael; Jeffreys, Anna E; Mendy, Alieu; Palotie, Aarno; Potter, Simon; Ragoussis, Jiannis; Rogers, Jane; Rowlands, Kate; Somaskantharajah, Elilan; Whittaker, Pamela; Widden, Claire; Donnelly, Peter; Howie, Bryan; Marchini, Jonathan; Morris, Andrew; SanJoaquin, Miguel; Achidi, Eric Akum; Agbenyega, Tsiri; Allen, Angela; Amodu, Olukemi; Corran, Patrick; Djimde, Abdoulaye; Dolo, Amagana; Doumbo, Ogobara K; Drakeley, Chris; Dunstan, Sarah; Evans, Jennifer; Farrar, Jeremy; Fernando, Deepika; Hien, Tran Tinh; Horstmann, Rolf D; Ibrahim, Muntaser; Karunaweera, Nadira; Kokwaro, Gilbert; Koram, Kwadwo A; Lemnge, Martha; Makani, Julie; Marsh, Kevin; Michon, Pascal; Modiano, David; Molyneux, Malcolm E; Mueller, Ivo; Parker, Michael; Peshu, Norbert; Plowe, Christopher V; Puijalon, Odile; Reeder, John; Reyburn, Hugh; Riley, Eleanor M; Sakuntabhai, Anavaj; Singhasivanon, Pratap; Sirima, Sodiomon; Tall, Adama; Taylor, Terrie E; Thera, Mahamadou; Troye-Blomberg, Marita; Williams, Thomas N; Wilson, Michael; Kwiatkowski, Dominic P

    2009-01-01

    We report a genome-wide association (GWA) study of severe malaria in The Gambia. The initial GWA scan included 2,500 children genotyped on the Affymetrix 500K GeneChip, and a replication study included 3,400 children. We used this to examine the performance of GWA methods in Africa. We found considerable population stratification, and also that signals of association at known malaria resistance loci were greatly attenuated owing to weak linkage disequilibrium (LD). To investigate possible solutions to the problem of low LD, we focused on the HbS locus, sequencing this region of the genome in 62 Gambian individuals and then using these data to conduct multipoint imputation in the GWA samples. This increased the signal of association, from P = 4 × 10−7 to P = 4 × 10−14, with the peak of the signal located precisely at the HbS causal variant. Our findings provide proof of principle that fine-resolution multipoint imputation, based on population-specific sequencing data, can substantially boost authentic GWA signals and enable fine mapping of causal variants in African populations. PMID:19465909

  4. Intra-seasonal variability and predictability over West and Central Africa in northern spring (Invited)

    NASA Astrophysics Data System (ADS)

    Janicot, S.; Kamsu-Tamo, P.; Lenouo, A.; Monkam, D.

    2013-12-01

    The main objective of this study is to characterize the intra-seasonal variability of precipitation and convection over the Guinean coast and Central Africa during the spring season March-June. The data used cover the period 1998-2010 and are derived from satellite products for rainfall (TRMM 3B42) and convection (NOAA OLR, CLAUS Brightness Temperature), and ERA-Interim reanalyses to characterize the associated atmospheric patterns. Three main periodicities have been detected at 3-8-day, 8-22-day and 20-90-day, by a Singular Spectral Analysis applied to an OLR index averaged over the Guinean Coast. Both three indices represent a homogeneous convective activity propagating eastward over the Guinean Coast from the western equatorial Atlantic to the equatorial Indian basin. Space-time spectral decompositions show that these modes are significantly controlled by convectively-coupled Kelvin wave dynamics. In this presentation the 8-22-day mode will be detailed. Their medium-range predictability (at 5, 10 and 15-day range) will be evaluated in the TIGGE (THORPEX Interactive Grand Global Ensemble) dataset over the period 2008-2012.

  5. Genome-wide and fine-resolution association analysis of malaria in West Africa.

    PubMed

    Jallow, Muminatou; Teo, Yik Ying; Small, Kerrin S; Rockett, Kirk A; Deloukas, Panos; Clark, Taane G; Kivinen, Katja; Bojang, Kalifa A; Conway, David J; Pinder, Margaret; Sirugo, Giorgio; Sisay-Joof, Fatou; Usen, Stanley; Auburn, Sarah; Bumpstead, Suzannah J; Campino, Susana; Coffey, Alison; Dunham, Andrew; Fry, Andrew E; Green, Angela; Gwilliam, Rhian; Hunt, Sarah E; Inouye, Michael; Jeffreys, Anna E; Mendy, Alieu; Palotie, Aarno; Potter, Simon; Ragoussis, Jiannis; Rogers, Jane; Rowlands, Kate; Somaskantharajah, Elilan; Whittaker, Pamela; Widden, Claire; Donnelly, Peter; Howie, Bryan; Marchini, Jonathan; Morris, Andrew; SanJoaquin, Miguel; Achidi, Eric Akum; Agbenyega, Tsiri; Allen, Angela; Amodu, Olukemi; Corran, Patrick; Djimde, Abdoulaye; Dolo, Amagana; Doumbo, Ogobara K; Drakeley, Chris; Dunstan, Sarah; Evans, Jennifer; Farrar, Jeremy; Fernando, Deepika; Hien, Tran Tinh; Horstmann, Rolf D; Ibrahim, Muntaser; Karunaweera, Nadira; Kokwaro, Gilbert; Koram, Kwadwo A; Lemnge, Martha; Makani, Julie; Marsh, Kevin; Michon, Pascal; Modiano, David; Molyneux, Malcolm E; Mueller, Ivo; Parker, Michael; Peshu, Norbert; Plowe, Christopher V; Puijalon, Odile; Reeder, John; Reyburn, Hugh; Riley, Eleanor M; Sakuntabhai, Anavaj; Singhasivanon, Pratap; Sirima, Sodiomon; Tall, Adama; Taylor, Terrie E; Thera, Mahamadou; Troye-Blomberg, Marita; Williams, Thomas N; Wilson, Michael; Kwiatkowski, Dominic P

