N-player mosquito net game: individual and social rationality in the misuse of insecticide-treated nets.

PubMed

Honjo, Keita; Satake, Akiko

2014-02-07

Many governmental and non-governmental organizations have distributed insecticide-treated nets (ITNs) to malaria endemic areas, which contributed to the reduction of malaria deaths. However, some people in malaria endemic areas used ITNs for alternative purposes such as fishery and agriculture. It is unclear why people threatened by malaria misuse ITNs. Here we develop a N-player mosquito net game, and theoretically show that the misuse of ITNs might be underpinned by individual and social rationality. In the mosquito net game, each player uses ITNs for malaria prevention or alternative purposes. The proper ITN use decreases the probability of malaria infection, while the improper ITN use increases the player's labor productivity. Each player's expected payoff is influenced by other players' strategies. We found that the misuse of ITNs can be a Pareto efficient Nash equilibrium. The maximum number of players using ITNs for malaria prevention is limited by insecticidal effectiveness of ITNs and extra income from ITN misuse. Furthermore, we found that players in a low-income community are attracted to the misuse of ITNs even if the probability of malaria infection is high. Introduction of a tax on ITN misuse was shown to be effective to motivate the players to use ITNs for malaria prevention. Our results demonstrate that understanding decision making of people in malaria endemic areas is essential to design more effective malaria control programs. © 2013 Published by Elsevier Ltd. All rights reserved.

Insecticide-treated nets and treatment service: a trial using public and private sector channels in rural United Republic of Tanzania.

PubMed Central

Fraser-Hurt, N.; Lyimo, E. O.

1998-01-01

The Rotary Net Initiative, implemented in Kilombero District, southern United Republic of Tanzania, allowed us to explore different sales channels for the distribution of insecticide-treated nets (ITNs) and the insecticide treatment service in a rural area of very high malaria transmission. Several types of ITNs were promoted and sold through different channels in the public and private sector, i.e. hospital pharmacy, mother and child health (MCH) clinic, net committee, village health workers and retail shops. The ITNs were sold for US$ 5.0-9.2, with profit margins of 9-16%. Net treatment cost US$ 0.33, with commission fees of 75%. Net transport and treatment were partially subsidized. Some outlets established their own fund by ITN sales. Sales of nets and treatments were seasonal, and certain net types were preferred. Demand for insecticide treatment was generally low. Changes in net coverage were assessed in two villages. A range of outlet features were compared qualitatively. Our experience supports suggestions that ITN technology should be delivered through MCH care services and demonstrates that specific promotion and innovation are necessary to achieve substantial net treatment levels. A large-scale ITN project in the same area and other ITN studies should lead to better understanding of ITN implementation at the population level. PMID:10191557

Costs and effects of the Tanzanian national voucher scheme for insecticide-treated nets

PubMed Central

Mulligan, Jo-Ann; Yukich, Joshua; Hanson, Kara

2008-01-01

Background The cost-effectiveness of insecticide-treated nets (ITNs) in reducing morbidity and mortality is well established. International focus has now moved on to how best to scale up coverage and what financing mechanisms might be used to achieve this. The approach in Tanzania has been to deliver a targeted subsidy for those most vulnerable to the effects of malaria while at the same time providing support to the development of the commercial ITN distribution system. In October 2004, with funds from the Global Fund to Fight AIDS Tuberculosis and Malaria, the government launched the Tanzania National Voucher Scheme (TNVS), a nationwide discounted voucher scheme for ITNs for pregnant women and their infants. This paper analyses the costs and effects of the scheme and compares it with other approaches to distribution. Methods Economic costs were estimated using the ingredients approach whereby all resources required in the delivery of the intervention (including the user contribution) are quantified and valued. Effects were measured in terms of number of vouchers used (and therefore nets delivered) and treated nets years. Estimates were also made for the cost per malaria case and death averted. Results and Conclusion The total financial cost of the programme represents around 5% of the Ministry of Health's total budget. The average economic cost of delivering an ITN using the voucher scheme, including the user contribution, was $7.57. The cost-effectiveness results are within the benchmarks set by other malaria prevention studies. The Government of Tanzania's approach to scaling up ITNs uses both the public and private sectors in order to achieve and sustain the level of coverage required to meet the Abuja targets. The results presented here suggest that the TNVS is a cost-effective strategy for delivering subsidized ITNs to targeted vulnerable groups. PMID:18279509

Insecticide resistance in Culex quinquefasciatus mosquitoes after the introduction of insecticide-treated bed nets in Macha, Zambia

PubMed Central

Norris, Douglas E.

2014-01-01

Culex quinquefasciatus , an arboviral and filarial vector, is present in high numbers throughout sub-Saharan Africa, and insecticide-resistant populations have been reported worldwide. In order to determine the insecticide resistance status of Cx. quinquefasciatus in Macha, Zambia, adult mosquitoes reared from eggs collected from oviposition traps were tested by bioassay. High levels of resistance to DDT, pyrethroids, malathion, and deltamethrin-treated net material were detected, and molecular assays revealed that the knockdown resistance (kdr) allele was frequent in the Cx. quinquefasciatus population, with 7.0% homozygous for the kdr L1014 allele and 38.5% heterozygous (0.263 kdr frequency). The kdr frequency was significantly higher in mosquitoes that had successfully fed on human hosts, and screening archived specimens revealed that kdr was present at lower frequency prior to the introduction of ITNs, indicating that ITNs might be a selective force in this population. Additionally, metabolic detoxification enzyme activity assays showed upregulated glutathione S-transferases, α-esterases, and β-esterases. Continued monitoring and assessment of the Cx. quinquefasciatus population is necessary to determine levels of resistance. PMID:22129413

A Meta-Regression Analysis of the Effectiveness of Mosquito Nets for Malaria Control: The Value of Long-Lasting Insecticide Nets

PubMed Central

Yang, Gi-geun; Pham, Anh

2018-01-01

Long-lasting insecticidal nets (LLINs) have been widely used as an effective alternative to conventional insecticide-treated nets (ITNs) for over a decade. Due to the growing number of field trials and interventions reporting the effectiveness of LLINs in controlling malaria, there is a need to systematically review the literature on LLINs and ITNs to examine the relative effectiveness and characteristics of both insecticide nettings. A systematic review of over 2000 scholarly articles published since the year 2000 was conducted. The odds ratios (ORs) of insecticidal net effectiveness in reducing malaria were recorded. The final dataset included 26 articles for meta-regression analysis, with a sample size of 154 subgroup observations. While there is substantial heterogeneity in study characteristics and effect size, we found that the overall OR for reducing malaria by LLIN use was 0.44 (95% CI = 0.41–0.48, p < 0.01) indicating a risk reduction of 56%, while ITNs were slightly less effective with an OR of 0.59 (95% CI = 0.57–0.61, p <0.01). A meta-regression model confirms that LLINs are significantly more effective than ITNs in the prevention of malaria, when controlling for other covariates. For both types of nets, protective efficacy was greater in high transmission areas when nets were used for an extended period. However, cross-sectional studies may overestimate the effect of the nets. The results surprisingly suggest that nets are less effective in protecting children under the age of five, which may be due to differences in child behavior or inadequate coverage. Compared to a previous meta-analysis, insecticide-treated nets appear to have improved their efficacy despite the risks of insecticide resistance. These findings have practical implications for policymakers seeking effective malaria control strategies. PMID:29562673

Mass distribution of free insecticide-treated nets do not interfere with continuous net distribution in Tanzania.

PubMed

Eze, Ikenna C; Kramer, Karen; Msengwa, Amina; Mandike, Renata; Lengeler, Christian

2014-05-27

To protect the most vulnerable groups from malaria (pregnant women and infants) the Tanzanian Government introduced a subsidy (voucher) scheme in 2004, on the basis of a public-private partnership. These vouchers are provided to pregnant women at their first antenatal care visit and mothers of infants at first vaccination. The vouchers are redeemed at registered retailers for a long-lasting insecticidal net against the payment of a modest top-up price. The present work analysed a large body of data from the Tanzanian National Voucher Scheme, focusing on interactions with concurrent mass distribution campaigns of free nets. In an ecologic study involving all regions of Tanzania, voucher redemption data for the period 2007-2011, as well as data on potential determinants of voucher redemption were analysed. The four outcome variables were: pregnant woman and infant voucher redemption rates, use of treated bed nets by all household members and by under- five children. Each of the outcomes was regressed with selected determinants, using a generalized estimating equation model and accounting for regional data clustering. There was a consistent improvement in voucher redemption rates over the selected time period, with rates >80% in 2011. The major determinants of redemption rates were the top-up price paid by the voucher beneficiary, the retailer- clinic ratio, and socio-economic status. Improved redemption rates after 2009 were most likely due to reduced top-up prices (following a change in policy). Redemption rates were not affected by two major free net distribution campaigns. During this period, there was a consistent improvement in net use across all the regions, with rates of up to 75% in 2011. The key components of the National Treated Nets Programme (NATNETS) seem to work harmoniously, leading to a high level of net use in the entire population. This calls for the continuation of this effort in Tanzania and for emulation by other countries with endemic malaria.

Long-term field performance of a polyester-based long-lasting insecticidal mosquito net in rural Uganda

PubMed Central

Kilian, Albert; Byamukama, Wilson; Pigeon, Olivier; Atieli, Francis; Duchon, Stephan; Phan, Chi

2008-01-01

Background In order to evaluate whether criteria for LLIN field performance (phase III) set by the WHO Pesticide Evaluation Scheme are met, first and second generations of one of these products, PermaNet®, a polyester net using the coating technology were tested. Methods A randomized, double blinded study design was used comparing LLIN to conventionally treated nets and following LLIN for three years under regular household use in rural conditions. Primary outcome measures were deltamethrin residue and bioassay performance (60 minute knock-down and 24 hour mortality after a three minute exposure) using a strain of Anopheles gambiae s.s. sensitive to pyrethroid insecticides. Results Baseline concentration of deltamethrin was within targets for all net types but was rapidly lost in conventionally treated nets and first generation PermaNet® with median of 0.7 and 2.5 mg/m2 after six months respectively. In contrast, second generation PermaNet® retained insecticide well and had 41.5% of baseline dose after 36 months (28.7 mg/m2). Similarly, vector mortality and knockdown dropped to 18% and 70% respectively for first generation LLIN after six months but remained high (88.5% and 97.8% respectively) for second generation PermaNet® after 36 months of follow up at which time 90.0% of nets had either a knockdown rate ≥ 95% or mortality rate ≥ 80%. Conclusion Second generation PermaNet® showed excellent results after three years of field use and fulfilled the WHOPES criteria for LLIN. Loss of insecticide on LLIN using coating technology under field conditions was far more influenced by factors associated with handling rather than washing. PMID:18355408

Inequalities in purchase of mosquito nets and willingness to pay for insecticide-treated nets in Nigeria: Challenges for malaria control interventions

PubMed Central

Onwujekwe, Obinna; Hanson, Kara; Fox-Rushby, Julia

2004-01-01

Objective To explore the equity implications of insecticide-treated nets (ITN) distribution programmes that are based on user charges. Methods A questionnaire was used to collect information on previous purchase of untreated nets and hypothetical willingness to pay (WTP) for ITNs from a random sample of householders. A second survey was conducted one month later to collect information on actual purchases of ITNs. An economic status index was used for characterizing inequity. Major findings The lower economic status quintiles were less likely to have previously purchased untreated nets and also had a lower hypothetical and actual WTP for ITNs. Conclusion ITN distribution programmes need to take account of the diversity in WTP for ITNs if they are to ensure equity in access to the nets. This could form part of the overall poverty reduction strategy. PMID:15023234

Africa's largest long-lasting insecticide-treated net producer: lessons from A to Z Textiles.

PubMed

Masum, Hassan; Shah, Ronak; Schroeder, Karl; Daar, Abdallah S; Singer, Peter A

2010-12-13

Field trials have demonstrated the efficacy of insecticide-treated nets, and the WHO has recently endorsed a shift toward Long-Lasting Insecticide Treated nets (LLINs) due to factors such as reduced distribution costs. However, the need for LLINs poses several challenges. Is it possible to manufacture LLINs in large quantities in the African continent, where malaria is most endemic? When production is located in low-income countries, what role is played by local funding and employment, scaling up manufacturing, and partnerships? What factors influence availability and pricing? A case study of A to Z Textiles was undertaken to answer the question of how large-scale production of LLINs can occur in a low income setting. One of the largest sources of bed nets for Africa, A to Z Textiles is Africa-based, and its Tanzanian operations have a production capacity of 30 million LLINs per year, along with full WHO recommendation for its nets. Our analysis is based on semi-structured interviews with key informants familiar with A to Z, site visits in Tanzania, and literature reviews.This paper discusses the history and current status of A to Z Textiles, identifies the factors that led to its success, and suggests policy considerations that could support similar initiatives in the future. Local funding, scaling up manufacturing, technology transfer, and partnerships all played important roles in A to Z's ascent, as did perceived benefits of local employment and capacity-building. Regulatory issues and procurement rules acted as barriers. A to Z cost-effectively manufactures high-quality LLINs where malaria is most endemic. With a production capacity of 30 million LLINs per year, and full WHOPES (WHO Pesticide Evaluation Scheme) certification, A to Z Textiles demonstrates how key health goods can be successfully produced in the low-income countries that use them. Its example may be instructive and of high interest to readers in the malaria community, especially in developing

Insecticide resistance in Culex quinquefasciatus mosquitoes after the introduction of insecticide-treated bed nets in Macha, Zambia.

PubMed

Norris, Laura C; Norris, Douglas E

2011-12-01

Culex quinquefasciatus, an arboviral and filarial vector, is present in high numbers throughout sub-Saharan Africa, and insecticide-resistant populations have been reported worldwide. In order to determine the insecticide resistance status of Cx. quinquefasciatus in Macha, Zambia, adult mosquitoes reared from eggs collected from oviposition traps were tested by bioassay. High levels of resistance to DDT, pyrethroids, malathion, and deltamethrin-treated net material were detected, and molecular assays revealed that the knockdown resistance (kdr) allele was frequent in the Cx. quinquefasciatus population, with 7.0% homozygous for the kdr L1014 allele and 38.5% heterozygous (0.263 kdr frequency). The kdr frequency was significantly higher in mosquitoes that had successfully fed on human hosts, and screening archived specimens revealed that kdr was present at lower frequency prior to the introduction of ITNs, indicating that ITNs might be a selective force in this population. Additionally, metabolic detoxification enzyme activity assays showed upregulated glutathione S-transferases, α-esterases, and β-esterases. Continued monitoring and assessment of the Cx. quinquefasciatus population is necessary to determine levels of resistance. © 2011 The Society for Vector Ecology.

Optimal Control of Malaria Transmission using Insecticide Treated Nets and Spraying

NASA Astrophysics Data System (ADS)

Athina, D.; Bakhtiar, T.; Jaharuddin

2017-03-01

In this paper, we consider a model of the transmission of malaria which was developed by Silva and Torres equipped with two control variables, namely the use of insecticide treated nets (ITN) to reduce the number of human beings infected and spraying to reduce the number of mosquitoes. Pontryagin maximum principle was applied to derive the differential equation system as optimality conditions which must be satisfied by optimal control variables. The Mangasarian sufficiency theorem shows that Pontryagin maximum principle is necessary as well as sufficient conditions for optimization problem. The 4th-order Runge Kutta method was then performed to solve the differential equations system. The numerical results show that both controls given at once can reduce the number of infected individuals as well as the number of mosquitoes which reduce the impact of malaria transmission.

Field efficacy of pyrethroid treated plastic sheeting (durable lining) in combination with long lasting insecticidal nets against malaria vectors.

PubMed

Chandre, Fabrice; Dabire, Roch K; Hougard, Jean-Marc; Djogbenou, Luc S; Irish, Seth R; Rowland, Mark; N'guessan, Raphael

2010-08-03

Insecticide treated plastic sheeting (ITPS), sometimes known as durable lining, has potential as a long-lasting insecticidal surface for malaria vector control when used as lining for interior walls and ceilings inside the home. Against a backdrop of increasing long lasting net (LN) coverage, we examined the effect of combining permethrin-treated plastic sheeting (ITPS) with LNs in Burkina Faso. A verandah trap experimental hut trial of ITPS with or without Olyset LN was conducted in the Vallée du Kou near Bobo-Dioulasso, where the two molecular forms of Anopheles gambiae s.s., S (frequency 65%) and M (frequency 35%), occur. The S form is mostly pyrethroid resistant (Fkdr = 92%) owing to the kdr mechanism, and the M form is mostly kdr susceptible (Fkdr = 7%). The treatment arms included ITPS, Olyset, ITPS plus Olyset, ITPS plus untreated net (with or without holes), and untreated control. ITPS was significantly inferior to Olyset LN in terms of mortality (37% vs 63%), blood feeding inhibition (20% vs 81%) and deterrence (0 vs 42%) effects, and hence altogether inferior as a means of personal protection (16% vs 89%). The addition of ITPS to Olyset did not improve mortality (62%), blood feeding inhibition (75%), deterrence (50%) or personal protection (88%) over that of Olyset used alone. Use of untreated nets - both holed and intact - with ITPS provided greater protection from blood-feeding. The intact net/ITPS combination killed more mosquitoes than ITPS on its own. Although ITPS has a potential role for community control of malaria, at low coverage it is unlikely to be as good as Olyset LNs for household protection. The combination of pyrethroid IRS and pyrethroid LN - as practiced in some countries - is unlikely to be additive except, perhaps, at high levels of IRS coverage. A combination of LN and ITPS treated with an alternative insecticide is likely to be more effective, particularly in areas of pyrethroid resistance.

Insecticide-treated nets provide protection against malaria to children in an area of insecticide resistance in Southern Benin.

PubMed

Bradley, John; Ogouyèmi-Hounto, Aurore; Cornélie, Sylvie; Fassinou, Jacob; de Tove, Yolande Sissinto Savi; Adéothy, Adicath Adéola; Tokponnon, Filémon T; Makoutode, Patrick; Adechoubou, Alioun; Legba, Thibaut; Houansou, Telesphore; Kinde-Gazard, Dorothée; Akogbeto, Martin C; Massougbodji, Achille; Knox, Tessa Bellamy; Donnelly, Martin; Kleinschmidt, Immo

2017-05-26

Malaria control is heavily reliant on insecticides, especially pyrethroids. Resistance of mosquitoes to insecticides may threaten the effectiveness of insecticide-based vector control and lead to a resurgence of malaria in Africa. In 21 villages in Southern Benin with high levels of insecticide resistance, the resistance status of local vectors was measured at the same time as the prevalence of malaria infection in resident children. Children who used LLINs had lower levels of malaria infection [odds ratio = 0.76 (95% CI 0.59, 0.98, p = 0.033)]. There was no evidence that the effectiveness of nets was different in high and low resistance locations (p = 0.513). There was no association between village level resistance and village level malaria prevalence (p = 0.999). LLINs continue to offer individual protection against malaria infection in an area of high resistance. Insecticide resistance is not a reason to stop efforts to increase coverage of LLINs in Africa.

Insecticide-Treated Nets Can Reduce Malaria Transmission by Mosquitoes Which Feed Outdoors

PubMed Central

Govella, Nicodem J.; Okumu, Fredros O.; Killeen, Gerry F.

2010-01-01

Insecticide treated nets (ITNs) represent a powerful means for controlling malaria in Africa because the mosquito vectors feed primarily indoors at night. The proportion of human exposure that occurs indoors, when people are asleep and can conveniently use ITNs, is therefore very high. Recent evidence suggests behavioral changes by malaria mosquito populations to avoid contact with ITNs by feeding outdoors in the early evening. We adapt an established mathematical model of mosquito behavior and malaria transmission to illustrate how ITNs can achieve communal suppression of malaria transmission exposure, even where mosquito evade them and personal protection is modest. We also review recent reports from Tanzania to show that conventional mosquito behavior measures can underestimate the potential of ITNs because they ignore the importance of human movements. PMID:20207866

Planning long lasting insecticide treated net campaigns: should households' existing nets be taken into account?

PubMed

Yukich, Joshua; Bennett, Adam; Keating, Joseph; Yukich, Rudy K; Lynch, Matt; Eisele, Thomas P; Kolaczinski, Kate

2013-06-14

Mass distribution of long-lasting insecticide treated bed nets (LLINs) has led to large increases in LLIN coverage in many African countries. As LLIN ownership levels increase, planners of future mass distributions face the challenge of deciding whether to ignore the nets already owned by households or to take these into account and attempt to target individuals or households without nets. Taking existing nets into account would reduce commodity costs but require more sophisticated, and potentially more costly, distribution procedures. The decision may also have implications for the average age of nets in use and therefore on the maintenance of universal LLIN coverage over time. A stochastic simulation model based on the NetCALC algorithm was used to determine the scenarios under which it would be cost saving to take existing nets into account, and the potential effects of doing so on the age profile of LLINs owned. The model accounted for variability in timing of distributions, concomitant use of continuous distribution systems, population growth, sampling error in pre-campaign coverage surveys, variable net 'decay' parameters and other factors including the feasibility and accuracy of identifying existing nets in the field. Results indicate that (i) where pre-campaign coverage is around 40% (of households owning at least 1 LLIN), accounting for existing nets in the campaign will have little effect on the mean age of the net population and (ii) even at pre-campaign coverage levels above 40%, an approach that reduces LLIN distribution requirements by taking existing nets into account may have only a small chance of being cost-saving overall, depending largely on the feasibility of identifying nets in the field. Based on existing literature the epidemiological implications of such a strategy is likely to vary by transmission setting, and the risks of leaving older nets in the field when accounting for existing nets must be considered. Where pre-campaign coverage

Cost-Effectiveness of Long-Lasting Insecticide-Treated Hammocks in Preventing Malaria in South-Central Vietnam

PubMed Central

Morel, Chantal M.; Thang, Ngo Duc; Erhart, Annette; Xa, Nguyen Xuan; Peeters Grietens, Koen; Xuan Hung, Le; Thuan, Le Khan; Van Ky, Pham; Hung, Nguyen Manh; Coosemans, Marc; D'Alessandro, Umberto; Mills, Anne

2013-01-01

Background Despite much success in reducing the burden of malaria in Vietnam, pockets of malaria persist and eliminating them remains an important development goal. In central Vietnam, insecticide-treated hammocks have recently been introduced to help counter the disease in the highly forested, mountainous areas, where other measures have so far been unsuccessful. This study assesses the cost-effectiveness of using long-lasting insecticide-treated hammocks in this area. Methods and Findings This cost-effectiveness study was run alongside a randomized control trial testing the efficacy of the long-lasting insecticide-treated hammocks. Data were collected through an exit survey, a household survey, expenditure records and key informant interviews. The study estimates that under normal (non-trial) conditions the total net societal cost per malaria episode averted in using long-lasting insecticide-treated hammocks in this area was 126 USD. Cost per hammock, including insecticidal netting, sewing, transport, and distribution was found to be approximately 11.76 USD per hammock. Average savings per episode averted were estimated to be $14.60 USD for the health system and 14.37 USD for households (including both direct and indirect cost savings). The study estimates that the annual financial outlay required of government to implement this type of programme to be 3.40 USD per person covered per year. Conclusion The study finds that the use of a hammock intervention could represent good value for money to help prevent malaria in more remote areas, where traditional control measures such as insecticide-treated bednets and indoor residual spraying are insufficient or inappropriate to control malaria. However, the life span of the hammock–the number of years over which it effectively deters mosquitoes–has a significant impact on the cost-effectiveness of the intervention and study results should be interpreted in light of the evidence on effectiveness gathered in the years

Infrared video tracking of Anopheles gambiae at insecticide-treated bed nets reveals rapid decisive impact after brief localised net contact

PubMed Central

Parker, Josephine E.A.; Angarita-Jaimes, Natalia; Abe, Mayumi; Towers, Catherine E.; Towers, David; McCall, Philip J.

2015-01-01

Long-lasting insecticidal bed nets (LLINs) protect humans from malaria transmission and are fundamental to malaria control worldwide, but little is known of how mosquitoes interact with nets. Elucidating LLIN mode of action is essential to maintain or improve efficacy, an urgent need as emerging insecticide resistance threatens their future. Tracking multiple free-flying Anopheles gambiae responding to human-occupied bed nets in a novel large-scale system, we characterised key behaviours and events. Four behavioural modes with different levels of net contact were defined: swooping, visiting, bouncing and resting. Approximately 75% of all activity occurred at the bed net roof where multiple brief contacts were focussed above the occupant’s torso. Total flight and net contact times were lower at LLINs than untreated nets but the essential character of the response was unaltered. LLINs did not repel mosquitoes but impacted rapidly: LLIN contact of less than 1 minute per mosquito during the first ten minutes reduced subsequent activity; after thirty minutes, activity at LLINs was negligible. Velocity measurements showed that mosquitoes detected nets, including unbaited untreated nets, prior to contact. This is the most complete characterisation of mosquito-LLIN interactions to date, and reveals many aspects of LLIN mode of action, important for developing the next generation of LLINs. PMID:26323965

House screening with insecticide-treated netting provides sustained reductions in domestic populations of Aedes aegypti in Merida, Mexico

PubMed Central

Che-Mendoza, Azael; Medina-Barreiro, Anuar; Koyoc-Cardeña, Edgar; Uc-Puc, Valentín; Contreras-Perera, Yamili; Herrera-Bojórquez, Josué; Dzul-Manzanilla, Felipe; Correa-Morales, Fabian; Ranson, Hilary; Lenhart, Audrey; McCall, Philip J.; Kroeger, Axel; Vazquez-Prokopec, Gonzalo

2018-01-01

Background There is a need for effective methods to control Aedes aegypti and prevent the transmission of dengue, chikungunya, yellow fever and Zika viruses. Insecticide treated screening (ITS) is a promising approach, particularly as it targets adult mosquitoes to reduce human-mosquito contact. Methodology/Principal findings A cluster-randomised controlled trial evaluated the entomological efficacy of ITS based intervention, which consisted of the installation of pyrethroid-impregnated long-lasting insecticide-treated netting material fixed as framed screens on external doors and windows. A total of 10 treatment and 10 control clusters (100 houses/cluster) were distributed throughout the city of Merida, Mexico. Cross-sectional entomological surveys quantified indoor adult mosquito infestation at baseline (pre-intervention) and throughout four post-intervention (PI) surveys spaced at 6-month intervals corresponding to dry/rainy seasons over two years (2012–2014). A total of 844 households from intervention clusters (86% coverage) were protected with ITS at the start of the trial. Significant reductions in the indoor presence and abundance of Ae. aegypti adults (OR = 0.48 and IRR = 0.45, P<0.05 respectively) and the indoor presence and abundance of Ae. aegypti female mosquitoes (OR = 0.47 and IRR = 0.44, P<0.05 respectively) were detected in intervention clusters compared to controls. This high level of protective effect was sustained for up to 24 months PI. Insecticidal activity of the ITS material declined with time, with ~70% mortality being demonstrated in susceptible mosquito cohorts up to 24 months after installation. Conclusions/Significance The strong and sustained entomological impact observed in this study demonstrates the potential of house screening as a feasible, alternative approach to a sustained long-term impact on household infestations of Ae. aegypti. Larger trials quantifying the effectiveness of ITS on epidemiological endpoints are warranted

Can insecticide-treated netting provide protection for Equids from Culicoides biting midges in the United Kingdom?

PubMed

Baker, Tiffany; Carpenter, Simon; Gubbins, Simon; Newton, Richard; Lo Iacono, Giovanni; Wood, James; Harrup, Lara Ellen

2015-11-25

Biting midges of the genus Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) cause a significant biting nuisance to equines and are responsible for the biological transmission of African horse sickness virus (AHSV). While currently restricted in distribution to sub-Saharan Africa, AHSV has a history of emergence into southern Europe and causes one of the most lethal diseases of horses and other species of Equidae. In the event of an outbreak of AHSV, the use of insecticide treated nets (ITNs) to screen equine accomodation is recommended by competent authorities including the Office International des Épizooties (OIE) in order to reduce vector-host contact. Seven commercially avaliable pyrethroid insecticides and three repellent compounds, all of which are licensed for amateur use, were assessed in modified World Health Organization (WHO) cone bioassay trials in the laboratory using a colony line of Culicoides nubeculosus (Meigen), 1830. Two field trials were subsequently conducted to test the efficiency of treated net screens in preventing entry of Culicoides. A formulation of cypermethrin (0.15 % w/w) and pyrethrins (0.2 % w/w) (Tri-Tec 14®, LS Sales (Farnham) Ltd, Bloxham, UK) applied to black polyvinyl-coated polyester insect screen (1.6 mm aperture; 1.6 mm thickness) inflicted 100 % mortality on batches of C. nubeculosus following a three minute exposure in the WHO cone bioassays at 1, 7 and 14 days post-treatment. Tri-Tec 14® outperformed all other treatments tested and was subsequently selected for use in field trials. The first trial demonstrated that treated screens placed around an ultraviolet light-suction trap entirely prevented Culicoides being collected, despite their collection in identical traps with untreated screening or no screening. The second field trial examined entry of Culicoides into stables containing horses and found that while the insecticide treated screens reduced entry substantially, there was still a small risk of exposure

Social marketing of insecticide-treated bednets: the case for Pakistan.

PubMed

Qazi, S; Shaikh, B T

2007-01-01

With an estimated half a million cases of malaria annually in Pakistan, and drug resistant cases on the increase, more practical preventive measures such as insecticide-treated bednets are essential. Social marketing through commercial channels has become an important cost-effective means to deliver health products and services to low income people and to motivate them to use these services. It has been demonstrated that social marketing of insecticide-treated bednets has saved the lives of millions of people in malaria-endemic regions at a cost as low as U.S. $2 per person. Social marketing could be an effective strategy for getting insecticide-treated nets to poor communities in Pakistan who are most vulnerable to malaria.

Evaluation of the effects of repeated hand washing, sunlight, smoke and dirt on the persistence of deltamethrin on insecticide-treated nets.

PubMed

Kayedi, M H; Lines, J D; Haghdoost, A A; Vatandoost, M H; Rassi, Y; Khamisabady, K

2008-08-01

Field studies were carried out in Iran to evaluate the effect of various factors (washing, sun, smoke, dust and dirt) on the residual insecticidal activity of PermaNet (a brand of long-lasting insecticidal net), and on nets conventionally treated with deltamethrin (K-O Tab), using bioassay tests. Thirty-two nets were washed five or 15 times, and eight nets were not washed at all. Nets were washed vigorously in cold tap water (17 degrees C, pH 8.9) with a detergent. Hand rubbing continued for 3min. After washing, some nets were exposed to dense smoke from a dung-hay fire for 3min and were also left exposed to the dusty wind between washes. One group of nets was exposed to the sunlight for the full 3-d interval between washes; another was exposed to sunlight for just 3h after each wash; two other groups were kept in the shade. There was a significantly greater loss of activity in nets exposed to the sun throughout the 3-d interval between washes: that is, for a total of 15 to 45 d. However, short sunlight exposure (maximum 3h between washes) during drying did not have any effect. We did not find any significant effect of exposure to dirt, dust and smoke after washing. It is concluded that the effect of sun is much smaller than that of washing, and that drying nets for a few hours in the sun is not harmful.

Indoor Residual Spraying in Combination with Insecticide-Treated Nets Compared to Insecticide-Treated Nets Alone for Protection against Malaria: A Cluster Randomised Trial in Tanzania

PubMed Central

West, Philippa A.; Protopopoff, Natacha; Wright, Alexandra; Kivaju, Zuhura; Tigererwa, Robinson; Mosha, Franklin W.; Kisinza, William; Rowland, Mark; Kleinschmidt, Immo

2014-01-01

Background Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) of houses provide effective malaria transmission control. There is conflicting evidence about whether it is more beneficial to provide both interventions in combination. A cluster randomised controlled trial was conducted to investigate whether the combination provides added protection compared to ITNs alone. Methods and Findings In northwest Tanzania, 50 clusters (village areas) were randomly allocated to ITNs only or ITNs and IRS. Dwellings in the ITN+IRS arm were sprayed with two rounds of bendiocarb in 2012. Plasmodium falciparum prevalence rate (PfPR) in children 0.5–14 y old (primary outcome) and anaemia in children <5 y old (secondary outcome) were compared between study arms using three cross-sectional household surveys in 2012. Entomological inoculation rate (secondary outcome) was compared between study arms. IRS coverage was approximately 90%. ITN use ranged from 36% to 50%. In intention-to-treat analysis, mean PfPR was 13% in the ITN+IRS arm and 26% in the ITN only arm, odds ratio = 0.43 (95% CI 0.19–0.97, n = 13,146). The strongest effect was observed in the peak transmission season, 6 mo after the first IRS. Subgroup analysis showed that ITN users were additionally protected if their houses were sprayed. Mean monthly entomological inoculation rate was non-significantly lower in the ITN+IRS arm than in the ITN only arm, rate ratio = 0.17 (95% CI 0.03–1.08). Conclusions This is the first randomised trial to our knowledge that reports significant added protection from combining IRS and ITNs compared to ITNs alone. The effect is likely to be attributable to IRS providing added protection to ITN users as well as compensating for inadequate ITN use. Policy makers should consider deploying IRS in combination with ITNs to control transmission if local ITN strategies on their own are insufficiently effective. Given the uncertain generalisability of these findings

Increasing Coverage and Decreasing Inequity in Insecticide-Treated Bed Net Use among Rural Kenyan Children

PubMed Central

Noor, Abdisalan M; Amin, Abdinasir A; Akhwale, Willis S; Snow, Robert W

2007-01-01

Background Inexpensive and efficacious interventions that avert childhood deaths in sub-Saharan Africa have failed to reach effective coverage, especially among the poorest rural sectors. One particular example is insecticide-treated bed nets (ITNs). In this study, we present repeat observations of ITN coverage among rural Kenyan homesteads exposed at different times to a range of delivery models, and assess changes in coverage across socioeconomic groups. Methods and Findings We undertook a study of annual changes in ITN coverage among a cohort of 3,700 children aged 0–4 y in four districts of Kenya (Bondo, Greater Kisii, Kwale, and Makueni) annually between 2004 and 2006. Cross-sectional surveys of ITN coverage were undertaken coincidentally with the incremental availability of commercial sector nets (2004), the introduction of heavily subsidized nets through clinics (2005), and the introduction of free mass distributed ITNs (2006). The changing prevalence of ITN coverage was examined with special reference to the degree of equity in each delivery approach. ITN coverage was only 7.1% in 2004 when the predominant source of nets was the commercial retail sector. By the end of 2005, following the expansion of heavily subsidized clinic distribution system, ITN coverage rose to 23.5%. In 2006 a large-scale mass distribution of ITNs was mounted providing nets free of charge to children, resulting in a dramatic increase in ITN coverage to 67.3%. With each subsequent survey socioeconomic inequity in net coverage sequentially decreased: 2004 (most poor [2.9%] versus least poor [15.6%]; concentration index 0.281); 2005 (most poor [17.5%] versus least poor [37.9%]; concentration index 0.131), and 2006 with near-perfect equality (most poor [66.3%] versus least poor [66.6%]; concentration index 0.000). The free mass distribution method achieved highest coverage among the poorest children, the highly subsidised clinic nets programme was marginally in favour of the least poor

Insecticide-treated nets mass distribution campaign: benefits and lessons in Zambia.

PubMed

Masaninga, Freddie; Mukumbuta, Nawa; Ndhlovu, Ketty; Hamainza, Busiku; Wamulume, Pauline; Chanda, Emmanuel; Banda, John; Mwanza-Ingwe, Mercy; Miller, John M; Ameneshewa, Birkinesh; Mnzava, Abraham; Kawesha-Chizema, Elizabeth

2018-04-24

Zambia was an early adopter of insecticide-treated nets strategy in 2001, and policy for mass distribution with long-lasting insecticidal nets (LLINs) in 2005. Since then, the country has implemented mass distribution supplemented with routine delivery through antenatal care and under five clinics in health facilities. The national targets of universal (100%) coverage and 80% utilization of LLINs have not been attained. Free mass LLIN distribution campaign in Zambia offers important lessons to inform future campaigns in the African region. This study reviewed LLIN free mass distribution campaign information derived from Zambia's national and World Health Organization Global Malaria Programme annual reports and strategic plans published between 2001 and 2016. In 2014, a nationwide mass distribution campaign in Zambia delivered all the 6.0 million LLINs in 6 out of 10 provinces in 4 months between June and September before the onset of the rainy season. Compared with 235,800 LLINs and 2.9 million LLINs distributed on a rolling basis in 2008 and 2013, respectively, the 2014 mass campaign, which distributed 6 million LLINs represented the largest one-time-nationwide LLIN distribution in Zambia. The province (Luapula) with highest malaria transmission, mostly with rural settings recorded 98-100% sleeping spaces in homes covered with LLINs. The percentage of households owning at least 1 LLIN increased from 50.9% in 2006 to 77.7% in 2015. The 2014 mass campaign involved a coordinated response with substantial investments into macro (central) and micro (district) level planning, capacity building, tracking and logistics management supported by a new non-health sector partnership landscape. Coordination of LLIN distribution and logistics benefited from the mobile phone technology to transmit "real time" data on commodity tracking that facilitated timely delivery to districts. Free mass distribution of LLINs policy was adopted in 2005 in Zambia. Consistently implemented

Costing the distribution of insecticide-treated nets: a review of cost and cost-effectiveness studies to provide guidance on standardization of costing methodology

PubMed Central

Kolaczinski, Jan; Hanson, Kara

2006-01-01

Background Insecticide-treated nets (ITNs) are an effective and cost-effective means of malaria control. Scaling-up coverage of ITNs is challenging. It requires substantial resources and there are a number of strategies to choose from. Information on the cost of different strategies is still scarce. To guide the choice of a delivery strategy (or combination of strategies), reliable and standardized cost information for the different options is required. Methods The electronic online database PubMed was used for a systematic search of the published English literature on costing and economic evaluations of ITN distribution programmes. The keywords used were: net, bednet, insecticide, treated, ITN, cost, effectiveness, economic and evaluation. Identified papers were analysed to determine and evaluate the costing methods used. Methods were judged against existing standards of cost analysis to arrive at proposed standards for undertaking and presenting cost analyses. Results Cost estimates were often not readily comparable or could not be adjusted to a different context. This resulted from the wide range of methods applied and measures of output chosen. Most common shortcomings were the omission of certain costs and failure to adjust financial costs to generate economic costs. Generalisability was hampered by authors not reporting quantities and prices of resources separately and not examining the sensitivity of their results to variations in underlying assumptions. Conclusion The observed shortcomings have arisen despite the abundance of literature and guidelines on costing of health care interventions. This paper provides ITN specific recommendations in the hope that these will help to standardize future cost estimates. PMID:16681856

Experience of targeting subsidies on insecticide-treated nets: what do we know and what are the knowledge gaps?

PubMed

Worrall, Eve; Hill, Jenny; Webster, Jayne; Mortimer, Julia

2005-01-01

Widespread coverage of vulnerable populations with insecticide-treated nets (ITNs) constitutes an important component of the Roll Back Malaria (RBM) strategy to control malaria. The Abuja Targets call for 60% coverage of children under 5 years of age and pregnant women by 2005; but current coverage in Africa is unacceptably low. The RBM 'Strategic Framework for Coordinated National Action in Scaling-up Insecticide-Treated Netting Programmes in Africa' promotes coordinated national action and advocates sustained public provision of targeted subsidies to maximise public health benefits, alongside support and stimulation of the private sector. Several countries have already planned or initiated targeted subsidy schemes either on a pilot scale or on a national scale, and have valuable experience which can inform future interventions. The WHO RBM 'Workshop on mapping models for delivering ITNs through targeted subsidies' held in Zambia in 2003 provided an opportunity to share and document these country experiences. This paper brings together experiences presented at the workshop with other information on experiences of targeting subsidies on ITNs, net treatment kits and retreatment services (ITN products) in order to describe alternative approaches, highlight their similarities and differences, outline lessons learnt, and identify gaps in knowledge. We find that while there is a growing body of knowledge on different approaches to targeting ITN subsidies, there are significant gaps in knowledge in crucial areas. Key questions regarding how best to target, how much it will cost and what outcomes (levels of coverage) to expect remain unanswered. High quality, well-funded monitoring and evaluation of alternative approaches to targeting ITN subsidies is vital to develop a knowledge base so that countries can design and implement effective strategies to target ITN subsidies.

Enhanced Protection against Malaria by Indoor Residual Spraying in Addition to Insecticide Treated Nets: Is It Dependent on Transmission Intensity or Net Usage?

PubMed Central

West, Philippa A.; Protopopoff, Natacha; Wright, Alexandra; Kivaju, Zuhura; Tigererwa, Robinson; Mosha, Franklin W.; Kisinza, William; Rowland, Mark; Kleinschmidt, Immo

2015-01-01

Background Insecticide treated nets (ITNs) and indoor residual spraying (IRS) are effective vector control tools that protect against malaria. There is conflicting evidence regarding whether using ITNs and IRS in combination provides additional benefit over using either of these methods alone. This study investigated factors that may modify the effect of the combined use of IRS and ITNs compared to using ITNs alone on malaria infection prevalence. Methods Secondary analysis was carried out on data from a cluster randomised trial in north-west Tanzania. 50 clusters received ITNs from a universal coverage campaign; of these 25 were randomly allocated to additionally receive two rounds of IRS in 2012. In cross-sectional household surveys children 0.5–14 years old were tested for Plasmodium falciparum infections (PfPR) two, six and ten months after the first IRS round. Results IRS protected those sleeping under nets (OR = 0.38, 95%CI 0.26–0.57) and those who did not (OR = 0.43, 95%CI 0.29–0.63). The protective effect of IRS was not modified by community level ITN use (ITN use<50%, OR = 0.39, 95%CI 0.26–0.59; ITN use> = 50%, OR = 0.46, 95%CI 0.28–0.74). The additional protection from IRS was similar in low (<10% PfPR, OR = 0.38, 95%CI 0.19–0.75) and high transmission areas (≥10% PfPR, OR = 0.34, 95%CI 0.18–0.67). ITN use was protective at the individual-level regardless of whether the village had been sprayed (OR = 0.83, 95%CI 0.70–0.98). Living in a sprayed village was protective regardless of whether the individual slept under an ITN last night (OR = 0.41, 95%CI 0.29–0.58). Interpretation Implementing IRS in addition to ITNs was beneficial for individuals from villages with a wide range of transmission intensities and net utilisation levels. Net users received additional protection from IRS. ITNs were providing some individual protection, even in this area with high levels of pyrethroid insecticide resistance. These results demonstrate that there

Preventing Childhood Malaria in Africa by Protecting Adults from Mosquitoes with Insecticide-Treated Nets

PubMed Central

Killeen, Gerry F; Smith, Tom A; Ferguson, Heather M; Mshinda, Hassan; Abdulla, Salim; Lengeler, Christian; Kachur, Steven P

2007-01-01

Background Malaria prevention in Africa merits particular attention as the world strives toward a better life for the poorest. Insecticide-treated nets (ITNs) represent a practical means to prevent malaria in Africa, so scaling up coverage to at least 80% of young children and pregnant women by 2010 is integral to the Millennium Development Goals (MDG). Targeting individual protection to vulnerable groups is an accepted priority, but community-level impacts of broader population coverage are largely ignored even though they may be just as important. We therefore estimated coverage thresholds for entire populations at which individual- and community-level protection are equivalent, representing rational targets for ITN coverage beyond vulnerable groups. Methods and Findings Using field-parameterized malaria transmission models, we show that high (80% use) but exclusively targeted coverage of young children and pregnant women (representing <20% of the population) will deliver limited protection and equity for these vulnerable groups. In contrast, relatively modest coverage (35%–65% use, with this threshold depending on ecological scenario and net quality) of all adults and children, rather than just vulnerable groups, can achieve equitable community-wide benefits equivalent to or greater than personal protection. Conclusions Coverage of entire populations will be required to accomplish large reductions of the malaria burden in Africa. While coverage of vulnerable groups should still be prioritized, the equitable and communal benefits of wide-scale ITN use by older children and adults should be explicitly promoted and evaluated by national malaria control programmes. ITN use by the majority of entire populations could protect all children in such communities, even those not actually covered by achieving existing personal protection targets of the MDG, Roll Back Malaria Partnership, or the US President's Malaria Initiative. PMID:17608562

Evaluation of sunlight-exposed pyrethroid-treated netting for the control of face fly and housefly (Diptera: Muscidae).

PubMed

Peck, George W; Ferguson, Holly J; LePage, Jane T; Hebert, Vincent R; O'Neal, Sally D; Walsh, Douglas B

2014-01-01

Face flies, Musca autumnalis De Geer (Diptera: Muscidae), and houseflies, Musca domestica L. (Diptera: Muscidae), have a significant impact on livestock and dairy production throughout North America. Pyrethroid insecticide efficacy can be affected by exposure to direct sunlight, and the rate of photodegradation is substrate and formulation dependent. Insecticide-treated netting (ITN) is finding new applications in crop and livestock production systems. A baseline study using long-duration no-choice assays has been carried out to gauge the effectiveness of ITN treated with β-cyfluthrin, λ-cyhalothrin and bifenthrin on face flies and houseflies. After 12 weeks in direct sunlight, ITN treated with β-cyfluthrin was still highly insecticidal to face flies and houseflies, producing 100% mortality in petri dish assays. However, sunlight reduced the insecticidal activity of λ-cyhalothrin, with 3% of face flies and 50% of houseflies surviving after exposure to ITN that had been deployed for 10 weeks. Insecticidal activity was greatly reduced on bifenthrin-treated netting, with 20% of face flies and 50% of houseflies surviving in assays with netting deployed for only 3 weeks. With careful choice of the pyrethroid applied, treated netting could be an important component of livestock integrated pest management programs focused on sustainable practices. © 2013 Society of Chemical Industry.

Modelling the impact of the long-term use of insecticide-treated bed nets on Anopheles mosquito biting time.

PubMed

Ferreira, Claudia P; Lyra, Silas P; Azevedo, Franciane; Greenhalgh, David; Massad, Eduardo

2017-09-15

Evidence of changing in biting and resting behaviour of the main malaria vectors has been mounting up in recent years as a result of selective pressure by the widespread and long-term use of insecticide-treated bed nets (ITNs), and indoor residual spraying. The impact of resistance behaviour on malaria intervention efficacy has important implications for the epidemiology and malaria control programmes. In this context, a theoretical framework is presented to understand the mechanisms determining the evolution of feeding behaviour under the pressure of use of ITNs. An agent-based stochastic model simulates the impact of insecticide-treated bed nets on mosquito fitness by reducing the biting rates, as well as increasing mortality rates. The model also incorporates a heritability function that provides the necessary genetic plasticity upon which natural selection would act to maximize the fitness under the pressure of the control strategy. The asymptotic equilibrium distribution of mosquito population versus biting time is shown for several daily uses of ITNs, and the expected disruptive selection on this mosquito trait is observed in the simulations. The relative fitness of strains that bite at much earlier time with respect to the wild strains, when a threshold of about 50% of ITNs coverage highlights the hypothesis of a behaviour selection. A sensitivity analysis has shown that the top three parameters that play a dominant role on the mosquito fitness are the proportion of individuals using bed nets and its effectiveness, the impact of bed nets on mosquito oviposition, and the mosquito genetic plasticity related to changing in biting time. By taking the evolutionary aspect into account, the model was able to show that the long-term use of ITNs, although representing an undisputed success in reducing malaria incidence and mortality in many affected areas, is not free of undesirable side effects. From the evolutionary point of view of the parasite virulence, it

Estimation of insecticide persistence, biological activity and mosquito resistance to PermaNet® 2 long-lasting insecticidal nets over three to 32 months of use in Ethiopia.

PubMed

Anshebo, Gedeon Yohannes; Graves, Patricia M; Smith, Stephen C; Wills, Aprielle B; Damte, Mesele; Endeshaw, Tekola; Shargie, Estifanos Biru; Gebre, Teshome; Mosher, Aryc W; Patterson, Amy E; Emerson, Paul M

2014-03-06

Information is needed on the expected durability of insecticidal nets under operational conditions. The persistence of insecticidal efficacy is important to estimate the median serviceable life of nets under field conditions and to plan for net replacement. Deltamethrin residue levels were evaluated by the proxy method of X-ray fluorescence spectrometry on 189 nets used for three to six months from nine sites, 220 nets used for 14-20 months from 11 sites, and 200 nets used for 26-32 months from ten sites in Ethiopia. A random sample of 16.5-20% of nets from each time period (total 112 of 609 nets) were tested by bioassay with susceptible mosquitoes, and nets used for 14-20 months and 26-32 months were also tested with wild caught mosquitoes. Mean insecticide levels estimated by X-ray fluorescence declined by 25.9% from baseline of 66.2 (SD 14.6) mg/m2 at three to six months to 44.1 (SD 21.2) mg/m2 at 14-20 months and by 30.8% to 41.1 (SD 18.9) mg/m2 at 26-32 months. More than 95% of nets retained greater than 10 mg/m2 of deltamethrin and over 79% had at least 25 mg/m2 at all time periods. By bioassay with susceptible Anopheles, mortality averaged 89.0% on 28 nets tested at three to six months, 93.3% on 44 nets at 14-20 months and 94.1% on 40 nets at 26-32 months. With wild caught mosquitoes, mortality averaged 85.4% (range 79.1 to 91.7%) at 14-20 months but had dropped significantly to 47.2% (39.8 to 54.7%) at 26-32 months. Insecticide residue level, as estimated by X-ray fluorescence, declined by about one third between three and six months and 14-20 months, but remained relatively stable and above minimum requirements thereafter up to 26-32 months. The insecticidal activity of PermaNet® 2.0 long-lasting insecticidal nets in the specified study area may be considered effective to susceptible mosquitoes at least for the duration indicated in this study (32 months). However, results indicated that resistance in the wild population is already rendering nets with

Are Long-Lasting Insecticidal Nets Effective for Preventing Childhood Deaths among Non-Net Users? A Community-Based Cohort Study in Western Kenya

PubMed Central

Komazawa, Osuke; Kaneko, Satoshi; K’Opiyo, James; Kiche, Ibrahim; Wanyua, Sheru; Shimada, Masaaki; Karama, Mohamed

2012-01-01

Background Increasing the distribution and use of insecticide-treated nets (ITNs) in Sub-Saharan Africa has made controlling malaria with ITNs more practical. We evaluated community effects induced by ITNs, specifically long-lasting insecticidal nets (LLINs), under ordinary conditions in an endemic malaria area of Western Kenya. Methods Using the database from Mbita Health and Demographic Surveillance System (HDSS), children younger than 5 years old were assessed over four survey periods. We analyzed the effect of bed net usage, LLIN density and population density of young people around a child on all-cause child mortality (ACCM) rates using Cox PH models. Results During the study, 14,554 children were followed and 250 deaths were recorded. The adjusted hazard ratios (HRs) for LLIN usage compared with no net usage were not significant among the models: 1.08 (95%CI 0.76–1.52), 1.19 (95%CI 0.69–2.08) and 0.92 (95%CI 0.42–2.02) for LLIN users, untreated net users, and any net users, respectively. A significant increasing linear trend in risk across LLIN density quartiles (HR = 1.25; 95%CI 1.03–1.51) and a decreasing linear trend in risk across young population density quartiles among non-net user children (HR = 0.77; 95%CI 0.63–0.94) were observed. Conclusions Although our data showed that current LLIN coverage level (about 35%) could induce a community effect to protect children sleeping without bed nets even in a malaria-endemic area, it appears that a better system is needed to monitor the current malaria situation globally in order to optimize malaria control programs with limited resources. PMID:23185378

Insecticide-impregnated netting as a potential tool for long-lasting control of the leishmaniasis vector Lutzomyia longipalpis in animal shelters

PubMed Central

2013-01-01

Background Leishmaniasis remains a serious neglected disease, with more than 350 million people potentially at risk worldwide. Control strategies often rely on spraying residual insecticides to target populations of the sand fly vectors that transmit Leishmania parasites when blood-feeding. These programmes are often difficult to sustain effectively, as sand fly resting sites must be resprayed on a regular basis. Here, we investigate whether application of insecticide-impregnated netting to a surface could act as an alternative to residual spraying for controlling the American visceral leishmaniasis vector Lutzomyia longipalpis. Methods Female L. longipalpis from our laboratory colony were exposed for 1 h to three treatments applied to plywood surfaces: 2% permethrin-impregnated netting (Olyset®), 20 mg a.i.m-2 micro-encapsulated lambda-cyhalothrin (Demand CS®) and a no-treatment control. We compared the speed at which these treatments acted, by measuring the percentage of sand flies killed both immediately after exposure to the treatment for 1 hour, as well as the number that had died 24 h after the 1 hour exposure. We repeated the experiment at 6 and 12 months following application to test the effectiveness of each treatment over time. Results When first applied, the lambda-cyhalothrin killed more sand flies in the first hour than the permethrin-impregnated netting. However, the effectiveness of the lambda-cyhalothrin diminished over time, so that there was no difference between the two treatments at 12 months. Both killed more sand flies than the control. When measured 24 h following exposure, both test treatments had killed close to 100% of sand flies when first applied, but while the lethal effect of the netting was maintained at close to 100% over 12 months, the effectiveness of the residual insecticide diminished to approximately 80% after 6 months. Conclusions The results of these initial laboratory experiments indicate that covering surfaces

Costs and cost-effectiveness of vector control in Eritrea using insecticide-treated bed nets.

PubMed

Yukich, Joshua O; Zerom, Mehari; Ghebremeskel, Tewolde; Tediosi, Fabrizio; Lengeler, Christian

2009-03-30

While insecticide-treated nets (ITNs) are a recognized effective method for preventing malaria, there has been an extensive debate in recent years about the best large-scale implementation strategy. Implementation costs and cost-effectiveness are important elements to consider when planning ITN programmes, but so far little information on these aspects is available from national programmes. This study uses a standardized methodology, as part of a larger comparative study, to collect cost data and cost-effectiveness estimates from a large programme providing ITNs at the community level and ante-natal care facilities in Eritrea. This is a unique model of ITN implementation fully integrated into the public health system. Base case analysis results indicated that the average annual cost of ITN delivery (2005 USD 3.98) was very attractive when compared with past ITN delivery studies at different scales. Financing was largely from donor sources though the Eritrean government and net users also contributed funding. The intervention's cost-effectiveness was in a highly attractive range for sub-Saharan Africa. The cost per DALY averted was USD 13 - 44. The cost per death averted was USD 438-1449. Distribution of nets coincided with significant increases in coverage and usage of nets nationwide, approaching or exceeding international targets in some areas. ITNs can be cost-effectively delivered at a large scale in sub-Saharan Africa through a distribution system that is highly integrated into the health system. Operating and sustaining such a system still requires strong donor funding and support as well as a functional and extensive system of health facilities and community health workers already in place.

Ownership and utilisation of long lasting insecticide treated nets following free distribution campaign in South West Nigeria.

PubMed

Aderibigbe, Sunday Adedeji; Olatona, Foluke Adenike; Sogunro, Oluremi; Alawode, Gafar; Babatunde, Oluwole Adeyemi; Onipe, Ambrose Itopa; Bolarinwa, Oladimeji Akeem; Ameen, Hafsat Abolore; Osagbemi, Gordon Kayode; Sanya, Emmanuel Olatunde; Olarinoye, Adebunmi Oyeladun; Akande, Tanimola Makanjuola

2014-01-01

Malaria has proven to be the most horrendous and intractable amongst the health problems confronting countries in the sub-Saharan Africa. This study aims to determine the ownership and utilisation of long lasting insecticide treated nets following free distribution campaign in a state in South West Nigeria. Multi-stage sampling technique was used to recruit 2560 households spread across the 16 LGAs of the state. Interviewer administered standardized questionnaire was used for the survey. Data analysis was done using Stata 10 software. Sixty eight point six percent (68.6%) of the households had at least one under-five child living in the household while 32.6% had at least one pregnant woman living in the household. A total of 2440 (95.3%) households received LLIN during the campaign. Overall, the utilization rate for all respondents was 58.5%. Despite the fact that 2440 households received LLINs during the campaign, only 84.3% of them were seen to have hung theirs during the survey. Coverage and ownership of LLINs increased significantly following the free distribution campaign. There was a discrepancy between net possession and net use with rate of use lower than possession. Post distribution educational campaign should be incorporated into future distribution campaigns to help increase net utilisation.

INSECTICIDE-TREATED BED NETS IN RONDÔNIA, BRAZIL: EVALUATION OF THEIR IMPACT ON MALARIA CONTROL

PubMed Central

Vieira, Gabriel de Deus; Basano, Sergio de Almeida; Katsuragawa, Tony Hiroshi; Camargo, Luís Marcelo Aranha

2014-01-01

Mosquito nets treated with long-lasting insecticide (LLINs), when used in compliance with guidelines of the World Health Organization, may be effective for malaria vector control. In 2012, approximately 150,000 LLINs were installed in nine municipalities in the state of Rondônia. However, no studies have assessed their impact on the reduction of malaria incidence. This study analyzed secondary data of malaria incidence, in order to assess the impact of LLINs on the annual parasite incidence (API). The results showed no statistically significant differences in API one year after LLIN installation when compared to municipalities without LLINs. The adoption of measures for malaria vector control should be associated with epidemiological studies and evaluations of their use and efficiency, with the aim of offering convincing advantages that justify their implementation and limit malaria infection in the Amazon Region. PMID:25351543

Success of Senegal's first nationwide distribution of long-lasting insecticide-treated nets to children under five - contribution toward universal coverage

PubMed Central

2011-01-01

Background In 2009, the first national long-lasting insecticide-treated net (LLIN) distribution campaign in Senegal resulted in the distribution of 2.2 million LLINs in two phases to children aged 6-59 months. Door-to-door teams visited all households to administer vitamin A and mebendazole, and to give a coupon to redeem later for an LLIN. Methods A nationwide community-based two-stage cluster survey was conducted, with clusters selected within regions by probability proportional to size sampling, followed by GPS-assisted mapping, simple random selection of households in each cluster, and administration of a questionnaire using personal digital assistants (PDAs). The questionnaire followed the Malaria Indicator Survey format, with rosters of household members and bed nets, and questions on campaign participation. Results There were 3,280 households in 112 clusters representing 33,993 people. Most (92.1%) guardians of eligible children had heard about the campaign, the primary sources being health workers (33.7%), neighbours (26.2%), and radio (22.0%). Of eligible children, 82.4% received mebendazole, 83.8% received vitamin A, and 75.4% received LLINs. Almost all (91.4%) LLINs received during the campaign remained in the household; of those not remaining, 74.4% had been given away and none were reported sold. At least one insecticide-treated net (ITN) was present in 82.3% of all households, 89.2% of households with a child < 5 years and 57.5% of households without a child < 5 years. Just over half (52.4%) of ITNs had been received during the campaign. Considering possible indicators of universal coverage, 39.8% of households owned at least one ITN per two people, 21.6% owned at least one ITN per sleeping space and 34.7% of the general population slept under an ITN the night before the survey. In addition, 45.6% of children < 5 years, and 49.2% of pregnant women had slept under an ITN. Conclusions The nationwide integrated LLIN distribution campaign allowed

Equity trends in ownership of insecticide-treated nets in 19 sub-Saharan African countries.

PubMed

Taylor, Cameron; Florey, Lia; Ye, Yazoume

2017-05-01

To examine the change in equity of insecticide-treated net (ITN) ownership among 19 malaria-endemic countries in sub-Saharan Africa before and after the launch of the Cover The Bed Net Gap initiative. To assess change in equity in ownership of at least one ITN by households from different wealth quintiles, we used data from Demographic and Health Surveys and Malaria Indicator Surveys. We assigned surveys conducted before the launch (2003-2008) as baseline surveys and surveys conducted between 2009-2014 as endpoint surveys. We did country-level and pooled multicountry analyses. Pooled analyses based on malaria transmission risk, were done by dividing geographical zones into either low- and intermediate-risk or high-risk. To assess changes in equity, we calculated the Lorenz concentration curve and concentration index (C-index). Out of the 19 countries we assessed, 13 countries showed improved equity between baseline and endpoint surveys and two countries showed no changes. Four countries displayed worsened equity, two favouring the poorer households and two favouring the richer. The multicountry pooled analysis showed an improvement in equity (baseline survey C-index: 0.11; 95% confidence interval, CI: 0.10 to 0.11; and endpoint survey C-index: 0.00; 95% CI: -0.01 to 0.00). Similar trends were seen in both low- and intermediate-risk and high-risk zones. The mass ITN distribution campaigns to increase coverage, linked to the launch of the Cover The Bed Net Gap initiative, have led to improvement in coverage of ITN ownership across sub-Saharan Africa with significant reduction in inequity among wealth quintiles.

Scepticism towards insecticide treated mosquito nets for malaria control in rural community in north-western Tanzania.

PubMed

Nnko, Soori E; Whyte, Susan R; Geissler, Wenzel P; Aagaard-Hansen, Jens

2012-04-01

Despite existence of effective tools for malaria control, malaria continues to be one of the leading killer diseases especially among under-five year children and pregnant women in poor rural populations of Sub Saharan Africa. In Tanzania Mainland the disease contributes to 39.4% of the total OPD attendances. In terms of mortality, malaria is known to be responsible for more than one third of deaths among children of age below 5 years and also contributes for up to one fifth of deaths among pregnant women. This paper is based on a study conducted in a rural community along the shores of Lake Victoria in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional approach that tend to study low uptake of health interventions in terms of structural practical constraints--cost, accessibility, everyday priorities--or in terms of cognition--insufficient knowledge of benefits e.g. ignorance of public health messages. This paper has shown that, the majority of people who could afford the prices of ITNs and who knew where to obtain the insecticides did not necessarily buy them. This suggests that, although people tend to report cost-related factors as a barrier against the use of ITNs, there are other critical concerns at work. Without underestimating the practical factors, our study have recommended to consider critical examinations of those other concerns that hinder optimal utilization of ITN for malaria control, and the basis for those concerns.

Impact of malaria related messages on insecticide-treated net (ITN) use for malaria prevention in Ghana.

PubMed

Owusu Adjah, Ebenezer S; Panayiotou, Andrie G

2014-03-28

Media messages have been used in Ghana to promote insecticide-treated net (ITN)/bed net usage in an effort to impact on malaria prevention. The aim of this study was to assess the effect of such malaria-related messages delivered through electronic/print media and by volunteers/health workers on the use of ITNs by children living in a household. Data was collected from September to November of 2008 using a structured, interviewer-administered questionnaire by the Ghana Statistical Service as part of a national demographic and health survey (DHS). Secondary data analysis was performed on the collected data using multivariate logistic regression for both individual messages and a composite (any of) message variable. From the 11,788 households surveyed, 45% had at least one net. Households with male heads were more likely to have a child sleeping under a bed net the previous night (p = 0.0001). Individual Messages delivered by a health worker or a dedicated radio programme, had the highest effect for one or more children sleeping under a net the night before (OR(adjusted) = 1.65; 95% CI = 1.44 to 1.88 and OR(adjusted) = 1.26; 95% CI =1.12 to 1.42 respectively) while hearing any of the eight messages (composite score) resulted in the highest odds for one or more children (OR(adjusted) = 3.06; 95% CI = 2.27 to 4.12) sleeping under a bed net. Efforts to relate ITN messages to the public are very useful in increasing use of bed nets and having multiple ways of reaching the public increases their effect, with the biggest effect seen when health workers and volunteers were used to deliver malaria-related messages to the public.

Effectiveness of a long-lasting piperonyl butoxide-treated insecticidal net and indoor residual spray interventions, separately and together, against malaria transmitted by pyrethroid-resistant mosquitoes: a cluster, randomised controlled, two-by-two factorial design trial.

PubMed

Protopopoff, Natacha; Mosha, Jacklin F; Lukole, Eliud; Charlwood, Jacques D; Wright, Alexandra; Mwalimu, Charles D; Manjurano, Alphaxard; Mosha, Franklin W; Kisinza, William; Kleinschmidt, Immo; Rowland, Mark

2018-04-21

Progress in malaria control is under threat by wide-scale insecticide resistance in malaria vectors. Two recent vector control products have been developed: a long-lasting insecticidal net that incorporates a synergist piperonyl butoxide (PBO) and a long-lasting indoor residual spraying formulation of the insecticide pirimiphos-methyl. We evaluated the effectiveness of PBO long-lasting insecticidal nets versus standard long-lasting insecticidal nets as single interventions and in combination with the indoor residual spraying of pirimiphos-methyl. We did a four-group cluster randomised controlled trial using a two-by-two factorial design of 48 clusters derived from 40 villages in Muleba (Kagera, Tanzania). We randomly assigned these clusters using restricted randomisation to four groups: standard long-lasting insecticidal nets, PBO long-lasting insecticidal nets, standard long-lasting insecticidal nets plus indoor residual spraying, or PBO long-lasting insecticidal nets plus indoor residual spraying. Both standard and PBO nets were distributed in 2015. Indoor residual spraying was applied only once in 2015. We masked the inhabitants of each cluster to the type of nets received, as well as field staff who took blood samples. Neither the investigators nor the participants were masked to indoor residual spraying. The primary outcome was the prevalence of malaria infection in children aged 6 months to 14 years assessed by cross-sectional surveys at 4, 9, 16, and 21 months after intervention. The endpoint for assessment of indoor residual spraying was 9 months and PBO long-lasting insecticidal nets was 21 months. This trial is registered with ClinicalTrials.gov, number NCT02288637. 7184 (68·0%) of 10 560 households were selected for post-intervention survey, and 15 469 (89·0%) of 17 377 eligible children from the four surveys were included in the intention-to-treat analysis. Of the 878 households visited in the two indoor residual spraying groups, 827 (94%) had

Equity trends in ownership of insecticide-treated nets in 19 sub-Saharan African countries

PubMed Central

Florey, Lia; Ye, Yazoume

2017-01-01

Abstract Objective To examine the change in equity of insecticide-treated net (ITN) ownership among 19 malaria-endemic countries in sub-Saharan Africa before and after the launch of the Cover The Bed Net Gap initiative. Methods To assess change in equity in ownership of at least one ITN by households from different wealth quintiles, we used data from Demographic and Health Surveys and Malaria Indicator Surveys. We assigned surveys conducted before the launch (2003–2008) as baseline surveys and surveys conducted between 2009–2014 as endpoint surveys. We did country-level and pooled multicountry analyses. Pooled analyses based on malaria transmission risk, were done by dividing geographical zones into either low- and intermediate-risk or high-risk. To assess changes in equity, we calculated the Lorenz concentration curve and concentration index (C-index). Findings Out of the 19 countries we assessed, 13 countries showed improved equity between baseline and endpoint surveys and two countries showed no changes. Four countries displayed worsened equity, two favouring the poorer households and two favouring the richer. The multicountry pooled analysis showed an improvement in equity (baseline survey C-index: 0.11; 95% confidence interval, CI: 0.10 to 0.11; and endpoint survey C-index: 0.00; 95% CI: −0.01 to 0.00). Similar trends were seen in both low- and intermediate-risk and high-risk zones. Conclusion The mass ITN distribution campaigns to increase coverage, linked to the launch of the Cover The Bed Net Gap initiative, have led to improvement in coverage of ITN ownership across sub-Saharan Africa with significant reduction in inequity among wealth quintiles. PMID:28479633

KINET: a social marketing programme of treated nets and net treatment for malaria control in Tanzania, with evaluation of child health and long-term survival.

PubMed

Schellenberg, J R; Abdulla, S; Minja, H; Nathan, R; Mukasa, O; Marchant, T; Mponda, H; Kikumbih, N; Lyimo, E; Manchester, T; Tanner, M; Lengeler, C

1999-01-01

We present a large-scale social marketing programme of insecticide-treated nets in 2 rural districts in southwestern Tanzania (population 350,000) and describe how the long-term child health and survival impact will be assessed. Formative and market research were conducted in order to understand community perceptions, knowledge, attitudes and practice with respect to the products to be socially marketed. We identified Zuia Mbu (Kiswahili for 'prevent mosquitoes') as a suitable brand name for both treated nets and single-dose insecticide treatment sachets. A mix of public and private sales outlets is used for distribution. In the first stage of a stepped introduction 31 net agents were appointed and trained in 18 villages: 15 were shop owners, 14 were village leaders, 1 was a parish priest and 1 a health worker. For net treatment 37 young people were appointed in the same villages and trained as agents. Further institutions in both districts such as hospitals, development projects and employers were also involved in distribution. Promotion for both products was intense and used a variety of channels. A total of 22,410 nets and 8072 treatments were sold during the first year: 18 months after launching, 46% of 312 families with children aged under 5 years reported that their children were sleeping under treated nets. A strong evaluation component in over 50,000 people allows assessment of the long-term effects of insecticide-treated nets on child health and survival, anaemia in pregnancy, and the costs of the intervention. This evaluation is based on cross-sectional surveys, and case-control and cohort studies.

Evaluation of the 2011 long-lasting, insecticide-treated net distribution for universal coverage in Togo.

PubMed

Stevens, Elizabeth R; Aldridge, Abigail; Degbey, Yawo; Pignandi, Akou; Dorkenoo, Monique A; Hugelen-Padin, Justin

2013-05-16

Malaria remains a substantial public health problem in Togo. An integrated child health campaign was conducted in Togo in October 2011. This campaign included a component of free distribution of 2,799,800 long-lasting, insecticide-treated nets (LLINs) to households throughout Togo. This distribution marked the first effort in Togo at universal LLIN coverage and was not targeted specifically to children under five years and pregnant women, but to all household members. This study reports the results of the LLIN distribution campaign in terms of bed net possession and utilization. A representative household survey was implemented during the rainy season nine months after the LLIN distribution component of the campaign. Some 6,015 households selected through two stages of probability proportion to size stratified random sampling were interviewed using a brief questionnaire that included a demographic section with questions on the number of household members and sleeping spaces, and a campaign participation section with questions used to evaluate non-LLIN aspects of the campaign. A net roster listed all nets and their characteristics, and a household roster listed all members and visitors with information about bed net use. The questions addressed different aspects of bed net and LLIN possession and utilization. Crude weighted frequencies, percentages, and t- tests of association were calculated using the Stata 12.0 Survey features. Possession of at least one bed net and/or LLIN increased from 41.3% to 96.7% (P <0.001). Household possession of at least one campaign LLIN was 93.3%. Report LLIN among pregnant women was 77.5% and 79.3% for children under five. For the general population LLIN use was 68.3%. Due to the gap in LLIN possession and use and the significant number of individuals reporting a lack of nets as a reason for non-use, additional national LLIN distribution campaigns with a stronger educational component need to be implemented in order increase the use

Public-private delivery of insecticide-treated nets: a voucher scheme in Volta Region, Ghana

PubMed Central

Kweku, Margaret; Webster, Jayne; Taylor, Ian; Burns, Susan; Dedzo, McDamien

2007-01-01

Background Coverage of vulnerable groups with insecticide-treated nets (ITNs) in Ghana, as in the majority of countries of sub-Saharan Africa is currently low. A voucher scheme was introduced in Volta Region as a possible sustainable delivery system for increasing this coverage through scale-up to other regions. Successful scale-up of public health interventions depends upon optimal delivery processes but operational research for delivery processes in large-scale implementation has been inadequate. Methods A simple tool was developed to monitor numbers of vouchers given to each health facility, numbers issued to pregnant women by the health staff, and numbers redeemed by the distributors back to the management agent. Three rounds of interviews were undertaken with health facility staff, retailers and pregnant women who had attended antenatal clinic (ANC). Results During the one year pilot 25,926 vouchers were issued to eligible women from clinics, which equates to 50.7% of the 51,658 ANC registrants during this time period. Of the vouchers issued 66.7% were redeemed by distributors back to the management agent. Initially, non-issuing of vouchers to pregnant women was mainly due to eligibility criteria imposed by the midwives; later in the year it was due to decisions of the pregnant women, and supply constraints. These in turn were heavily influenced by factors external to the programme: current household ownership of nets, competing ITN delivery strategies, and competition for the limited number of ITNs available in the country from major urban areas of other regions. Conclusion Both issuing and redemption of vouchers should be monitored as factors assumed to influence voucher redemption had an influence on issuing, and vice versa. More evidence is needed on how specific contextual factors influence the success of voucher schemes and other models of delivery of ITNs. Such an evidence base will facilitate optimal strategic decision making so that the delivery model

Host-seeking activity of a Tanzanian population of Anopheles arabiensis at an insecticide treated bed net.

PubMed

Parker, Josephine E A; Angarita Jaimes, Natalia C; Gleave, Katherine; Mashauri, Fabian; Abe, Mayumi; Martine, Jackline; Towers, Catherine E; Towers, David; McCall, Philip J

2017-07-04

Understanding how mosquitoes respond to long lasting insecticide treated nets (LLINs) is fundamental to sustaining the effectiveness of this essential control tool. We report on studies with a tracking system to investigate behaviour of wild anophelines at an LLIN, in an experimental hut at a rural site in Mwanza, Tanzania. Groups of adult female mosquitoes (n = 10 per replicate) reared from larvae of a local population, identified as predominantly (95%) Anopheles arabiensis, were released in the hut. An infrared video tracking system recorded flight and net contact activity over 1 h as the mosquitoes attempted to reach a supine human volunteer within a bed net (either a deltamethrin-treated LLIN or an untreated control net). A range of activities, including flight path, position in relation to the bed net and duration of net contact, were quantified and compared between treatments. The total time that female An. arabiensis spent in flight around LLINs was significantly lower than at untreated nets [F(1,10) = 9.26, p = 0.012], primarily due to a substantial reduction in the time mosquitoes spent in persistent 'bouncing' flight [F(1,10) = 18.48, p = 0.002]. Most activity occurred at the net roof but significantly less so with LLINs (56.8% of total) than untreated nets [85.0%; Χ 2 (15) = 234.69, p < 0.001]. Activity levels at the bed net directly above the host torso were significantly higher with untreated nets (74.2%) than LLINs [38.4%; Χ 2 (15) = 33.54, p = 0.004]. 'Visiting' and 'bouncing' rates were highest above the volunteer's chest in untreated nets (39.9 and 50.4%, respectively) and LLINs [29.9 and 42.4%; Χ 2 (13) = 89.91, p < 0.001; Χ 2 (9) = 45.73, p < 0.001]. Highest resting rates were above the torso in untreated nets [77%; Χ 2 (9) = 63.12, p < 0.001], but in LLINs only 33.2% of resting occurred here [Χ 2 (9) = 27.59, p = 0.001], with resting times spread between the short vertical side of the net adjacent to the

A qualitative study on the acceptability and preference of three types of long-lasting insecticide-treated bed nets in Solomon Islands: implications for malaria elimination

PubMed Central

Atkinson, Jo-An; Bobogare, Albino; Fitzgerald, Lisa; Boaz, Leonard; Appleyard, Bridget; Toaliu, Hilson; Vallely, Andrew

2009-01-01

Background In March 2008, the Solomon Islands and Vanuatu governments raised the goal of their National Malaria Programmes from control to elimination. Vector control measures, such as indoor residual spraying (IRS) and long-lasting insecticidal bed nets (LLINs) are key integral components of this programme. Compliance with these interventions is dependent on their acceptability and on the socio-cultural context of the local population. These factors need to be investigated locally prior to programme implementation. Method Twelve focus group discussions (FGDs) were carried out in Malaita and Temotu Provinces, Solomon Islands in 2008. These discussions explored user perceptions of acceptability and preference for three brands of long-lasting insecticide-treated bed nets (LLINs) and identified a number of barriers to their proper and consistent use. Results Mosquito nuisance and perceived threat of malaria were the main determinants of bed net use. Knowledge of malaria and the means to prevent it were not sufficient to guarantee compliance with LLIN use. Factors such as climate, work and evening social activities impact on the use of bed nets, particularly in men. LLIN acceptability plays a varying role in compliance with their use in villages involved in this study. Participants in areas of reported high and year round mosquito nuisance and perceived threat of malaria reported LLIN use regardless of any reported unfavourable characteristics. Those in areas of low or seasonal mosquito nuisance were more likely to describe the unfavourable characteristics of LLINs as reasons for their intermittent or non-compliance. The main criterion for LLIN brand acceptability was effectiveness in preventing mosquito bites and malaria. Discussions highlighted considerable confusion around LLIN care and washing which may be impacting on their effectiveness and reducing their acceptability in Solomon Islands. Conclusion Providing LLINs that are acceptable will be more important for

Combining indoor residual spraying and insecticide-treated nets for malaria control in Africa: a review of possible outcomes and an outline of suggestions for the future

PubMed Central

2011-01-01

Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are currently the preferred methods of malaria vector control. In many cases, these methods are used together in the same households, especially to suppress transmission in holoendemic and hyperendemic scenarios. Though widespread, there has been limited evidence suggesting that such co-application confers greater protective benefits than either ITNs or IRS when used alone. Since both methods are insecticide-based and intradomicilliary, this article hypothesises that outcomes of their combination would depend on effects of the candidate active ingredients on mosquitoes that enter or those that attempt to enter houses. It is suggested here that enhanced household level protection can be achieved if the ITNs and IRS have divergent yet complementary properties, e.g. highly deterrent IRS compounds coupled with highly toxic ITNs. To ensure that the problem of insecticide resistance is avoided, the ITNs and IRS products should preferably be of different insecticide classes, e.g. pyrethroid-based nets combined with organophosphate or carbamate based IRS. The overall community benefits would however depend also on other factors such as proportion of people covered by the interventions and the behaviour of vector species. This article concludes by emphasizing the need for basic and operational research, including mathematical modelling to evaluate IRS/ITN combinations in comparison to IRS alone or ITNs alone. PMID:21798053

Comparison of the Laboratory Standard Washing Using CIPAC Washing Agent and the Domestic Washing on Three Recommended Types of Long-Lasting Insecticidal Mosquito Nets

PubMed Central

Ouattara, Jean Pierre Nabléni; Louwagie, Johanna; Pigeon, Olivier; Spanoghe, Pieter

2013-01-01

Background One of the best ways to prevent malaria is the use of insecticide-treated bed nets. Manufacturers pursue easier, safer and more efficient nets. Hence, many studies on the efficacy and wash resistance using World Health Organization standards have been reported. The commonly used detergent is “Savon de Marseille”, because it closely resembles actually used soaps. At the 54th Collaborative International Pesticides Analytical Council (CIPAC) Technical Meeting in 2010, it was suggested to replace it by a standardized “CIPAC washing agent”. The aim of this study was to investigate the difference between a laboratory hand washing simulation using the CIPAC washing agent (method-1) and a domestic washing (method-2) on different bed nets, as well as the effect of the drying process on the release of active ingredient. Methods Interceptor®, Permanet®2.0 and Netprotect® nets were used in three treatments, each repeated 20 times. The first treatment included method-1 washing and indoor drying. The second treatment included method-2 washing and indoor drying. The third treatment used method-2 washing and UV-drying. The residual insecticide contents were determined using gas chromatography. Results The washing procedure and the number of washes have a significant effect on the release of active ingredient. Statistically, the two washing methods have the same effect on removing the active ingredient from the Interceptor® and Permanet®2.0 net, but a significantly different influence on the Netprotect® nets. The drying process has no significant effect on the insecticide. Conclusion Both washing procedures affected the amount of insecticide remaining on nets independently of the impregnation technology. The active ingredient decreases with the number of washing cycles following an exponential or logarithmic model for coated nets. The laboratory hand washing simulation had more impact on the decrease of active ingredient content of the Netprotect® nets

Efficacy of long-lasting insecticidal nets in use in Macha, Zambia, against the local Anopheles arabiensis population.