    2009-06-01

    We report a genome-wide association (GWA) study of severe malaria in The Gambia. The initial GWA scan included 2,500 children genotyped on the Affymetrix 500K GeneChip, and a replication study included 3,400 children. We used this to examine the performance of GWA methods in Africa. We found considerable population stratification, and also that signals of association at known malaria resistance loci were greatly attenuated owing to weak linkage disequilibrium (LD). To investigate possible solutions to the problem of low LD, we focused on the HbS locus, sequencing this region of the genome in 62 Gambian individuals and then using these data to conduct multipoint imputation in the GWA samples. This increased the signal of association, from P = 4 × 10(-7) to P = 4 × 10(-14), with the peak of the signal located precisely at the HbS causal variant. Our findings provide proof of principle that fine-resolution multipoint imputation, based on population-specific sequencing data, can substantially boost authentic GWA signals and enable fine mapping of causal variants in African populations. PMID:19465909

  6. Crustal structure of Nigeria and Southern Ghana, West Africa from P-wave receiver functions

    NASA Astrophysics Data System (ADS)

    Akpan, Ofonime; Nyblade, Andrew; Okereke, Chiedu; Oden, Michael; Emry, Erica; Julià, Jordi

    2016-04-01

    We report new estimates of crustal thickness (Moho depth), Poisson's ratio and shear-wave velocities for eleven broadband seismological stations in Nigeria and Ghana. Data used for this study came from teleseismic earthquakes recorded at epicentral distances between 30° and 95° and with moment magnitudes greater than or equal to 5.5. P-wave receiver functions were modeled using the Moho Ps arrival times, H-k stacking, and joint inversion of receiver functions and Rayleigh wave group velocities. The average crustal thickness of the stations in the Neoproterozoic basement complex of Nigeria is 36 km, and 23 km for the stations in the Cretaceous Benue Trough. The crustal structure of the Paleoproterozoic Birimian Terrain, and Neoproterozoic Dahomeyan Terrain and Togo Structural Unit in southern Ghana is similar, with an average Moho depth of 44 km. Poisson's ratios for all the stations range from 0.24 to 0.26, indicating a bulk felsic to intermediate crustal composition. The crustal structure of the basement complex in Nigeria is similar to the average crustal structure of Neoproterozoic terrains in other parts of Africa, but the two Neoproterozoic terrains in southern Ghana have a thicker crust with a thick mafic lower crust, ranging in thickness from 12 to 17 km. Both the thicker crust and thick mafic lower crustal section are consistent with many Precambrian suture zones, and thus we suggest that both features are relict from the collisional event during the formation of Gondwana.

  7. Improving malaria control in West Africa: interruption of transmission as a paradigm shift.

    PubMed

    Doumbia, Seydou O; Ndiaye, Daouda; Koita, Ousmane A; Diakité, Mahamadou; Nwakanma, Davis; Coulibaly, Mamadou; Traoré, Sekou F; Keating, Joseph; Milner, Danny A; Ndiaye, Jean-Louis; Sene, Papa Diogoye; Ahouidi, Ambroise; Dieye, Tandakha N; Gaye, Oumar; Okebe, Joseph; Ceesay, Serign J; Ngwa, Alfred; Oriero, Eniyou C; Konaté, Lassana; Sy, Ngayo; Jawara, Musa; Faye, Ousmane; Kéita, Moussa; Cissé, Moussa; Sogoba, Nafomon; Poudiougou, Belco; Diawara, Sory; Sangaré, Lansana; Coulibaly, Tinzana; Seck, Ibrahima; Abubakar, Ismaela; Gomis, Jules; Mather, Frances J; Sissako, Aliou; Diarra, Ayouba; Kandeh, Balla; Whalen, Christopher; Moyer, Brian; Nnedu, Obinna; Thiero, Oumar; Bei, Amy K; Daniels, Rachel; Miura, Kazutoyo; Long, Carole A; Fairhurst, Rick M; Duraisingh, Manoj; Muskavitch, Marc A T; D'Alessandro, Umberto; Conway, David J; Volkman, Sarah K; Valim, Clarissa; Wirth, Dyann F; Krogstad, Donald J

    2012-03-01

    With the paradigm shift from the reduction of morbidity and mortality to the interruption of transmission, the focus of malaria control broadens from symptomatic infections in children ≤5 years of age to include asymptomatic infections in older children and adults. In addition, as control efforts intensify and the number of interventions increases, there will be decreases in prevalence, incidence and transmission with additional decreases in morbidity and mortality. Expected secondary consequences of these changes include upward shifts in the peak ages for infection (parasitemia) and disease, increases in the ages for acquisition of antiparasite humoral and cellular immune responses and increases in false-negative blood smears and rapid diagnostic tests. Strategies to monitor these changes must include: (1) studies of the entire population (that are not restricted to children ≤5 or ≤10 years of age), (2) study sites in both cities and rural areas (because of increasing urbanization across sub-Saharan Africa) and (3) innovative strategies for surveillance as the prevalence of infection decreases and the frequency of false-negative smears and rapid diagnostic tests increases. PMID:22142790