PubMed

Norris, Laura C; Norris, Douglas E

2011-08-31

The mosquito Anopheles arabiensis is the primary vector of Plasmodium falciparum in Macha, Zambia. A major portion of Zambia's current malaria control programme relies on long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) with insecticides. Currently, the efficacy of these measures against An. arabiensis in Macha is unknown, and previous data has shown that An. arabiensis has continued to feed on human hosts, despite high ITN coverage. It is possible that this could be due to either decreased efficacy of ITNs in used in Macha, or pyrethroid resistance in the vector. F1 offspring of field-collected adult An. arabiensis were tested for insecticide resistance, using CDC bottle bioassays and deltamethrin ITN susceptibility assays. The mosquitoes were characterized for the knock-down resistance (kdr) allele by PCR. LLINs that had been in use for two years in nearby villages were collected and tested for residual deltamethrin concentration and net quality, and were used in bioassays against susceptible colonized Anopheles gambiae s.s. Keele. Additionally, a survey on ITN use and care was conducted among LLIN owners. In the F1 An. arabiensis field population, low levels of resistance to DDT and deltamethrin-treated net material were detected by bioassay, although the knock-down resistance (kdr) allele not present in the population. ITN evaluations revealed high variability in residual deltamethrin concentration, quality of the nets, and mosquito mortality in bioassays. Mortality against An. gambiae s.s. in bioassays was correlated with residual deltamethrin concentration, which was dependent upon the number of washes each net had received. Proper LLIN care was a strong determinant of LLIN efficacy, indicating that education on the importance of LLIN use and care is key when distributing nets. As there is little insecticide resistance in the local vector population, degradation of LLINs most likely allowed for continued human feeding by An

Experimental hut evaluation of bednets treated with an organophosphate (chlorpyrifos-methyl) or a pyrethroid (lambdacyhalothrin) alone and in combination against insecticide-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes

PubMed Central

Asidi, Alex N; N' Guessan, Raphael; Koffi, Alphonsine A; Curtis, Christopher F; Hougard, Jean-Marc; Chandre, Fabrice; Corbel, Vincent; Darriet, Frédéric; Zaim, Morteza; Rowland, Mark W

2005-01-01

Background Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is important to identify alternative insecticides which, if necessary, could be used to replace or supplement the pyrethroids for use on treated nets. Certain compounds of an earlier generation of insecticides, the organophosphates may have potential as net treatments. Methods Comparative studies of chlorpyrifos-methyl (CM), an organophosphate with low mammalian toxicity, and lambdacyhalothrin (L), a pyrethroid, were conducted in experimental huts in Côte d'Ivoire, West Africa. Anopheles gambiae and Culex quinquefasciatus mosquitoes from the area are resistant to pyrethroids and organophosphates (kdr and insensitive acetylcholinesterase Ace.1R). Several treatments and application rates on intact or holed nets were evaluated, including single treatments, mixtures, and differential wall/ceiling treatments. Results and Conclusion All of the treatments were effective in reducing blood feeding from sleepers under the nets and in killing both species of mosquito, despite the presence of the kdr and Ace.1R genes at high frequency. In most cases, the effects of the various treatments did not differ significantly. Five washes of the nets in soap solution did not reduce the impact of the insecticides on A. gambiae mortality, but did lead to an increase in blood feeding. The three combinations performed no differently from the single insecticide treatments, but the low dose mixture performed encouragingly well indicating that such combinations might be used for controlling insecticide resistant mosquitoes. Mortality of mosquitoes that carried both Ace.1R and Ace.1S genes did not differ significantly from mosquitoes that carried only Ace.1S genes on any of the treated nets, indicating that the Ace.1R allele does not confer effective resistance to chlorpyrifos-methyl under the realistic conditions of an experimental hut. PMID:15918909

A comparative cost analysis of insecticide-treated nets and indoor residual spraying in highland Kenya.

PubMed

Guyatt, H L; Kinnear, J; Burini, M; Snow, R W

2002-06-01

The relative cost of indoor residual house-spraying (IRS) versus insecticide-treated bednets (ITNs) forms part of decisions regarding selective malaria prevention. This paper presents a cost comparison of these two approaches as recently implemented by Merlin, a UK emergency relief organization funded through international donor support and working in the highland districts of Gucha and Kisii in Kenya. The financial costs (cash expenditures) and the economic costs (including the opportunity costs of using existing staff and volunteers, and an annualized cost for capital items) were assessed. The financial cost for IRS was US dollars 0.86 per person protected, compared with 4.21 dollars for ITNs (reducing to 3.42 dollars to the provider assuming cost recovery). The economic cost per person protected for IRS was 0.88 dollars, compared with 2.34 dollars for ITNs. The costs for ITNs were sensitive to the number of nets sold per community group ('efficiency'), as the delivery costs constituted upwards of 40% of the total cost. However, even marked increases in efficiency of these groups could not reduce the costs of ITNs to that comparable with IRS, except if more than one cycle of IRS was needed. The implications of predicted reductions in the cost of insecticide for both IRS and ITNs are also explored. The provision of itemized cost data allows predictions to be made on changes in the design of these programmes. Under almost all design scenarios, IRS would appear to be a more cost-efficient means of vector control in the Kenyan highlands.

Ownership and Use of Insecticide-Treated Nets among People Living in Malaria Endemic Areas of Eastern Myanmar.

PubMed

Aung, Tin; Wei, Chongyi; McFarland, Willi; Aung, Ye Kyaw; Khin, Hnin Su Su

2016-01-01

Myanmar has the highest burden of malaria in the Greater Mekong. However, there is limited information on ownership and use of insecticide-treated nets (ITNs) in areas of Myanmar most severely affected by malaria. We describe ownership and use of ITNs among people in the malaria-endemic eastern parts of Myanmar and factors associated with ITN use. A cross-sectional household survey using a multi-stage cluster design was conducted in malaria-endemic townships in eastern Myanmar during the high malaria season of August to September, 2014. An effective ITN was defined as 1) a long-lasting insecticide-treated net obtained within the past three years, or 2) any net treated with insecticide within the past year. In 4,679 households, the average number of ITNs per household was higher in rural compared to urban areas (0.6 vs. 0.4, p <0.001) as well as the proportion of households owning at least one ITN (27.3% vs. 15.5%, p<0.001). The proportion of households in which all members slept under an ITN was also higher in rural compared to urban areas (15.3% vs 6.9%, p<0.001). In multivariate analysis, rural households (adjusted odds ratio [aOR] 1.78, 95% CI: 1.43-2.21, p<0.001), households in which respondents knew malaria is transmitted by mosquitoes (aOR 1.35, 95% CI: 1.10-1.65, p = 0.004), and in which respondents knew malaria can be prevented by ITN use (aOR 1.86, 95% CI: 1.28-2.70, p<0.001) were more likely to have all members sleep under an ITN. Compared to the lowest socio-economic quintile, households in the richest quintile were less likely to have all members sleep under an ITN (aOR 0.47; 95% CI: 0.33-0.66, p<0.001). Households in which the main income earner was a skilled worker or a businessman were less likely to have all members sleep under an ITN (aOR, 0.70, 95% CI: 0.52-0.96, p<0.025) compared to those headed by farmers or fishermen. Households in which all children slept under an ITN were more likely to be in rural areas (aOR 1.58, 95% CI: 1.19-2.09, p = 0

Entomological evaluation of PermaNet 2.0® and K-O Tab 1-2-3® treated nets in comparison to nets conventionally treated with deltamethrin, after repeated washing.

PubMed

Kayedi, Mohammad Hassan; Khamisabadi, Kiumars; Dehghani, Nader; Haghdoost, Ali Akbar

2015-06-01

The residual insecticidal power of two types of ITNs (PermaNet 2.0® (PN2) and K-O Tab 1-2-3® (KO 123)), compared to K-O Tab® (KO) treated nets, was assessed. The nets were tested unwashed, and after being washed, by hand 5, 15 and 21 times, respectively. After each wash, the nets were dried vertically on a line, in the shade. Two types of bioassays (mean median knock down times (MMKDT) and mortality 24 hours after a 3-minute exposure (%mortality)) were used, along with reared female Anopheles stephensi. The number of washes had a great impact on MMKDT and %mortality of all types of nets. This impact was greater for conventionally treated nets, indicating that PN2 and KO 123 nets are significantly more wash resistant than KO nets after 21 washes. There was no significant difference between PN2 and KO 123 with respect to %mortality 24 hours after a 3-minute exposure at 0, 15 and 21 washes. Similarly, the same results were obtained for MMKDT, and the differences between PN2 and KO 123 were not statistically significant. This study demonstrates that the efficacy of KO 123 nets is as beneficial as the efficacy of PN2 nets up to 21 washes.

The impact of insecticide-treated material to reduce flies among pork outlets in Kampala, Uganda.

PubMed

Heilmann, Martin; Roesel, Kristina; Grace, Delia; Bauer, Burkhard; Clausen, Peter-Henning

2017-06-01

Synanthropic flies have adapted to the mass of decaying organic matter near human settlements. As such, they feed and breed on food, faeces and other organic material and are known vectors for various diseases. Many of these diseases are associated with food, and foodborne diseases are of growing concern in developing countries where human population and food consumption increase. This pilot study aims at investigating the impact of a novel application of insecticide-treated material (ZeroFly®) to reduce flies among pork outlets in Kampala, Uganda. A cross-sectional survey randomly selected 60 of 179 pork outlets in Kampala. A controlled longitudinal trial followed in which 23 out of the 60 pork outlets were recruited for an intervention with insecticide-treated material. The pork outlets were randomly allocated to a group of 18 netted pork outlets (intervention) and five non-netted pork outlets (control). Monitoring took place over 15 weeks including 2 weeks as the baseline survey. The units were monitored for fly abundance using non-attractant sticky traps, which were placed within the pork outlet once per week for 48 consecutive hours. Medians of fly numbers before and after the intervention indicated a decrease of fly numbers of 48% (p = 0.002). Fly bioassays showed that the insecticidal activity of the netting remained active over the entire intervention period and led to a total paralysis of flies within at least 6 h after exposure. Insecticide-treated material provides a practical and sustainable solution in controlling flies and is therefore recommended as a complementary strategy for an integrated vector control and hygiene management.

Implications of bio-efficacy and persistence of insecticides when indoor residual spraying and long-lasting insecticide nets are combined for malaria prevention

PubMed Central

2012-01-01

Background Bio-efficacy and residual activity of insecticides used for indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs) were assessed against laboratory-reared and wild populations of the malaria vector, Anopheles arabiensis in south eastern Tanzania. Implications of the findings are examined in the context of potential synergies and redundancies where IRS and LLINs are combined. Methods Bioassays were conducted monthly for six months on three LLIN types (Olyset® PermaNet 2.0®,and Icon Life®) and three IRS treatments (2 g/m2 pirimiphos-methyl, 2 g/m2 DDT and 0.03 g/m2 lambda-cyhalothrin, sprayed on mud walls and palm ceilings of experimental huts). Tests used susceptible laboratory-reared An. arabiensis exposed in cones (nets and IRS) or wire balls (nets only). Susceptibility of wild populations was assessed using WHO diagnostic concentrations and PCR for knock-down resistance (kdr) genes. Results IRS treatments killed ≥ 85% of mosquitoes exposed on palm ceilings and ≥ 90% of those exposed on mud walls, but up to 50% of this toxicity decayed within 1–3 months, except for DDT. By 6th month, only 7.5%, 42.5% and 30.0% of mosquitoes died when exposed to ceilings sprayed with pirimiphos-methyl, DDT or lambda-cyhalothrin respectively, while 12.5%, 36.0% and 27.5% died after exposure to mud walls sprayed with the same insecticides. In wire-ball assays, mortality decreased from 98.1% in 1st month to 92.6% in 6th month in tests on PermaNet 2.0®, from 100% to 61.1% on Icon Life® and from 93.2% to 33.3% on Olyset® nets. In cone bioassays, mortality reduced from 92.8% in 1st month to 83.3% in 6th month on PermaNet 2.0®, from 96.9% to 43.80% on Icon Life® and from 85.6% to 14.6% on Olyset®. Wild An. arabiensis were 100% susceptible to DDT, 95.8% to deltamethrin, 90.2% to lambda cyhalothrin and 95.2% susceptible to permethrin. No kdr gene mutations were detected. Conclusions In bioassays where sufficient contact with treated surfaces is

Strategies for delivering insecticide-treated nets at scale for malaria control: a systematic review

PubMed Central

Paintain, Lucy Smith; Mangham, Lindsay; Car, Josip; Schellenberg, Joanna Armstrong

2012-01-01

Abstract Objective To synthesize findings from recent studies of strategies to deliver insecticide-treated nets (ITNs) at scale in malaria-endemic areas. Methods Databases were searched for studies published between January 2000 and December 2010 in which: subjects resided in areas with endemicity for Plasmodium falciparum and Plasmodium vivax malaria; ITN delivery at scale was evaluated; ITN ownership among households, receipt by pregnant women and/or use among children aged < 5 years was evaluated; and the study design was an individual or cluster-randomized controlled design, nonrandomized, quasi-experimental, before-and-after, interrupted time series or cross-sectional without temporal or geographical controls. Papers describing qualitative studies, case studies, process evaluations and cost-effectiveness studies linked to an eligible paper were also included. Study quality was assessed using the Cochrane risk of bias checklist and GRADE criteria. Important influences on scaling up were identified and assessed across delivery strategies. Findings A total of 32 papers describing 20 African studies were reviewed. Many delivery strategies involved health sectors and retail outlets (partial subsidy), antenatal care clinics (full subsidy) and campaigns (full subsidy). Strategies achieving high ownership among households and use among children < 5 delivered ITNs free through campaigns. Costs were largely comparable across strategies; ITNs were the main cost. Cost-effectiveness estimates were most sensitive to the assumed net lifespan and leakage. Common barriers to delivery included cost, stock-outs and poor logistics. Common facilitators were staff training and supervision, cooperation across departments or ministries and stakeholder involvement. Conclusion There is a broad taxonomy of strategies for delivering ITNs at scale. PMID:22984312

Frequent blood feeding enables insecticide-treated nets to reduce transmission by mosquitoes that bite predominately outdoors.

PubMed

Russell, Tanya L; Beebe, Nigel W; Bugoro, Hugo; Apairamo, Allan; Chow, Weng K; Cooper, Robert D; Collins, Frank H; Lobo, Neil F; Burkot, Thomas R

2016-03-10

The effectiveness of vector control on malaria transmission by long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) depends on the vectors entering houses to blood feed and rest when people are inside houses. In the Solomon Islands, significant reductions in malaria have been achieved in the past 20 years with insecticide-treated bed nets, IRS, improved diagnosis and treatment with artemisinin combination therapies; despite the preference of the primary vector, Anopheles farauti, to feed outdoors and early in the evening and thereby avoid potential exposure to insecticides. Rational development of tools to complement LLINs and IRS by attacking vectors outdoor requires detailed knowledge of the biology and behaviours of the target species. Malaria transmission in Central Province, Solomon Islands was estimated by measuring the components comprising the entomological inoculation rate (EIR) as well as the vectorial capacity of An. farauti. In addition, the daily and seasonal biting behaviour of An. farauti, was examined and the duration of the feeding cycle was estimated with a mark-release-recapture experiment. Anopheles farauti was highly exophagic with 72% captured by human landing catches (HLC) outside of houses. Three-quarters (76%) of blood feeding on humans was estimated to occur before 21.00 h. When the hourly location of humans was considered, the proportion of exposure to mosquito bites on humans occurring indoors (πi) was only 0.130 ± 0.129. Peak densities of host seeking An. farauti occurred between October and January. The annual EIR was estimated to be 2.5 for 2012 and 33.2 for 2013. The length of the feeding cycle was 2.1 days. The short duration of the feeding cycle by this species offers an explanation for the substantial control of malaria that has been achieved in the Solomon Islands by LLINs and IRS. Anopheles farauti is primarily exophagic and early biting, with 13% of mosquitoes entering houses to feed late at night during

Implications of insecticide resistance for malaria vector control with long-lasting insecticidal nets: a WHO-coordinated, prospective, international, observational cohort study.

PubMed

Kleinschmidt, Immo; Bradley, John; Knox, Tessa Bellamy; Mnzava, Abraham Peter; Kafy, Hmooda Toto; Mbogo, Charles; Ismail, Bashir Adam; Bigoga, Jude D; Adechoubou, Alioun; Raghavendra, Kamaraju; Cook, Jackie; Malik, Elfatih M; Nkuni, Zinga José; Macdonald, Michael; Bayoh, Nabie; Ochomo, Eric; Fondjo, Etienne; Awono-Ambene, Herman Parfait; Etang, Josiane; Akogbeto, Martin; Bhatt, Rajendra M; Chourasia, Mehul Kumar; Swain, Dipak K; Kinyari, Teresa; Subramaniam, Krishanthi; Massougbodji, Achille; Okê-Sopoh, Mariam; Ogouyemi-Hounto, Aurore; Kouambeng, Celestin; Abdin, Mujahid Sheikhedin; West, Philippa; Elmardi, Khalid; Cornelie, Sylvie; Corbel, Vincent; Valecha, Neena; Mathenge, Evan; Kamau, Luna; Lines, Jonathan; Donnelly, Martin James

2018-04-09

Scale-up of insecticide-based interventions has averted more than 500 million malaria cases since 2000. Increasing insecticide resistance could herald a rebound in disease and mortality. We aimed to investigate whether insecticide resistance was associated with loss of effectiveness of long-lasting insecticidal nets and increased malaria disease burden. This WHO-coordinated, prospective, observational cohort study was done at 279 clusters (villages or groups of villages in which phenotypic resistance was measurable) in Benin, Cameroon, India, Kenya, and Sudan. Pyrethroid long-lasting insecticidal nets were the principal form of malaria vector control in all study areas; in Sudan this approach was supplemented by indoor residual spraying. Cohorts of children from randomly selected households in each cluster were recruited and followed up by community health workers to measure incidence of clinical malaria and prevalence of infection. Mosquitoes were assessed for susceptibility to pyrethroids using the standard WHO bioassay test. Country-specific results were combined using meta-analysis. Between June 2, 2012, and Nov 4, 2016, 40 000 children were enrolled and assessed for clinical incidence during 1·4 million follow-up visits. 80 000 mosquitoes were assessed for insecticide resistance. Long-lasting insecticidal net users had lower infection prevalence (adjusted odds ratio [OR] 0·63, 95% CI 0·51-0·78) and disease incidence (adjusted rate ratio [RR] 0·62, 0·41-0·94) than did non-users across a range of resistance levels. We found no evidence of an association between insecticide resistance and infection prevalence (adjusted OR 0·86, 0·70-1·06) or incidence (adjusted RR 0·89, 0·72-1·10). Users of nets, although significantly better protected than non-users, were nevertheless subject to high malaria infection risk (ranging from an average incidence in net users of 0·023, [95% CI 0·016-0·033] per person-year in India, to 0·80 [0·65-0·97] per person

Combination of indoor residual spraying with long-lasting insecticide-treated nets for malaria control in Zambezia, Mozambique: a cluster randomised trial and cost-effectiveness study protocol

PubMed Central

Alonso, Sergi; Zulliger, Rose; Wagman, Joe; Saifodine, Abuchahama; Candrinho, Baltazar; Macete, Eusébio; Brew, Joe; Fornadel, Christen; Kassim, Hidayat; Loch, Lourdes; Sacoor, Charfudin; Varela, Kenyssony; Carty, Cara L; Robertson, Molly; Saute, Francisco

2018-01-01

Background Most of the reduction in malaria prevalence seen in Africa since 2000 has been attributed to vector control interventions. Yet increases in the distribution and intensity of insecticide resistance and higher costs of newer insecticides pose a challenge to sustaining these gains. Thus, endemic countries face challenging decisions regarding the choice of vector control interventions. Methods A cluster randomised trial is being carried out in Mopeia District in the Zambezia Province of Mozambique, where malaria prevalence in children under 5 is high (68% in 2015), despite continuous and campaign distribution of long-lasting insecticide-treated nets (LLINs). Study arm 1 will continue to use the standard, LLIN-based National Malaria Control Programme vector control strategy (LLINs only), while study arm 2 will receive indoor residual spraying (IRS) once a year for 2 years with a microencapsulated formulation of pirimiphos-methyl (Actellic 300 CS), in addition to the standard LLIN strategy (LLINs+IRS). Prior to the 2016 IRS implementation (the first of two IRS campaigns in this study), 146 clusters were defined and stratified per number of households. Clusters were then randomised 1:1 into the two study arms. The public health impact and cost-effectiveness of IRS intervention will be evaluated over 2 years using multiple methods: (1) monthly active malaria case detection in a cohort of 1548 total children aged 6–59 months; (2) enhanced passive surveillance at health facilities and with community health workers; (3) annual cross-sectional surveys; and (4) entomological surveillance. Prospective microcosting of the intervention and provider and societal costs will be conducted. Insecticide resistance status pattern and changes in local Anopheline populations will be included as important supportive outcomes. Discussion By evaluating the public health impact and cost-effectiveness of IRS with a non-pyrethroid insecticide in a high-transmission setting with

Costing the distribution of insecticide-treated nets: a review of cost and cost-effectiveness studies to provide guidance on standardization of costing methodology.

PubMed

Kolaczinski, Jan; Hanson, Kara

2006-05-08

Insecticide-treated nets (ITNs) are an effective and cost-effective means of malaria control. Scaling-up coverage of ITNs is challenging. It requires substantial resources and there are a number of strategies to choose from. Information on the cost of different strategies is still scarce. To guide the choice of a delivery strategy (or combination of strategies), reliable and standardized cost information for the different options is required. The electronic online database PubMed was used for a systematic search of the published English literature on costing and economic evaluations of ITN distribution programmes. The keywords used were: net, bednet, insecticide, treated, ITN, cost, effectiveness, economic and evaluation. Identified papers were analysed to determine and evaluate the costing methods used. Methods were judged against existing standards of cost analysis to arrive at proposed standards for undertaking and presenting cost analyses. Cost estimates were often not readily comparable or could not be adjusted to a different context. This resulted from the wide range of methods applied and measures of output chosen. Most common shortcomings were the omission of certain costs and failure to adjust financial costs to generate economic costs. Generalisability was hampered by authors not reporting quantities and prices of resources separately and not examining the sensitivity of their results to variations in underlying assumptions. The observed shortcomings have arisen despite the abundance of literature and guidelines on costing of health care interventions. This paper provides ITN specific recommendations in the hope that these will help to standardize future cost estimates.

Comparison of Insecticide-Treated Nets and Indoor Residual Spraying to Control the Vector of Visceral Leishmaniasis in Mymensingh District, Bangladesh

PubMed Central

Chowdhury, Rajib; Dotson, Ellen; Blackstock, Anna J.; McClintock, Shannon; Maheswary, Narayan P.; Faria, Shyla; Islam, Saiful; Akter, Tangin; Kroeger, Axel; Akhter, Shireen; Bern, Caryn

2011-01-01

Integrated vector management is a pillar of the South Asian visceral leishmaniasis (VL) elimination program, but the best approach remains a matter of debate. Sand fly seasonality was determined in 40 houses sampled monthly. The impact of interventions on Phlebotomus argentipes density was tested from 2006–2007 in a cluster-randomized trial with four arms: indoor residual spraying (IRS), insecticide-treated nets (ITNs), environmental management (EVM), and no intervention. Phlebotomus argentipes density peaked in March with the highest proportion of gravid females in May. The EVM (mud plastering of wall and floor cracks) showed no impact. The IRS and ITNs were associated with a 70–80% decrease in male and female P. argentipes density up to 5 months post intervention. Vector density rebounded by 11 months post-IRS, whereas ITN-treated households continued to show significantly lower density compared with households without intervention. Our data suggest that both IRS and ITNs may help to improve VL control in Bangladesh. PMID:21540372

The use and misuse of mass distributed free insecticide-treated bed nets in a semi-urban community in Rivers State, Nigeria.

PubMed

Ordinioha, Best

2012-01-01

Insecticide-treated bed net (ITN) is currently distributed free of charge to vulnerable groups in Nigeria, for malaria control. Consistent use of the nets is required for maximum effectiveness; but studies indicate that the nets are often jettisoned in periods of low mosquito activity and high night time temperature. The objective of this study has been to assess the use of mass distributed nets in a semi-urban community in Rivers State, south-south Nigeria, during the late dry season, when mosquito activity is at the lowest in the community. The study was carried out in Ishiodu - Emohua, using a cross-sectional study design. The data was collected using a structured, interviewer-administered questionnaire, administered to female head of households in the community, with under-five children. A total of 170 respondents were studied; they had an average age of 34.3 ± 7.6 years, most were married (86.5%), and had secondary school education (68.2%). All the households owned at least one ITN, and an average of 1.7 nets, with 75.3% of the households owning two or more ITNs. Almost all the nets (99.4%) were obtained free of charge. Of the 170 households that received the nets, 71.8% had hanged the nets as at the time of the survey; 83.6% of these hanged the nets over a bed, while 10.7% used the nets as window curtain. Of the 102 ITNs that were properly deployed, only 27.5% were occupied the night before the survey, by an average of 2.5 persons, mainly under-five children (37.7%). The distribution of free ITNs has resulted in universal household ownership, but the use of the nets is still very poor. Proper health education is required to encourage the consistent use of the nets, even in hot night, with low mosquito activity.

Evaluation of New Tools for Malaria Vector Control in Cameroon: Focus on Long Lasting Insecticidal Nets

PubMed Central

Etang, Josiane; Nwane, Philippe; Piameu, Michael; Manga, Blaise; Souop, Daniel; Awono-Ambene, Parfait

2013-01-01

Background From 2006 to 2011, biological activity of insecticides for Indoor Residual Spraying (IRS), conventional treatment of nets (CTNs) or long lasting insecticidal nets (LLINs) was evaluated before their approval in Cameroon. The objective of the study was to select the best tools for universal malaria vector control coverage. Methodology Bioassays were performed using WHO cones and the Kisumu susceptible strain of Anopheles gambiae s.s.. Among tested products, residual activity and wash resistance of Alpha-cypermethrin LLINs (Interceptor) and CTNs (Fendona) were assessed during 5 months in the Ntougou neighborhood. Principal Findings All the 14 tested products were found effective (95–100% knockdown and mortality rates), although a significant decrease of efficacy was seen with lambda-cyhalothrinWP IRS, alpha-cypermethrin CTNs and LLINs (p< 0.05). However, the efficacy of Interceptor nets did not decrease during the 5 months evaluation, even after 25 washes (0.07nets displayed a drastic decrease of activity after 5 washes, odds ratio was 3.07 (1.0–8.59). Conclusion This study provided useful data for decision making and community education toward universal coverage of malaria vector control in Cameroon. PMID:24086399

Efficacy of topical mosquito repellent (picaridin) plus long-lasting insecticidal nets versus long-lasting insecticidal nets alone for control of malaria: a cluster randomised controlled trial.

PubMed

Sluydts, Vincent; Durnez, Lies; Heng, Somony; Gryseels, Charlotte; Canier, Lydie; Kim, Saorin; Van Roey, Karel; Kerkhof, Karen; Khim, Nimol; Mao, Sokny; Uk, Sambunny; Sovannaroth, Siv; Grietens, Koen Peeters; Sochantha, Tho; Menard, Didier; Coosemans, Marc

2016-10-01

Although effective topical repellents provide personal protection against malaria, whether mass use of topical repellents in addition to long-lasting insecticidal nets can contribute to a further decline of malaria is not known, particularly in areas where outdoor transmission occurs. We aimed to assess the epidemiological efficacy of a highly effective topical repellent in addition to long-lasting insecticidal nets in reducing malaria prevalence in this setting. A cluster randomised controlled trial was done in the 117 most endemic villages in Ratanakiri province, Cambodia, to assess the efficacy of topical repellents in addition to long-lasting insecticidal nets in controlling malaria in a low-endemic setting. We did a pre-trial assessment of village accessibility and excluded four villages because of their inaccessibility during the rainy season. Another 25 villages were grouped because of their proximity to each other, resulting in 98 study clusters (comprising either a single village or multiple neighbouring villages). Clusters were randomly assigned (1:1) to either a control (long-lasting insecticidal nets) or intervention (long-lasting insecticidal nets plus topical repellent) study group after a restricted randomisation. All clusters received one long-lasting insecticidal net per individual, whereas those in the intervention group also received safe and effective topical repellents (picaridin KBR3023, SC Johnson, Racine, WI, USA), along with instruction and promotion of its daily use. Cross-sectional surveys of 65 randomly selected individuals per cluster were done at the beginning and end of the malaria transmission season in 2012 and 2013. The primary outcome was Plasmodium species-specific prevalence in participants obtained by real-time PCR, assessed in the intention-to-treat population. Complete safety analysis data will be published seperately; any ad-hoc adverse events are reported here. This trial is registered with ClinicalTrials.gov, number NCT

Impact of lambdacyhalothrin capsule suspension treated bed nets on malaria in tribal villages of Malkangiri district, Orissa, India.

PubMed

Sahu, S S; Vijayakumar, T; Kalyanasundaram, M; Subramanian, S; Jambulingam, P

2008-09-01

Insecticide treated mosquito nets are increasingly being used in malaria control programmes. One of the problems with the treatment of bed nets with conventional formulations of insecticides was that regular washing of treated nets diminish insecticidal effect. Lambdacyhalothrin 2.5 capsule suspension (CS) (2.5% a.i., w/v), a new water-based microencapsulated formulation is reported to have wash-resistant property and longer persistence on the netting material than other formulations. We evaluated the impact of the use of nylon bed nets treated with lambdacyhalothrin 2.5 CS at 10 mg (a.i.)/m(2) in comparison to untreated nets and no nets on malaria in tribal villages in Orissa. Nine foothill villages, highly endemic for falciparum malaria, from the Primary Health Centre (PHC) areas of Khairput and Kudumulugumma of Malkangiri district, Orissa, were divided into three groups, each with a population of about 500 and allocated randomly for treated (TN) and untreated nets (UN) and no nets (NN). Bed nets were distributed in September 2001 and retreatment was done in June 2002. The impact was assessed based on the changes in vector density, parous rate, malaria incidence and parasite rates. Indoor-resting collections of Anopheles fluviatilis and An. culicifacies were made at fortnightly intervals from fixed human dwellings. Mass blood surveys before and after distribution of nets and fortnightly active surveillance were carried out to assess the change in parasite rates and malaria incidence. Bioassays were conducted at fortnightly intervals on the bed nets supplied to the villagers. The reductions in indoor resting catches of An. fluviatilis and An. culicifacies were 96 and 38 per cent in villages with treated nets and 2.6 and 23 per cent in villages with untreated nets respectively compared to no net villages. For six months following treatment, 100 per cent mortality of An. fluviatilis was observed on the unwashed nets and on the nets washed once or twice. After re

Heterogeneity and changes in inequality of malaria risk after introduction of insecticide-treated bed nets in Macha, Zambia.

PubMed

Norris, Laura C; Norris, Douglas E

2013-04-01

In 2007, the first free mass distribution of insecticide-treated bed nets (ITNs) occurred in southern Zambia. To determine the effect of ITNs on heterogeneity in biting rates, human DNA from Anopheles arabiensis blood meals was genotyped to determine the number of hosts that had contributed to the blood meals. The multiple feeding rate decreased from 18.9% pre-ITN to 9.1% post-ITN, suggesting that mosquito biting had focused onto a smaller fraction of the population. Pre-ITN, 20% of persons in a household provided 40% of blood meals, which increased to 59% post-ITN. To measure heterogeneity over a larger scale, mosquitoes were collected in 90 households in two village areas. Of these households, 25% contributed 78.1% of An. arabiensis, and households with high frequencies of An. arabiensis were significantly spatially clustered. The results indicate that substantial heterogeneity in malaria risk exists at local and household levels, and household-level heterogeneity may be influenced by interventions, such as ITNs.

Comparative field evaluation of combinations of long-lasting insecticide treated nets and indoor residual spraying, relative to either method alone, for malaria prevention in an area where the main vector is Anopheles arabiensis

PubMed Central

2013-01-01

Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used together in the same households to improve malaria control despite inconsistent evidence on whether such combinations actually offer better protection than nets alone or IRS alone. Methods Comparative tests were conducted using experimental huts fitted with LLINs, untreated nets, IRS plus untreated nets, or combinations of LLINs and IRS, in an area where Anopheles arabiensis is the predominant malaria vector species. Three LLIN types, Olyset®, PermaNet 2.0® and Icon Life® nets and three IRS treatments, pirimiphos-methyl, DDT, and lambda cyhalothrin, were used singly or in combinations. We compared, number of mosquitoes entering huts, proportion and number killed, proportions prevented from blood-feeding, time when mosquitoes exited the huts, and proportions caught exiting. The tests were done for four months in dry season and another six months in wet season, each time using new intact nets. Results All the net types, used with or without IRS, prevented >99% of indoor mosquito bites. Adding PermaNet 2.0® and Icon Life®, but not Olyset® nets into huts with any IRS increased mortality of malaria vectors relative to IRS alone. However, of all IRS treatments, only pirimiphos-methyl significantly increased vector mortality relative to LLINs alone, though this increase was modest. Overall, median mortality of An. arabiensis caught in huts with any of the treatments did not exceed 29%. No treatment reduced entry of the vectors into huts, except for marginal reductions due to PermaNet 2.0® nets and DDT. More than 95% of all mosquitoes were caught in exit traps rather than inside huts. Conclusions Where the main malaria vector is An. arabiensis, adding IRS into houses with intact pyrethroid LLINs does not enhance house-hold level protection except where the IRS employs non-pyrethroid insecticides such as pirimiphos-methyl, which can confer modest enhancements. In

Traditional Nets Interfere with the Uptake of Long-Lasting Insecticidal Nets in the Peruvian Amazon: The Relevance of Net Preference for Achieving High Coverage and Use

PubMed Central

Grietens, Koen Peeters; Muela Ribera, Joan; Soto, Veronica; Tenorio, Alex; Hoibak, Sarah; Aguirre, Angel Rosas; Toomer, Elizabeth; Rodriguez, Hugo; Llanos Cuentas, Alejandro; D'Alessandro, Umberto; Gamboa, Dionicia; Erhart, Annette

2013-01-01

Background While coverage of long-lasting insecticide-treated nets (LLIN) has steadily increased, a growing number of studies report gaps between net ownership and use. We conducted a mixed-methods social science study assessing the importance of net preference and use after Olyset® LLINs were distributed through a mass campaign in rural communities surrounding Iquitos, the capital city of the Amazonian region of Peru. Methods The study was conducted in the catchment area of the Paujil and Cahuide Health Centres (San Juan district) between July 2007 and November 2008. During a first qualitative phase, participant observation and in-depth interviews collected information on key determinants for net preference and use. In a second quantitative phase, a survey among recently confirmed malaria patients evaluated the acceptability and use of both LLINs and traditional nets, and a case control study assessed the association between net preference/use and housing structure (open vs. closed houses). Results A total of 10 communities were selected for the anthropological fieldwork and 228 households participated in the quantitative studies. In the study area, bed nets are considered part of the housing structure and are therefore required to fulfil specific architectural and social functions, such as providing privacy and shelter, which the newly distributed Olyset® LLINs ultimately did not. The LLINs' failure to meet these criteria could mainly be attributed to their large mesh size, transparency and perceived ineffectiveness to protect against mosquitoes and other insects, resulting in 63.3% of households not using any of the distributed LLINs. Notably, LLIN usage was significantly lower in houses with no interior or exterior walls (35.2%) than in those with walls (73.8%) (OR = 5.2, 95CI [2.2; 12.3], p<0.001). Conclusion Net preference can interfere with optimal LLIN use. In order to improve the number of effective days of LLIN protection per dollar spent

Combining indoor and outdoor methods for controlling malaria vectors: an ecological model of endectocide-treated livestock and insecticidal bed nets.

PubMed

Yakob, Laith; Cameron, Mary; Lines, Jo

2017-03-13

Malaria is spread by mosquitoes that are increasingly recognised to have diverse biting behaviours. How a mosquito in a specific environment responds to differing availability of blood-host species is largely unknown and yet critical to vector control efficacy. A parsimonious mathematical model is proposed that accounts for a diverse range of host-biting behaviours and assesses their impact on combining long-lasting insecticidal nets (LLINs) with a novel approach to malaria control: livestock treated with insecticidal compounds ('endectocides') that kill biting mosquitoes. Simulations of a malaria control programme showed marked differences across biting ecologies in the efficacy of both LLINs as a stand-alone tool and the combination of LLINs with endectocide-treated cattle. During the intervals between LLIN mass campaigns, concordant use of endectocides is projected to reduce the bounce-back in malaria prevalence that can occur as LLIN efficacy decays over time, especially if replacement campaigns are delayed. Integrating these approaches can also dramatically improve the attainability of local elimination; endectocidal treatment schedules required to achieve this aim are provided for malaria vectors with different biting ecologies. Targeting blood-feeding mosquitoes by treating livestock with endectocides offers a potentially useful complement to existing malaria control programmes centred on LLIN distribution. This approach is likely to be effective against vectors with a wide range of host-preferences and biting behaviours, with the exception of species that are so strictly anthropophilic that most blood meals are taken on humans even when humans are much less available than non-human hosts. Identifying this functional relationship in wild mosquito populations and ascertaining the extent to which it differs, within as well as between species, is a critical next step before targets can be set for employing this novel approach and combination.

Malaria in Dielmo, a Senegal village: Is its elimination possible after seven years of implementation of long-lasting insecticide-treated nets?

PubMed

Wotodjo, Amélé Nyedzie; Doucoure, Souleymane; Gaudart, Jean; Diagne, Nafissatou; Diene Sarr, Fatoumata; Faye, Ngor; Tall, Adama; Raoult, Didier; Sokhna, Cheikh

2017-01-01

The malaria burden has decreased significantly in recent years in Africa through the widespread use of artemisinin-based combination therapy (ACT) and long-lasting insecticide-treated nets (LLINs). However, the occurrence of malaria resurgences, the loss of immunity of exposed populations constitute among other factors, serious concerns about the future of malaria elimination efforts. This study investigated the evolution of malaria morbidity in Dielmo (Senegal) before and after the implementation of LLINs. A longitudinal study was carried out in Dielmo over eight years, from July 2007 to July 2015. In July 2008, LLINs were offered to all villagers, and in July 2011 and August 2014 the LLINs were renewed. A survey on LLINs use was done each quarter of the year. Thick smears stained with Giemsa, a rapid diagnostic test (RDT) and quantitative polymerase chain reaction (PCR) methods were performed for all cases of fever to assess malaria clinical attacks. Malaria cases were treated with ACT since June 2006. Malaria morbidity has decreased significantly since the implementation of LLINs in Dielmo, together with ACT. However, malaria resurgences have occurred twice during the seven years of LLINs use. These resurgences occurred the first time during the third year after the introduction of LLINs (aIRR (adjusted incidence-rate ratio) [95%CI] = 5.90 [3.53; 9.88] p< 0.001) and a second time during the third year after the renewal of LLINs (aIRR [95%CI] = 5.60 [3.34; 9.39] p< 0.001). Sixty-nine percent (69%) of the nets tested for their long-lasting insecticidal activity remained effective after 3 years of use. Good management of malaria cases by the use of ACT as first-line treatment against malaria in addition to the use of LLINs has significantly reduced malaria in Dielmo and allowed to reach the phase of pre-elimination of the disease. However, the occurrence of malaria resurgences raised serious concerns about malaria elimination, which would require additional tools

Insecticide-treated mosquito nets in rural Burkina Faso: assessment of coverage and equity in the wake of a universal distribution campaign.

PubMed

Zöllner, Caroline; De Allegri, Manuela; Louis, Valérie R; Yé, Maurice; Sié, Ali; Tiendrebéogo, Justin; Jahn, Albrecht; Müller, Olaf

2015-03-01

Insecticide-treated mosquito nets (ITNs) are an essential tool of the Roll Back Malaria strategy. An increasing number of African countries have embarked on mass distribution campaigns of long-lasting insecticide-treated nets (LLINs) with the ultimate goal of universal coverage. Such a national campaign with the goal of one ITN for every two people has been conducted in Burkina Faso in 2010. Our aim was to assess the coverage and equity effect of the universal distribution campaign of LLINs in Burkina Faso and to identify determinants of ITN ownership across households after the campaign. We evaluated its effects through comparison of data from two household surveys conducted in early 2010 (before the campaign) and early 2011 (after the campaign) on a representative rural district in north-western Burkina Faso. Data were collected on household characteristics (including socio-economic status) and ITN ownership. We used concentration curves and indices to compare ITN coverage indicators before and after the campaign and multilevel multivariate logistic regression to estimate factors associated with achievement of the universal coverage target in 2011. The survey included 1106 households in 2010 and 1094 in 2011. We found that the proportion of households with at least one ITN increased from 59% before the campaign to 99% afterwards, whereas the concentration index dropped from 0.087 (standard error (SE): 0.014) to 0.002 (SE: 0.002). Fifty-two per cent of households reached the target of one ITN for every two people per household, with the relevant concentration index at -0.031 (SE: 0.016). Eighty-six per cent of households owned at least one ITN for every three people. The main characteristics significantly associated with the targeted intra-household coverage were family size and distance to the health centre but not socio-economic status. In conclusion, despite not having fully met its target, the national LLIN campaign achieved a high level of coverage and

Control of Malaria Vector Mosquitoes by Insecticide-Treated Combinations of Window Screens and Eave Baffles.

PubMed

Killeen, Gerry F; Masalu, John P; Chinula, Dingani; Fotakis, Emmanouil A; Kavishe, Deogratius R; Malone, David; Okumu, Fredros

2017-05-01

We assessed window screens and eave baffles (WSEBs), which enable mosquitoes to enter but not exit houses, as an alternative to indoor residual spraying (IRS) for malaria vector control. WSEBs treated with water, the pyrethroid lambda-cyhalothrin, or the organophosphate pirimiphos-methyl, with and without a binding agent for increasing insecticide persistence on netting, were compared with IRS in experimental huts. Compared with IRS containing the same insecticide, WSEBs killed similar proportions of Anopheles funestus mosquitoes that were resistant to pyrethroids, carbamates and organochlorines and greater proportions of pyrethroid-resistant, early exiting An. arabiensis mosquitoes. WSEBs with pirimiphos-methyl killed greater proportions of both vectors than lambda-cyhalothrin or lambda-cyhalothrin plus pirimiphos-methyl and were equally efficacious when combined with binding agent. WSEBs required far less insecticide than IRS, and binding agents might enhance durability. WSEBs might enable affordable deployment of insecticide combinations to mitigate against physiologic insecticide resistance and improve control of behaviorally resistant, early exiting vectors.

Maintenance and sustained use of insecticide-treated bednets and curtains three years after a controlled trial in western Kenya.

PubMed

Kachur, S P; Phillips-Howard, P A; Odhacha, A M; Ruebush, T K; Oloo, A J; Nahlen, B L

1999-11-01

In large experimental trials throughout Africa, insecticide-treated bednets and curtains have reduced child mortality in malaria-endemic communities by 15%-30%. While few questions remain about the efficacy of this intervention, operational issues around how to implement and sustain insecticide-treated materials (ITM) projects need attention. We revisited the site of a small-scale ITM intervention trial, 3 years after the project ended, to assess how local attitudes and practices had changed. Qualitative and quantitative methods, including 16 focus group discussions and a household survey (n = 60), were employed to assess use, maintenance, retreatment and perceptions of ITM and the insecticide in former study communities. Families that had been issued bednets were more likely to have kept and maintained them and valued bednets more highly than those who had been issued curtains. While most households retained their original bednets, none had treated them with insecticide since the intervention trial was completed 3 years earlier. Most of those who had been issued bednets repaired them, but none acquired new or replacement nets. In contrast, households that had been issued insecticide-treated curtains often removed them. Three (15%) of the households issued curtains had purchased one or more bednets since the study ended. In households where bednets had been issued, children 10 years of age and younger were a third as likely to sleep under a net as were adults (relative risk (RR) = 0. 32; 95% confidence interval (95%CI) = 0.19, 0.53). Understanding how and why optimal ITM use declined following this small-scale intervention trial can suggest measures that may improve the sustainability of current and future ITM efforts.

Combination of Insecticide Treated Nets and Indoor Residual Spraying in Northern Tanzania Provides Additional Reduction in Vector Population Density and Malaria Transmission Rates Compared to Insecticide Treated Nets Alone: A Randomised Control Trial.

PubMed

Protopopoff, Natacha; Wright, Alexandra; West, Philippa A; Tigererwa, Robinson; Mosha, Franklin W; Kisinza, William; Kleinschmidt, Immo; Rowland, Mark

2015-01-01

Indoor residual spraying (IRS) combined with insecticide treated nets (ITN) has been implemented together in several sub-Saharan countries with inconclusive evidence that the combined intervention provides added benefit. The impact on malaria transmission was evaluated in a cluster randomised trial comparing two rounds of IRS with bendiocarb plus universal coverage ITNs, with ITNs alone in northern Tanzania. From April 2011 to December 2012, eight houses in 20 clusters per study arm were sampled monthly for one night with CDC light trap collections. Anopheles gambiae s.l. were identified to species using real time PCR Taq Man and tested for the presence of Plasmodium falciparum circumsporozoite protein. ITN and IRS coverage was estimated from household surveys. IRS coverage was more than 85% in two rounds of spraying in January and April 2012. Household coverage with at least one ITN per house was 94.7% after the universal coverage net campaign in the baseline year and the proportion of household with all sleeping places covered by LLIN was 50.1% decreasing to 39.1% by the end of the intervention year. An.gambiae s.s. comprised 80% and An.arabiensis 18.3% of the anopheline collection in the baseline year. Mean An.gambiae s.l. density in the ITN+IRS arm was reduced by 84% (95%CI: 56%-94%, p = 0.001) relative to the ITN arm. In the stratum of clusters categorised as high anopheline density at baseline EIR was lower in the ITN+IRS arm compared to the ITN arm (0.5 versus 5.4 per house per month, Incidence Rate Ratio: 0.10, 95%CI: 0.01-0.66, p-value for interaction <0.001). This trial provides conclusive evidence that combining carbamate IRS and ITNs produces major reduction in Anopheles density and entomological inoculation rate compared to ITN alone in an area of moderate coverage of LLIN and high pyrethroid resistance in An.gambiae s.s.

The development of insecticide-treated durable wall lining for malaria control: insights from rural and urban populations in Angola and Nigeria

PubMed Central

2012-01-01

Background Durable lining (DL) is a deltamethrin-impregnated polyethylene material, which is designed to cover domestic walls that would normally be sprayed with residual insecticide. The operational success of DL as a long-lasting insecticidal substrate will be dependent on a high level of user acceptability as households must maintain correctly installed linings on their walls for several years. Preliminary trials were undertaken to identify a material to develop into a marketable wall lining and to assess its level of acceptability among rural and urban populations. Methods In Angola (n=60), prototype DL and insecticide-treated plastic sheeting (ITPS) were installed on urban house walls and ceilings, respectively, and acceptability was compared to indoor residual spraying (IRS) (n=20) using a knowledge, attitude and practice (KAP) questionnaire. In Nigeria (n=178), three materials (prototype DL, ITPS and insecticide-treated wall netting) were distributed among rural and urban households. User opinions were gathered from focus group discussions, in-depth interviews and KAP questionnaires. Results In Angola, after two weeks, the majority of participants (98%) expressed satisfaction with the products and identified the killing of insects as the materials’ principal benefits (73%). After one year, despite a loss of almost 50% of households to refugee repatriation, all 32 remaining households still asserted that they had liked the DL/ITPS in their homes and given the choice of intervention preferred DL/ITPS to IRS (94%) or insecticide-treated nets (78%). In Nigeria, a dichotomy between rural and urban respondents emerged. Rural participants favoured wall adornments and accepted wall linings because of their perceived decorative value and entomological efficacy. By contrast, urban households preferred minimal wall decoration and rejected the materials based upon objections to their aesthetics and installation feasibility. Conclusions The high level of acceptability

Implications of bio-efficacy and persistence of insecticides when indoor residual spraying and long-lasting insecticide nets are combined for malaria prevention.

PubMed

Okumu, Fredros O; Chipwaza, Beatrice; Madumla, Edith P; Mbeyela, Edgar; Lingamba, Geoffrey; Moore, Jason; Ntamatungro, Alex J; Kavishe, Deo R; Moore, Sarah J

2012-11-19

Bio-efficacy and residual activity of insecticides used for indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs) were assessed against laboratory-reared and wild populations of the malaria vector, Anopheles arabiensis in south eastern Tanzania. Implications of the findings are examined in the context of potential synergies and redundancies where IRS and LLINs are combined. Bioassays were conducted monthly for six months on three LLIN types (Olyset® PermaNet 2.0®,and Icon Life®) and three IRS treatments (2 g/m2 pirimiphos-methyl, 2 g/m2 DDT and 0.03 g/m2 lambda-cyhalothrin, sprayed on mud walls and palm ceilings of experimental huts). Tests used susceptible laboratory-reared An. arabiensis exposed in cones (nets and IRS) or wire balls (nets only). Susceptibility of wild populations was assessed using WHO diagnostic concentrations and PCR for knock-down resistance (kdr) genes. IRS treatments killed ≥ 85% of mosquitoes exposed on palm ceilings and ≥ 90% of those exposed on mud walls, but up to 50% of this toxicity decayed within 1-3 months, except for DDT. By 6th month, only 7.5%, 42.5% and 30.0% of mosquitoes died when exposed to ceilings sprayed with pirimiphos-methyl, DDT or lambda-cyhalothrin respectively, while 12.5%, 36.0% and 27.5% died after exposure to mud walls sprayed with the same insecticides. In wire-ball assays, mortality decreased from 98.1% in 1st month to 92.6% in 6th month in tests on PermaNet 2.0®, from 100% to 61.1% on Icon Life® and from 93.2% to 33.3% on Olyset® nets. In cone bioassays, mortality reduced from 92.8% in 1st month to 83.3% in 6th month on PermaNet 2.0®, from 96.9% to 43.80% on Icon Life® and from 85.6% to 14.6% on Olyset®. Wild An. arabiensis were 100% susceptible to DDT, 95.8% to deltamethrin, 90.2% to lambda cyhalothrin and 95.2% susceptible to permethrin. No kdr gene mutations were detected. In bioassays where sufficient contact with treated surfaces is assured, LLINs and IRS kill high

Ownership and use of insecticide-treated nets during pregnancy in sub-Saharan Africa: a review

PubMed Central

2013-01-01

Over the past decade, significant gains have been made in the implementation of malaria prevention measures in pregnancy in sub-Saharan Africa, including the distribution of insecticide-treated nets (ITNs). These have been shown to cause a reduction in the incidence of malaria and its consequences such as maternal anaemia, stillbirths and intrauterine growth restriction. Currently most nations in Africa have policies for distributing ITNs to pregnant women through various mechanisms, however coverage remains well below the targets. This review summarizes recent evidence regarding the correlation between ownership and use of ITNs and the determinants of both, in pregnancy in sub-Saharan Africa, and reviews interventions directed at improving coverage. A review of the literature using Pubmed, CINAHL and scanning of reference lists was conducted in October 2012 and 59 articles were selected for final review. The research obtained was a mixture of national and district level surveys, and a narrative synthesis of the data was undertaken. Ownership of ITNs varied from as low as 3% to greater than 80%, and the main determinants were found to be education level, knowledge of malaria, community involvement, socio-economic status and parity, although the significance of each varied between the different settings and studies reviewed. In more than half the settings where data were available, the combination of lack of availability and lack of use of an available net meant that less than half of all pregnancies received the recommended intervention. Supply and cost remain major barriers to achieving optimal coverage, but the additional important contributor to reduced efficiency of intervention was the clear discrepancy between ownership and use, with available ITN use below 60% in several settings. Cited reasons for not using an ITN, where one was available, included discomfort, problems with hanging up nets and lack of space, low awareness of need, and seasonal variations in

Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala

PubMed Central

2012-01-01

Background In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs) alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. Methods The study was conducted as a cluster randomized community trial using “reduction of the vector population” as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods) and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices) at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material) and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.). The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. Results At baseline (during the dry season) a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae). After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed) in 970 study households, tropical

Assessing bed net use and non-use after long-lasting insecticidal net distribution: a simple framework to guide programmatic strategies

PubMed Central

2010-01-01

Background Insecticide-treated nets (ITNs) are becoming increasingly available to vulnerable populations at risk for malaria. Their appropriate and consistent use is essential to preventing malaria, but ITN use often lags behind ITN ownership. In order to increase ITN use, it is necessary to devise strategies that accurately identify, differentiate, and target the reasons and types of non-use. Methods A simple method based on the end-user as the denominator was employed to classify each individual into one of four ITN use categories: 1) living in households not owning an ITN; 2) living in households owning, but not hanging an ITN; 3) living in households owning and hanging an ITN, but who are not sleeping under one; and 4) sleeping under an ITN. This framework was applied to survey data designed to evaluate long-lasting insecticidal nets (LLINs) distributions following integrated campaigns in five countries: Togo, Sierra Leone, Madagascar, Kenya and Niger. Results The percentage of children <5 years of age sleeping under an ITN ranged from 51.5% in Kenya to 81.1% in Madagascar. Among the three categories of non-use, children living in households without an ITN make up largest group (range: 9.4%-30.0%), despite the efforts of the integrated child health campaigns. The percentage of children who live in households that own but do not hang an ITN ranged from 5.1% to 16.1%. The percentage of children living in households where an ITN was suspended, but who were not sleeping under it ranged from 4.3% to 16.4%. Use by all household members in Sierra Leone (39.9%) and Madagascar (60.4%) indicate that integrated campaigns reach beyond their desired target populations. Conclusions The framework outlined in this paper provides a helpful tool to examine the deficiencies in ITN use. Monitoring and evaluation strategies designed to assess ITN ownership and use can easily incorporate this approach using existing data collection instruments that measure the standard indicators

Challenges for malaria elimination in Zanzibar: pyrethroid resistance in malaria vectors and poor performance of long-lasting insecticide nets

PubMed Central

2013-01-01

Background Long-lasting insecticide treated nets (LLINs) and indoor residual house spraying (IRS) are the main interventions for the control of malaria vectors in Zanzibar. The aim of the present study was to assess the susceptibility status of malaria vectors against the insecticides used for LLINs and IRS and to determine the durability and efficacy of LLINs on the island. Methods Mosquitoes were sampled from Pemba and Unguja islands in 2010–2011 for use in WHO susceptibility tests. One hundred and fifty LLINs were collected from households on Unguja, their physical state was recorded and then tested for efficacy as well as total insecticide content. Results Species identification revealed that over 90% of the Anopheles gambiae complex was An. arabiensis with a small number of An. gambiae s.s. and An. merus being present. Susceptibility tests showed that An. arabiensis on Pemba was resistant to the pyrethroids used for LLINs and IRS. Mosquitoes from Unguja Island, however, were fully susceptible to all pyrethroids tested. A physical examination of 150 LLINs showed that two thirds were damaged after only three years in use. All used nets had a significantly lower (p < 0.001) mean permethrin concentration of 791.6 mg/m2 compared with 944.2 mg/m2 for new ones. Their efficacy decreased significantly against both susceptible An. gambiae s.s. colony mosquitoes and wild-type mosquitoes from Pemba after just six washes (p < 0.001). Conclusion The sustainability of the gains achieved in malaria control in Zanzibar is seriously threatened by the resistance of malaria vectors to pyrethroids and the short-lived efficacy of LLINs. This study has revealed that even in relatively well-resourced and logistically manageable places like Zanzibar, malaria elimination is going to be difficult to achieve with the current control measures. PMID:23537463

Plant based insect repellent and insecticide treated bed nets to protect against malaria in areas of early evening biting vectors: double blind randomised placebo controlled clinical trial in the Bolivian Amazon.

PubMed

Hill, N; Lenglet, A; Arnéz, A M; Carneiro, I

2007-11-17

To determine the effectiveness in reducing malaria of combining an insect repellent with insecticide treated bed nets compared with the nets alone in an area where vector mosquitoes feed in the early evening. A double blind, placebo controlled cluster-randomised clinical study. Rural villages and peri-urban districts in the Bolivian Amazon. 4008 individuals in 860 households. All individuals slept under treated nets; one group also used a plant based insect repellent each evening, a second group used placebo. Episodes of Plasmodium falciparum or P vivax malaria confirmed by rapid diagnostic test or blood slide, respectively. We analysed 15,174 person months at risk and found a highly significant 80% reduction in episodes of P vivax in the group that used treated nets and repellent (incidence rate ratio 0.20, 95% confidence interval 0.11 to 0.38, P<0.001). Numbers of P falciparum cases during the study were small and, after adjustment for age, an 82% protective effect was observed, although this was not significant (0.18, 0.02 to 1.40, P=0.10). Reported episodes of fever with any cause were reduced by 58% in the group that used repellent (0.42, 0.31 to 0.56, P<0.001). Insect repellents can provide protection against malaria. In areas where vectors feed in the early evening, effectiveness of treated nets can be significantly increased by using repellent between dusk and bedtime. This has important implications in malaria vector control programmes outside Africa and shows that the combined use of treated nets and insect repellents, as advocated for most tourists travelling to high risk areas, is fully justified. NCT 00144716.

Increasing incidence of malaria in children despite insecticide-treated bed nets and prompt anti-malarial therapy in Tororo, Uganda

PubMed Central

2012-01-01

Background The burden of malaria has decreased in parts of Africa following the scaling up of control interventions. However, similar data are limited from high transmission settings. Methods A cohort of 100 children, aged six weeks to 10 months of age, were enrolled in an area of high malaria transmission intensity and followed through 48 months of age. Children were given a long-lasting insecticide-treated bed net (LLIN) at enrolment and received all care, including monthly blood smears and treatment with artemisinin-based combination therapy (ACT) for uncomplicated malaria, at a dedicated clinic. The incidence of malaria was estimated by passive surveillance and associations between malaria incidence and age, calendar time and season were measured using generalized estimating equations. Results Reported compliance with LLINs was 98% based on monthly routine evaluations. A total of 1,633 episodes of malaria were observed, with a median incidence of 5.3 per person-year (PPY). There were only six cases of complicated malaria, all single convulsions. Malaria incidence peaked at 6.5 PPY at 23 months of age before declining to 3.5 PPY at 48 months. After adjusting for age and season, the risk of malaria increased by 52% from 2008 to 2011 (RR 1.52, 95% CI 1.10-2.09). Asymptomatic parasitaemia was uncommon (monthly prevalence <10%) and rarely observed prior to 24 months of age. Conclusions In Tororo, despite provision of LLINs and prompt treatment with ACT, the incidence of malaria is very high and appears to be rising. Additional malaria control interventions in high transmission settings are likely needed. Trial registration Current Controlled Trials Identifier NCT00527800 PMID:23273022

Socio-economic inequity in demand for insecticide-treated nets, in-door residual house spraying, larviciding and fogging in Sudan

PubMed Central

Onwujekwe, Obinna; Malik, El-Fatih Mohamed; Mustafa, Sara Hassan; Mnzava, Abraham

2005-01-01

Background In order to optimally prioritize and use public and private budgets for equitable malaria vector control, there is a need to determine the level and determinants of consumer demand for different vector control tools. Objectives To determine the demand from people of different socio-economic groups for indoor residual house-spraying (IRHS), insecticide-treated nets (ITNs), larviciding with chemicals (LWC), and space spraying/fogging (SS) and the disease control implications of the result. Methods Ratings and levels of willingness-to-pay (WTP) for the vector control tools were determined using a random cross-sectional sample of 720 householdes drawn from two states. WTP was elicited using the bidding game. An asset-based socio-economic status (SES) index was used to explore whether WTP was related to SES of the respondents. Results IRHS received the highest proportion of highest preferred rating (41.0%) followed by ITNs (23.1%). However, ITNs had the highest mean WTP followed by IRHS, while LWC had the least. The regression analysis showed that SES was positively and statistically significantly related to WTP across the four vector control tools and that the respondents' rating of IRHS and ITNs significantly explained their levels of WTP for the two tools. Conclusion People were willing to pay for all the vector-control tools, but the demand for the vector control tools was related to the SES of the respondents. Hence, it is vital that there are public policies and financing mechanisms to ensure equitable provision and utilisation of vector control tools, as well as protecting the poor from cost-sharing arrangements. PMID:16356177

Different delivery mechanisms for insecticide-treated nets in rural Burkina Faso: a provider's perspective.

PubMed

Beiersmann, Claudia; De Allegri, Manuela; Tiendrebéogo, Justin; Yé, Maurice; Jahn, Albrecht; Mueller, Olaf

2010-12-04

Insecticide-treated nets (ITNs) have been confirmed to be a very effective tool in malaria control. Two different delivery strategies for roll-out of ITN programmes have been the focus of debate in the last years: free distribution and distribution through commercial marketing systems. They are now seen as complementary rather than opponent. Acceptance of these programmes by the community and involved providers is an important aspect influencing their sustainability. This paper looks at how providers perceived, understood and accepted two interventions involving two different delivery strategies (subsidized sales supported by social marketing and free distribution to pregnant women attending antenatal care services). The interventions took place in one province of north-western Burkina Faso in 2006 in the frame of a large randomized controlled ITN intervention study. For this descriptive qualitative study data were collected through focus group discussions and individual interviews. A total of four focus group discussions and eleven individual interviews have been conducted with the providers of the study interventions. The free distribution intervention was well accepted and perceived as running well. The health care staff had a positive and beneficial view of the intervention and did not feel overwhelmed by the additional workload. The social marketing intervention was also seen as positive by the rural shopkeepers. However, working in market economy, shopkeepers feared the risk of unsold ITNs, due to the low demand and capacity to pay for the product in the community. The combination of ITN free distribution and social marketing was in general well accepted by the different providers. However, low purchasing power of clients and the resulting financial insecurities of shopkeepers remain a challenge to ITN social marketing in rural SSA.

Pilot study on the combination of an organophosphate-based insecticide paint and pyrethroid-treated long lasting nets against pyrethroid resistant malaria vectors in Burkina Faso.

PubMed

Mosqueira, Beatriz; Soma, Dieudonné D; Namountougou, Moussa; Poda, Serge; Diabaté, Abdoulaye; Ali, Ouari; Fournet, Florence; Baldet, Thierry; Carnevale, Pierre; Dabiré, Roch K; Mas-Coma, Santiago

2015-08-01

A pilot study to test the efficacy of combining an organophosphate-based insecticide paint and pyrethroid-treated Long Lasting Insecticide Treated Nets (LLINs) against pyrethroid-resistant malaria vector mosquitoes was performed in a real village setting in Burkina Faso. Paint Inesfly 5A IGR™, comprised of two organophosphates (OPs) and an Insect Growth Regulator (IGR), was tested in combination with pyrethroid-treated LLINs. Efficacy was assessed in terms of mortality for 12 months using Early Morning Collections of malaria vectors and 30-minute WHO bioassays. Resistance to pyrethroids and OPs was assessed by detecting the frequency of L1014F and L1014S kdr mutations and Ace-1(R)G119S mutation, respectively. Blood meal origin was identified using a direct enzyme-linked immunosorbent assay (ELISA). The combination of Inesfly 5A IGR™ and LLINs was effective in killing 99.9-100% of malaria vector populations for 6 months regardless of the dose and volume treated. After 12 months, mortality rates decreased to 69.5-82.2%. The highest mortality rates observed in houses treated with 2 layers of insecticide paint and a larger volume. WHO bioassays supported these results: mortalities were 98.8-100% for 6 months and decreased after 12 months to 81.7-97.0%. Mortality rates in control houses with LLINs were low. Collected malaria vectors consisted exclusively of Anopheles coluzzii and were resistant to pyrethroids, with a L1014 kdr mutation frequency ranging from 60 to 98% through the study. About 58% of An. coluzzii collected inside houses had bloodfed on non-human animals. Combining Inesfly 5A IGR™ and LLINs yielded a one year killing efficacy against An. coluzzii highly resistant to pyrethroids but susceptible to OPs that exhibited an anthropo-zoophilic behaviour in the study area. The results obtained in a real setting supported previous work performed in experimental huts and underscore the need to study the impact that this novel strategy may have on clinical

The Impact of Pyrethroid Resistance on the Efficacy of Insecticide-Treated Bed Nets against African Anopheline Mosquitoes: Systematic Review and Meta-Analysis

PubMed Central

Strode, Clare; Donegan, Sarah; Garner, Paul; Enayati, Ahmad Ali; Hemingway, Janet

2014-01-01

Background Pyrethroid insecticide-treated bed nets (ITNs) help contribute to reducing malaria deaths in Africa, but their efficacy is threatened by insecticide resistance in some malaria mosquito vectors. We therefore assessed the evidence that resistance is attenuating the effect of ITNs on entomological outcomes. Methods and Findings We included laboratory and field studies of African malaria vectors that measured resistance at the time of the study and used World Health Organization–recommended impregnation regimens. We reported mosquito mortality, blood feeding, induced exophily (premature exit of mosquitoes from the hut), deterrence, time to 50% or 95% knock-down, and percentage knock-down at 60 min. Publications were searched from 1 January 1980 to 31 December 2013 using MEDLINE, Cochrane Central Register of Controlled Trials, Science Citation Index Expanded, Social Sciences Citation Index, African Index Medicus, and CAB Abstracts. We stratified studies into three levels of insecticide resistance, and ITNs were compared with untreated bed nets (UTNs) using the risk difference (RD). Heterogeneity was explored visually and statistically. Included were 36 laboratory and 24 field studies, reported in 25 records. Studies tested and reported resistance inconsistently. Based on the meta-analytic results, the difference in mosquito mortality risk for ITNs compared to UTNs was lower in higher resistance categories. However, mortality risk was significantly higher for ITNs compared to UTNs regardless of resistance. For cone tests: low resistance, risk difference (RD) 0.86 (95% CI 0.72 to 1.01); moderate resistance, RD 0.71 (95% CI 0.53 to 0.88); high resistance, RD 0.56 (95% CI 0.17 to 0.95). For tunnel tests: low resistance, RD 0.74 (95% CI 0.61 to 0.87); moderate resistance, RD 0.50 (95% CI 0.40 to 0.60); high resistance, RD 0.39 (95% CI 0.24 to 0.54). For hut studies: low resistance, RD 0.56 (95% CI 0.43 to 0.68); moderate resistance, RD 0.39 (95% CI 0.16 to 0

Push by a net, pull by a cow: can zooprophylaxis enhance the impact of insecticide treated bed nets on malaria control?

PubMed Central

2014-01-01

Background Mass insecticide treated bed net (ITN) deployment, and its associated coverage of populations at risk, had “pushed” a decline in malaria transmission. However, it is unknown whether malaria control is being enhanced by zooprophylaxis, i.e., mosquitoes diverted to feed on hosts different from humans, a phenomenon that could further reduce malaria entomological transmission risk in areas where livestock herding is common. Methods Between May and July 2009, we collected mosquitoes in 104 houses from three neighboring villages with high ITN coverage (over 80%), along Lake Victoria. We also performed a census of livestock in the area and georeferenced tethering points for all herds, as well as, mosquito larval habitats. Bloodmeal contents from sampled mosquitoes were analyzed, and each mosquito was individually tested for malaria sporozoite infections. We then evaluated the association of human density, ITN use, livestock abundance and larval habitats with mosquito abundance, bloodfeeding on humans and malaria sporozoite rate using generalized linear mixed effects models. Results We collected a total of 8123 mosquitoes, of which 1664 were Anopheles spp. malaria vectors over 295 household spray catches. We found that vector household abundance was mainly driven by the number of householders (P < 0.05), goats/sheep tethered around the house (P < 0.05) and ITNs, which halved mosquito abundance (P < 0.05). In general, similar patterns were observed for Anopheles arabiensis, but not An. gambiae s.s. and An. funestus s.s., whose density did not increase with the presence of livestock animals. Feeding on humans significantly increased in all species with the number of householders (P < 0.05), and only significantly decreased for An. arabiensis in the presence of cattle (P < 0.05). Only 26 Anopheles spp. vectors had malaria sporozoites with the sporozoite rate significantly decreasing as the proportion of cattle feeding mosquitoes increased

Impact of Insecticide-Treated Net Ownership on All-Cause Child Mortality in Malawi, 2006-2010.

PubMed

Florey, Lia S; Bennett, Adam; Hershey, Christine L; Bhattarai, Achuyt; Nielsen, Carrie F; Ali, Doreen; Luhanga, Misheck; Taylor, Cameron; Eisele, Thomas P; Yé, Yazoume

2017-09-01

Insecticide-treated nets (ITNs) have been shown to be highly effective at reducing malaria morbidity and mortality in children. However, there are limited studies that assess the association between increasing ITN coverage and child mortality over time, at the national level, and under programmatic conditions. Two analytic approaches were used to examine this association: a retrospective cohort analysis of individual children and a district-level ecologic analysis. To evaluate the association between household ITN ownership and all-cause child mortality (ACCM) at the individual level, data from the 2010 Demographic and Health Survey (DHS) were modeled in a Cox proportional hazards framework while controlling for numerous environmental, household, and individual confounders through the use of exact matching. To evaluate population-level association between ITN ownership and ACCM between 2006 and 2010, program ITN distribution data and mortality data from the 2006 Multiple Indicator Cluster Survey and the 2010 DHS were aggregated at the district level and modeled using negative binomial regression. In the Cox model controlling for household, child and maternal health factors, children between 1 and 59 months in households owning an ITN had significantly lower mortality compared with those without an ITN (hazard ratio = 0.75, 95% confidence interval [CI] = 0.62-90). In the district-level model, higher ITN ownership was significantly associated with lower ACCM (incidence rate ratio = 0.77; 95% CI = 0.60-0.98). These findings suggest that increasing ITN ownership may have contributed to the decline in ACCM during 2006-2010 in Malawi and represent a novel use of district-level data from nationally representative surveys.

Implementation of an insecticide-treated net subsidy scheme under a public-private partnership for malaria control in Tanzania – challenges in implementation

PubMed Central

2009-01-01

Background In the past decade there has been increasing visibility of malaria control efforts at the national and international levels. The factors that have enhanced this scenario are the availability of proven interventions such as artemisinin-based combination therapy, the wide scale use of insecticide-treated nets (ITNs) and a renewed emphasis in indoor residual house-spraying. Concurrently, there has been a window of opportunity of financial commitments from organizations such as the Global Fund for HIV/AIDS, Tuberculosis and Malaria (GFATM), the President's Malaria Initiative and the World Bank Booster programme. Methods The case study uses the health policy analysis framework to analyse the implementation of a public-private partnership approach embarked upon by the government of Tanzania in malaria control – 'The Tanzania National Voucher Scheme'- and in this synthesis, emphasis is on the challenges faced by the scheme during the pre-implementation (2001 – 2004) and implementation phases (2004 – 2005). Qualitative research tools used include: document review, interview with key informants, stakeholder's analysis, force-field analysis, time line of events, policy characteristic analysis and focus group discussions. The study is also complemented by a cross-sectional survey, which was conducted at the Rufiji Health Demographic Surveillance Site, where a cohort of women of child-bearing age were followed up regarding access and use of ITNs. Results The major challenges observed include: the re-introduction of taxes on mosquito nets and related products, procurement and tendering procedures in the implementation of the GFATM, and organizational arrangements and free delivery of mosquito nets through a Presidential initiative. Conclusion The lessons gleaned from this synthesis include: (a) the consistency of the stakeholders with a common vision, was an important strength in overcoming obstacles, (b) senior politicians often steered the policy agenda when

Bed net ownership in Kenya: the impact of 3.4 million free bed nets

PubMed Central

2010-01-01

Background In July and September 2006, 3.4 million long-lasting insecticide-treated bed nets (LLINs) were distributed free in a campaign targeting children 0-59 months old (CU5s) in the 46 districts with malaria in Kenya. A survey was conducted one month after the distribution to evaluate who received campaign LLINs, who owned insecticide-treated bed nets and other bed nets received through other channels, and how these nets were being used. The feasibility of a distribution strategy aimed at a high-risk target group to meet bed net ownership and usage targets is evaluated. Methods A stratified, two-stage cluster survey sampled districts and enumeration areas with probability proportional to size. Handheld computers (PDAs) with attached global positioning systems (GPS) were used to develop the sampling frame, guide interviewers back to chosen households, and collect survey data. Results In targeted areas, 67.5% (95% CI: 64.6, 70.3%) of all households with CU5s received campaign LLINs. Including previously owned nets, 74.4% (95% CI: 71.8, 77.0%) of all households with CU5s had an ITN. Over half of CU5s (51.7%, 95% CI: 48.8, 54.7%) slept under an ITN during the previous evening. Nearly forty percent (39.1%) of all households received a campaign net, elevating overall household ownership of ITNs to 50.7% (95% CI: 48.4, 52.9%). Conclusions The campaign was successful in reaching the target population, families with CU5s, the risk group most vulnerable to malaria. Targeted distribution strategies will help Kenya approach indicator targets, but will need to be combined with other strategies to achieve desired population coverage levels. PMID:20576145

Prevention of malaria with pyrethroid treated bednets.

PubMed

Curtis, C

1997-01-01

Malaria parasites (Plasmodium) are carried from person to person by female mosquitoes of the genus Anopheles. 80-90% of malaria incidence worldwide occurs in Africa. The main Anopheles species in Africa which bite humans are A. gambiae and A. funestus. Since these animals feed upon humans mainly during late night when most people are in bed, the consistent use of bednets can block the transmission of malaria. However, bednets should be treated with synthetic pyrethroid insecticides, for the physical barrier of bednets is often inadequate to prevent the entry of Anopheles. In addition, the mosquitoes are drawn to the bednets by the carbon dioxide and body odor emitted by the occupant. The insecticide-treated nets therefore double as mosquito traps. Bednets are treated by dipping them into an aqueous emulsion of a pyrethroid, wringing them out, then laying them out to dry. A considerable number of mosquitoes can be killed with a relatively small amount of insecticide. A treated net's insecticidal power can be tested by wrapping part of it around a wire frame, then introducing some Anopheles mosquitoes inside the frame. A median mosquito knockdown time of less than 10 minutes inside the net indicates a good pyrethroid deposit. The persistence of a net's insecticidal power is considerably reduced if the net is vigorously washed. People vary in the frequency they wash their nets. Most villagers in Tanzania were found to wash and retreat their nets every 6 months.

Electrostatic coating enhances bioavailability of insecticides and breaks pyrethroid resistance in mosquitoes

PubMed Central

Andriessen, Rob; Snetselaar, Janneke; Suer, Remco A.; Osinga, Anne J.; Deschietere, Johan; Lyimo, Issa N.; Mnyone, Ladslaus L.; Brooke, Basil D.; Ranson, Hilary; Knols, Bart G. J.; Farenhorst, Marit

2015-01-01

Insecticide resistance poses a significant and increasing threat to the control of malaria and other mosquito-borne diseases. We present a novel method of insecticide application based on netting treated with an electrostatic coating that binds insecticidal particles through polarity. Electrostatic netting can hold small amounts of insecticides effectively and results in enhanced bioavailability upon contact by the insect. Six pyrethroid-resistant Anopheles mosquito strains from across Africa were exposed to similar concentrations of deltamethrin on electrostatic netting or a standard long-lasting deltamethrin-coated bednet (PermaNet 2.0). Standard WHO exposure bioassays showed that electrostatic netting induced significantly higher mortality rates than the PermaNet, thereby effectively breaking mosquito resistance. Electrostatic netting also induced high mortality in resistant mosquito strains when a 15-fold lower dose of deltamethrin was applied and when the exposure time was reduced to only 5 s. Because different types of particles adhere to electrostatic netting, it is also possible to apply nonpyrethroid insecticides. Three insecticide classes were effective against strains of Aedes and Culex mosquitoes, demonstrating that electrostatic netting can be used to deploy a wide range of active insecticides against all major groups of disease-transmitting mosquitoes. Promising applications include the use of electrostatic coating on walls or eave curtains and in trapping/contamination devices. We conclude that application of electrostatically adhered particles boosts the efficacy of WHO-recommended insecticides even against resistant mosquitoes. This innovative technique has potential to support the use of unconventional insecticide classes or combinations thereof, potentially offering a significant step forward in managing insecticide resistance in vector-control operations. PMID:26324912

How will the reduction of tariffs and taxes on insecticide- treated bednets affect household purchases?

PubMed

Simon, Jonathon L; Larson, Bruce A; Zusman, Alexander; Rosen, Sydney

2002-01-01

One of the steps called for in the fight against malaria is the removal of tariffs and taxes on insecticide-treated bednets (ITNs), netting materials, and insecticides, with a view to reducing the retail prices of ITNs and thus increasing utilization. In this paper we develop an approach for analysing the extent to which reform of tariff and tax policy can be expected to increase ITN purchases. We consider the following questions: (1). How much does the retail price of ITNs change if tariffs and taxes are reduced or eliminated? (2). How responsive is consumer demand to changes in the retail price of ITNs? Data on the price elasticity of demand for ITNs are very limited. Nevertheless, they suggest that ITN demand is not highly responsive to lower prices if household preferences are held constant. The reduction in retail prices associated with the removal of tariffs and taxes depends on the structure of the market in individual countries. In Nigeria, reducing the tariff on insecticides from 42% to zero and the tariff on netting materials from 40% to 5% is expected to increase ITN purchases by 9-27%, depending on the elasticity used. Country-specific information about market structure and cost conditions is needed if predictions are to be made as to how a specific policy change will affect ITN purchases.