  8. Risk perceptions of MSF healthcare workers on the recent Ebola epidemic in West Africa.

    PubMed

    Sridhar, S; Brouqui, P; Fontaine, J; Perivier, I; Ruscassier, P; Gautret, P; Régner, I

    2016-07-01

    Healthcare workers (HCW) in general are considered to be at high risk during epidemics. Their training for Ebola provided by Médecins sans frontières (MSF) is presently based on imparting factual information, which does not necessarily translate into knowledge or appropriate practices. We aimed to understand the importance of risk perception during training. A total of 130 MSF-trained HCW traveling to Africa during the Ebola epidemic of 2014-2015 participated in this longitudinal cohort study. Their baseline knowledge was good but did not significantly increase after training except for minor symptoms, case fatality rate and wearing personal protective equipment as a preventive measure. Additionally, they underestimated their likelihood for contracting Ebola compared to their colleagues of same age and sex, and despite their high-risk status, they showed little concern about contracting Ebola during their mission. Our findings suggest that the use of individualized risk feedback during training in appraising erroneous perceptions will increase adherence to preventive measures. PMID:27330816

  9. Diagnosing GCM errors over West Africa using relaxation experiments. Part II: intraseasonal variability and African easterly waves

    NASA Astrophysics Data System (ADS)

    Pohl, Benjamin; Douville, Hervé

    2011-10-01

    A near-global grid-point nudging of the Arpege-Climat atmospheric General Circulation Model towards ECMWF reanalyses is used to diagnose the regional versus remote origin of the summer model biases and variability over West Africa. First part of this study revealed a limited impact on the monsoon climatology compared to a control experiment without nudging, but a significant improvement of interannual variability, although the amplitude of the seasonal anomalies remained underestimated. Focus is given here on intraseasonal variability of monsoon rainfall and dynamics. The reproducible part of these signals is investigated through 30-member ensemble experiments computed for the 1994 rainy season, a year abnormally wet over the Sahel but representative of the model systematic biases. In the control experiment, Arpege-Climat simulates too few rainy days that are associated with too low rainfall amounts over the central and western Sahel, in line with the seasonal dry biases. Nudging the model outside Africa tends to slightly increase the number of rainy days over the Sahel, but has little effect on associated rainfall amounts. However, results do indicate that a significant part of the monsoon intraseasonal variability simulated by Arpege-Climat is controlled by lateral boundary conditions. Parts of the wet/dry spells over the Sahel occur in phase in the 30 members of the nudging experiment, and are therefore embedded in larger-scale variability patterns. Inter-member spread is however not constant across the selected summer season. It is partly controlled by African Easterly Waves, which show dissimilar amplitude from one member to another, but a coherent phasing in all members. A lowpass filtering of the nudging fields suggests that low frequency variations in the lateral boundary conditions can lead to eastward extensions of the African Easterly Jet, creating a favorable environment for easterly waves, while high frequency perturbations seem to control their

  10. Condom use and associated factors among men who have sex with men in Togo, West Africa

    PubMed Central

    Bakai, Tchaa Abalo; Ekouevi, Didier Koumavi; Tchounga, Boris Kévin; Balestre, Eric; Afanvi, Kossivi Agbélénko; Goilibe, Kariyiare Benjamin; Kassankogno, Yao; Pitche, Vincent Palokinam

    2016-01-01

    Introduction In 2011, the prevalence of HIV among men who have sex with men (MSM) in Togo was estimated at 19.6% compared to 3.4% in the general population. This study aimed to describe condom use and associated factors among MSM in Togo. Methods In 2011, a cross-sectional survey was conducted using the snowball sampling method among MSM in Togo. This study enrolled MSM aged 18 years and above who reported having sexual contact with other men within the last 30 days. A standardized survey form was used for data collection, and multivariate analyses were performed. Results A total of 724 MSM were included in this study. The median age was 25 years [22-28], 90.3% had at least a secondary school level. The sexual practices during the last sexual encounter with another man included: insertive anal sex (62.2%), receptive anal sex (56.6%), oral sex (33.8%) and oral-anal sex (8.6%). A condom was used during the last insertive and receptive anal encounters in 78.4% and 81.2% of the time, respectively. In multivariate analysis, condom use was positively associated with previous participation in HIV/STD prevention activities (aOR=1.72; 95% CI=[1.09-2.71]), with the consideration of the last sexual partner as a casual one (aOR=1.87; 95% CI=[1.24-2.82]) and with having at least a secondary school level (aOR=2.40; 95% CI=[1.22-4.69]). Conclusion One out of five MSM did not use a condom during the last anal encounter with another man. HIV prevention programs in Africa should develop specific interventions targeting MSM to reduce the incidence of HIV in this hidden population. PMID:27279945

  11. Kanda fault: A major seismogenic element west of the Rukwa Rift (Tanzania, East Africa)

    NASA Astrophysics Data System (ADS)

    Vittori, Eutizio; Delvaux, Damien; Kervyn, François

    1997-09-01

    The NW-SE trending Rukwa Rift, part of the East African Rift System, links the approximately N-S oriented Tanganyika and Nyassa (Malawi) depressions. The rift has a complex half-graben structure, generally interpreted as the result of normal and strike-slip faulting. Morphological and structural data (e.g. fault scarps, faceted spurs, tilting of Quaternary continental deposits, volcanism, seismicity) indicate Late Quaternary activity within the rift. In 1910 an earthquake of M = 7.4 (historically the largest felt in Africa) struck the Rukwa region. The epicentre was located near the Kanda fault, which affects the Ufipa plateau, separating the Rukwa depression from the south-Tanganyika basin. The geomorphic expression of the Kanda fault is a prominent fresh-looking scarp more than 180 km long, from Tunduma to north of Sumbawanga, that strikes roughly NW-SE, and dips constantly northeast. No evidence for horizontal slip was observed. Generally, the active faulting affects a very narrow zone, and is only locally distributed over several subparallel scarps. The height of the scarp progressively decreases towards the northwest, from about 40-50 m to a few metres north of Sumbawanga. Faulted lacustrine deposits exposed in a road cut near Kaengesa were dated as 8340 ± 700 and 13 600 ± 1240 radiocarbon years. These low-energy deposits now hang more than 15 m above the present-day valley floor, suggesting rapid uplift during the Holocene. Due to its high rate of activity in very recent times, the Kanda Fault could have produced the 1910 earthquake. Detailed paleoseismological studies are used to characterize its recent history. In addition, the seismic hazard posed by this fault, which crosses the fast growing town of Sumbawanga, must be seriously considered in urban planning.

  12. Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa

    PubMed Central

    Beckley, Carl S.; Shaban, Salisu; Palmer, Guy H.; Hudak, Andrew T.; Noh, Susan M.; Futse, James E.

    2016-01-01

    Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc) were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B. bigemina prevalence

  13. Treatment uptake by individuals infected with Plasmodium falciparum in rural Gambia, West Africa.

    PubMed Central

    von Seidlein, Lorenz; Clarke, Sian; Alexander, Neâl; Manneh, Fandingding; Doherty, Tom; Pinder, Margaret; Walraven, Gijs; Greenwood, Brian

    2002-01-01

    OBJECTIVE: To find out what proportion of Plasmodium falciparum infections are treated in rural Gambia. METHODS: Subjects from four villages in the Gambia were followed over nine months through visits to village health workers. Monthly cross-sectional malaria surveys measured the prevalence of P. falciparum infection. Linked databases were searched for treatment requests. Treated cases were individuals with parasitaemia who requested treatment during narrow or extended periods (14 or 28 days, respectively) before or after a positive blood film was obtained. FINDINGS: Parasite prevalence peaked in November 1998, when 399/653 (61%) individuals had parasitaemia. Parasite prevalence was highest throughout the study in children aged 5-10 years. Although access to treatment was better than in most of sub-Saharan Africa, only 20% of infected individuals sought medical treatment up to 14 days before or after a positive blood film. Within two months of a positive blood film, 199/726 (27%) individuals with parasitaemia requested treatment. Despite easy access to health care, less than half (42%) of those with parasite densities consistent with malaria attacks (5000/ l) requested treatment. High parasite density and infection during October-November were associated with more frequent treatment requests. Self-treatment was infrequent in study villages: in 3/120 (2.5%) households antimalarial drugs had been used in the preceding malaria season. CONCLUSION: Many P. falciparum infections may be untreated because of their subclinical nature. Intermittent presumptive treatment may reduce morbidity and mortality. It is likely that not all untreated infections were asymptomatic. Qualitative research should explore barriers to treatment uptake, to allow educational interventions to be planned. PMID:12471399

  14. Aflatoxin Exposure and Viral Hepatitis in the Etiology of Liver Cirrhosis in The Gambia, West Africa

    PubMed Central

    Kuniholm, Mark H.; Lesi, Olufunmilayo A.; Mendy, Maimuna; Akano, Aliu O.; Sam, Omar; Hall, Andrew J.; Whittle, Hilton; Bah, Ebrima; Goedert, James J.; Hainaut, Pierre; Kirk, Gregory D.

    2008-01-01

    Background Cirrhosis of the liver is thought to be a major cause of morbidity and mortality in sub-Saharan Africa, but few controlled studies on the etiology of cirrhosis have been conducted in this region. Objectives We aimed to elucidate the association between environmental and infectious exposures and cirrhosis in The Gambia. Methods Ninety-seven individuals were diagnosed with cirrhosis using a validated ultrasound scoring system and were compared with 397 controls. Participants reported demographic and food frequency information. Blood samples were tested for hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), hepatitis C virus (HCV) antibody, HCV RNA, and the aflatoxin-associated 249ser TP53 mutation. Results HBsAg seropositivity was associated with a significant increase in risk of cirrhosis [odds ratio (OR) = 8.0; 95% confidence interval (CI), 4.4–14.7] as was the presence of HBeAg (OR = 10.3; 95% CI, 2.0–53.9) and HCV infection (OR = 3.3; 95% CI, 1.2–9.5). We present novel data that exposure to aflatoxin, as assessed both by high lifetime groundnut (peanut) intake and by the presence of the 249ser TP53 mutation in plasma, is associated with a significant increase in the risk for cirrhosis (OR = 2.8; 95% CI, 1.1–7.7 and OR = 3.8; 95% CI, 1.5–9.6, respectively). Additionally, aflatoxin and hepatitis B virus exposure appeared to interact synergistically to substantially increase the risk of cirrhosis, although this was not statistically significant. Conclusions Our results suggest that the spectrum of morbidity associated with aflatoxin exposure could include cirrhosis. PMID:19057710

  15. Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa.