How will the reduction of tariffs and taxes on insecticide- treated bednets affect household purchases?

PubMed Central

Simon, Jonathon L.; Larson, Bruce A.; Zusman, Alexander; Rosen, Sydney

2002-01-01

One of the steps called for in the fight against malaria is the removal of tariffs and taxes on insecticide-treated bednets (ITNs), netting materials, and insecticides, with a view to reducing the retail prices of ITNs and thus increasing utilization. In this paper we develop an approach for analysing the extent to which reform of tariff and tax policy can be expected to increase ITN purchases. We consider the following questions: (1). How much does the retail price of ITNs change if tariffs and taxes are reduced or eliminated? (2). How responsive is consumer demand to changes in the retail price of ITNs? Data on the price elasticity of demand for ITNs are very limited. Nevertheless, they suggest that ITN demand is not highly responsive to lower prices if household preferences are held constant. The reduction in retail prices associated with the removal of tariffs and taxes depends on the structure of the market in individual countries. In Nigeria, reducing the tariff on insecticides from 42% to zero and the tariff on netting materials from 40% to 5% is expected to increase ITN purchases by 9-27%, depending on the elasticity used. Country-specific information about market structure and cost conditions is needed if predictions are to be made as to how a specific policy change will affect ITN purchases. PMID:12481212

A stitch in time: a cross-sectional survey looking at long lasting insecticide-treated bed net ownership, utilization and attrition in SNNPR, Ethiopia.

PubMed

Batisso, Esey; Habte, Tedila; Tesfaye, Gezahegn; Getachew, Dawit; Tekalegne, Agonafer; Kilian, Albert; Mpeka, Betty; Lynch, Caroline

2012-06-07

Since 2002/03, an estimated 4.7 million nets have been distributed in the Southern Nations, Nationalities and Peoples Region (SNNPR) among an at risk population of approximately 10 million people. Evidence from the region suggests that large-scale net ownership rapidly increased over a relatively short period of time. However, little is known about how coverage is being maintained given that the last mass distribution was in 2006/2007. This study sought to determine the status of current net ownership, utilization and rate of long lasting insecticide-treated nets (LLIN) loss in the previous three years in the context of planning for future net distribution to try to achieve sustainable universal coverage. A total of 750 household respondents were interviewed across malarious, rural kebeles of SNNPR. Households were randomly selected following a two-stage cluster sampling design where kebeles were defined as clusters. Kebeles were chosen using proportional population sampling (PPS), and 25 households within 30 kebeles randomly chosen. Approximately 67.5% (95%CI: 64.1-70.8) of households currently owned at least one net. An estimated 31.0% (95%CI 27.9-34.4) of all nets owned in the previous three years had been discarded by owners, the majority of whom considered the nets too torn, old or dirty (79.9%: 95%CI 75.8-84.0). Households reported that one-third of nets (33.7%) were less than one year old when they were discarded. The majority (58.8%) of currently owned nets had 'good' structural integrity according to a proportionate Hole Index. Nearly two-thirds of households (60.6%) reported using their nets the previous night. The overriding reason for not using nets was that they were too torn (45.7%, 95% CI 39.1-50.7). Yet, few households are making repairs to their nets (3.7%, 95% CI: 2.4-5.1). Results suggest that the life span of nets may be shorter than previously thought, with little maintenance by their owners. With the global move towards malaria elimination it

Distributing insecticide-treated bednets during measles vaccination: a low-cost means of achieving high and equitable coverage.

PubMed Central

Grabowsky, Mark; Nobiya, Theresa; Ahun, Mercy; Donna, Rose; Lengor, Miata; Zimmerman, Drake; Ladd, Holly; Hoekstra, Edward; Bello, Aliu; Baffoe-Wilmot, Aba; Amofah, George

2005-01-01

OBJECTIVE: To achieve high and equitable coverage of insecticide-treated bednets by integrating their distribution into a measles vaccination campaign. METHODS: In December 2002 in the Lawra district in Ghana, a measles vaccination campaign lasting 1 week targeted all children aged 9 months-15 years. Families with one or more children less than five years old were targeted to receive a free insecticide-treated bednet. The Ghana Health Service, with support from the Ghana Red Cross and UNICEF, provided logistical support, volunteer workers and social mobilization during the campaign. Volunteers visited homes to inform caregivers about the campaign and encourage them to participate. We assessed pre-campaign coverage of bednets by interviewing caregivers leaving vaccination and distribution sites. Five months after distribution, a two-stage cluster survey using population-proportional sampling assessed bednet coverage, retention and use. Both the pre-campaign and post-campaign survey assessed household wealth using an asset inventory. FINDINGS: At the campaign exit interview 636/776 (82.0%) caregivers reported that they had received a home visit by a Red Cross volunteer before the campaign and that 32/776 (4.1%) of the youngest children in each household who were less than 5 years of age slept under an insecticide-treated bednet. Five months after distribution caregivers reported that 204/219 (93.2%) of children aged 9 months to 5 years had been vaccinated during the campaign; 234/248 (94.4%) of households were observed to have an insecticide-treated bednet; and 170/249 (68.3%) were observed to have a net hung over a bed. Altogether 222/248 (89.5%) caregivers reported receiving at least one insecticide-treated bednet during the campaign, and 153/254 (60.2%) said that on the previous night their youngest child had slept under a bednet received during the campaign. For households in the poorest quintile, post-campaign coverage of insecticide-treated bednets was 10 times

Use of insecticide treated nets by pregnant women and associated factors in a pre-dominantly rural population in northern Ethiopia.

PubMed

Belay, Mebrahtom; Deressa, Wakgari

2008-10-01

To describe the use of insecticide treated nets (ITNs) among pregnant women and examine factors associated with its access and use. Community-based cross-sectional study of 815 pregnant women in eight malarious kebeles in northern Ethiopia based on two-stage cluster design from May to June 2006. Knowledge on malaria, its cause and preventive measures; treatment seeking behaviour; possession and use of ITNs by pregnant women and under-five children were ascertained through interview and observation. Logistic regression was used to determine factors associated with ITNs use. Knowledge about the cause, transmission and preventive measures of malaria was relatively good; 90.2% of women associated malaria with mosquito bites and 94.2% with living near water ponds. Ten per cent reported malaria illness within the 14 days before the survey, and sought treatment mainly from public health facilities (56.5%) and community health workers (37.6%). Of 815 households surveyed, 59% owned at least one non-long lasting or long-lasting ITN (59.5% rural vs. 54.5% urban; P = 0.401). Lack of access to ITNs (68.3%) and the perception that nets could not prevent malaria (27%) were the main reasons for non-ownership of nets. A total of 58.4% of 481 pregnant women from households owning at least one ITN had slept under it during the previous night. Fewer rural (56.7%) than urban women (76.2%) used ITNs (P = 0.001). In 57.6% of households with at least one ITN, under-five children had used it the night before. Higher educational attainment was an important predictor of ITNs use (OR = 3.1, 95% CI = 2.1, 4.6). Household ownership of ITNs and their use by pregnant women is promising with the current efforts to scale-up ITNs implementation, but the gap between ownership and use remains high. Consistent and proper use of nets by pregnant women should be ensured through information campaigns. Rapid expansion of access to long lasting ITNs requires that government and NGOs supply them in adequate

Potential benefits of combining transfluthrin-treated sisal products and long-lasting insecticidal nets for controlling indoor-biting malaria vectors.

PubMed

Masalu, John P; Okumu, Fredros O; Mmbando, Arnold S; Sikulu-Lord, Maggy T; Ogoma, Sheila B

2018-04-10

Transfluthrin vapour prevents mosquito bites by disrupting their host-seeking behaviors. We measured the additional benefits of combining transfluthrin-treated sisal decorations and long-lasting insecticidal nets (LLINs) with an aim of extending protection against early evening, indoor-biting malaria vectors when LLINs are ineffective. We investigated the indoor protective efficacy of locally made sisal decorative baskets (0.28 m 2 ) treated with 2.5 ml and 5.0 ml transfluthrin, in terms of mosquito density, exposure to bites and 24 h mortality. Experiments were conducted in experimental huts, located in Lupiro village, Ulanga District, south-eastern Tanzania. Human landing catches (HLC) were used to measure exposure to bites between 19:00-23:00 h. Each morning, at 06:00 h, mosquitoes were collected inside huts and in exit traps and monitored for 24 h mortality. Sisal decorative baskets (0.28 m 2 ) treated with 2.5 ml and 5.0 ml transfluthrin deterred three-quarters of Anopheles arabiensis mosquitoes from entering huts (relative rate, RR = 0.26, 95% confidence interval, CI: 0.20-0.34, P < 0.001 and RR= 0.29, 95% CI: 0.22-0.37, P < 0.001, respectively). Both treatments induced a 10-fold increase in 24 h mortality of An. arabiensis mosquitoes (odds ratio, OR = 12.26, 95% CI: 7.70-19.51, P < 0.001 and OR = 18.42, 95% CI: 11.36-29.90, P < 0.001, respectively). Sisal decorative items treated with spatial repellents provide additional household and personal protection against indoor biting malaria and nuisance mosquitoes in the early evening, when conventional indoor vector control tools, such as LLINs, are not in use. We recommend future studies to investigate the epidemiological relevance of combining LLINs and transfluthrin decorated baskets in terms of their effect on reduction in malaria prevalence.

Ownership and usage of insecticide-treated bed nets after free distribution via a voucher system in two provinces of Mozambique.

PubMed

Macedo de Oliveira, Alexandre; Wolkon, Adam; Krishnamurthy, Ramesh; Erskine, Marcy; Crenshaw, Dana P; Roberts, Jacquelin; Saúte, Francisco

2010-08-04

Insecticide-treated bed nets (ITNs) are an efficacious intervention for malaria prevention. During a national immunization campaign in Mozambique, vouchers, which were to be redeemed at a later date for free ITNs, were distributed in Manica and Sofala provinces. A survey to evaluate ITN ownership and usage post-campaign was conducted. Four districts in each province and four enumeration areas (EAs) in each district were selected using probability proportional to size. Within each EA, 32 households (HHs) were selected using a simple random sample. Interviews to assess ownership and usage were conducted in each of the selected HHs using personal digital assistants. Valid interviews were completed for 947 (92.5%) (440 in Manica and 507 in Sofala) of the 1,024 selected HHs. Among participating HHs, 65.0% in Manica and 63.1% in Sofala reported that at least one child under five years of age slept in the house the previous night. HH ownership of at least one bed net of any kind was 20.6% (95% confidence interval [CI]: 7.9%-43.6%) and 35.6% (95% CI: 27.8%-44.3%) pre-campaign; and 55.1% (95% CI: 43.6%-66.1%) and 59.6 (95% CI: 42.4%-74.7%) post-campaign in Manica and Sofala, respectively. Post-campaign HH ownership of at least one ITN was 50.2% (95% CI: 41.8%-58.5%) for both provinces combined. In addition, 60.3% (95% CI: 50.6%-69.2%) of children under five years of age slept under an ITN the previous night. This ITN distribution increased bed net ownership and usage rates. Integration of ITN distribution with immunization campaigns presents an opportunity for reaching malaria control targets and should continue to be considered.

Rapid Scale-Up of Long-Lasting Insecticide-Treated Bed Nets through Integration into the National Immunization Program during Child Health Week in Togo, 2004

PubMed Central

Wolkon, Adam; Vanden Eng, Jodi L.; Morgah, Kodjo; Eliades, M. James; Thwing, Julie; Terlouw, Dianne J.; Takpa, Vincent; Dare, Aboudou; Sodahlon, Yao K.; Doumanou, Yao; Hightower, Allen W.; Lama, Marcel; Thawani, Neeta; Slutsker, Laurence; Hawley, William A.

2010-01-01

In December 2004, Togo was the first country to conduct a nationwide free insecticide-treated net (ITN) distribution as part of its National Integrated Child Health Campaign. Community-based cross-sectional surveys were conducted one and nine months post-campaign as part of a multidisciplinary evaluation of the nationwide distribution of ITNs to children 9–59 months of age to evaluate ITN ownership, equity, and use. Our results demonstrated that at one month post-campaign, 93.1% of all eligible children received an ITN. Household ITN ownership and equity increased significantly post-campaign. Nine months post-campaign, 78.6% of households with a child eligible to participate in the campaign retained at least one campaign net. Use by eligible children was 43.5% at one month post-campaign (during the dry season) and 52.9% at nine months post-campaign (during the rainy season). Household ownership of at least one ITN increased from 8.0% pre-campaign to 62.5% one month post-campaign. Together, these findings demonstrate that in this setting, increased household ITN ownership, equity, and retention can be achieved on a national scale through free ITN distribution during an integrated campaign. PMID:21036829

Free distribution of insecticidal bed nets improves possession and preferential use by households and is equitable: findings from two cross-sectional surveys in thirteen malaria endemic districts of Bangladesh.

PubMed

Ahmed, Syed M; Hossain, Shamim; Kabir, Mohammad M; Roy, Sanjit

2011-12-13

BRAC, an indigenous non-governmental development organization (NGO), has been implementing a programme to prevent and control malaria in the 13 malaria-endemic districts of Bangladesh since 2007. One of the critical preventive interventions is the distribution of insecticidal bed nets (long-lasting insecticide-treated nets, LLINs and insecticide-treated ordinary nets, ITNs) to the community free of cost. This study aimed to assess progress in the possession, preferential use, and knowledge on use of the LLIN/ITNs including the programme's avowed pro-poor inclination one and three and half years after intervention began. A convenient sampling strategy based on malaria endemicity in the districts was adopted. First, thirty upazila (sub-district, with a population around 250,000)s were selected at random, with high prevalent districts contributing more upazilas; second, from each upazila, one (2008) to two (2011) villages (covered by insecticidal bed net distribution programme) were selected. From each village, households that had either one under-five child and/or a pregnant woman were included in the survey, one household being included only once. Data were collected using a pre-tested structured questionnaire. In all, 3,760 households in 2008 and 7,895 households in 2011 were surveyed for collecting relevant information. Proportion of households with at least one LLIN, and at least one LLIN/ITN increased (22-59 to 62-67% and 22-64% to 74-76% respectively) over time, including increase in the mean number of LLIN/ITNs per household (≤ 1 to 1 +). The programme achieved > 80% coverage in sleeping under an LLIN/ITN in the case of under-five children and pregnant women, especially in the high-endemic districts. Knowledge regarding critical time of hanging the net also increased over time (7-22 to 44-54%), but remained low. The pro-poor inclination of the programme is reflected in the status of relevant indicators according to self-rated poverty status of the households

Combination of indoor residual spraying with long-lasting insecticide-treated nets for malaria control in Zambezia, Mozambique: a cluster randomised trial and cost-effectiveness study protocol.

PubMed

Chaccour, Carlos J; Alonso, Sergi; Zulliger, Rose; Wagman, Joe; Saifodine, Abuchahama; Candrinho, Baltazar; Macete, Eusébio; Brew, Joe; Fornadel, Christen; Kassim, Hidayat; Loch, Lourdes; Sacoor, Charfudin; Varela, Kenyssony; Carty, Cara L; Robertson, Molly; Saute, Francisco

2018-01-01

Most of the reduction in malaria prevalence seen in Africa since 2000 has been attributed to vector control interventions. Yet increases in the distribution and intensity of insecticide resistance and higher costs of newer insecticides pose a challenge to sustaining these gains. Thus, endemic countries face challenging decisions regarding the choice of vector control interventions. A cluster randomised trial is being carried out in Mopeia District in the Zambezia Province of Mozambique, where malaria prevalence in children under 5 is high (68% in 2015), despite continuous and campaign distribution of long-lasting insecticide-treated nets (LLINs). Study arm 1 will continue to use the standard, LLIN-based National Malaria Control Programme vector control strategy (LLINs only), while study arm 2 will receive indoor residual spraying (IRS) once a year for 2 years with a microencapsulated formulation of pirimiphos-methyl (Actellic 300 CS), in addition to the standard LLIN strategy (LLINs+IRS). Prior to the 2016 IRS implementation (the first of two IRS campaigns in this study), 146 clusters were defined and stratified per number of households. Clusters were then randomised 1:1 into the two study arms. The public health impact and cost-effectiveness of IRS intervention will be evaluated over 2 years using multiple methods: (1) monthly active malaria case detection in a cohort of 1548 total children aged 6-59 months; (2) enhanced passive surveillance at health facilities and with community health workers; (3) annual cross-sectional surveys; and (4) entomological surveillance. Prospective microcosting of the intervention and provider and societal costs will be conducted. Insecticide resistance status pattern and changes in local Anopheline populations will be included as important supportive outcomes. By evaluating the public health impact and cost-effectiveness of IRS with a non-pyrethroid insecticide in a high-transmission setting with high LLIN ownership, it is

Utilization of insecticide treated nets during pregnancy among postpartum women in Ibadan, Nigeria: a cross-sectional study

PubMed Central

2012-01-01

Background Pregnant women are susceptible to symptomatic malaria due to invasion of the placenta by plasmodium. Malaria increases the risk of adverse pregnancy outcomes for mothers, the foetuses and newborns. The effective use of Insecticide Treated Nets (ITNs) would be of benefit to these vulnerable women. Previous studies have focused on prenatal-women but this study sought to explore the actual trend of utilization of the proven strategy across all the pregnancy stages among postpartum women in Ibadan. Methods This cross-sectional survey utilized a validated structured questionnaire for data collection. A calculated sample of 335 postpartum women was proportionately recruited from three fee-paying facilities within Ibadan, Nigeria using a simple random sampling technique. These hospitals have high client flow for maternity cases and are known for provision of care under traditional ANC model. The data collected were analyzed using descriptive and inferential statistics by means of Statistical Package of Social Sciences (SPSS) version 15. The level of significance was set at = 0.05. Results The women's age ranged between 18 and 47 years, mean age was 29.4 ± 0.8 years. Various irregularities marked the traditional model of ANC provided at the settings and no exposure to preconception care. Also, 276 (82.4%) had heard of ITNs. Antenatal clinics formed the major source of information. Low utilization and compliance rates were observed. One hundred and twenty-seven (37.9%) of the women had high knowledge of Malaria in Pregnancy (MIP) but only 70 (20.9%) demonstrated positive attitude towards the use of ITNs. Participants' educational status, family types, employment and residential areas significantly influenced ITNs utilization. Conclusions The women knew and learned about ITNs from ANC visits. Majority of the women did not own ITNs because of lack of access to free distribution. The existing traditional model of ANC was marked by irregularities and none of the

Long-lasting insecticide-treated bed net ownership and use among children under five years of age following a targeted distribution in central Uganda

PubMed Central

2014-01-01

Background Universal coverage of long-lasting insecticide-treated bed nets (LLINs) for prevention of malaria was adopted by the Uganda National Malaria Control Programme in 2007. The first mass distribution of LLINs was implemented in 2010. Initially, a campaign targeted to households with pregnant women and children aged net (80.7 vs 35.2%, p < 0.001). LLIN ownership and use was equitable after the targeted campaign, with no significant differences by household wealth status. However, the proportion of households with at least one LLIN per two people was still low after the first campaign phase, increasing from 8.5 to 25.9%. Conclusions The first phase of the campaign led to substantial increases in both LLIN ownership and equitable use among children 

Multicentre studies of insecticide-treated durable wall lining in Africa and South-East Asia: entomological efficacy and household acceptability during one year of field use

PubMed Central

2012-01-01

Background Indoor residual spraying (IRS) is a primary method of malaria vector control, but its potential impact is constrained by several inherent limitations: spraying must be repeated when insecticide residues decay, householders can tire of the annual imposition and campaign costs are recurrent. Durable lining (DL) can be considered an advanced form of long-lasting IRS where insecticide is gradually released from an aesthetically attractive wall lining material to provide vector control for several years. A multicentre trial was carried out in Equatorial Guinea, Ghana, Mali, South Africa and Vietnam to assess the feasibility, durability, bioefficacy and household acceptability of DL, compared to conventional IRS or insecticide-treated curtains (LLITCs), in a variety of operational settings. Methods This study was conducted in 220 households in traditional rural villages over 12-15 months. In all sites, rolls of DL were cut to fit house dimensions and fixed to interior wall surfaces (usually with nails and caps) by trained teams. Acceptability was assessed using a standardized questionnaire covering such topics as installation, exposure reactions, entomology, indoor environment, aesthetics and durability. Bioefficacy of interventions was evaluated using WHO cone bioassay tests at regular intervals throughout the year. Results The deltamethrin DL demonstrated little to no decline in bioefficacy over 12-15 months, supported by minimal loss of insecticide content. By contrast, IRS displayed a significant decrease in bioactivity by 6 months and full loss after 12 months. The majority of participants in DL households perceived reductions in mosquito density (93%) and biting (82%), but no changes in indoor temperature (83%). Among those households that wanted to retain the DL, 73% cited protective reasons, 20% expressed a desire to keep theirs for decoration and 7% valued both qualities equally. In Equatorial Guinea, when offered a choice of vector control product at

Impact of Insecticide-Treated Net Ownership on All-Cause Child Mortality in Malawi, 2006–2010

PubMed Central

Florey, Lia S.; Bennett, Adam; Hershey, Christine L.; Bhattarai, Achuyt; Nielsen, Carrie F.; Ali, Doreen; Luhanga, Misheck; Taylor, Cameron; Eisele, Thomas P.; Yé, Yazoume

2017-01-01

Abstract. Insecticide-treated nets (ITNs) have been shown to be highly effective at reducing malaria morbidity and mortality in children. However, there are limited studies that assess the association between increasing ITN coverage and child mortality over time, at the national level, and under programmatic conditions. Two analytic approaches were used to examine this association: a retrospective cohort analysis of individual children and a district-level ecologic analysis. To evaluate the association between household ITN ownership and all-cause child mortality (ACCM) at the individual level, data from the 2010 Demographic and Health Survey (DHS) were modeled in a Cox proportional hazards framework while controlling for numerous environmental, household, and individual confounders through the use of exact matching. To evaluate population-level association between ITN ownership and ACCM between 2006 and 2010, program ITN distribution data and mortality data from the 2006 Multiple Indicator Cluster Survey and the 2010 DHS were aggregated at the district level and modeled using negative binomial regression. In the Cox model controlling for household, child and maternal health factors, children between 1 and 59 months in households owning an ITN had significantly lower mortality compared with those without an ITN (hazard ratio = 0.75, 95% confidence interval [CI] = 0.62–90). In the district-level model, higher ITN ownership was significantly associated with lower ACCM (incidence rate ratio = 0.77; 95% CI = 0.60–0.98). These findings suggest that increasing ITN ownership may have contributed to the decline in ACCM during 2006–2010 in Malawi and represent a novel use of district-level data from nationally representative surveys. PMID:28990922

Community cooperatives and insecticide-treated materials for malaria control: a new experience in Latin America

PubMed Central

Kroeger, Axel; Aviñna, Ana; Ordoñnez-Gonzalez, José; Escandon, Celia

2002-01-01

Background and objectives Insecticide-treated materials (ITMs) are effective in substantially reducing the burden of malaria and other vector-borne diseases; but how can high coverage rates of ITMs be achieved and maintained? In south Mexico and on the Pacific and Atlantic coasts of Colombia 14 community-based cooperatives offering three different kinds of ITM services (sale of impregnation services; sale of impregnated nets; production of nets and sale of impregnated nets) were formed and supervised by a national health service (IMSS-SOLIDARIDAD, Mexico) and by an academic institution (the Colombian Institute of Tropical Medicine) along with local district health services. The objectives of this research were to analyse the processes and results of this approach and to identify the favourable and limiting factors. Methods The methods used for data collection and analysis were group discussions, individual and semi-structured interviews with users and non-users of ITMs, individual in-depth interviews with cooperative members and supervisors, checks of sales book and observation of impregnation services. Results Coverage with unimpregnated nets was above 50% in all study areas. The fastest increase of ITM coverage was achieved through the exclusive sale of impregnation services. Low-cost social marketing techniques were used to increase demand. The large-scale production of nets in two cooperatives was only possible with the aid of an international NGO which ordered impregnated bednets for their target group. A number of favourable and limiting factors relating to the success of ITM cooperatives were identified. Of particular importance for the more successful Mexican cooperatives were: a) support by health services, b) smaller size, c) lesser desire for quick returns and d) lower ITM unit costs. Conclusions ITM community cooperatives supported and supervised by the health services have good potential in the Latin American context for achieving and maintaining high

Investigating mosquito net durability for malaria control in Tanzania - attrition, bioefficacy, chemistry, degradation and insecticide resistance (ABCDR): study protocol.

PubMed

Lorenz, Lena M; Overgaard, Hans J; Massue, Dennis J; Mageni, Zawadi D; Bradley, John; Moore, Jason D; Mandike, Renata; Kramer, Karen; Kisinza, William; Moore, Sarah J

2014-12-13

Long-Lasting Insecticidal Nets (LLINs) are one of the major malaria vector control tools, with most countries adopting free or subsidised universal coverage campaigns of populations at-risk from malaria. It is essential to understand LLIN durability so that public health policy makers can select the most cost effective nets that last for the longest time, and estimate the optimal timing of repeated distribution campaigns. However, there is limited knowledge from few countries of the durability of LLINs under user conditions. This study investigates LLIN durability in eight districts of Tanzania, selected for their demographic, geographic and ecological representativeness of the country as a whole. We use a two-stage approach: First, LLINs from recent national net campaigns will be evaluated retrospectively in 3,420 households. Those households will receive one of three leading LLIN products at random (Olyset®, PermaNet®2.0 or Netprotect®) and will be followed up for three years in a prospective study to compare their performance under user conditions. LLIN durability will be evaluated by measuring Attrition (the rate at which nets are discarded by households), Bioefficacy (the insecticidal efficacy of the nets measured by knock-down and mortality of mosquitoes), Chemical content (g/kg of insecticide available in net fibres) and physical Degradation (size and location of holes). In addition, we will extend the current national mosquito insecticide Resistance monitoring program to additional districts and use these data sets to provide GIS maps for use in health surveillance and decision making by the National Malaria Control Program (NMCP). The data will be of importance to policy makers and vector control specialists both in Tanzania and the SSA region to inform best practice for the maintenance of high and cost-effective coverage and to maximise current health gains in malaria control.

Dengue vector management using insecticide treated materials and targeted interventions on productive breeding-sites in Guatemala.

PubMed

Rizzo, Nidia; Gramajo, Rodrigo; Escobar, Maria Cabrera; Arana, Byron; Kroeger, Axel; Manrique-Saide, Pablo; Petzold, Max

2012-10-30

In view of the epidemiological expansion of dengue worldwide and the availability of new tools and strategies particularly for controlling the primary dengue vector Aedes aegypti, an intervention study was set up to test the efficacy, cost and feasibility of a combined approach of insecticide treated materials (ITMs) alone and in combination with appropriate targeted interventions of the most productive vector breeding-sites. The study was conducted as a cluster randomized community trial using "reduction of the vector population" as the main outcome variable. The trial had two arms: 10 intervention clusters (neighborhoods) and 10 control clusters in the town of Poptun Guatemala. Activities included entomological assessments (characteristics of breeding-sites, pupal productivity, Stegomyia indices) at baseline, 6 weeks after the first intervention (coverage of window and exterior doorways made of PermaNet 2.0 netting, factory treated with deltamethrin at 55 mg/m2, and of 200 L drums with similar treated material) and 6 weeks after the second intervention (combination of treated materials and other suitable interventions targeting productive breeding-sites i.e larviciding with Temephos, elimination etc.). The second intervention took place 17 months after the first intervention. The insecticide residual activity and the insecticidal content were also studied at different intervals. Additionally, information about demographic characteristics, cost of the intervention, coverage of houses protected and satisfaction in the population with the interventions was collected. At baseline (during the dry season) a variety of productive container types for Aedes pupae were identified: various container types holding >20 L, 200 L drums, washbasins and buckets (producing 83.7% of all pupae). After covering 100% of windows and exterior doorways and a small number of drums (where the commercial cover could be fixed) in 970 study households, tropical rains occurred in the area and

Evaluation of a national universal coverage campaign of long-lasting insecticidal nets in a rural district in north-west Tanzania.

PubMed

West, Philippa A; Protopopoff, Natacha; Rowland, Mark W; Kirby, Matthew J; Oxborough, Richard M; Mosha, Franklin W; Malima, Robert; Kleinschmidt, Immo

2012-08-10

Insecticide-treated nets (ITN) are one of the most effective measures for preventing malaria. Mass distribution campaigns are being used to rapidly increase net coverage in at-risk populations. This study had two purposes: to evaluate the impact of a universal coverage campaign (UCC) of long-lasting insecticidal nets (LLINs) on LLIN ownership and usage, and to identify factors that may be associated with inadequate coverage. In 2011 two cross-sectional household surveys were conducted in 50 clusters in Muleba district, north-west Tanzania. Prior to the UCC 3,246 households were surveyed and 2,499 afterwards. Data on bed net ownership and usage, demographics of household members and household characteristics including factors related to socio-economic status were gathered, using an adapted version of the standard Malaria Indicator Survey. Specific questions relating to the UCC process were asked. The proportion of households with at least one ITN increased from 62.6% (95% Confidence Interval (CI) = 60.9-64.2) before the UCC to 90.8% (95% CI = 89.0-92.3) afterwards. ITN usage in all residents rose from 40.8% to 55.7%. After the UCC 58.4% (95% CI = 54.7-62.1) of households had sufficient ITNs to cover all their sleeping places. Households with children under five years (OR = 2.4, 95% CI = 1.9-2.9) and small households (OR = 1.9, 95% CI = 1.5-2.4) were most likely to reach universal coverage. Poverty was not associated with net coverage. Eighty percent of households surveyed received LLINs from the campaign. The UCC in Muleba district of Tanzania was equitable, greatly improving LLIN ownership and, more moderately, usage. However, the goal of universal coverage in terms of the adequate provision of nets was not achieved. Multiple, continuous delivery systems and education activities are required to maintain and improve bed net ownership and usage.

An experimental hut evaluation of Olyset Plus, a long-lasting insecticidal net treated with a mixture of permethrin and piperonyl butoxide, against Anopheles fluviatilis in Odisha State, India.

PubMed

Gunasekaran, Kasinathan; Sahu, Sudhansu Sekhar; Vijayakumar, Tharmalingam; Subramanian, Swaminathan; Yadav, Rajpal Singh; Pigeon, Olivier; Jambulingam, Purushothaman

2016-07-21

Fast development of pyrethroid resistance in malaria vectors prompted the development of new vector control tools including combination of insecticides with different modes of action as part of resistance management strategies. Olyset Plus® is a new long-lasting insecticidal net, in which, permethrin and a synergist, piperonyl butoxide (PBO), are incorporated into filaments. Mixture nets such as this may have application against resistant mosquitoes, particularly those whose resistance is based on oxidative metabolism. There may also be enhanced activity against susceptible mosquitoes since mixed function oxidases are involved in a many metabolic activities including activation to form bioactive compounds. Bio-efficacy of Olyset Plus was evaluated against susceptible malaria vector, Anopheles fluviatilis in experimental huts. Deterrence, blood feeding inhibition, induced exophily and killing effect were measured to assess the bio-efficacy. The results were compared with Olyset Net®, a polyethylene permethrin-incorporated LLIN and a conventionally treated polyester net (with permethrin) washed to just before exhaustion. Results showed significant reduction in entry (treatment: 0.4-0.8; control: 4.2 per trap-night) and increase in exit (56.3-82.9 % and 44.2 %) rates of Anopheles fluviatilis in the treatment arms compared to control (P < 0.05). While blood feeding rates declined in treatment arms (18.8-30.6 %), it increased in control (77.6 %) (P < 0.05). This was further evident from the blood-feeding inhibition rates in treatment arms (60.6-90.6 %). Total mortality was significantly higher in all treatment arms (96.3-100 %) compared to control arm (2 %) (P < 0.05). Chemical analysis for active ingredient (AI) showed retention of 75 and 88 % in Olyset plus and Olyset net respectively after 20 washes. Performance of Olyset Plus washed 20 times was equal to the CTN and Olyset Net against the susceptible malaria vector An. fluviatilis, fulfilling the

Improving estimates of insecticide-treated mosquito net coverage from household surveys: using geographic coordinates to account for endemicity

PubMed Central

2014-01-01

Background Coverage estimates of insecticide-treated nets (ITNs) are often calculated at the national level, but are intended to be a proxy for coverage among the population at risk of malaria. The analysis uses data for surveyed households, linking survey enumeration areas (clusters) with levels of malaria endemicity and adjusting coverage estimates based on the population at risk. This analysis proposes an approach that is not dependent on being able to identify malaria risk in a location during the survey design (since survey samples are typically selected on the basis of census sampling frames that do not include information on malaria zones), but rather being able to assign risk zones after a survey has already been completed. Methods The analysis uses data from 20 recent nationally representative Demographic and Health Survey (DHS), Malaria Indicator Surveys (MIS), an AIDS Indicator Survey (AIS), and an Anemia and Malaria Prevalence Survey (AMP). The malaria endemicity classification was assigned from the Malaria Atlas Project (MAP) 2010 interpolated data layers, using the Geographic Positioning System (GPS) location of the survey clusters. National ITN coverage estimates were compared with coverage estimates in intermediate/high endemicity zones (i.e., the population at risk of malaria) to determine whether the difference between estimates was statistically different from zero (p-value <0.5). Results Endemicity varies substantially in eight of the 20 studied countries. In these countries with heterogeneous transmission of malaria, stratification of households by endemicity zones shows that ITN coverage in intermediate/high endemicity zones is significantly higher than ITN coverage at the national level (Burundi, Kenya, Namibia, Rwanda, Tanzania, Senegal, Zambia, and Zimbabwe.). For example in Zimbabwe, the national ownership of ITNs is 28%, but ownership in the intermediate/high endemicity zone is 46%. Conclusion Incorporating this study’s basic and easily

Traditional nets interfere with the uptake of long-lasting insecticidal nets in the Peruvian Amazon: the relevance of net preference for achieving high coverage and use.

PubMed

Grietens, Koen Peeters; Muela Ribera, Joan; Soto, Veronica; Tenorio, Alex; Hoibak, Sarah; Aguirre, Angel Rosas; Toomer, Elizabeth; Rodriguez, Hugo; Llanos Cuentas, Alejandro; D'Alessandro, Umberto; Gamboa, Dionicia; Erhart, Annette

2013-01-01

While coverage of long-lasting insecticide-treated nets (LLIN) has steadily increased, a growing number of studies report gaps between net ownership and use. We conducted a mixed-methods social science study assessing the importance of net preference and use after Olyset® LLINs were distributed through a mass campaign in rural communities surrounding Iquitos, the capital city of the Amazonian region of Peru. The study was conducted in the catchment area of the Paujil and Cahuide Health Centres (San Juan district) between July 2007 and November 2008. During a first qualitative phase, participant observation and in-depth interviews collected information on key determinants for net preference and use. In a second quantitative phase, a survey among recently confirmed malaria patients evaluated the acceptability and use of both LLINs and traditional nets, and a case control study assessed the association between net preference/use and housing structure (open vs. closed houses). A total of 10 communities were selected for the anthropological fieldwork and 228 households participated in the quantitative studies. In the study area, bed nets are considered part of the housing structure and are therefore required to fulfil specific architectural and social functions, such as providing privacy and shelter, which the newly distributed Olyset® LLINs ultimately did not. The LLINs' failure to meet these criteria could mainly be attributed to their large mesh size, transparency and perceived ineffectiveness to protect against mosquitoes and other insects, resulting in 63.3% of households not using any of the distributed LLINs. Notably, LLIN usage was significantly lower in houses with no interior or exterior walls (35.2%) than in those with walls (73.8%) (OR = 5.2, 95CI [2.2; 12.3], p<0.001). Net preference can interfere with optimal LLIN use. In order to improve the number of effective days of LLIN protection per dollar spent, appropriate quantitative and qualitative methods

Evaluation of community-based continuous distribution of long-lasting insecticide-treated nets in Toamasina II District, Madagascar.

PubMed

de Beyl, Celine Zegers; Kilian, Albert; Brown, Andrea; Sy-Ar, Mohamad; Selby, Richmond Ato; Randriamanantenasoa, Felicien; Ranaivosoa, Jocelyn; Zigirumugabe, Sixte; Gerberg, Lilia; Fotheringham, Megan; Lynch, Matthew; Koenker, Hannah

2017-08-10

Continuous distribution of insecticide-treated nets (ITNs) is thought to be an effective mechanism to maintain ITN ownership and access between or in the absence of mass campaigns, but evidence is limited. A community-based ITN distribution pilot was implemented and evaluated in Toamasina II District, Madagascar, to assess this new channel for continuous ITN distribution. Beginning 9 months after the December 2012 mass campaign, a community-based distribution pilot ran for an additional 9 months, from September 2013 to June 2014. Households requested ITN coupons from community agents in their village. After verification by the agents, households exchanged the coupon for an ITN at a distribution point. The evaluation was a two-stage cluster survey with a sample size of 1125 households. Counterfactual ITN ownership and access were calculated by excluding ITNs received through the community pilot. At the end of the pilot, household ownership of any ITN was 96.5%, population access to ITN was 81.5 and 61.5% of households owned at least 1 ITN for every 2 people. Without the ITNs provided through the community channel, household ownership of any ITN was estimated at 74.6%, population access to an ITN at 55.5%, and households that owned at least 1 ITN for 2 people at only 34.7%, 18 months after the 2012 campaign. Ownership of community-distributed ITNs was higher among the poorest wealth quintiles. Over 80% of respondents felt the community scheme was fair and simple to use. Household ITN ownership and population ITN access exceeded RBM targets after the 9-month community distribution pilot. The pilot successfully provided coupons and ITNs to households requesting them, particularly for the least poor wealth quintiles, and the scheme was well-perceived by communities. Further research is needed to determine whether community-based distribution can sustain ITN ownership and access over the long term, how continuous availability of ITNs affects household net replacement

Examining equity in access to long-lasting insecticide nets and artemisinin-based combination therapy in Anambra state, Nigeria

PubMed Central

2012-01-01

Background In order to achieve universal health coverage, the government of Anambra State, southeast Nigeria has distributed free Long-lasting Insecticide treated Nets (LLINs) to the general population and delivered free Artemisinin-based Combination Therapy (ACT) to pregnant women and children less than 5 years. However, the levels of coverage with LLINS and ACTs is not clear, especially coverage of different socio-economic status (SES) population groups. This study was carried out to determine the level of coverage and access to LLINs and ACTs amongst different SES groups. Methods A questionnaire was used to collect data from randomly selected households in 19 local government areas of the State. Selected households had a pregnant woman and/or a child less than 5 years. The lot quality assurance sampling (LQAS) methodology was used in sampling. The questionnaire explored the availability and utilization of LLINs and ACTs from 2394 households. An asset-based SES index was used to examine the level of access of LLINS and ACTs to different SES quintiles. Results It was found that 80.5 % of the households had an LLIN and 64.4 % of the households stated that they actually used the nets the previous night. The findings showed that 42.3 % of pregnant women who had fever within the past month received ACTs, while 37.5 % of children ≪5 years old who had malaria in the past month had received ACTs. There was equity in ownership of nets for the range 1–5 nets per household. No significant SES difference was found in use of ACTs for treatment of malaria in children under five years old and in pregnant women. Conclusions The free distribution of LLINs and ACTs increased household coverage of both malaria control interventions and bridged the equity gap in access to them among the most vulnerable groups. PMID:22545723

Insecticidal, acaricidal and repellent effects of DEET- and IR3535-impregnated bed nets using a novel long-lasting polymer-coating technique.