    PubMed

    Beckley, Carl S; Shaban, Salisu; Palmer, Guy H; Hudak, Andrew T; Noh, Susan M; Futse, James E

    2016-01-01

    Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc) were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B. bigemina prevalence

  16. Neogene desertification of Africa

    NASA Astrophysics Data System (ADS)

    Senut, Brigitte; Pickford, Martin; Ségalen, Loïc

    2009-08-01

    Throughout the Neogene, the faunas and floras in Africa recorded global climatic changes. We present an overview of Neogene desertification in Africa by tracing stable isotopes in eggshells and mammalian enamel, by faunal (changes in hypsodonty, etc.) and floral changes in sequences at the latitudinal extremities of the continent and the equator. This work reveals that desertification started in the southwest ca 17-16 Ma, much earlier than the region of the present-day Sahara (ca 8-7 Ma) and long before the deserts in East Africa (Plio-Pleistocene). A consequence of this history is that animals and plants inhabiting the South of the continent had a long period of time in which to adapt to arid, unstable climatic conditions. When parts of East Africa became arid during the Late Miocene and Plio-Pleistocene, several of these lineages expanded northwards and occupied developing arid niches before local lineages could adapt. Several of the latter became extinct, while others withdrew westwards as the tropical forest diminished in extent. It is proposed that the history of desertification in Africa was related to that of the polar ice caps (Antarctic, Arctic).

  17. Body size and form of children of predominantly black ancestry living in West and Central Africa, North and South America, and the West Indies.

    PubMed

    Spurgeon, J H; Meredith, E M; Meredith, H V

    1978-05-01

    Stature, sitting height, hip width, arm and calf circumferences and body weight have been measured in black children of Richland County, South Carolina. Lower limb height and three indices of body shape were obtained from the measurements. Sample size exceeded 200 for each of five age-sex groups representing girls and boys aged 6 years, girls and boys aged 9 years, and boys aged 11 years. Comparisons are made with findings from previous research on children of predominantly black ancestry living in west and central Africa, the West Indies, and North, Central and South America. Black children of Richland County measured during 1974--77 are taller than black children studied since 1960 in Angola, Chad, Ghana, Liberia, Nigeria, Senegal, Uganda, Anguilla, Barbados, Cuba, Guyana, Jamaica, Nevis, St. Kitts, St. Vincent, and Surinam. Children of well-to-do black families in Accra and Ibadan are no taller or heavier than black children of Richland County taken without regard to socio-economic status. In hip width, averages for Richland County black children are larger than those for children of the Hutu and Yoruba tribes; in arm girth they are larger than children of the Hutu and Tutsi tribes. Age changes and group differences are reported for hip width relative to lower limb height, and lower limb height relative to sitting height. During childhood, the hip/lower limb index decreases, and the lower limb/sitting height index increases. Almost identical hip/lower limb indices characterize black populations in Africa, Cuba, and the United States. PMID:686664

  18. High Genetic Diversity of Newcastle Disease Virus in Poultry in West and Central Africa: Cocirculation of Genotype XIV and Newly Defined Genotypes XVII and XVIII

    PubMed Central

    Snoeck, Chantal J.; Owoade, Ademola A.; Couacy-Hymann, Emmanuel; Alkali, Bello R.; Okwen, Mbah P.; Adeyanju, Adeniyi T.; Komoyo, Giscard F.; Nakouné, Emmanuel; Le Faou, Alain

    2013-01-01

    Despite rampant Newcastle disease virus (NDV) outbreaks in Africa for decades, the information about the genetic characteristics of the virulent strains circulating in West and Central Africa is still scarce. In this study, 96 complete NDV fusion gene sequences were obtained from poultry sampled in Cameroon, Central African Republic, Côte d'Ivoire, and Nigeria between 2006 and 2011. Based on rational criteria recently proposed for the classification of NDV strains into classes, genotypes, and subgenotypes, we revisited the classification of virulent strains, in particular those from West and Central Africa, leading to their grouping into genotype XIV and newly defined genotypes XVII and XVIII, each with two subgenotypes. Phylogenetic analyses revealed that several (sub)genotypes are found in almost every country. In Cameroon, most strains were related to vaccine strains, but a single genotype XVII strain was also found. Only three highly similar genotype XVII strains were detected in Central African Republic. Subgenotypes XVIIa, XVIIIa, and XVIIIb cocirculated in Côte d'Ivoire, while subgenotypes XIVa, XIVb, XVIIa, XVIIb, and XVIIIb were found in Nigeria. While these genotypes are so far geographically restricted, local and international trade of domestic and exotic birds may lead to their spread beyond West and Central Africa. A high genetic diversity, mutations in important neutralizing epitopes paired with suboptimal vaccination, various levels of clinical responses of poultry and wild birds to virulent strains, strains with new cleavage sites, and other genetic modifications found in these genotypes tend to undermine and complicate NDV management in Africa. PMID:23658271

  19. WASCAL - West African Science Service Center on Climate Change and Adapted Land Use Regional Climate Simulations and Land-Atmosphere Simulations for West Africa at DKRZ and elsewhere

    NASA Astrophysics Data System (ADS)

    Hamann, Ilse; Arnault, Joel; Bliefernicht, Jan; Klein, Cornelia; Heinzeller, Dominikus; Kunstmann, Harald