PubMed

Faulde, Michael K; Albiez, Gunther; Nehring, Oliver

2010-03-01

A novel long-lasting repellent-treated net (LLRTN) has been designed by binding the skin repellents N,N-diethyl-m-toluamide (DEET), or IR3535, onto the fibres of bed net fabric using a new polymer-coating technique. The repellent toxicological effectiveness and residual activity of a factory-based repellent-impregnated fabric has been evaluated by laboratory testing against adult Aedes aegypti mosquitoes and nymphal Ixodes ricinus ticks. By using this repellent-embedding impregnation technique, concentrations exceeding 10 g/m(2) could be achieved with one single polymer layer. Both DEET- and IR3535-impregnated fabrics revealed a dose-dependent insecticidal as well as acaricidal activity. One hundred percent knockdown times of DEET-treated bed nets ranged from 187.5 +/- 31.8 to 27.5 +/- 3.5 min against A. aegypti, and between 214 +/- 47 and 22.6 +/- 5 min against nymphal I. ricinus, linked to a DEET concentration of 1.08 and 10.58 g/m(2), respectively. With IR3535, A. aegypti produced dose-dependent 100% knockdown times varying from 87.5 +/- 10.6 to 57.5 +/- 3.5 min and between 131.4 +/- 6.5 and 33.8 +/- 5 min against nymphal I. ricinus, respectively, linked to concentrations between 1.59 and 10.02 g/m(2). One hundred percent repellency measured by complete landing and biting protection of impregnated fabric by using the arm-in-cage test could be achieved at DEET concentrations exceeding 3.7 to 3.9 g/m(2), and for IR3535 concentrations over 10 g/m(2). One hundred percent landing and biting protection could be preserved with DEET-treated fabrics for 29 weeks at an initial concentration of 4.66 g/m(2), 54 weeks at 8.8 g/m(2), 58 weeks at 9.96 g/m(2) and 61 weeks at 10.48 g/m(2) for DEET, and 23 weeks for IR3535-treated fabric at a concentration of 10.02 g/m(2). Unlike repellent-treated fabric, a brand of a commercially available long-lasting insecticide-treated net tested containing 500 mg permethrin/m(2) did not protect from mosquito bites. First results on

Impact of Cotrimoxazole and Insecticide-Treated Nets for Malaria Prevention on Key Outcomes Among HIV-Infected Adults in Low- and Middle-Income Countries: A Systematic Review

PubMed Central

Hassani, Ahmed Saadani; Marston, Barbara J.

2016-01-01

Background HIV-infected adults are at increased risk of severe malaria and death. Malaria prevention in people living with HIV (PLHIV) consists of several interventions, including cotrimoxazole (CTX) prophylaxis and insecticide-treated nets (ITNs). We conducted a systematic review of the available evidence. Methods MEDLINE, EmBase, Global Health, CINAHL, SOCA, and African Index Medicus were used to identify articles relevant to the CTX prophylaxis and ITNs interventions from 1995 to July 2014. For each individual study, we assessed the quality of evidence and the impact of the 2 interventions on the outcomes of mortality, morbidity, retention in care, quality of life, and/or prevention of ongoing HIV transmission. For each outcome, we summarized the quality of the overall body of evidence, the expected impact, and costing and cost-effectiveness (CE). Findings The overall quality of evidence regarding malaria-related morbidity was rated as “good” for CTX prophylaxis and “fair” for ITN use; the expected “impact” of these interventions on morbidity was rated “high” and “uncertain,” respectively. Three studies that addressed the costing and CE of ITN provision for malaria prevention in PLHIV consisted of 2 full “level 1” and 1 partial “level 2” economic evaluations. Conclusions CTX prophylaxis is effective in reducing malaria-related morbidity among PLHIV. Limited evidence is available with respect to the impact and the CE of ITN use and/or provision in this population. PMID:25768870

Impact of a behaviour change intervention on long-lasting insecticidal net care and repair behaviour and net condition in Nasarawa State, Nigeria.

PubMed

Koenker, Hannah; Kilian, Albert; Hunter, Gabrielle; Acosta, Angela; Scandurra, Leah; Fagbemi, Babafunke; Onyefunafoa, Emmanuel O; Fotheringham, Megan; Lynch, Matthew

2015-01-21

While some data on net durability have been accumulating in recent years, including formative qualitative research on attitudes towards net care and repair, no data are available on how the durability of a net is influenced by behaviour of net maintenance, care and repair, and whether behavioural change interventions (BCC) could substantially impact on the average useful life of the net. The study used an intervention-control design with before-after assessment through repeated cross-sectional household surveys with two-stage cluster sampling following Nasarawa State's December 2010 mass campaign. All campaign nets were 100-denier polyester, long-lasting insecticidal nets (LLIN). Baseline, midline, and endline surveys occurred at one-year intervals, in March 2012, March 2013, and April 2014, respectively. Outcome measures were the proportion of confirmed campaign nets with observed repairs, and the proportion in serviceable condition, measured with proportionate hole index (pHI) and according to WHO guidelines. For all respondents, exposure to BCC messages was strongly correlated with increased positive attitude towards care and repair, and increases in attitude were positively correlated with observed net repairs, and with the proportion of nets in serviceable condition. In a multivariate regression model, positive care and repair attitude (OR 6.17 p = 0.001) and level of exposure (1 source: OR 4.00 p = 0.000; 3 sources: OR 9.34 p = 0.000) remained the most significant predictors of net condition, controlling for background and environmental factors. Nets that were tied up had 2.70 higher odds of being in serviceable condition (p = 0.001), while repairs made to nets were not sufficient to improve their pHI category. Estimated median net lifespan was approximately one full year longer for nets in households with a positive compared to a negative attitude. Exposure to multiple channels of a comprehensive BCC intervention was associated with improved

Effectiveness and Cost of Insecticide-Treated Bed Nets and Indoor Residual Spraying for the Control of Cutaneous Leishmaniasis: A Cluster-Randomized Control Trial in Morocco

PubMed Central

Faraj, Chafika; Yukich, Joshua; Adlaoui, El Bachir; Wahabi, Rachid; Mnzava, Abraham Peter; Kaddaf, Mustapha; El Idrissi, Abderrahmane Laamrani; Ameur, Btissam; Kleinschmidt, Immo

2016-01-01

Cutaneous leishmaniasis (CL) remains an important public health problem in Morocco. A cluster-randomized trial was conducted with the following three study arms: 1) long-lasting insecticide-treated nets (LLINs) plus standard of care environmental management (SoC-EM), 2) indoor residual spraying (IRS) with α-cypermethrin plus SoC-EM, and 3) SoC-EM alone. Incidence of new CL cases by passive and active case detection, sandfly abundance, and cost and cost-effectiveness was compared between study arms over 5 years. Incidence of CL and sandfly abundance were significantly lower in the IRS arm compared with SoC-EM (CL incidence rate ratio = 0.32, 95% confidence interval [CI] = 0.15–0.69, P = 0.005 and sandfly abundance ratio = 0.39, 95% CI = 0.18–0.85, P = 0.022). Reductions in the LLIN arm of the study were not significant, possibly due to poor compliance. IRS was effective and more cost-effective for the prevention of CL in Morocco. PMID:26811431

Evaluation of Polyethylene-Based Long Lasting Treated Bed Net Netprotect on Anopheles Mosquitoes, Malaria Incidence, and Net Longivity in Western Kenya

PubMed Central

Odhiambo, M. T. O.; Skovmand, O.; Vulule, J. M.; Kokwaro, E. D.

2013-01-01

We studied the effect on malaria incidence, mosquito abundance, net efficacy, net use rate, chemical analysis, and holes of a long lasting insecticide treated bed net (Netprotect) in western Kenya, 2007–2010. Nets were hung in 150 households 6 months before they were hung in a second, 2 km away. Indoor resting densities were monitored by pyrethrum spray catch and malaria cases by passive detection using clinical manifestations and rapid diagnostic test. The probability of finding An. arabiensis in the control area was 2.6 times higher than that in intervention area during the first 6 months. Human blood feeding index of Anopheles funestus declined 17%. After bed nets were hung in the second area, malaria incidence declined 25% down to the level in the first area. Incidence remained at this low level for 2 years. 90% of collected nets were efficacious after 3-year use. Deltamethrin dosage declined from 1.9 to 0.5 g/kg over 3 years. Attrition rate after 3 years was 21%. WHO hole index changed from 333 to 114 to 381 over the three years. This index summarizes the numbers of holes in size categories and multiplies with the mean hole area per category. It is very sensitive to the impact of big holes in a few nets. PMID:24194770

Evaluation of the efficacy of DDT indoor residual spraying and long-lasting insecticidal nets against insecticide resistant populations of Anopheles arabiensis Patton (Diptera: Culicidae) from Ethiopia using experimental huts

PubMed Central

2014-01-01

Background Indoor Residual Spraying (IRS) and Long-Lasting Insecticidal nets (LLINs) are major malaria vector control tools in Ethiopia. However, recent reports from different parts of the country showed that populations of Anopheles arabiensis, the principal malaria vector, have developed resistance to most families of insecticides recommended for public health use which may compromise the efficacy of both of these key vector control interventions. Thus, this study evaluated the efficacy of DDT IRS and LLINs against resistant populations of An. arabiensis using experimental huts in Asendabo area, southwestern Ethiopia. Methods The susceptibility status of populations of An. arabiensis was assessed using WHO test kits to DDT, deltamethrin, malathion, lambda-cyhalothrin, fenitrothion and bendiocarb. The efficacy of LLIN (PermaNet® 2.0), was evaluated using the WHO cone bioassay. Moreover, the effect of the observed resistance against malaria vector control interventions (DDT IRS and LLINs) were assessed using experimental huts. Results The findings of this study revealed that populations of An. arabiensis were resistant to DDT, deltamethrin, lambda-cyhalothrin and malathion with mortality rates of 1.3%, 18.8%, 36.3% and 72.5%, respectively but susceptible to fenitrothion and bendiocarb with mortality rates of 98.81% and 97.5%, respectively. The bio-efficacy test of LLIN (PermaNet® 2.0) against An. arabiensis revealed that the mosquito population showed moderate knockdown (64%) and mortality (78%). Moreover, mosquito mortalities in DDT sprayed huts and in huts with LLINs were not significantly different (p > 0.05) from their respective controls. Conclusion The evaluation of the efficacy of DDT IRS and LLINs using experimental huts showed that both vector control tools had only low to moderate efficacy against An. arabiensis populations from Ethiopia. Despite DDT being replaced by carbamates for IRS, the low efficacy of LLINs against the resistant population of An

Evaluation of new tools for malaria vector control in Cameroon: focus on long lasting insecticidal nets.

PubMed

Etang, Josiane; Nwane, Philippe; Piameu, Michael; Manga, Blaise; Souop, Daniel; Awono-Ambene, Parfait

2013-01-01

From 2006 to 2011, biological activity of insecticides for Indoor Residual Spraying (IRS), conventional treatment of nets (CTNs) or long lasting insecticidal nets (LLINs) was evaluated before their approval in Cameroon. The objective of the study was to select the best tools for universal malaria vector control coverage. Bioassays were performed using WHO cones and the Kisumu susceptible strain of Anopheles gambiae s.s.. Among tested products, residual activity and wash resistance of Alpha-cypermethrin LLINs (Interceptor) and CTNs (Fendona) were assessed during 5 months in the Ntougou neighborhood. All the 14 tested products were found effective (95-100% knockdown and mortality rates), although a significant decrease of efficacy was seen with lambda-cyhalothrinWP IRS, alpha-cypermethrin CTNs and LLINs (p< 0.05). However, the efficacy of Interceptor nets did not decrease during the 5 months evaluation, even after 25 washes (0.07nets displayed a drastic decrease of activity after 5 washes, odds ratio was 3.07 (1.0-8.59). This study provided useful data for decision making and community education toward universal coverage of malaria vector control in Cameroon.

Possession and Usage of Insecticidal Bed Nets among the People of Uganda: Is BRAC Uganda Health Programme Pursuing a Pro-Poor Path?

PubMed Central

Ahmed, Syed Masud; Zerihun, Abebual

2010-01-01

Background The use of insecticidal bed nets is found to be an effective public health tool for control of malaria, especially for under-five children and pregnant women. BRAC, an indigenous Bangladeshi non-governmental development organization, started working in the East African state of Uganda in June 2006. As part of its efforts to improve the health and well-being of its participants, BRAC Uganda has been distributing long lasting insecticide-treated bed nets (LLIN) at a subsidized price through health volunteers since February 2008. This study was conducted in March-April 2009 to examine how equitable the programme had been in consistence with BRAC Uganda's pro-poor policy. Methodology/Principal Findings Information on possession of LLINs and relevant knowledge on its proper use and maintenance was collected from households either with an under-five child and/or a pregnant woman. The sample included three villages from each of the 10 branch offices where BRAC Uganda's community-based health programme was operating. Data were collected by trained enumerators through face-to-face interviews using a hand-held personal digital assistant (PDA). Findings reveal that the study population had superficial knowledge on malaria and its transmission, including the use and maintenance of LLINs. The households' rate of possession of bed nets (41–59%), and the proportion of under-five children (17–19%) and pregnant women (25–27%) who reported sleeping under an LLIN were not encouraging. Inequity was observed in the number of LLINs possessed by the households, in the knowledge on its use and maintenance, and between the two programme areas. Conclusions/Significance The BRAC Uganda's LLINs distribution at a subsidized price appeared to be inadequate and inequitable, and BRAC's knowledge dissemination is insufficient for initiating preventive actions such as proper use of LLINs to interrupt malaria transmission. Findings contribute to the on-going debate on LLINs

Prevention of malaria in Afghanistan through social marketing of insecticide-treated nets: evaluation of coverage and effectiveness by cross-sectional surveys and passive surveillance.

PubMed

Rowland, Mark; Webster, Jayne; Saleh, Padshah; Chandramohan, Daniel; Freeman, Tim; Pearcy, Barbara; Durrani, Naeem; Rab, Abdur; Mohammed, Nasir

2002-10-01

Malaria is often a major health problem in countries undergoing war or conflict owing to breakdown of health systems, displacement of vulnerable populations, and the increased risk of epidemics. After 23 years of conflict, malaria has become prevalent in many rural areas of Afghanistan. From 1993 to the present, a network of non-governmental organizations, co-ordinated by HealthNet International, has operated a programme of bednet sales and re-treatment in lowland areas. To examine whether a strategy based on insecticide-treated nets (ITN) is a viable public health solution to malaria, communities were given the opportunity to buy nets and then monitored to determine population coverage and disease control impact. This was carried out using two contrasting methods: cross-sectional surveys and passive surveillance from clinics using a case-control design. Nets were purchased by 59% of families. Cross-sectional surveys demonstrated a 59% reduction in the risk of Plasmodium falciparum infection among ITN users compared with non-users (OR 0.41; 95% CI 0.25-0.66). The passive surveillance method showed a comparable reduction in the risk of symptomatic P. falciparum malaria among ITN users (OR 0.31; 95% CI 0.21-0.47). The cross-sectional method showed a 50% reduction in risk of P. vivax infection in ITN users compared with non-users (OR 0.50; 95% CI 0.17-1.49) but this effect was not statistically significant. The passive surveillance method showed a 25% reduction in the risk of symptomatic P. vivax malaria (OR 0.75; 95% CI 0.66-0.85). ITN appeared to be less effective against P. vivax because of relapsing infections; hence an effect took more than one season to become apparent. Passive surveillance was cheaper to perform and gave results consistent with cross-sectional surveys. Untreated nets provided some protection. Data on socioeconomic status, a potential confounding factor, was not collected. However, at the time of net sales, there was no difference in malaria

Efficacy of permethrin treated long-lasting insecticidal nets on malaria transmission and observations on the perceived side effects, collateral benefits and human safety in a hyperendemic tribal area of Orissa, India.

PubMed

Sharma, Surya K; Tyagi, Prajesh K; Upadhyay, Ashok K; Haque, Mohammed A; Mohanty, Suman S; Raghavendra, Kamaraju; Dash, Aditya P

2009-11-01

Studies were conducted on the efficacy of Olyset nets-a long-lasting insecticidal net (LLIN) factory treated with 2% (w/w) permethrin on malaria transmission in an area under the influence of pyrethroid susceptible vector species Anopheles culicifacies and A. fluviatilis in Sundargarh District, Orissa, India. The study area comprised 22 villages that were randomized into three clusters and designated as Olyset net, untreated net, and no net area. Malaria incidence in the study population was measured through longitudinal active surveillance at fortnightly intervals. There was a reduction of 65-70% in malaria incidence in Olyset net area as compared to the control areas. The attack rate of Plasmodium falciparum or number of episodes per person per year in different age groups also showed significant reduction in Olyset net area as compared to untreated net and no net areas. Cross-sectional point prevalence surveys showed 45.7% reduction of malaria prevalence in Olyset net users, whereas there was an increase of 33.3% and 51% in untreated net and no net villages respectively. The compliance rate of Olyset net usage in the study population was 80-98% during different months, whereas it was between 70% and 90% for untreated nets. There were minimal complains of skin irritation (4%), itching (8%) and eye irritation (1.2%). However, these effects were only transitory in nature lasting for few hours of the first usage. Olyset nets also provided collateral benefits in terms of relief not only from mosquitoes and malaria but also from other household pests such as head lice, bed bugs, cockroaches, ants and houseflies. The Olyset nets were found to be safe to humans as no adverse event was recorded in the net users that can be attributed to the use of net. The study showed that Olyset nets are effective personal protection tool that can be used in a community based intervention programme.

Gender and willingness to pay for insecticides treated bed nets in a poor rural area in Tanzania.

PubMed

Mujinja, P G M; Makwaya, C K; Sauerborn, R

2004-12-01

To examine socio-economic and malaria related differences between males and females that may cause gender differences in willingness to pay (WTP) for insecticide treated bed nets in a poor rural area. A two-week-interval (test re-test) cross-sectional study. Kisarawe District in coastal Tanzania. Two hundred and fifty one males and two hundred dollars females were interviewed. Females had about 50% of the males' income. The monthly average income was about US dollars 10.50 for females and US dollars 20.20 for males. The proportion of respondents willing to pay for an ITN, for both males and females, declined as the ITN prices increased (P<0.05). The mean maximum WTP difference between men and women, between both rounds were not statistically significant (p>0.05). Male respondents reported a higher mean number of own underfives living in the household compared to women, the difference was not statistically significant (P>0.8). Willingness to pay for ITN was found to be independent of having an under five child with recent history of malaria. Among both males and females, there was an association between a recent experience with malaria episode and WTP, p=0.05 and p=0.02 respectively. Among females, the proportion of those willing to pay for another person, at the lowest ITN price, was significantly higher in those with under five children in their households than in those with no underfives. This was not the case among the male respondents as the association was not statistically significant. Contrary to expectations were was no statistically significant difference in WTP for an ITN between females and males. Further studies that link willingness and ability to pay are required in rural poor population, such studies may be valuable inputs to government policy on and planning of ITN interventions in the public and private sector.

The impact of pyrethroid resistance on the efficacy of insecticide-treated bed nets against African anopheline mosquitoes: systematic review and meta-analysis.

PubMed

Strode, Clare; Donegan, Sarah; Garner, Paul; Enayati, Ahmad Ali; Hemingway, Janet

2014-03-01

Pyrethroid insecticide-treated bed nets (ITNs) help contribute to reducing malaria deaths in Africa, but their efficacy is threatened by insecticide resistance in some malaria mosquito vectors. We therefore assessed the evidence that resistance is attenuating the effect of ITNs on entomological outcomes. We included laboratory and field studies of African malaria vectors that measured resistance at the time of the study and used World Health Organization-recommended impregnation regimens. We reported mosquito mortality, blood feeding, induced exophily (premature exit of mosquitoes from the hut), deterrence, time to 50% or 95% knock-down, and percentage knock-down at 60 min. Publications were searched from 1 January 1980 to 31 December 2013 using MEDLINE, Cochrane Central Register of Controlled Trials, Science Citation Index Expanded, Social Sciences Citation Index, African Index Medicus, and CAB Abstracts. We stratified studies into three levels of insecticide resistance, and ITNs were compared with untreated bed nets (UTNs) using the risk difference (RD). Heterogeneity was explored visually and statistically. Included were 36 laboratory and 24 field studies, reported in 25 records. Studies tested and reported resistance inconsistently. Based on the meta-analytic results, the difference in mosquito mortality risk for ITNs compared to UTNs was lower in higher resistance categories. However, mortality risk was significantly higher for ITNs compared to UTNs regardless of resistance. For cone tests: low resistance, risk difference (RD) 0.86 (95% CI 0.72 to 1.01); moderate resistance, RD 0.71 (95% CI 0.53 to 0.88); high resistance, RD 0.56 (95% CI 0.17 to 0.95). For tunnel tests: low resistance, RD 0.74 (95% CI 0.61 to 0.87); moderate resistance, RD 0.50 (95% CI 0.40 to 0.60); high resistance, RD 0.39 (95% CI 0.24 to 0.54). For hut studies: low resistance, RD 0.56 (95% CI 0.43 to 0.68); moderate resistance, RD 0.39 (95% CI 0.16 to 0.61); high resistance, RD 0.35 (95% CI

An exploratory study of treated-bed nets in Timor-Leste: patterns of intended and alternative usage

PubMed Central

2011-01-01

Background The Timor-Leste Ministry of Health has recently finalized the National Malaria Control Strategy for 2010-2020. A key component of this roadmap is to provide universal national coverage with long-lasting insecticide-treated nets (LLINs) in support of achieving the primary goal of reducing both morbidity and mortality from malaria by 30% in the first three years, followed by a further reduction of 20% by end of the programme cycle in 2020 [1]. The strategic plan calls for this target to be supported by a comprehensive information, education and communication (IEC) programme; however, there is limited prior research into household and personal usage patterns to assist in the creation of targeted, effective, and socio-culturally specific behaviour change materials. Methods Nine separate focus group discussions (FGDs) were carried out in Dili, Manatuto, and Covalima districts, Democratic Republic of Timor-Leste, in July 2010. These focus groups primarily explored themes of perceived malaria risk, causes of malaria, net usage patterns within families, barriers to correct and consistent usage, and the daily experience of users (both male and female) in households with at least one net. Comprehensive qualitative analysis utilized open source analysis software. Results The primary determinants of net usage were a widespread perception that nets could or should only be used by pregnant women and young children, and the availability of sufficient sleeping space under a limited number of nets within households. Both nuisance biting and disease prevention were commonly cited as primary motivations for usage, while seasonality was not a significant factor. Long-term net durability and ease of hanging were seen as key attributes in net design preference. Very frequent washing cycles were common, potentially degrading net effectiveness. Finally, extensive re-purposing of nets (fishing, protecting crops) was both reported and observed, and may significantly decrease

Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases.

PubMed

Messenger, Louisa A; Rowland, Mark

2017-05-22

While long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control throughout sub-Saharan Africa, there is an urgent need for the development of novel insecticide delivery mechanisms to sustain and consolidate gains in disease reduction and to transition towards malaria elimination and eradication. Insecticide-treated durable wall lining (ITWL) may represent a new paradigm for malaria control as a potential complementary or alternate longer-lasting intervention to IRS. ITWL can be attached to inner house walls, remain efficacious over multiple years and overcome some of the operational constraints of first-line control strategies, specifically nightly behavioural compliance required of LLINs and re-current costs and user fatigue associated with IRS campaigns. Initial experimental hut trials of insecticide-treated plastic sheeting reported promising results, achieving high levels of vector mortality, deterrence and blood-feeding inhibition, particularly when combined with LLINs. Two generations of commercial ITWL have been manufactured to date containing either pyrethroid or non-pyrethroid formulations. While some Phase III trials of these products have demonstrated reductions in malaria incidence, further large-scale evidence is still required before operational implementation of ITWL can be considered either in a programmatic or more targeted community context. Qualitative studies of ITWL have identified aesthetic value and observable entomological efficacy as key determinants of household acceptability. However, concerns have been raised regarding installation feasibility and anticipated cost-effectiveness. This paper critically reviews ITWL as both a putative mechanism of house improvement or more conventional intervention and discusses its future prospects as a method for controlling malaria and other vector-borne diseases.

Multi-country comparison of delivery strategies for mass campaigns to achieve universal coverage with insecticide-treated nets: what works best?

PubMed

Zegers de Beyl, Celine; Koenker, Hannah; Acosta, Angela; Onyefunafoa, Emmanuel Obi; Adegbe, Emmanuel; McCartney-Melstad, Anna; Selby, Richmond Ato; Kilian, Albert

2016-02-03

The use of insecticide-treated nets (ITNs) is widely recognized as one of the main interventions to prevent malaria. High ITN coverage is needed to reduce transmission. Mass distribution campaigns are the fastest way to rapidly scale up ITN coverage. However, the best strategy to distribute ITNs to ensure household coverage targets are met is still under debate. This paper presents results from 14 post-campaign surveys in five African countries to assess whether the campaign strategy used had any effect on distribution outcome. Data from 13,901 households and 14 campaigns from Ghana, Nigeria, Senegal, South Sudan and Uganda, were obtained through representative cross-sectional questionnaire surveys, conducted three to 16 months after ITN distribution. All evaluations used a multi-stage sampling approach and similar methods for data collection. Key outcomes examined were the proportion of households having received a net from the campaign and the proportion of households with one net for every two people. Household registration rates proved to be the most important determinant of a household receiving any net from the campaign (adjusted odds ratio [OR] 74.8; 95 % confidence interval [CI]: 55.3-101.1) or had enough ITNs for all household members (adjusted OR 19.1; 95 % CI: 55.34-101.05). Factors that positively influenced registration were larger household size (adjusted OR 1.7; 95 % CI: 1.5-2.1) and families with children under five (adjusted OR 1.4; 95 % CI: 1.2-1.6). Urban residence was negatively associated with receipt of a net from the campaign (adjusted OR 0.73; 95 % CI: 0.58-0.92). Registration was equitable in most campaigns except for Uganda and South Sudan, where the poorest wealth quintiles were less likely to have been reached. After adjusting for other factors, delivery strategy (house-to-house vs. fixed point) and distribution approach (integrated versus stand-alone) did not show a systematic impact on registration or owning any ITN. Campaigns that

Impact of Artemisinin-Based Combination Therapy and Insecticide-Treated Nets on Malaria Burden in Zanzibar

PubMed Central

Bhattarai, Achuyt; Ali, Abdullah S; Kachur, S. Patrick; Mårtensson, Andreas; Abbas, Ali K; Khatib, Rashid; Al-mafazy, Abdul-wahiyd; Ramsan, Mahdi; Rotllant, Guida; Gerstenmaier, Jan F; Molteni, Fabrizio; Abdulla, Salim; Montgomery, Scott M; Kaneko, Akira; Björkman, Anders

2007-01-01

Background The Roll Back Malaria strategy recommends a combination of interventions for malaria control. Zanzibar implemented artemisinin-based combination therapy (ACT) for uncomplicated malaria in late 2003 and long-lasting insecticidal nets (LLINs) from early 2006. ACT is provided free of charge to all malaria patients, while LLINs are distributed free to children under age 5 y (“under five”) and pregnant women. We investigated temporal trends in Plasmodium falciparum prevalence and malaria-related health parameters following the implementation of these two malaria control interventions in Zanzibar. Methods and Findings Cross-sectional clinical and parasitological surveys in children under the age of 14 y were conducted in North A District in May 2003, 2005, and 2006. Survey data were analyzed in a logistic regression model and adjusted for complex sampling design and potential confounders. Records from all 13 public health facilities in North A District were analyzed for malaria-related outpatient visits and admissions. Mortality and demographic data were obtained from District Commissioner's Office. P. falciparum prevalence decreased in children under five between 2003 and 2006; using 2003 as the reference year, odds ratios (ORs) and 95% confidence intervals (CIs) were, for 2005, 0.55 (0.28–1.08), and for 2006, 0.03 (0.00–0.27); p for trend < 0.001. Between 2002 and 2005 crude under-five, infant (under age 1 y), and child (aged 1–4 y) mortality decreased by 52%, 33%, and 71%, respectively. Similarly, malaria-related admissions, blood transfusions, and malaria-attributed mortality decreased significantly by 77%, 67% and 75%, respectively, between 2002 and 2005 in children under five. Climatic conditions favorable for malaria transmission persisted throughout the observational period. Conclusions Following deployment of ACT in Zanzibar 2003, malaria-associated morbidity and mortality decreased dramatically within two years. Additional distribution of

The effect of Insecticide Treated Nets (ITNs) on Plasmodium falciparum infection in rural and semi-urban communities in the south west region of Cameroon.

PubMed

Apinjoh, Tobias O; Anchang-Kimbi, Judith K; Mugri, Regina N; Tangoh, Delphine A; Nyingchu, Robert V; Chi, Hanesh F; Tata, Rolland B; Njumkeng, Charles; Njua-Yafi, Clarisse; Achidi, Eric A

2015-01-01

Insecticide Treated Nets (ITNs) have been shown to reduce morbidity and mortality, but coverage and proper utilization continues to be moderate in many parts of sub-Saharan Africa. The gains made through a nationwide free distribution were explored as well as the effect on malaria prevalence in semi-urban and rural communities in south western Cameroon. A cross sectional survey was conducted between August and December 2013. Information on net possession, status and use were collected using a structured questionnaire while malaria parasitaemia was determined on Giemsa-stained blood smears by light microscopy. ITN ownership increased from 41.9% to 68.1% following the free distribution campaign, with 58.3% (466/799) reportedly sleeping under the net. ITN ownership was lower in rural settings (adjusted OR = 1.93, 95%CI = 1.36-2.74, p<0.001) and at lower altitude (adjusted OR = 1.79, 95%CI = 1.22-2.62, p = 0.003) compared to semi-urban settings and intermediate altitude respectively. Conversely, ITN usage was higher in semi-urban settings (p = 0.002) and at intermediate altitude (p = 0.002) compared with rural localities and low altitude. Malaria parasitaemia prevalence was higher in rural (adjusted OR = 1.63, 95%CI = 1.07-2.49) compared to semi-urban settings and in those below 15 years compared to those 15 years and above. Overall, participants who did not sleep under ITN were more susceptible to malaria parasitaemia (adjusted OR = 1.70, 95%CI = 1.14-2.54, p = 0.009). Despite the free distribution campaign, ITN ownership and usage, though improved, is still low. As children who reside in rural settings have greater disease burden (parasitemia) than children in semi-urban settings, the potential gains on both reducing inequities in ITN possession as well as disease burden might be substantial if equitable distribution strategies are adopted.

Design, implementation and evaluation of a national campaign to deliver 18 million free long-lasting insecticidal nets to uncovered sleeping spaces in Tanzania

PubMed Central

2013-01-01

Background Since 2004, the Tanzanian National Voucher Scheme has increased availability and accessibility of insecticide-treated nets (ITNs) to pregnant women and infants by subsidizing the cost of nets purchased. From 2008 to 2010, a mass distribution campaign delivered nine million long-lasting insecticidal nets (LLINs) free-of-charge to children under-five years of age in Tanzania mainland. In 2010 and 2011, a Universal Coverage Campaign (UCC) led by the Ministry of Health and Social Welfare (MoHSW) was implemented to cover all sleeping spaces not yet reached through previous initiatives. Methods The UCC was coordinated through a unit within the National Malaria Control Programme. Partners were contracted by the MoHSW to implement different activities in collaboration with local government authorities. Volunteers registered the number of uncovered sleeping spaces in every household in the country. On this basis, LLINs were ordered and delivered to village level, where they were issued over a three-day period in each zone (three regions). Household surveys were conducted in seven districts immediately after the campaign to assess net ownership and use. Results The UCC was chiefly financed by the Global Fund to Fight AIDS, Tuberculosis and Malaria with important contributions from the US President’s Malaria Initiative. A total of 18.2 million LLINs were delivered at an average cost of USD 5.30 per LLIN. Overall, 83% of the expenses were used for LLIN procurement and delivery and 17% for campaign associated activities. Preliminary results of the latest Tanzania HIV Malaria Indicator Survey (2011–12) show that household ownership of at least one ITN increased to 91.5%. ITN use, among children under-five years of age, improved to 72.7% after the campaign. ITN ownership and use data post-campaign indicated high equity across wealth quintiles. Conclusion Close collaboration among the MoHSW, donors, contracted partners, local government authorities and volunteers

Targeted subsidy for malaria control with treated nets using a discount voucher system in Tanzania.

PubMed

Mushi, Adiel K; Schellenberg, Joanna R M Armstrong; Mponda, Haji; Lengeler, Christian

2003-06-01

During the last decade insecticide-treated nets have become a key strategy for malaria control. Social marketing is an appealing tool for getting such nets to poor rural African communities who are most afflicted by malaria. This approach usually involves subsidized prices to make nets and insecticide more affordable and help establish a commercial market. We evaluated a voucher system for targeted subsidy of treated nets in young children and pregnant women in two rural districts of southern Tanzania. Qualitative work involved focus group discussions with community leaders, male and female parents of children under 5 years. In-depth interviews were held with maternal and child health clinic staff and retail agents. Quantitative data were collected through interviewing more than 750 mothers of children under 5 years during a cluster sample survey of child health. The voucher return rate was extremely high at 97% (7720/8000). However, 2 years after the start of the scheme awareness among target groups was only 43% (45/104), and only 12% of women (12/103; 95% CI 4-48%) had used a voucher towards the cost of a net. We found some evidence of increased voucher use among least poor households, compared with the poorest households. On the basis of these results we renewed our information, education and communication (IEC) campaign about vouchers. Discount vouchers are a feasible system for targeted subsidies, although a substantial amount of time and effort may be needed to achieve high awareness and uptake - by which we mean the proportion of eligible women who used the vouchers - among those targeted. Within a poor society, vouchers may not necessarily increase health equity unless they cover a high proportion of the total cost: since some cash is needed when using a voucher as part-payment, poorer women among the target group are likely to have lower uptake than richer women. The vouchers have two important additional functions: strengthening the role of public health

Socio-economic inequity in demand for insecticide-treated nets, in-door residual house spraying, larviciding and fogging in Sudan.

PubMed

Onwujekwe, Obinna; Malik, El-Fatih Mohamed; Mustafa, Sara Hassan; Mnzava, Abraham

2005-12-15

In order to optimally prioritize and use public and private budgets for equitable malaria vector control, there is a need to determine the level and determinants of consumer demand for different vector control tools. To determine the demand from people of different socio-economic groups for indoor residual house-spraying (IRHS), insecticide-treated nets (ITNs), larviciding with chemicals (LWC), and space spraying/fogging (SS) and the disease control implications of the result. Ratings and levels of willingness-to-pay (WTP) for the vector control tools were determined using a random cross-sectional sample of 720 householdes drawn from two states. WTP was elicited using the bidding game. An asset-based socio-economic status (SES) index was used to explore whether WTP was related to SES of the respondents. IRHS received the highest proportion of highest preferred rating (41.0%) followed by ITNs (23.1%). However, ITNs had the highest mean WTP followed by IRHS, while LWC had the least. The regression analysis showed that SES was positively and statistically significantly related to WTP across the four vector control tools and that the respondents' rating of IRHS and ITNs significantly explained their levels of WTP for the two tools. People were willing to pay for all the vector-control tools, but the demand for the vector control tools was related to the SES of the respondents. Hence, it is vital that there are public policies and financing mechanisms to ensure equitable provision and utilisation of vector control tools, as well as protecting the poor from cost-sharing arrangements.

Insecticide resistance status in Anopheles gambiae in southern Benin

PubMed Central

2010-01-01

Background The emergence of pyrethroid resistance in Anopheles gambiae has become a serious concern to the future success of malaria control. In Benin, the National Malaria Control Programme has recently planned to scaling up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) for malaria prevention. It is, therefore, crucial to monitor the level and type of insecticide resistance in An. gambiae, particularly in southern Benin where reduced efficacy of insecticide-treated nets (ITNs) and IRS has previously been reported. Methods The protocol was based on mosquito collection during both dry and rainy seasons across forty districts selected in southern Benin. Bioassay were performed on adults collected from the field to assess the susceptibility of malaria vectors to insecticide-impregnated papers (permethrin 0.75%, delthamethrin 0.05%, DDT 4%, and bendiocarb 0.1%) following WHOPES guidelines. The species within An. gambiae complex, molecular form and presence of kdr and ace-1 mutations were determined by PCR. Results Strong resistance to permethrin and DDT was found in An. gambiae populations from southern Benin, except in Aglangandan where mosquitoes were fully susceptible (mortality 100%) to all insecticides tested. PCR showed the presence of two sub-species of An. gambiae, namely An. gambiae s.s, and Anopheles melas, with a predominance for An. gambiae s.s (98%). The molecular M form of An. gambiae was predominant in southern Benin (97%). The kdr mutation was detected in all districts at various frequency (1% to 95%) whereas the Ace-1 mutation was found at a very low frequency (≤ 5%). Conclusion This study showed a widespread resistance to permethrin in An. gambiae populations from southern Benin, with a significant increase of kdr frequency compared to what was observed previously in Benin. The low frequency of Ace-1 recorded in all populations is encouraging for the use of bendiocarb as an alternative insecticide to pyrethroids for IRS

Malaria control under the Taliban regime: insecticide-treated net purchasing, coverage, and usage among men and women in eastern Afghanistan

PubMed Central

2010-01-01

Background Scaling up insecticide-treated mosquito net (ITN) coverage is a key malaria control strategy even in conflict-affected countries [1,2]. Socio-economic factors influence access to ITNs whether subsidized or provided free to users. This study examines reported ITN purchasing, coverage, and usage in eastern Afghanistan and explores women's access to health information during the Taliban regime (1996-2001). This strengthens the knowledge base on household-level health choices in complex-emergency settings. Methods Fifteen focus group discussions (FGDs) and thirty in-depth interviews were conducted with men and women from ITN-owning and non-owning households. FGDs included rank ordering, pile sorting and focused discussion of malaria knowledge and ITN purchasing. Interviews explored general health issues, prevention and treatment practices, and women's malaria knowledge and concerns. Seven key informant interviews with health-related workers and a concurrent survey of 200 ITN-owning and 214 non-owning households were used to clarify or quantify findings. Results Malaria knowledge was similar among men and women and ITN owners and non-owners. Women reported obtaining health information through a variety of sources including clinic staff, their husbands who had easier access to information, and particularly female peers. Most participants considered ITNs very desirable, though not usually household necessities. ITN owners reported more household assets than non-owners. Male ITN owners and non-owners ranked rugs and ITNs as most desired, while women ranked personal assets such as jewellery highest. While men were primarily responsible for household decision-making and purchasing, older women exerted considerable influence. Widow-led and landless households reported most difficulties purchasing ITNs. Most participants wanted to buy ITNs only if they could cover all household members. When not possible, preferential usage was given to women and children

Implementation of an insecticide-treated net subsidy scheme under a public-private partnership for malaria control in Tanzania--challenges in implementation.

PubMed

Njau, Ritha J A; de Savigny, Don; Gilson, Lucy; Mwageni, Eleuther; Mosha, Franklin W

2009-08-21

In the past decade there has been increasing visibility of malaria control efforts at the national and international levels. The factors that have enhanced this scenario are the availability of proven interventions such as artemisinin-based combination therapy, the wide scale use of insecticide-treated nets (ITNs) and a renewed emphasis in indoor residual house-spraying. Concurrently, there has been a window of opportunity of financial commitments from organizations such as the Global Fund for HIV/AIDS, Tuberculosis and Malaria (GFATM), the President's Malaria Initiative and the World Bank Booster programme. The case study uses the health policy analysis framework to analyse the implementation of a public-private partnership approach embarked upon by the government of Tanzania in malaria control - 'The Tanzania National Voucher Scheme'- and in this synthesis, emphasis is on the challenges faced by the scheme during the pre-implementation (2001 - 2004) and implementation phases (2004 - 2005). Qualitative research tools used include: document review, interview with key informants, stakeholder's analysis, force-field analysis, time line of events, policy characteristic analysis and focus group discussions. The study is also complemented by a cross-sectional survey, which was conducted at the Rufiji Health Demographic Surveillance Site, where a cohort of women of child-bearing age were followed up regarding access and use of ITNs. The major challenges observed include: the re-introduction of taxes on mosquito nets and related products, procurement and tendering procedures in the implementation of the GFATM, and organizational arrangements and free delivery of mosquito nets through a Presidential initiative. The lessons gleaned from this synthesis include: (a) the consistency of the stakeholders with a common vision, was an important strength in overcoming obstacles, (b) senior politicians often steered the policy agenda when the policy in question was a 'crisis event

Efficacy of mosquito netting for sustainable small holders' cabbage production in Africa.

PubMed

Martin, T; Assogba-Komlan, F; Houndete, T; Hougard, J M; Chandre, F

2006-04-01

The efficacy of a mosquito netting to protect cabbages, Brassica oleracea L., against pests was investigated in field trials in Benin, West Africa. A polyester net covered the plants at night by using a wood armature. The net was removed during the day to prevent overheating and excessive shade, both problems of insect-proof screens used under tropical conditions. The number of all lepidopteran larvae with netting protection and foliar insecticide sprays was significantly lower than the unprotected control. The number of diamondback moth, Plutella xylostella (L.), was significantly lower with netting protection compared with foliar insecticide sprays and control. Netting treated with deltamethrin gave total protection of young plants against the aphid Lipaphis erysimi (Kaltenbach). At harvest, the number of marketable cabbages protected with untreated netting was significantly higher compared with the production with foliar insecticide sprays. The protection of cabbages with netting can be an economically viable method. Considering the price of cabbages on local markets (US dollars 1/unit), the net returns per 100 m2 were US dollars 247 by using netting, US dollars 149 by using insecticides, and US dollars 117 for controls. The net returns for using netting are based on replacing the netting each crop cycle. But netting can be reused several times, depending upon conditions, increasing the profit margin. The netting protection may be an alternative to the growing unsustainable practices of vegetable cropping in peri-urban areas of tropical countries.

First report of the infection of insecticide-resistant malaria vector mosquitoes with an entomopathogenic fungus under field conditions

PubMed Central

2011-01-01

Background Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control malaria vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecticide-resistant mosquitoes under laboratory conditions. The goal of this study was to see whether entomopathogenic fungi could be used to infect insecticide-resistant malaria vectors under field conditions, and to see whether the virulence and viability of the fungal conidia decreased after exposure to ambient African field conditions. Methods This study used the fungus Beauveria bassiana to infect the insecticide-resistant malaria vector Anopheles gambiae s.s (Diptera: Culicidae) VKPER laboratory colony strain. Fungal conidia were applied to polyester netting and kept under West African field conditions for varying periods of time. The virulence of the fungal-treated netting was tested 1, 3 and 5 days after net application by exposing An. gambiae s.s. VKPER mosquitoes in WHO cone bioassays carried out under field conditions. In addition, the viability of B. bassiana conidia was measured after up to 20 days exposure to field conditions. Results The results show that B. bassiana infection caused significantly increased mortality with the daily risk of dying being increased by 2.5× for the fungus-exposed mosquitoes compared to the control mosquitoes. However, the virulence of the B. bassiana conidia decreased with increasing time spent exposed to the field conditions, the older the treatment on the net, the lower the fungus-induced mortality rate. This is likely to be due to the climate because laboratory trials found no such decline within the same trial time period. Conidial viability also decreased with increasing exposure to the net and natural abiotic environmental conditions. After 20 days field exposure the conidial viability was 30%, but the viability of control

Impact of changing over of insecticide from synthetic pyrethroids to DDT for indoor residual spray in a malaria endemic area of Orissa, India

PubMed Central

Sharma, Surya K.; Upadhyay, Ashok K.; Haque, Mohammed A.; Tyagi, Prajesh K.; Kindo, Bikrant K.

2012-01-01

Background & objectives: Development of insecticide resistance in malaria vectors has been a major problem for achieving effective vector control. Due to limited availability of insecticides, the only option is management of resistance by judiciously using the insecticides and rotating them to maintain their effectiveness. This study was carried out in a malaria endemic area of Sundergarh district in Orissa where synthetic pyrethroids (SP) were in use for the last couple of years. The change-over from SP to DDT was done in one arm of study, and the other two arms remained on SP and insecticide-treated nets (ITN). Entomological and parasitological monitoring was done to assess the impact. Methods: The study design comprised of three arms (i) two rounds of indoor residual spraying (IRS) with DDT 1g/m2 as a change-over insecticide in areas previously under synthetic pyrethroids; (ii) two rounds of IRS with synthetic pyrethroid (alphacypermethrin, ACM) @ 25 mg/m2; and (iii) an unsprayed area under ITN/long lasting insecticide nets (LNs). Indoor residual spraying was undertaken under strict supervision to maintain quality and coverage. Contact bioassays were conducted to know the persistence of insecticide on sprayed surfaces and adult vector density was monitored in fixed and randomly selected houses. Malaria incidence was measured through fortnightly domiciliary surveillance under primary health care system in all the study villages. Results: The insecticide susceptibility tests showed that An.culicifacies was resistant to DDT but susceptible to malathion and ACM. However, An. fluviatilis was susceptible to all the three insecticides. ACM was effective in killing An. culicifacies on mud and wooden sprayed surfaces and maintained effective bioefficacy ranging from 92 to 100 per cent up to five months, whereas DDT failed to achieve effective mortality in An.culicifacies. However, there was significant decline in the density of An.culicifacies in ACM and DDT areas in

An elaborated feeding cycle model for reductions in vectorial capacity of night-biting mosquitoes by insecticide-treated nets.

PubMed

Le Menach, Arnaud; Takala, Shannon; McKenzie, F Ellis; Perisse, Andre; Harris, Anthony; Flahault, Antoine; Smith, David L

2007-01-25

Insecticide Treated Nets (ITNs) are an important tool for malaria control. ITNs are effective because they work on several parts of the mosquito feeding cycle, including both adult killing and repelling effects. Using an elaborated description of the classic feeding cycle model, simple formulas have been derived to describe how ITNs change mosquito behaviour and the intensity of malaria transmission, as summarized by vectorial capacity and EIR. The predicted changes are illustrated as a function of the frequency of ITN use for four different vector populations using parameter estimates from the literature. The model demonstrates that ITNs simultaneously reduce mosquitoes' lifespans, lengthen the feeding cycle, and by discouraging human biting divert more bites onto non-human hosts. ITNs can substantially reduce vectorial capacity through small changes to all of these quantities. The total reductions in vectorial capacity differ, moreover, depending on baseline behavior in the absence of ITNs. Reductions in lifespan and vectorial capacity are strongest for vector species with high baseline survival. Anthropophilic and zoophilic species are affected differently by ITNs; the feeding cycle is lengthened more for anthrophilic species, and the proportion of bites that are diverted onto non-human hosts is higher for zoophilic species. This model suggests that the efficacy of ITNs should be measured as a total reduction in transmission intensity, and that the quantitative effects will differ by species and by transmission intensity. At very high rates of ITN use, ITNs can generate large reductions in transmission intensity that could provide very large reductions in transmission intensity, and effective malaria control in some areas, especially when used in combination with other control measures. At high EIR, ITNs will probably not substantially reduce the parasite rate, but when transmission intensity is low, reductions in vectorial capacity combine with reductions in

Impact of insecticide-treated bed nets on malaria transmission indices on the south coast of Kenya

PubMed Central

2011-01-01

Background Besides significantly reducing malaria vector densities, prolonged usage of bed nets has been linked to decline of Anopheles gambiae s.s. relative to Anopheles arabiensis, changes in host feeding preference of malaria vectors, and behavioural shifts to exophagy (outdoor biting) for the two important malaria vectors in Africa, An. gambiae s.l. and Anopheles funestus. In southern coastal Kenya, bed net use was negligible in 1997-1998 when Anopheles funestus and An. gambiae s.s. were the primary malaria vectors, with An. arabiensis and Anopheles merus playing a secondary role. Since 2001, bed net use has increased progressively and reached high levels by 2009-2010 with corresponding decline in malaria transmission. Methods To evaluate the impact of the substantial increase in household bed net use within this area on vector density, vector composition, and human-vector contact, indoor and outdoor resting mosquitoes were collected in the same region during 2009-2010 using pyrethrum spray catches and clay pots for indoor and outdoor collections respectively. Information on bed net use per sleeping spaces and factors influencing mosquito density were determined in the same houses using Poisson regression analysis. Species distribution was determined, and number of mosquitoes per house, human-biting rates (HBR), and entomological inoculation rate (EIR) were compared to those reported for the same area during 1997-1998, when bed net coverage had been minimal. Results Compared to 1997-1998, a significant decline in the relative proportion of An. gambiae s.s. among collected mosquitoes was noted, coupled with a proportionate increase of An. arabiensis. Following > 5 years of 60-86% coverage with bed nets, the density, human biting rate and EIR of indoor resting mosquitoes were reduced by more than 92% for An. funestus and by 75% for An. gambiae s.l. In addition, the host feeding choice of both vectors shifted more toward non-human vertebrates. Besides bed net use

Efficacy, Safety and Cost of Insecticide Treated Wall Lining, Insecticide Treated Bed Nets and Indoor Wall Wash with Lime for Visceral Leishmaniasis Vector Control in the Indian Sub-continent: A Multi-country Cluster Randomized Controlled Trial

PubMed Central

Das, Pradeep; Ghosh, Debashis; Priyanka, Jyoti; Matlashewski, Greg; Kroeger, Axel; Upfill-Brown, Alexander

2016-01-01

Background We investigated the efficacy, safety and cost of lime wash of household walls plus treatment of sand fly breeding places with bleach (i.e. environmental management or EM), insecticide impregnated durable wall lining (DWL), and bed net impregnation with slow release insecticide (ITN) for sand fly control in the Indian sub-continent. Methods This multi-country cluster randomized controlled trial had 24 clusters in each three sites with eight clusters per high, medium or low sand fly density stratum. Every cluster included 45–50 households. Five households from each cluster were randomly selected for entomological measurements including sand fly density and mortality at one, three, nine and twelve months post intervention. Household interviews were conducted for socioeconomic information and intervention acceptability assessment. Cost for each intervention was calculated. There was a control group without intervention. Findings Sand fly mortality [mean and 95%CI] ranged from 84% (81%-87%) at one month to 74% (71%-78%) at 12 months for DWL, 75% (71%-79%) at one month to 49% (43%-55%) at twelve months for ITN, and 44% (34%-53%) at one month to 22% (14%-29%) at twelve months for EM. Adjusted intervention effect on sand fly density measured by incidence rate ratio ranged from 0.28 (0.23–0.34) at one month to 0.62 (0.51–0.75) at 12 months for DWL; 0.72 (0.62–0.85) at one month to 1.02 (0.86–1.22) at 12 months for ITN; and 0.89 (0.76–1.03) at one months to 1.49 (1.26–1.74) at 12 months for EM. Household acceptance of EM was 74% compared to 94% for both DWL and ITN. Operational cost per household in USD was about 5, 8, and 2 for EM, DWL and ITN, respectively. Minimal adverse reactions were reported for EM and ITN while 36% of households with DWL reported transient itching. Interpretation DWL is the most effective, durable and acceptable control method followed by ITN. The Visceral Leishmaniasis (VL) Elimination Program in the Indian sub

Effectiveness of post-campaign, door-to-door, hang-up, and communication interventions to increase long-lasting, insecticidal bed net utilization in Togo (2011–2012): a cluster randomized, control trial

PubMed Central

2014-01-01

Background It is well established that insecticide-treated bed nets (ITNs), in particular long-lasting, insecticidal nets (LLINs), can be used as one of the primary interventions for effective malaria control. A consistent gap between net ownership and use has been observed, indicating that factors exist that prevent an owned mosquito net from being used. One approach used in the context of LLIN campaigns is a post-distribution, door-to-door visit of households with educational messages and to physically assist with hang-up of nets. Methods A cluster randomized trial was conducted in the Plateaux Region of Togo to evaluate the effectiveness of different approaches to post-LLIN campaign home visits (number of visits and timing) by volunteers to enhance LLIN hang-up and utilization. Results It was found that, in general, households that received intervention visits, particularly the most recent intervention visit, had levels of use that were typically 5 to 10% higher than the control households, while access did not differ among control and intervention households. Eight months post-campaign, ITN use by all individuals, children under five years and women of reproductive age was 11.3 to 14.4 percentage points greater in the study arm that received all three intervention visits than in the control communities. In households that received one or two additional door-to-door visits, the majority of respondents indicated that the volunteer provided new information during the visit regarding the use and importance of ITNs despite having received previous multiple visits. Conclusions The impact of the interventions appears to have been primarily through the delivery and reinforcement of key behaviour-change communication (BCC) messages regarding the importance of using an ITN and its care. Regardless of whether the respondents in fact received new information or had forgotten earlier information, this suggests that regular visits from community agents are useful in

Clinical malaria among pregnant women on combined insecticide treated nets (ITNs) and intermittent preventive treatment (IPTp) with sulphadoxine-pyrimethamine in Yaounde, Cameroon

PubMed Central

2014-01-01

Background Malaria remains a burden for pregnant women and the under 5. Intermittent preventive treatment of pregnant women (IPTp) for malaria with sulfadoxine – pyrimethamine (SP) has since replaced prophylaxis and legislation has been reinforced in the area of insecticide treated mosquito nets (ITNs) in Cameroon. Clinical malaria despite all these measures remains a problem. We compared the socio-obstetrical characteristics of women who developed clinical malaria and those who did not though in the same regimen. Methods A 5 – year nested cohort study (2007 – 2011 inclusive) at the tertiary level hospitals in Yaounde. Pregnant women who willingly accepted to participate in the study were enrolled at booking and three doses of SP were administered between 18 – 20 weeks of gestation, between 26–28 weeks and between 32 – 34 weeks. Those who developed clinical malaria were considered as cases and were compared for socio – obstetrical characteristics with those who did not. Venous blood was drawn from the women in both arms for parasite density estimation and identification and all the clinical cases were treated conventionally. Results Each arm had 166 cases and many women who developed clinical malaria were between 15 and 19 years (OR 5.5, 95% CI 3.9 – 5.3, p < 0.001). They were of low gravidity (OR 6.5, 95% CI 3.8 – 11.3, p < 0.001) as well as low parity (OR 4.6, 95% CI 2.7 – 7.9, p < 0.001). The cases were single women (OR 4.58, 95% CI 2.54 – 8.26, p < 0.001) and had attained only primary level of education (OR 4.6, 95% CI 2.8 – 7.9, p < 0.001). Gestational ages were between 20 to 30 weeks during clinical malaria (OR 6.8, 95% CI 4.1 – 11.7, p < 0.001). The time between the first and second dose of SP was longer than ten weeks in the cases (OR 5.5, 95% CI 3.2 – 9.3, p < 0.001) and parasite density was higher also among the cases (OR 6.9, 95% CI 5.9 – 12.1, p < 0.001). Conclusion Long spacing between the

Assessing the ownership, usage and knowledge of Insecticide Treated Nets (ITNs) in Malaria Prevention in the Hohoe Municipality, Ghana

PubMed Central

Nyavor, Kunche Delali; Kweku, Margaret; Agbemafle, Isaac; Takramah, Wisdom; Norman, Ishmael; Tarkang, Elvis; Binka, Fred

2017-01-01

Introduction Malaria remains one of the top five killer diseases in sub-Saharan Africa (SSA) and its burden is skewed towards pregnant women and children under five. Insecticide Treated Bed-Net (ITN) usage is considered one of the most cost-effective, preventive interventions against malaria. This study sought to assess ownership, usage, effectiveness, knowledge, access and availability of ITNs among mothers with children under five in the Hohoe municipality. Methods In August 2010 a cross-sectional survey was carried out in 30 communities, selected using the WHO 30 cluster sampling technique. In the selected communities, mothers/caregivers with children under five years were selected using the snowball method. Data were collected through questionnaires and direct observation of ITN. Descriptive statistics was used to analyse the data collected. Results A total of 450 mothers/caregivers were interviewed and their mean age was 30 ± 7 years. ITN ownership was 81.3%, and usage was 66.4%. The majority (97.8%) of the mothers/caregivers said ITNs were effective for malaria prevention. Awareness about ITNs was high (98.7%) and the majority (52.9%) had heard about ITNs from Reproductive and Child Health (RCH) Clinic and antenatal care ANC clinic (33.6%). Over 60% of the ITNs were acquired through free distribution at RCH clinics, clinic and home distribution during mass immunization sessions. The majority of the mothers/caregivers (78.6%) knew the signs and symptoms of malaria, what causes malaria (82.2%) and who is most at risk (90%). Conclusion Behaviour change communication strategies on ITN use may need to be further targeted to ensure full use of available ITNs. PMID:29255537

Assessing the ownership, usage and knowledge of Insecticide Treated Nets (ITNs) in Malaria Prevention in the Hohoe Municipality, Ghana.

PubMed

Nyavor, Kunche Delali; Kweku, Margaret; Agbemafle, Isaac; Takramah, Wisdom; Norman, Ishmael; Tarkang, Elvis; Binka, Fred

2017-01-01

Malaria remains one of the top five killer diseases in sub-Saharan Africa (SSA) and its burden is skewed towards pregnant women and children under five. Insecticide Treated Bed-Net (ITN) usage is considered one of the most cost-effective, preventive interventions against malaria. This study sought to assess ownership, usage, effectiveness, knowledge, access and availability of ITNs among mothers with children under five in the Hohoe municipality. In August 2010 a cross-sectional survey was carried out in 30 communities, selected using the WHO 30 cluster sampling technique. In the selected communities, mothers/caregivers with children under five years were selected using the snowball method. Data were collected through questionnaires and direct observation of ITN. Descriptive statistics was used to analyse the data collected. A total of 450 mothers/caregivers were interviewed and their mean age was 30 ± 7 years. ITN ownership was 81.3%, and usage was 66.4%. The majority (97.8%) of the mothers/caregivers said ITNs were effective for malaria prevention. Awareness about ITNs was high (98.7%) and the majority (52.9%) had heard about ITNs from Reproductive and Child Health (RCH) Clinic and antenatal care ANC clinic (33.6%). Over 60% of the ITNs were acquired through free distribution at RCH clinics, clinic and home distribution during mass immunization sessions. The majority of the mothers/caregivers (78.6%) knew the signs and symptoms of malaria, what causes malaria (82.2%) and who is most at risk (90%). Behaviour change communication strategies on ITN use may need to be further targeted to ensure full use of available ITNs.

Bed net ownership in Kenya: the impact of 3.4 million free bed nets.

PubMed

Hightower, Allen; Kiptui, Rebecca; Manya, Ayub; Wolkon, Adam; Vanden Eng, Jodi Leigh; Hamel, Mary; Noor, Abdisalan; Sharif, Shahnaz K; Buluma, Robert; Vulule, John; Laserson, Kayla; Slutsker, Laurence; Akhwale, Willis

2010-06-24

In July and September 2006, 3.4 million long-lasting insecticide-treated bed nets (LLINs) were distributed free in a campaign targeting children 0-59 months old (CU5s) in the 46 districts with malaria in Kenya. A survey was conducted one month after the distribution to evaluate who received campaign LLINs, who owned insecticide-treated bed nets and other bed nets received through other channels, and how these nets were being used. The feasibility of a distribution strategy aimed at a high-risk target group to meet bed net ownership and usage targets is evaluated. A stratified, two-stage cluster survey sampled districts and enumeration areas with probability proportional to size. Handheld computers (PDAs) with attached global positioning systems (GPS) were used to develop the sampling frame, guide interviewers back to chosen households, and collect survey data. In targeted areas, 67.5% (95% CI: 64.6, 70.3%) of all households with CU5s received campaign LLINs. Including previously owned nets, 74.4% (95% CI: 71.8, 77.0%) of all households with CU5s had an ITN. Over half of CU5s (51.7%, 95% CI: 48.8, 54.7%) slept under an ITN during the previous evening. Nearly forty percent (39.1%) of all households received a campaign net, elevating overall household ownership of ITNs to 50.7% (95% CI: 48.4, 52.9%). The campaign was successful in reaching the target population, families with CU5s, the risk group most vulnerable to malaria. Targeted distribution strategies will help Kenya approach indicator targets, but will need to be combined with other strategies to achieve desired population coverage levels.

A Systematic Review of Health Economic Analyses of Housing Improvement Interventions and Insecticide-Treated Bednets in the Home

PubMed Central

Pega, Frank; Wilson, Nick

2016-01-01

Background Housing improvements have considerable potential for improving health. So does the provision of insecticide-treated bednets for malaria prevention. Therefore we aimed to conduct updated systematic reviews of health economic analyses in both these intervention domains. Methods and findings The search strategy included economic analyses of housing improvement interventions and use of insecticide-treated bednets for community-dwelling, healthy populations (published between 1 January 2000 and 15 April 2014). We searched the Cochrane Database of Systematic Reviews, MEDLINE, PubMed, EMBASE, and three health economics databases. Thirty-five economic analyses of seven types of intervention fulfilled the inclusion criteria. Most included studies adopted a health sector perspective and were cost-effectiveness analyses using decision analytic modeling or conducted alongside trials. The overall quality of the studies was generally likely to be adequate for informing policy-making (albeit with limitations in some areas). There was fairly consistent evidence for the cost-effectiveness/favorable cost-benefit of removing indoor lead to prevent lead poisoning and sequelae, and retrofitting insulation to prevent lung disease. But the value of assessing and improving home safety and providing smoke alarms to prevent injuries was more mixed and the economic evidence was inconclusive or insufficient for: home ventilation to prevent lung disease, installing heaters to prevent lung disease and regulating tap water temperatures to prevent scalding. Few studies (n = 4) considered health equity. The 12 studies of providing insecticide-treated bednets or hammocks to prevent malaria found these interventions to be moderately to highly cost-effective. Conclusions This systematic review provides updated evidence that several housing improvement interventions (such as removing indoor lead and retrofitting insulation) and also the provision of insecticide-treated bednets are cost

Caretakers' understanding of malaria, use of insecticide treated net and care seeking-behavior for febrile illness of their children in Ethiopia.

PubMed

Birhanu, Zewdie; Yihdego, Yemane Ye-Ebiyo; Yewhalaw, Delenasaw

2017-09-18

Local understandings of malaria and use of preventive measures-are critical factors in sustained control of malaria. This study assessed caretakers' knowledge on malaria, use of Long Lasting Insecticide Treated Nets (LLINs) and care-seeking behavior for their children's illness in different malaria transmission settings of Ethiopia. Data were collected from 709 caretakers of children of 2-9 years of age during in 2016. A standard questionnaire was used to assess caretakers' perceptions of malaria, use of LLIN and care seeking behavior for febrile illness of children aged 2-9 years. The caretakers recognized malaria mostly by chills (70.4%, 499/709), fever (45.7%, 324/709) and headache (39.8%, 282/709). Overall, only 66.4% (471) of the caretakers knew that mosquito bite caused malaria and that it was quite heterogeneous by localities (ranging from 26.1% to 89.4%) and altitude (p < 0.05). Majority, 72.2% (512), of the caretakers knew that sleeping under LLIN could prevent malaria. Overall knowledge on malaria (mean = 51.2%) was very low with significant variations by localities, altitude and levels of malaria transmission, being low in high altitude and low in transmission areas (p < 0.05). Four hundred ninety-one (69.3%, 491/709) of the children slept under LLIN in the previous night. Of malaria related knowledge items, only knowledge of LLIN was associated with net use; non-use of LLN was higher among caretakers who did not know the role of LLIN (AOR = 0.47, 95%CI: 0.28-0.77, p = 0.003). Of course, attributing causation of malaria to stagnant water discouraged use of net (p = 0.021). Of febrile children (n = 122), only 50 (41.0%) sought care with only 17 (34.0%) seeking the care promptly. There was no significant link between knowledge of malaria and care seeking behavior (p > 0.05). However, knowledge of malaria had some level of influence on treatment source preference where caretakers with greater knowledge preferred pharmacy as

Field efficacy of a new mosaic long-lasting mosquito net (PermaNet® 3.0) against pyrethroid-resistant malaria vectors: a multi centre study in Western and Central Africa

PubMed Central

2010-01-01

Background Due to the spread of pyrethroid-resistance in malaria vectors in Africa, new strategies and tools are urgently needed to better control malaria transmission. The aim of this study was to evaluate the performances of a new mosaic long-lasting insecticidal net (LLIN), i.e. PermaNet® 3.0, against wild pyrethroid-resistant Anopheles gambiae s.l. in West and Central Africa. Methods A multi centre experimental hut trial was conducted in Malanville (Benin), Vallée du Kou (Burkina Faso) and Pitoa (Cameroon) to investigate the exophily, blood feeding inhibition and mortality induced by PermaNet® 3.0 (i.e. a mosaic net containing piperonyl butoxide and deltamethrin on the roof) comparatively to the WHO recommended PermaNet® 2.0 (unwashed and washed 20-times) and a conventionally deltamethrin-treated net (CTN). Results The personal protection and insecticidal activity of PermaNet 3.0 and PermaNet® 2.0 were excellent (>80%) in the "pyrethroid-tolerant" area of Malanville. In the pyrethroid-resistance areas of Pitoa (metabolic resistance) and Vallée du Kou (presence of the L1014F kdr mutation), PermaNet® 3.0 showed equal or better performances than PermaNet® 2.0. It should be noted however that the deltamethrin content on PermaNet® 3.0 was up to twice higher than that of PermaNet® 2.0. Significant reduction of efficacy of both LLIN was noted after 20 washes although PermaNet® 3.0 still fulfilled the WHO requirement for LLIN. Conclusion The use of combination nets for malaria control offers promising prospects. However, further investigations are needed to demonstrate the benefits of using PermaNet® 3.0 for the control of pyrethroid resistant mosquito populations in Africa. PMID:20423479

Underpinning Sustainable Vector Control through Informed Insecticide Resistance Management

PubMed Central

Hemmings, Kay; Hughes, Angela J.; Chanda, Emmanuel; Musapa, Mulenga; Kamuliwo, Mulakwa; Phiri, Faustina N.; Muzia, Lucy; Chanda, Javan; Kandyata, Alister; Chirwa, Brian; Poer, Kathleen; Hemingway, Janet; Wondji, Charles S.; Ranson, Hilary; Coleman, Michael

2014-01-01

Background There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambia's programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions. Methodology/Principal Findings A country-wide survey on insecticide resistance in Zambian malaria vectors was performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids, DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s. Conclusions/Significance Currently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan. PMID:24932861

"Before we used to get sick all the time": perceptions of malaria and use of long-lasting insecticide-treated bed nets (LLINs) in a rural Kenyan community

PubMed Central

2010-01-01

Background Malaria is a leading global cause of preventable morbidity and mortality, especially in sub-Saharan Africa, despite recent advances in treatment and prevention technologies. Scale-up and wide distribution of long-lasting insecticide-treated nets (LLINs) could rapidly decrease malarial disease in endemic areas, if used properly and continuously. Studies have shown that effective use of LLINs depends, in part, upon understanding causal factors associated with malaria. This study examined malaria beliefs, attitudes, and practices toward LLINs assessed during a large-scale integrated prevention campaign (IPC) in rural Kenya. Methods Qualitative interviews were conducted with 34 IPC participants who received LLINs as part of a comprehensive prevention package of goods and services. One month after distribution, interviewers asked these individuals about their attitudes and beliefs regarding malaria, and about their use of LLINs. Results Virtually all participants noted that mosquitoes were involved in causing malaria, though a substantial proportion of participants (47 percent) also mentioned an incorrect cause in addition to mosquitoes. For example, participants commonly noted that the weather (rain, cold) or consumption of bad food and water caused malaria. Regardless, most participants used the LLINs they were given and most mentioned positive benefits from their use, namely reductions in malarial illness and in the costs associated with its diagnosis and treatment. Conclusions Attitudes toward LLINs were positive in this rural community in Western Kenya, and respondents noted benefits with LLIN use. With improved understanding and clarification of the direct (mosquitoes) and indirect (e.g., standing water) causes of malaria, it is likely that LLIN use can be sustained, offering effective household-level protection against malaria. PMID:21118550

Cost-effectiveness analysis of vaccinating children in Malawi with RTS,S vaccines in comparison with long-lasting insecticide-treated nets

PubMed Central

2014-01-01

Background New RTS,S malaria vaccines may soon be licensed, yet its cost-effectiveness is unknown. Before the widespread introduction of RTS,S vaccines, cost-effectiveness studies are needed to help inform governments in resource-poor settings about how best to prioritize between the new vaccine and existing malaria interventions. Methods A Markov model simulated malaria progression in a hypothetical Malawian birth cohort. Parameters were based on published data. Three strategies were compared: no intervention, vaccination at one year, and long-lasting, insecticide-treated nets (LLINs) at birth. Both health service and societal perspectives were explored. Health outcomes were measured in disability-adjusted life years (DALYs) averted and costed in 2012 US$. Incremental cost-effectiveness ratios (ICERs) were calculated and extensive sensitivity analyses were conducted. Three times GDP per capita ($1,095) per DALY averted was used for a cost-effectiveness threshold, whilst one times GDP ($365) was considered ‘very cost-effective’. Results From a societal perspective the vaccine strategy was dominant. It averted 0.11 more DALYs than LLINs and 0.372 more DALYs than the no intervention strategy per person, while costing $10.04 less than LLINs and $59.74 less than no intervention. From a health service perspective the vaccine’s ICER was $145.03 per DALY averted, and thus can be considered very cost-effective. The results were robust to changes in all variables except the vaccine and LLINs’ duration of efficacy. Vaccines remained cost-effective even at the lowest assumed efficacy levels of 49.6% (mild malaria) and 14.2% (severe malaria), and the highest price of $15. However, from a societal perspective, if the vaccine duration efficacy was set below 2.69 years or the LLIN duration of efficacy was greater than 4.24 years then LLINs became the more cost-effective strategy. Conclusion The results showed that vaccinating Malawian children with RTS,S vaccines was

"When I sleep under the net, nothing bothers me; I sleep well and I'm happy": Senegal's culture of net use and how inconveniences to net use do not translate to net abandonment.

PubMed

Berthe, Sara; Loll, Dana; Faye, Sylvain L; Wone, Issa; Koenker, Hannah; Arnold, Bethany; Weber, Rachel

2014-09-12

Despite recent advances in the fight against the disease, malaria remains a serious threat to the health and well-being of populations in endemic countries. The use of long-lasting insecticidal nets (LLIN) reduces contact between the vector and humans, thereby reducing transmission of the disease. LLINs have become an essential component of malaria control programmes worldwide. The Culture of Net Use study used qualitative and quantitative methods in a longitudinal and iterative design over two phases, in order to capture changes in net use over a year and a half period and covering both dry and rainy seasons. Data were collected from a total of 56 households in eight regions to understand variations due to geographical, cultural, and universal coverage differences. At the time of the data collection, the universal coverage campaign had been completed in six of the eight regions (Dakar and Thies excluded). Perceived barriers to use were primarily related to the characteristics of the net itself, include shape, insecticide, and a variety of minority responses, such as perceived lack of mosquito density and being unaccustomed to using nets. Insecticide-related complaints found that insecticide did not present a significant barrier to use, but was cited as a nuisance. Feelings of suffocation continued to be the most commonly cited nuisance. Respondents who favoured the use of insecticide on nets appeared to be more aware of the health and malaria prevention benefits of the insecticide than those who perceived it negatively. Despite prior evidence that barriers such as heat, shape, insecticide and perceived mosquito density contribute to non-use of LLINs in other countries, this study has shown that these factors are considered more as nuisances and that they do not consistently prevent the use of nets among respondents in Senegal. Of those who cited inconveniences with their nets, few were moved to stop using a net. Respondents from this study overcame these barriers

Costs and effects of two public sector delivery channels for long-lasting insecticidal nets in Uganda

PubMed Central

2010-01-01

Background In Uganda, long-lasting insecticidal nets (LLIN) have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC) services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda. Methods Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY). These effects were calculated for the total number of LLINs delivered and for those retained and used. Results After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja) and 99% (ANC Adjumani) were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja). Economic cost for ANC distribution were considerably higher (USD 2.27) compared to campaign costs (USD 1.23) in Adjumani. Conclusions Targeted campaigns and routine ANC services can both

Comparative cost analysis of insecticide-treated net delivery strategies: sales supported by social marketing and free distribution through antenatal care.

PubMed

De Allegri, Manuela; Marschall, Paul; Flessa, Steffen; Tiendrebéogo, Justin; Kouyaté, Bocar; Jahn, Albrecht; Müller, Olaf

2010-01-01

Insecticide-treated nets (ITNs) are effective in substantially reducing malaria transmission. Still, ITN coverage in sub-Saharan Africa (SSA) remains extremely low. Policy makers are concerned with identifying the most suitable delivery mechanism to achieve rapid yet sustainable increases in ITN coverage. Little is known, however, on the comparative costs of alternative ITN distribution strategies. This paper aimed to fill this gap in knowledge by developing such a comparative cost analysis, looking at the cost per ITN distributed for two alternative interventions: subsidized sales supported by social marketing and free distribution to pregnant women through antenatal care (ANC). The study was conducted in rural Burkina Faso, where the two interventions were carried out alongside one another in 2006/07. Cost information was collected prospectively to derive both a financial analysis adopting a provider's perspective and an economic analysis adopting a societal perspective. The average financial cost per ITN distributed was US$8.08 and US$7.21 for sales supported by social marketing and free distribution through ANC, respectively. The average economic cost per ITN distributed was US$4.81 for both interventions. Contrary to common belief, costs did not differ substantially between the two interventions. Due to the district's ability to rely fully on the use of existing resources, financial costs associated with free ITN distribution through ANC were in fact even lower than those associated with the social marketing campaign. This represents an encouraging finding for SSA governments and points to the possibility to invest in programmes to favour free ITN distribution through existing health facilities. Given restricted budgets, however, free distribution programmes are unlikely to be feasible.

Universal coverage with insecticide-treated nets - applying the revised indicators for ownership and use to the Nigeria 2010 malaria indicator survey data.

PubMed

Kilian, Albert; Koenker, Hannah; Baba, Ebenezer; Onyefunafoa, Emmanuel O; Selby, Richmond A; Lokko, Kojo; Lynch, Matthew

2013-09-10

Until recently only two indicators were used to evaluate malaria prevention with insecticide-treated nets (ITN): "proportion of households with any ITN" and "proportion of the population using an ITN last night". This study explores the potential of the expanded set of indicators recommended by the Roll Back Malaria Monitoring and Evaluation Reference Group (MERG) for comprehensive analysis of universal coverage with ITN by applying them to the Nigeria 2010 Malaria Indicator Survey data. The two additional indicators of "proportion of households with at least one ITN for every two people" and "proportion of population with access to an ITN within the household" were calculated as recommended by MERG. Based on the estimates for each of the four ITN indicators three gaps were calculated: i) households with no ITN, ii) households with any but not enough ITN, iii) population with access to ITN not using it. In addition, coverage with at least one ITN at community level was explored by applying Lot Quality Assurance Sampling (LQAS) decision rules to the cluster level of the data. All outcomes were analysed by household background characteristics and whether an ITN campaign had recently been done. While the proportion of households with any ITN was only 42% overall, it was 75% in areas with a recent mass campaign and in these areas 66% of communities had coverage of 80% or better. However, the campaigns left a considerable intra-household ownership gap with 66% of households with any ITN not having enough for every family member. In contrast, the analysis comparing actual against potential use showed that ITN utilization was good overall with only 19% of people with access not using the ITN, but with a significant difference between the North, where use was excellent (use gap 11%), and the South (use gap 36%) indicating the need for enhanced behaviour change communication. The expanded ITN indicators to assess universal coverage provide strong tools for a comprehensive

Who attends antenatal care and expanded programme on immunization services in Chad, Mali and Niger? the implications for insecticide-treated net delivery

PubMed Central

2011-01-01

Background Malaria remains one of the largest public health problems facing the developing world. Insecticide-treated nets (ITNs) are an effective intervention against malaria. ITN delivery through routine health services, such as antenatal care (ANC) and childhood vaccination (EPI), is a promising channel of delivery to reach individuals with the highest risk (pregnant women and children under five years old). Decisions on whether to deliver ITNs through both channels depends upon the reach of each of these systems, whether these are independent and the effectiveness and cost effectiveness of each. Predictors of women attending ANC and EPI separately have been studied, but the predictors of those who attend neither service have not been identified. Methods Data from Chad, Mali and Niger demographic and health surveys (DHS) were analyzed to determine risk factors for attending neither service. A conceptual framework for preventative health care-seeking behaviour was created to illustrate the hierarchical relationships between the potential risk factors. The independence of attending both ANC and EPI was investigated. A multivariate model of predictors for non-attendance was developed using logistic regression. Results ANC and EPI attendance were found to be strongly associated in all three countries. However, 47% of mothers in Chad, 12% in Mali and 36% in Niger did not attend either ANC or EPI. Region, mother's education and partner's education were predictors of non-attendance in all three countries. Wealth index, ethnicity, and occupation were associated with non-attendance in Mali and Niger. Other predictors included religion, healthcare autonomy, household size and number of children under five. Conclusions Attendance of ANC and EPI are not independent and therefore the majority of pregnant women in these countries will have the opportunity to receive ITNs through both services. Although attendance at ANC and EPI are not independent, delivery through both

Insecticide treated curtains and residual insecticide treatment to control Aedes aegypti: An acceptability study in Santiago de Cuba

PubMed Central

Van der Stuyft, Patrick; Toledo, María Eugenia; Ceballos, Enrique; Fabré, Francisco; Lefèvre, Pierre

2018-01-01

Background Within the context of a field trial conducted by the Cuban vector control program (AaCP), we assessed acceptability of insecticide-treated curtains (ITCs) and residual insecticide treatment (RIT) with deltamethrin by the community. We also assessed the potential influence of interviewees’ risk perceptions for getting dengue and disease severity. Methodology/principal findings We embedded a qualitative study using in-depth interviews in a cluster randomized trial (CRT) testing the effectiveness of ITCs and RIT in Santiago de Cuba. In-depth interviews (N = 38) were conducted four and twelve months after deployment of the tools with people who accepted the tools, who stopped using them and who did not accept the tools. Data analysis was deductive. Main reasons for accepting ITCs at the start of the trial were perceived efficacy and not being harmful to health. Constraints linked to manufacturer instructions were the main reason for not using ITCs. People stopped using the ITCs due to perceived allergy, toxicity and low efficacy. Few heads of households refused RIT despite the noting reasons for rejection, such as allergy, health hazard and toxicity. Positive opinions of the vector control program influenced acceptability of both tools. However, frequent insecticide fogging as part of routine AaCP vector control actions diminished perceived efficacy of both tools and, therefore, acceptability. Fifty percent of interviewees did feel at risk for getting dengue and considered dengue a severe disease. However, this did not appear to influence acceptability of ITCs or RIT. Conclusion/significance Acceptability of ITCs and RIT was linked to acceptability of AaCP routine vector control activities. However, uptake and use were not always an indication of acceptability. Factors leading to acceptability may be best identified using qualitative methods, but more research is needed on the concept of acceptability and its measurement. PMID:29293501

Wash-resistance of pirimiphos-methyl insecticide treatments of window screens and eave baffles for killing indoor-feeding malaria vector mosquitoes: an experimental hut trial, South East of Zambia.