    2014-05-01

    Changing climate and hydro-meteorological boundary conditions are among the most severe challenges to Africa in the 21st century. In particular West Africa faces an urgent need to develop effective adaptation and mitigation strategies to cope with negative impacts on humans and environment due to climate change, increased hydro-meteorological variability and land use changes. To help meet these challenges, the German Federal Ministry of Education and Research (BMBF) started an initiative with institutions in Germany and West African countries to establish together a West African Science Service Center on Climate Change and Adapted Land Use (WASCAL). This activity is accompanied by an establishment of trans-boundary observation networks, an interdisciplinary core research program and graduate research programs on climate change and related issues for strengthening the analytical capabilities of the Science Service Center. A key research activity of the WASCAL Competence Center is the provision of regional climate simulations in a fine spatio-temporal resolution for the core research sites of WASCAL for the present and the near future. The climate information is needed for subsequent local climate impact studies in agriculture, water resources and further socio-economic sectors. The simulation experiments are performed using regional climate models such as COSMO-CLM, RegCM and WRF and statistical techniques for a further refinement of the projections. The core research sites of WASCAL are located in the Sudanian Savannah belt in Northern Ghana, Southern Burkina Faso and Northern Benin. The climate in this region is semi-arid with six rainy months. Due to the strong population growth in West Africa, many areas of the Sudanian Savannah have been already converted to farmland since the majority of the people are living directly or indirectly from the income produced in agriculture. The simulation experiments of the Competence Center and the Core Research Program are

  20. Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA

    NASA Astrophysics Data System (ADS)

    Reeves, C. E.; Formenti, P.; Afif, C.; Ancellet, G.; Attie, J.-L.; Bechara, J.; Borbon, A.; Cairo, F.; Coe, H.; Crumeyrolle, S.; Fierli, F.; Flamant, C.; Gomes, L.; Hamburger, T.; Lambert, C.; Law, K. S.; Mari, C.; Matsuki, A.; Methven, J.; Mills, G. P.; Minikin, A.; Murphy, J. G.; Nielsen, J. K.; Oram, D. E.; Parker, D. J.; Richter, A.; Schlager, H.; Schwarzenboeck, A.; Thouret, V.

    2010-03-01

    During June, July and August 2006 five aircraft took part in a campaign over West Africa to observe the aerosol content and chemical composition of the troposphere and lower stratosphere as part of the African Monsoon Multidisciplinary Analysis (AMMA) project. These are the first such measurements in this region during the monsoon period. In addition to providing an overview of the tropospheric composition, this paper provides a description of the measurement strategy (flights performed, instrumental payloads, wing-tip to wing-tip comparisons) and points to some of the important findings discussed in more detailed in other papers in this special issue. The ozone data exhibits an "S" shaped vertical profile which appears to result from significant losses in the lower troposphere due to rapid deposition to forested areas and photochemical destruction in the moist monsoon air, and convective uplift of O3-poor air to the upper troposphere. This profile is disturbed, particularly in the south of the region, by the intrusions in the lower and middle troposphere of air from the Southern Hemisphere impacted by biomass burning. Comparisons with longer term data sets suggest the impact of these intrusions on West Africa in 2006 was greater than in other recent wet seasons. There is evidence for net photochemical production of ozone in these biomass burning plumes as well as in urban plumes, in particular that from Lagos, convective outflow in the upper troposphere and in boundary layer air affected by nitrogen oxide emissions from recently wetted soils. This latter effect, along with enhanced deposition to the forested areas, contributes to a latitudinal gradient of ozone in the lower troposphere. Biogenic volatile organic compounds are also important in defining the composition both for the boundary layer and upper tropospheric convective outflow. Mineral dust was found to be the most abundant and ubiquitous aerosol type in the atmosphere over Western Africa. Data collected

  1. Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA

    NASA Astrophysics Data System (ADS)

    Reeves, C. E.; Formenti, P.; Afif, C.; Ancellet, G.; Attié, J.-L.; Bechara, J.; Borbon, A.; Cairo, F.; Coe, H.; Crumeyrolle, S.; Fierli, F.; Flamant, C.; Gomes, L.; Hamburger, T.; Jambert, C.; Law, K. S.; Mari, C.; Jones, R. L.; Matsuki, A.; Mead, M. I.; Methven, J.; Mills, G. P.; Minikin, A.; Murphy, J. G.; Nielsen, J. K.; Oram, D. E.; Parker, D. J.; Richter, A.; Schlager, H.; Schwarzenboeck, A.; Thouret, V.

    2010-08-01

    During June, July and August 2006 five aircraft took part in a campaign over West Africa to observe the aerosol content and chemical composition of the troposphere and lower stratosphere as part of the African Monsoon Multidisciplinary Analysis (AMMA) project. These are the first such measurements in this region during the monsoon period. In addition to providing an overview of the tropospheric composition, this paper provides a description of the measurement strategy (flights performed, instrumental payloads, wing-tip to wing-tip comparisons) and points to some of the important findings discussed in more detail in other papers in this special issue. The ozone data exhibits an "S" shaped vertical profile which appears to result from significant losses in the lower troposphere due to rapid deposition to forested areas and photochemical destruction in the moist monsoon air, and convective uplift of ozone-poor air to the upper troposphere. This profile is disturbed, particularly in the south of the region, by the intrusions in the lower and middle troposphere of air from the southern hemisphere impacted by biomass burning. Comparisons with longer term data sets suggest the impact of these intrusions on West Africa in 2006 was greater than in other recent wet seasons. There is evidence for net photochemical production of ozone in these biomass burning plumes as well as in urban plumes, in particular that from Lagos, convective outflow in the upper troposphere and in boundary layer air affected by nitrogen oxide emissions from recently wetted soils. This latter effect, along with enhanced deposition to the forested areas, contributes to a latitudinal gradient of ozone in the lower troposphere. Biogenic volatile organic compounds are also important in defining the composition both for the boundary layer and upper tropospheric convective outflow. Mineral dust was found to be the most abundant and ubiquitous aerosol type in the atmosphere over Western Africa. Data

  2. Processes Underpinning Development and Maintenance of Diversity in Rice in West Africa: Evidence from Combining Morphological and Molecular Markers

    PubMed Central

    Maat, Harro; Richards, Paul; Struik, Paul C.

    2014-01-01

    We assessed the interplay of artificial and natural selection in rice adaptation in low-input farming systems in West Africa. Using 20 morphological traits and 176 molecular markers, 182 farmer varieties of rice (Oryza spp.) from 6 West African countries were characterized. Principal component analysis showed that the four botanical groups (Oryza sativa ssp. indica, O. sativa ssp. japonica, O. glaberrima, and interspecific farmer hybrids) exhibited different patterns of morphological diversity. Regarding O. glaberrima, morphological and molecular data were in greater conformity than for the other botanical groups. A clear difference in morphological features was observed between O. glaberrima rices from the Togo hills and those from the Upper Guinea Coast, and among O. glaberrima rices from the Upper Guinea Coast. For the other three groups such clear patterns were not observed. We argue that this is because genetic diversity is shaped by different environmental and socio-cultural selection pressures. For O. glaberrima, recent socio-cultural selection pressures seemed to restrict genetic diversity while this was not observed for the other botanical groups. We also show that O. glaberrima still plays an important role in the selection practices of farmers and resulting variety development pathways. This is particularly apparent in the case of interspecific farmer hybrids where a relationship was found between pericarp colour, panicle attitude and genetic diversity. Farmer varieties are the product of long and complex trajectories of selection governed by local human agency. In effect, rice varieties have emerged that are adapted to West African farming conditions through genotype × environment × society interactions. The diversity farmers maintain in their rice varieties is understood to be part of a risk-spreading strategy that also facilitates successful and often serendipitous variety innovations. We advocate, therefore, that farmers and farmer varieties should

  3. Childhood cancer in Africa.

    PubMed

    Kruger, Mariana; Hendricks, Marc; Davidson, Alan; Stefan, Cristina D; van Eyssen, Ann L; Uys, Ronelle; van Zyl, Anel; Hesseling, Peter

    2014-04-01

    The majority of children with cancer live in low- and middle-income countries (LMICs) with little or no access to cancer treatment. The purpose of the paper is to describe the current status of childhood cancer treatment in Africa, as documented in publications, dedicated websites and information collected through surveys. Successful twinning programmes, like those in Malawi and Cameroon, as well as the collaborative clinical trial approach of the Franco-African Childhood Cancer Group (GFAOP), provide good models for childhood cancer treatment. The overview will hopefully influence health-care policies to facilitate access to cancer care for all children in Africa. PMID:24214130

  4. Hematology in Africa.

    PubMed

    Makani, Julie; Roberts, David J

    2016-04-01

    This review of hematology in Africa highlights areas of current practice and the immediate needs for development and clinical research. Acute hematological practice is dominated by anemia, sickle cell disease, and the need to provide a safe and rapidly available supply of blood. There is a growing need for specialist services for bleeding and coagulation, hematological malignancy, and palliative care. There are many areas of practice where straightforward measures could yield large gains in patient care. There is an urgent need for good clinical research to describe the epidemiology, natural history, and management of hematological diseases in Africa. PMID:27040965

  5. Identification of environmental anomaly hot spots in West Africa from time series of NDVI and rainfall

    NASA Astrophysics Data System (ADS)

    Boschetti, Mirco; Nutini, Francesco; Brivio, Pietro Alessandro; Bartholomé, Etienne; Stroppiana, Daniela; Hoscilo, Agata

    2013-04-01

    Studies of the impact of human activity on vegetation dynamics of the Sahelian belt of Africa have been recently re-invigorated by new scientific findings that highlighted the primary role of climate in the drought crises of the 1970s-1980s. Time series of satellite observations revealed a re-greening of the Sahelian belt that indicates no noteworthy human effect on vegetation dynamics at sub continental scale from the 1980s to late 1990s. However, several regional/local crises related to natural resources occurred in the last decades despite the re-greening thus underlying that more detailed studies are needed. In this study we used time-series (1998-2010) of SPOT-VGT NDVI and FEWS-RFE rainfall estimates to analyse vegetation - rainfall correlation and to map areas of local environmental anomalies where significant vegetation variations (increase/decrease) are not fully explained by seasonal changes of rainfall. Some of these anomalous zones (hot spots) were further analysed with higher resolution images Landsat TM/ETM+ to evaluate the reliability of the identified anomalous behaviour and to provide an interpretation of some example hot spots. The frequency distribution of the hot spots among the land cover classes of the GlobCover map shows that increase in vegetation greenness is mainly located in the more humid southern part and close to inland water bodies where it is likely to be related to the expansion/intensification of irrigated agricultural activities. On the contrary, a decrease in vegetation greenness occurs mainly in the northern part (12°-15°N) in correspondence with herbaceous vegetation covers where pastoral and cropping practices are often critical due to low and very unpredictable rainfall. The results of this study show that even if a general positive re-greening due to increased rainfall is evident for the entire Sahel, some local anomalous hot spots exist and can be explained by human factors such as population growth whose level reaches the

  6. Scorpion envenoming in the north of Mali (West Africa): epidemiological, clinical and therapeutic aspects.

    PubMed

    Dabo, A; Golou, G; Traoré, M S; Diarra, N; Goyffon, M; Doumbo, O

    2011-08-01

    Scorpion envenomation remains a poorly known problem in sub-Saharan Africa, particularly in Mali, where the incidence is high in Northern area of the country (Sahara desert). We conducted a prospective study in two district health centers, Kidal and Tessalit (North-east of Mali), to describe the epidemiological, clinical and therapeutic features of scorpion stings. This study consisted of an exhaustive follow-up from admission to discharge of all patients stung by scorpions. Of a total of 282 cases recorded during one year, 207 (73.4%) occurred in Kidal, and the remaining 75 (26.6%) took place in Tessalit. The annual incidence was significantly higher in Tessalit (437 cases/100,000 population/year) than in Kidal (243 cases/100,000 population/year) (p < 10⁻⁶). Two hundred two (71.6%) stings occurred inside human dwellings, 142 (50.4%) during sleeping/resting, especially in August. One hundred ninety-one (67.7%) were on the lower extremities. Nocturnal stings, 168 (59.6%), occurred more often than diurnal stings, 114 (40.4%). Most patients, 163 (57.8%), were admitted less than 1 h after being stung. Local pain at the sting site was the common primary complaint. However, moderate and severe clinical signs were significantly higher in children than in adults (p < 0.05). The death rate (3.9%) was higher in children (3.5%) than in adults (0.3%) (p = 8.10⁻⁶; RR = 0.90 [IC: 0.84-0.06]). Of the 22 scorpion species identified, 13 (59.1%) were Leiurus quinquestriiatus, 8 (36.4%) were Androctonus amoreuxi, and 1 (4.5%) specimen was Buthiscus bicalcaratus. From these species, L. quinquestriiatus and A. amoreuxi were responsible of stings. The medical treatment was only symptomatic, and one hundred twenty-eight (45.3%) patients received traditional remedies before seeking medical attention. Our findings suggest that scorpion stings are common in the north of Mali and are a significant threat to human health. PMID:21605586

  7. Chinese Public Attention to the Outbreak of Ebola in West Africa: Evidence from the Online Big Data Platform

    PubMed Central

    Liu, Kui; Li, Li; Jiang, Tao; Chen, Bin; Jiang, Zhenggang; Wang, Zhengting; Chen, Yongdi; Jiang, Jianmin; Gu, Hua

    2016-01-01

    Objective: The outbreak of the Ebola epidemic in West Africa in 2014 exerted enormous global public reaction via the Internet and social media. This study aimed to investigate and evaluate the public reaction to Ebola in China and identify the primitive correlation between possible influence factors caused by the outbreak of Ebola in West Africa and Chinese public attention via Internet surveillance. Methods: Baidu Index (BDI) and Sina Micro Index (SMI) were collected from their official websites, and the disease-related data were recorded from the websites of the World Health Organization (WHO), U.S. Centers for Disease Control and Prevention (CDC), and U.S. National Ministries of Health. The average BDI of Internet users in different regions were calculated to identify the public reaction to the Ebola outbreak. Spearman’s rank correlation was used to check the relationship of epidemic trends with BDI and SMI. Additionally, spatio-temporal analysis and autocorrelation analysis were performed to detect the clustered areas with the high attention to the topic of “Ebola”. The related news reports were collected from authoritative websites to identify potential patterns. Results: The BDI and the SMI for “Ebola” showed a similar fluctuating trend with a correlation coefficient = 0.9 (p < 0.05). The average BDI in Beijing, Tibet, and Shanghai was higher than other cities. However, the disease-related indicators did not identify potential correlation with both indices above. A hotspot area was detected in Tibet by local autocorrelation analysis. The most likely cluster identified by spatiotemporal cluster analysis was in the northeast regions of China with the relative risk (RR) of 2.26 (p ≤ 0.01) from 30 July to 14 August in 2014. Qualitative analysis indicated that negative news could lead to a continuous increase of the public’s attention until the appearance of a positive news report. Conclusions: Confronted with the risk of cross-border transmission of

  8. Cloud resolving modelling of the life cycle of a MCS: Sensitivity to soil conditions over West Africa

    NASA Astrophysics Data System (ADS)

    Gantner, L.; Kalthoff, N.

    2009-09-01

    In the African Sahelian (12°N-18°N) and Sudanian climate zone (9°N-11°N) convective systems contribute about 80-90% and about 50%, respectively, to the annual rainfall. Thus, they play a key role in the water cycle of West Africa. Their rainfall, however, is highly variable in space as well as in time. The initiation and modification of rain-producing convective systems in West Africa are still not well understood. In addition to mid- and upper-tropospheric forcing, the influence of surface and convective boundary layer (CBL) processes on the initiation of convection is often emphasised. Major factors are the spatial distribution and temporal development of water vapour in the CBL. Besides advective processes, water vapour is made available in the atmosphere locally through evapotranspiration from soil and vegetation; the latter is an important component of the earth's surface energy balance. Soil moisture affects the energy balance via the albedo and emissivity of the surface, the conduction of heat in the soil and the stomata resistance of vegetation. Research findings show that the soil moisture exerts greater influence on the CBL than vegetation. Cloud resolving real-case simulations initialized with ECMWF analysis data were performed to investigate the sensitivity of a mesoscale convective system (MCS) to soil properties. Several scenarios with different content of soil moisture and distribution of soil conditions were investigated. Initiation of convection was observed in all experiments. The initiation area was characterised by very low convective inhibition (CIN) and high convective available potential energy. The simulations showed some evidence that convection was initiated in the vicinity of orography and along soil moisture inhomogeneities. In a moist case precipitating cells were weak and disappeared when entering a region with higher CIN. In the other experiments MCSs developed. In the control run a weakening of the system was observed when

  9. Regional Climate Simulations with COSMO-CLM for West Africa using three different soil-vegetation-atmosphere-transfer (SVAT) module