PubMed

Chinula, Dingani; Sikaala, Chadwick H; Chanda-Kapata, Pascalina; Hamainza, Busiku; Zulu, Reuben; Reimer, Lisa; Chizema, Elizabeth; Kiware, Samson; Okumu, Fredros O; Killeen, Gerry

2018-04-13

The effectiveness of long-lasting insecticidal-treated nets (LLINs) and indoor residual spraying (IRS) for malaria control is threatened by resistance to commonly used pyrethroid insecticides. Rotations, mosaics, combinations, or mixtures of insecticides from different complementary classes are recommended by the World Health Organization (WHO) for mitigating against resistance, but many of the alternatives to pyrethroids are prohibitively expensive to apply in large national IRS campaigns. Recent evaluations of window screens and eave baffles (WSEBs) treated with pirimiphos-methyl (PM), to selectively target insecticides inside houses, demonstrated malaria vector mortality rates equivalent or superior to IRS. However, the durability of efficacy when co-applied with polyacrylate-binding agents (BA) remains to be established. This study evaluated whether WSEBs, co-treated with PM and BA have comparable wash resistance to LLINs and might therefore remain insecticidal for years rather than months. WHO-recommended wire ball assays of insecticidal efficacy were applied to polyester netting treated with or without BA plus 1 or 2 g/sq m PM. They were then tested for insecticidal efficacy using fully susceptible insectary-reared Anopheles gambiae mosquitoes, following 0, 5, 10, 15, then 20 washes as per WHO-recommended protocols for accelerated ageing of LLINs. This was followed by a small-scale field trial in experimental huts to measure malaria vector mortality achieved by polyester netting WSEBs treated with BA and 2 g/sq m PM after 0, 10 and then 20 standardized washes, alongside recently applied IRS using PM. Co-treatment with BA and either dosage of PM remained insecticidal over 20 washes in the laboratory. In experimental huts, WSEBs treated with PM plus BA consistently killed similar proportions of Anopheles arabiensis mosquitoes to PM-IRS (both consistently ≥ 94%), even after 20 washes. Co-treating WSEBs with both PM and BA results in wash

Effects of educational intervention on long-lasting insecticidal nets use in a malarious area, southeast Iran.

PubMed

Soleimani Ahmadi, Mussa; Vatandoost, Hassan; Shaeghi, Mansoreh; Raeisi, Ahmad; Abedi, Farshid; Eshraghian, Mohammad Reza; Aghamolaei, Teimur; Madani, Abdol Hossein; Safari, Reza; Jamshidi, Mahin; Alimorad, Abbas

2012-01-01

Long-lasting insecticidal nets (LLINs) have been advocated as an effective tool against malaria transmission. However, success of this community based intervention largely depends on the knowledge and practice regarding malaria and its prevention. According to the national strategy plan on evaluation of LLINs (Olyset nets), this study was conducted to determine the perceptions and practices about malaria and to improve use of LLINs in Bashagard district, one of the important foci of malaria in southeast Iran. The study area comprised 14 villages that were randomized in two clusters and designated as LLINs and untreated nets. Each of households in both clusters received two bed nets by the free distribution and delivery. After one month quantitative data collection method was used to collect information regarding the objectives of the study. On the basis of this information, an educational program was carried out in both areas to increase motivation for use of bed nets. Community knowledge and practice regarding malaria and LLIN use assessed pre- and post-educational program. The data were analyzed using SPSS ver.16 software. At baseline, 77.5% of respondents in intervention and 69.4 % in control area mentioned mosquito bite as the cause of malaria, this awareness increased significantly in intervention (90.3%) and control areas (87.9%), following the educational program. A significant increase also was seen in the proportion of households who used LLINs the previous night (92.5%) compared with untreated nets (87.1%). Educational status was an important predictor of LLINs use. Regular use of LLIN was considerably higher than the targeted coverage (80%) which recommended by World Heaths Organization. About 81.1% and 85.3% of respondents from LLIN and control areas reported that mosquito nuisance and subsequent malaria transmission were the main determinants of bed net use. These findings highlight a need for educational intervention in implementation of long

Mobility of adult Tribolium castaneum (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (Coleoptera: Bostrichidae) after exposure to long-lasting insecticide netting

USDA-ARS?s Scientific Manuscript database

Stored products represent an enormous economic output, but insects regularly immigrate into stored products from the surrounding landscape throughout the post-harvest supply chain. Long-lasting insecticide netting (LLIN), which usually contains an impregnated pyrethroid, has been used as part of a s...

Insecticide-treated clothes for the control of vector-borne diseases: a review on effectiveness and safety.

PubMed

Banks, S D; Murray, N; Wilder-Smith, A; Logan, J G

2014-08-01

Insecticide-treated clothing has been used for many years by the military and in recreational activities as personal protection against bites from a variety of arthropods including ticks, chigger mites, sandflies and mosquitoes. Permethrin is the most commonly used active ingredient, but others, including bifenthrin, deltamethrin, cyfluthrin, DEET (N,N-diethyl-3-methylbenz-amide) and KBR3023, have also been trialled. Treatment is usually carried out by home or factory dipping. However, new microencapsulation technologies which may prolong the activity of insecticides on clothing are now available and may help to overcome the inevitable reduction in efficacy over time that occurs as a result of washing, ultraviolet light exposure, and the normal wear and tear of the fabric. The aim of this article is to review the evidence base for the use of insecticide-treated clothing for protection against bites from arthropods and its effect on arthropod-borne pathogen transmission. Although some studies do demonstrate protection against pathogen transmission, there are surprisingly few, and the level of protection provided varies according to the disease and the type of study conducted. For example, insecticide-treated clothing has been reported to give between 0% and 75% protection against malaria and between 0% and 79% protection against leishmaniasis. Studies vary in the type of treatment used, the age group of participants, the geographical location of the study, and the pathogen transmission potential. This makes it difficult to compare and assess intervention trials. Overall, there is substantial evidence that insecticide-treated clothing can provide protection against arthropod bites. Bite protection evidence suggests that insecticide-treated clothing may be useful in the prevention of pathogen transmission, but further investigations are required to accurately demonstrate transmission reduction. © 2014 The Royal Entomological Society.

Impact of mass distribution of free long-lasting insecticidal nets on childhood malaria morbidity: The Togo National Integrated Child Health Campaign

PubMed Central

2010-01-01

Background An evaluation of the short-term impact on childhood malaria morbidity of mass distribution of free long-lasting insecticidal nets (LLINs) to households with children aged 9-59 months as part of the Togo National Integrated Child Health Campaign. Methods The prevalence of anaemia and malaria in children aged zero to 59 months was measured during two cross-sectional household cluster-sample surveys conducted during the peak malaria transmission, three months before (Sept 2004, n = 2521) and nine months after the campaign (Sept 2005, n = 2813) in three districts representative of Togo's three epidemiological malaria transmission regions: southern tropical coastal plains (Yoto), central fertile highlands (Ogou) and northern semi-arid savannah (Tone). Results In households with children <5 years of age, insecticide-treated net (ITN) ownership increased from <1% to >65% in all 3 districts. Reported ITN use by children during the previous night was 35.9%, 43.8% and 80.6% in Yoto, Ogou and Tone, respectively. Rainfall patterns were comparable in both years. The overall prevalence of moderate to severe anaemia (Hb < 8.0 g/dL) was reduced by 28% (prevalence ratio [PR] 0.72, 95% CI 0.62-0.84) and mean haemoglobin was increased by 0.35 g/dL (95% CI 0.25-0.45). The effect was predominantly seen in children aged 18-59 months and in the two southern districts: PR (95% CI) for moderate to severe anaemia and clinical malaria: Yoto 0.62 (0.44-0.88) and 0.49 (0.35-0.75); Ogou 0.54 (0.37-0.79) and 0.85 (0.57-1.27), respectively. Similar reductions occurred in children <18 months in Ogou, but not in Yoto. No effect was seen in the semi-arid northern district despite a high malaria burden and ITN coverage. Conclusions A marked reduction in childhood malaria associated morbidity was observed in the year following mass distribution of free LLINs in two of the three districts in Togo. Sub-national level impact evaluations will contribute to a better understanding of the impact

The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control.

PubMed

Oxborough, Richard M; N'Guessan, Raphael; Jones, Rebecca; Kitau, Jovin; Ngufor, Corine; Malone, David; Mosha, Franklin W; Rowland, Mark W

2015-03-24

The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of experiments explored whether standard World Health Organization (WHO) guidelines for evaluation of long-lasting insecticidal nets, developed through testing of pyrethroid insecticides, are suitable for evaluation of non-neurotoxic insecticides. The efficacy of WHO recommended cone, cylinder and tunnel tests was compared for pyrethroids and chlorfenapyr. To establish bioassay exposure times predictive of insecticide-treated net (ITN) efficacy in experimental hut trials, standard three-minute bioassays of pyrethroid and chlorfenapyr ITNs were compared with longer exposures. Mosquito behaviour and response to chlorfenapyr ITN in bioassays conducted at night were compared to day and across a range of temperatures representative of highland and lowland transmission. Standard three-minute bioassay of chlorfenapyr produced extremely low levels of mortality compared to pyrethroids. Thirty-minute day-time bioassay produced mortality closer to hut efficacy of chlorfenapyr ITN but still fell short of the WHO threshold. Overnight tunnel test with chlorfenapyr produced 100% mortality and exceeded the WHO threshold of 80%. The endogenous circadian activity rhythm of anophelines results in inactivity by day and raised metabolism and flight activity by night. A model which explains improved toxicity of chlorfenapyr ITN when tested at night, and during the day at higher ambient temperature, is that activation of chlorfenapyr and disruption of respiratory pathways is enhanced when the insect is more metabolically

Construct validity of the bidding game, binary with follow-up, and a novel structured haggling question format in determining willingness to pay for insecticide-treated mosquito nets.

PubMed

Onwujekwe, Obinna; Fox-Rushby, Julia; Hanson, Kara

2008-01-01

This study examines whether making question formats better fit the cultural context of markets would improve the construct validity of estimates of willingness to pay (WTP). WTP for insecticide-treated mosquito nets was elicited using the bidding game, binary with follow-up (BWFU), and a novel structured haggling technique (SH) that mimicked price taking in market places in the study area. The results show that different question formats generated different distributions of WTP. Following a comparison of alternative models for each question format, construct validity was compared using the most consistently appropriate model across question formats for the positive WTP values, in this case, ordinary least squares. Three criteria (the number of statistically significant explanatory variables that had the anticipated sign, the value of the adjusted R(2), and the proportion that were statistically significant With the anticipated sign) used to assess the relative performance of each question format indicated that SH performed best and BWFU worst. However, differences in the levels of income, education, and percentage of household heads responding to the different question formats across the samples complicate this conclusion. Hence, the results suggest that the SH technique is worthy of further investigation and use.

Discovery of Rigidified α,β-Unsaturated Imines as New Resistance-breaking Insecticides for Malaria Vector Control.

PubMed

Arlt, Alexander; Böhnke, Niels; Horstmann, Sebastian; Vermeer, Arnoldus W P; Werner, Stefan; Velten, Robert

2016-10-01

During our continuous search for new resistance-breaking insecticides applicable to malaria vector control, a new class of α,β-unsaturated imines was identified by applying the principle of conformational rigidification as a powerful tool for compound optimisation. Herein we describe the successful synthesis of these compounds and their biological test results. Our lead compound 16 from this insecticidal class outperforms market standards, notably for the control of mosquito strains that exhibit either metabolic or target-site resistance to these established insecticides. In our model system for insecticide-treated mosquito nets the compound reveals long-lasting efficacy for up to several months.

Use of Insecticide-Treated School Uniforms for Prevention of Dengue in Schoolchildren: A Cost-Effectiveness Analysis

PubMed Central

Tozan, Yesim; Ratanawong, Pitcha; Louis, Valérie R.; Kittayapong, Pattamaporn; Wilder-Smith, Annelies

2014-01-01

Background Dengue-related illness is a leading cause of hospitalization and death, particularly among children. Practical, acceptable and affordable measures are urgently needed to protect this age group. Schools where children spend most of their day is proposed as an ideal setting to implement preventive strategies against day-biting Aedes mosquitoes. The use of insecticide-treated school uniforms is a promising strategy currently under investigation. Methods Using a decision-analytic model, we evaluated the cost-effectiveness of the use of insecticide-treated school uniforms for prevention of dengue, compared with a “do-nothing” alternative, in schoolchildren from the societal perspective. We explored how the potential economic value of the intervention varied under various scenarios of intervention effectiveness and cost, as well as dengue infection risk in school-aged children, using data specific to Thailand. Results At an average dengue incidence rate of 5.8% per year in school-aged children, the intervention was cost-effective (ICER≤$16,440) in a variety of scenarios when the intervention cost per child was $5.3 or less and the intervention effectiveness was 50% or higher. In fact, the intervention was cost saving (ICER<0) in all scenarios in which the intervention cost per child was $2.9 or less per year and the intervention effectiveness was 50% or higher. The results suggested that this intervention would be of no interest to Thai policy makers when the intervention cost per child was $10.6 or higher per year regardless of intervention effectiveness (ICER>$16,440). Conclusions Our results present the potential economic value of the use of insecticide-treated uniforms for prevention of dengue in schoolchildren in a typical dengue endemic setting and highlight the urgent need for additional research on this intervention. PMID:25247556

Long-lasting insecticide-treated bed net ownership and use among children under five years of age following a targeted distribution in central Uganda.

PubMed

Wanzira, Humphrey; Yeka, Adoke; Kigozi, Ruth; Rubahika, Denis; Nasr, Sussann; Sserwanga, Asadu; Kamya, Moses; Filler, Scott; Dorsey, Grant; Steinhardt, Laura

2014-05-19

Universal coverage of long-lasting insecticide-treated bed nets (LLINs) for prevention of malaria was adopted by the Uganda National Malaria Control Programme in 2007. The first mass distribution of LLINs was implemented in 2010. Initially, a campaign targeted to households with pregnant women and children aged net (80.7 vs 35.2%, p < 0.001). LLIN ownership and use was equitable after the targeted campaign, with no significant differences by household wealth status.However, the proportion of households with at least one LLIN per two people was still low after the first campaign phase, increasing from 8.5 to 25.9%. The first phase of the campaign led to substantial increases in both LLIN ownership and equitable use among children 

Mathematical evaluation of community level impact of combining bed nets and indoor residual spraying upon malaria transmission in areas where the main vectors are Anopheles arabiensis mosquitoes

PubMed Central

2013-01-01

Background Indoor residual insecticide spraying (IRS) and long-lasting insecticide treated nets (LLINs) are commonly used together even though evidence that such combinations confer greater protection against malaria than either method alone is inconsistent. Methods A deterministic model of mosquito life cycle processes was adapted to allow parameterization with results from experimental hut trials of various combinations of untreated nets or LLINs (Olyset®, PermaNet 2.0®, Icon Life® nets) with IRS (pirimiphos methyl, lambda cyhalothrin, DDT), in a setting where vector populations are dominated by Anopheles arabiensis, so that community level impact upon malaria transmission at high coverage could be predicted. Results Intact untreated nets alone provide equivalent personal protection to all three LLINs. Relative to IRS plus untreated nets, community level protection is slightly higher when Olyset® or PermaNet 2.0® nets are added onto IRS with pirimiphos methyl or lambda cyhalothrin but not DDT, and when Icon Life® nets supplement any of the IRS insecticides. Adding IRS onto any net modestly enhances communal protection when pirimiphos methyl is sprayed, while spraying lambda cyhalothrin enhances protection for untreated nets but not LLINs. Addition of DDT reduces communal protection when added to LLINs. Conclusions Where transmission is mediated primarily by An. arabiensis, adding IRS to high LLIN coverage provides only modest incremental benefit (e.g. when an organophosphate like pirimiphos methyl is used), but can be redundant (e.g. when a pyrethroid like lambda cyhalothin is used) or even regressive (e.g. when DDT is used for the IRS). Relative to IRS plus untreated nets, supplementing IRS with LLINs will only modestly improve community protection. Beyond the physical protection that intact nets provide, additional protection against transmission by An. arabiensis conferred by insecticides will be remarkably small, regardless of whether they are delivered

Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico

PubMed Central

Che-Mendoza, Azael; Guillermo-May, Guillermo; Herrera-Bojórquez, Josué; Barrera-Pérez, Mario; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Arredondo-Jiménez, Juan I.; Sánchez-Tejeda, Gustavo; Vazquez-Prokopec, Gonzalo; Ranson, Hilary; Lenhart, Audrey; Sommerfeld, Johannes; McCall, Philip J.; Kroeger, Axel; Manrique-Saide, Pablo

2015-01-01

Background Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Methods Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. Results LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. Conclusions These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. PMID:25604761

Effect of combining mosquito repellent and insecticide treated net on malaria prevalence in Southern Ethiopia: a cluster-randomised trial.

PubMed

Deressa, Wakgari; Yihdego, Yemane Y; Kebede, Zelalem; Batisso, Esey; Tekalegne, Agonafer; Dagne, Getachew A

2014-03-28

A mosquito repellent has the potential to prevent malaria infection, but there has been few studies demonstrating the effectiveness of combining this strategy with the highly effective long-lasting insecticidal nets (LLINs). This study aimed to determine the effect of combining community-based mosquito repellent with LLINs in the reduction of malaria. A community-based clustered-randomised trial was conducted in 16 rural villages with 1,235 households in southern Ethiopia between September and December of 2008. The villages were randomly assigned to intervention (mosquito repellent and LLINs, eight villages) and control (LLINs alone, eight villages) groups. Households in the intervention villages received mosquito repellent (i.e., Buzz-Off petroleum jelly, essential oil blend) applied every evening. The baseline survey was followed by two follow-up surveys, at one month interval. The primary outcome was detection of Plasmodium falciparum, Plasmodium vivax, or both parasites, through microscopic examination of blood slides. Analysis was by intention to treat. Baseline imbalances and clustering at individual, household and village levels were adjusted using a generalized linear mixed model. 3,078 individuals in intervention and 3,004 in control group were enrolled into the study. Compared with the control arm, the combined use of mosquito repellent and LLINs significantly reduced malaria infection of all types over time [adjusted Odds Ratio (aOR) = 0.66; 95% CI = 0.45-0.97]. Similarly, a substantial reduction in P. falciparum malaria infection during the follow-up surveys was observed in the intervention group (aOR = 0.53, 95% CI = 0.31-0.89). The protective efficacy of using mosquito repellent and LLINs against malaria infection of both P. falciparum/P. vivax and P. falciparum was 34% and 47%, respectively. Daily application of mosquito repellent during the evening followed by the use of LLINs during bedtime at community level has significantly

Evaluation of the association between long-lasting insecticidal nets mass distribution campaigns and child malaria in Nigeria.

PubMed

Kyu, Hmwe Hmwe; Georgiades, Katholiki; Shannon, Harry S; Boyle, Michael H

2013-01-09

Nigeria carries the greatest malaria burden among countries in the world. As part of the National Malaria Control Strategic Plan, free long-lasting insecticidal nets (LLINs) were distributed in 14 states of Nigeria through mass campaigns led by different organizations (the World Bank, UNICEF, or the Global Fund) between May 2009 and August 2010. The objective of this study was to evaluate the association between LLIN distribution campaigns and child malaria in Nigeria. Data were from the Nigeria Malaria Indicator Survey which was carried out from October to December 2010 on a nationally representative sample of households. Participants were women aged 15-49 years and their children aged less than five years (N = 4082). The main outcome measure was the presence or absence of malaria parasites in blood samples of children (6-59 months). Compared with children living in communities with no campaigns, those in the campaign areas were less likely to test positive for malaria after adjusting for geographic locations, community- and individual-level characteristics including child-level use of insecticide-treated nets (ITNs). The protective effects were statistically significant for the World Bank Booster Project areas (OR = 0.18, 95% CI = 0.04-0.73) but did not reach statistical significance for other campaign areas. Results also showed that community-level wealth (OR = 0.51, 95% CI = 0.34-0.76), community-level maternal knowledge regarding malaria prevention (OR = 0.70, 95% CI = 0.50-0.97), and child-level use of ITNs (OR = 0.79, 95% CI = 0.63-0.99) were negatively associated with child malaria. The observed protective effects on child malaria of these campaigns (statistically significant in the World Bank Booster Project areas and non-significant in the other areas) need to be corroborated by future effectiveness studies. Results also show that improving community-level maternal knowledge through appropriate channels might be helpful

Community cooperatives and insecticide-treated materials for malaria control: a new experience in Latin America.

PubMed

Kroeger, Axel; Aviñna, Ana; Ordoñnez-Gonzalez, José; Escandon, Celia

2002-11-15

Insecticide-treated materials (ITMs) are effective in substantially reducing the burden of malaria and other vector-borne diseases; but how can high coverage rates of ITMs be achieved and maintained? In south Mexico and on the Pacific and Atlantic coasts of Colombia 14 community-based cooperatives offering three different kinds of ITM services (sale of impregnation services; sale of impregnated nets; production of nets and sale of impregnated nets) were formed and supervised by a national health service (IMSS-SOLIDARIDAD, Mexico) and by an academic institution (the Colombian Institute of Tropical Medicine) along with local district health services. The objectives of this research were to analyse the processes and results of this approach and to identify the favourable and limiting factors. The methods used for data collection and analysis were group discussions, individual and semi-structured interviews with users and non-users of ITMs, individual in-depth interviews with cooperative members and supervisors, checks of sales book and observation of impregnation services. Coverage with unimpregnated nets was above 50% in all study areas. The fastest increase of ITM coverage was achieved through the exclusive sale of impregnation services. Low-cost social marketing techniques were used to increase demand. The large-scale production of nets in two cooperatives was only possible with the aid of an international NGO which ordered impregnated bednets for their target group. A number of favourable and limiting factors relating to the success of ITM cooperatives were identified. Of particular importance for the more successful Mexican cooperatives were: a) support by health services, b) smaller size, c) lesser desire for quick returns and d) lower ITM unit costs. ITM community cooperatives supported and supervised by the health services have good potential in the Latin American context for achieving and maintaining high impregnation rates.

Efficacy of PermaNet® 3.0 and PermaNet® 2.0 nets against laboratory-reared and wild Anopheles gambiae sensu lato populations in northern Tanzania.

PubMed

Kweka, Eliningaya J; Lyaruu, Lucile J; Mahande, Aneth M

2017-01-18

Mosquitoes have developed resistance against pyrethroids, the only class of insecticides approved for use on long-lasting insecticidal nets (LLINs). The present study sought to evaluate the efficacy of the pyrethroid synergist PermaNet® 3.0 LLIN versus the pyrethroid-only PermaNet® 2.0 LLIN, in an East African hut design in Lower Moshi, northern Tanzania. In this setting, resistance to pyrethroid insecticides has been identified in Anopheles gambiae mosquitoes. Standard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area where there was presence of a population of highly pyrethroid-resistant An. arabiensis mosquitoes. All nets used were subjected to cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition and personal protection rate were compared between untreated nets, unwashed LLINs and LLINs that were washed 20 times. Both washed and unwashed PermaNet® 2.0 and PermaNet® 3.0 LLINs had knockdown and mortality rates of 100% against a susceptible strain of An. gambiae sensu stricto. The adjusted mortality rate of the wild mosquito population after use of the unwashed PermaNet® 3.0 and PermaNet® 2.0 nets was found to be higher than after use of the washed PermaNet® 2.0 and PermaNet® 3.0 nets. Given the increasing incidence of pyrethroid resistance in An. gambiae mosquitoes in Tanzania, we recommend that consideration is given to its distribution in areas with pyrethroid-resistant malaria vectors within the framework of a national insecticide-resistance management plan.

Prevalence of malaria across Papua New Guinea after initial roll-out of insecticide-treated mosquito nets.

PubMed

Hetzel, Manuel W; Morris, Hector; Tarongka, Nandao; Barnadas, Céline; Pulford, Justin; Makita, Leo; Siba, Peter M; Mueller, Ivo

2015-12-01

To assess the population prevalence of malaria in villages across Papua New Guinea (PNG) following the first roll-out of free long-lasting insecticidal nets (LLIN). Between October 2008 and August 2009, a household survey was conducted in 49 random villages in districts covered by the LLIN distribution campaign. The survey extended to 19 villages in sentinel sites that had not yet been covered by the campaign. In each village, 30 households were randomly sampled, household heads were interviewed and capillary blood samples were collected from all consenting household members for microscopic diagnosis of malaria. Malaria prevalence ranged from 0% to 49.7% with a weighted average of 12.1% (95% CI 9.5, 15.3) in the national sample. More people were infected with Plasmodium falciparum (7.0%; 95% CI 5.4, 9.1) than with P. vivax (3.8%; 95% CI 2.4, 5.7) or P. malariae (0.3%; 95% CI 0.1, 0.6). Parasitaemia was strongly age-dependent with a P. falciparum peak at age 5-9 years and a P. vivax peak at age 1-4 years, yet with differences between geographical regions. Individual LLIN use and high community coverage were associated with reduced odds of infection (OR = 0.64 and 0.07, respectively; both P < 0.001). Splenomegaly in children and anaemia were common morbidities attributable to malaria. Malaria prevalence across PNG is again at levels comparable to the 1970s. The strong association of LLIN use with reduced parasitaemia supports efforts to achieve and maintain high country-wide coverage. P. vivax infections will require special targeted approaches across PNG. © 2015 The Authors. Tropical Medicine & International Health Published by John Wiley & Sons Ltd.

Examining equity in access to long-lasting insecticide nets and artemisinin-based combination therapy in Anambra State, Nigeria.

PubMed

Mbachu, Chinyere O; Onwujekwe, Obinna E; Uzochukwu, Benjamin S C; Uchegbu, Eloka; Oranuba, Joseph; Ilika, Amobi L

2012-05-22

In order to achieve universal health coverage, the government of Anambra State, southeast Nigeria has distributed free Long-lasting Insecticide treated Nets (LLINs) to the general population and delivered free Artemisinin-based Combination Therapy (ACT) to pregnant women and children less than 5 years. However, the levels of coverage with LLINS and ACTs is not clear, especially coverage of different socio-economic status (SES) population groups. This study was carried out to determine the level of coverage and access to LLINs and ACTs amongst different SES groups. A questionnaire was used to collect data from randomly selected households in 19 local government areas of the State. Selected households had a pregnant woman and/or a child less than 5 years. The lot quality assurance sampling (LQAS) methodology was used in sampling. The questionnaire explored the availability and utilization of LLINs and ACTs from 2394 households. An asset-based SES index was used to examine the level of access of LLINS and ACTs to different SES quintiles. It was found that 80.5% of the households had an LLIN and 64.4% of the households stated that they actually used the nets the previous night. The findings showed that 42.3% of pregnant women who had fever within the past month received ACTs, while 37.5% of children<5 years old who had malaria in the past month had received ACTs. There was equity in ownership of nets for the range 1-5 nets per household. No significant SES difference was found in use of ACTs for treatment of malaria in children under five years old and in pregnant women. The free distribution of LLINs and ACTs increased household coverage of both malaria control interventions and bridged the equity gap in access to them among the most vulnerable groups.

High retention and appropriate use of insecticide-treated nets distributed to HIV-affected households in Rakai, Uganda: results from interviews and home visits.

PubMed

Cohee, Lauren; Mills, Lisa A; Kagaayi, Joseph; Jacobs, Ilana; Galiwango, Ronald; Ludigo, James; Ssekasanvu, Joseph; Reynolds, Steven J

2009-04-22

Distribution of insecticide-treated nets (ITNs) has recently been incorporated into comprehensive care strategies for HIV-positive people in malaria-endemic areas. WHO now recommends free or low-cost distribution of ITNs to all persons in malaria-endemic areas, regardless of age, pregnancy and HIV status. Knowledge about and appropriate use of ITNs among HIV-positive ITN recipients and their household members has not been well characterized. 142 randomly selected adults were interviewed in July-August 2006 to assess knowledge, retention, and appropriate use of ITNs they had received through a PEPFAR-funded comprehensive HIV care programme in rural Uganda. Among all participants, 102 (72%, CI: 65%-79%) reported they had no ITNs except those provided by the programme. Of 131 participants who stated they were given >or= 1 ITN, 128 (98%, CI: 96%-100%) stated they still possessed at least one programme-provided ITN. Reported programme-ITN (pITN) use by participants was high: 119 participants (91%, CI: 86%-96%) reported having slept under pITN the night prior to the survey and 115 (88%, CI: 82%-94%) reported sleeping under pITN seven days per week. Being away from home and heat were the most common reasons given for not sleeping under an ITN. A sub-study of thirteen random home visits demonstrated concordance between participants' survey reports and actual use of ITNs in homes. There was excellent self-reported retention and appropriate use of ITNs distributed as a part of a community-based outpatient HIV care programme. Participants perceived ITNs as useful and were unlikely to have received ITNs from other sources.

Clinical malaria among pregnant women on combined insecticide treated nets (ITNs) and intermittent preventive treatment (IPTp) with sulphadoxine-pyrimethamine in Yaounde, Cameroon.

PubMed

Mbu, Robinson Enow; Takang, William Ako; Fouedjio, Hortence Jeanne; Fouelifack, Florent Ymele; Tumasang, Florence Ndikum; Tonye, Rebecca

2014-05-16

Malaria remains a burden for pregnant women and the under 5. Intermittent preventive treatment of pregnant women (IPTp) for malaria with sulfadoxine - pyrimethamine (SP) has since replaced prophylaxis and legislation has been reinforced in the area of insecticide treated mosquito nets (ITNs) in Cameroon. Clinical malaria despite all these measures remains a problem. We compared the socio-obstetrical characteristics of women who developed clinical malaria and those who did not though in the same regimen. A 5 - year nested cohort study (2007 - 2011 inclusive) at the tertiary level hospitals in Yaounde. Pregnant women who willingly accepted to participate in the study were enrolled at booking and three doses of SP were administered between 18 - 20 weeks of gestation, between 26-28 weeks and between 32 - 34 weeks. Those who developed clinical malaria were considered as cases and were compared for socio - obstetrical characteristics with those who did not. Venous blood was drawn from the women in both arms for parasite density estimation and identification and all the clinical cases were treated conventionally. Each arm had 166 cases and many women who developed clinical malaria were between 15 and 19 years (OR 5.5, 95% CI 3.9 - 5.3, p < 0.001). They were of low gravidity (OR 6.5, 95% CI 3.8 - 11.3, p < 0.001) as well as low parity (OR 4.6, 95% CI 2.7 - 7.9, p < 0.001). The cases were single women (OR 4.58, 95% CI 2.54 - 8.26, p < 0.001) and had attained only primary level of education (OR 4.6, 95% CI 2.8 - 7.9, p < 0.001). Gestational ages were between 20 to 30 weeks during clinical malaria (OR 6.8, 95% CI 4.1 - 11.7, p < 0.001). The time between the first and second dose of SP was longer than ten weeks in the cases (OR 5.5, 95% CI 3.2 - 9.3, p < 0.001) and parasite density was higher also among the cases (OR 6.9, 95% CI 5.9 - 12.1, p < 0.001). Long spacing between the first and second dose of SP seemed to be responsible for clinical

Non-target toxicity of synthetic insecticides on the biological performance and population growth of Bracon hebetor Say.

PubMed

Muslim, Mohammad; Ansari, M Shafiq; Hasan, Fazil

2018-05-24

Bracon hebetor Say (Hymenoptera: Braconidae) is an important biological control agent of various species of order Lepidoptera and extensively used in biological control program worldwide. Present study evaluated the lethal and sublethal effects of insecticides on B. hebetor using demographic and population growth parameters. Doses of all the tested insecticides were within a maximum range of their recommended field dosages and adults were treated using residual glass vials method. For control experiments adults were treated with distilled water. Among the tested insecticides, the survivorship of various stages of B. hebetor was considerably prolonged on cyantraniliprole followed by chlorantraniliprole and shortest on chlorpyrifos and profenofos treated group. Total immature development time was prolonged in chlorpyrifos and profenofos treated group. Population growth parameters like intrinsic rate of natural increase (r m ), net reproductive rate (R 0 ), finite rate of increase (λ) and mean generation time (T c ) were considerably reduced in B. hebetor groups treated with chlorpyrifos and profenofos. However, B. hebetor groups treated with chlorantraniliprole and cyantraniliprole showed a little or no much difference in population growth parameters when compared with untreated group. It was also observed that chlorpyrifos and profenofos modified the sex ratio, thereby female emergence get reduced. On the basis of present findings it can be concluded that all tested insecticides caused considerable ecotoxic effects on B. hebetor compared to control. However, comparisons among the tested insecticides on the basis of IOBC criteria showed that chlorantraniliprol and cyntraniliprol was less toxic as compared to other insecticides tested on this biological control agent.

Long lasting insecticidal net use and its associated factors in Limmu Seka District, South West Ethiopia.

PubMed

Hambisa, Mitiku Teshome; Debela, Tessema; Dessie, Yadeta; Gobena, Tesfaye

2018-01-10

Many countries in sub-Saharan Africa, including Ethiopia, are focusing on the distribution of Long Lasting Insecticidal Nets (LLINs) to combat malaria. However, utilization of the LLIN is low when compared with LLIN possession because of various factors. This study was conducted to measure the actual LLIN usage and identify factors associated with its utilization in Limmu Seka District, South West Ethiopia. A community based cross-sectional survey was conducted among 830 households from December 25, 2011 to February 29, 2012. A total of 830 households were selected by stratified systematic sampling and surveyed. Ninety percent of those surveyed owned LLINs and 68.3% reported that someone had slept under the net on the night prior to the survey. The factors associated with LLIN usage were knowledge of the mode of malaria transmission (AOR; 0.086, 95% CI 0.03, 0.24), the preferred conical shapes of the LLIN (AOR; 1.6, 95% CI 1.31, 4.1), receiving information about their use from Health Extension Workers (HEWs) (AOR; 2.4, 95% CI 1.5, 3.9), hearing media campaigns (AOR; 3.2 95% CI 3.5, 9.2), education at a health facility (AOR; 2 95% CI 1.5, 3.9) or having a family size of three or less (AOR; 2.1, 95% CI 1.3, 3.5). Although ownership of Long Lasting Insecticidal Nets was high at 90%, the actual usage of LLIN was low, and not all family members were protected. Promoting the usage of LLINs utilization by those at most risk, especially the conical shaped ones, through intensified health education using HEWs and mass media campaigns at all health facilities, schools and communities will improve LLIN utilization.

Use of insecticide-treated house screens to reduce infestations of dengue virus vectors, Mexico.

PubMed

Manrique-Saide, Pablo; Che-Mendoza, Azael; Barrera-Perez, Mario; Guillermo-May, Guillermo; Herrera-Bojorquez, Josue; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Lenhart, Audrey; Vazquez-Prokopec, Gonzalo; Sommerfeld, Johannes; McCall, Philip J; Kroeger, Axel; Arredondo-Jimenez, Juan I

2015-02-01

Dengue prevention efforts rely on control of virus vectors. We investigated use of insecticide-treated screens permanently affixed to windows and doors in Mexico and found that the screens significantly reduced infestations of Aedes aegypti mosquitoes in treated houses. Our findings demonstrate the value of this method for dengue virus vector control.

Assessing healthcare providers' knowledge and practices relating to insecticide-treated nets and the prevention of malaria in Ghana, Laos, Senegal and Tanzania

PubMed Central

2011-01-01

Background Research evidence is not always being disseminated to healthcare providers who need it to inform their clinical practice. This can result in the provision of ineffective services and an inefficient use of resources, the implications of which might be felt particularly acutely in low- and middle-income countries. Malaria prevention is a particularly compelling domain to study evidence/practice gaps given the proven efficacy, cost-effectiveness and disappointing utilization of insecticide-treated nets (ITNs). Methods This study compares what is known about ITNs to the related knowledge and practices of healthcare providers in four low- and middle-income countries. A new questionnaire was developed, pilot tested, translated and administered to 497 healthcare providers in Ghana (140), Laos (136), Senegal (100) and Tanzania (121). Ten questions tested participants' knowledge and clinical practice related to malaria prevention. Additional questions addressed their individual characteristics, working context and research-related activities. Ordinal logistic regressions with knowledge and practices as the dependent variable were conducted in addition to descriptive statistics. Results The survey achieved a 75% response rate (372/497) across Ghana (107/140), Laos (136/136), Senegal (51/100) and Tanzania (78/121). Few participating healthcare providers correctly answered all five knowledge questions about ITNs (13%) or self-reported performing all five clinical practices according to established evidence (2%). Statistically significant factors associated with higher knowledge within each country included: 1) training in acquiring systematic reviews through the Cochrane Library (OR 2.48, 95% CI 1.30-4.73); and 2) ability to read and write English well or very well (OR 1.69, 95% CI 1.05-2.70). Statistically significant factors associated with better clinical practices within each country include: 1) reading scientific journals from their own country (OR 1.67, 95% CI

Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis to experimental chicken sheds treated with insecticide

PubMed Central

2010-01-01

Background Current strategies for controlling American visceral leishmaniasis (AVL) have been unable to prevent the spread of the disease across Brazil. With no effective vaccine and culling of infected dogs an unpopular and unsuccessful alternative, new tools are urgently needed to manage populations of the sand fly vector, Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae). Here, we test two potential strategies for improving L. longipalpis control using the synthetic sand fly pheromone (±)-9-methylgermacrene-B: the first in conjunction with spraying of animal houses with insecticide, the second using coloured sticky traps. Results Addition of synthetic pheromone resulted in greater numbers of male and female sand flies being caught and killed at experimental chicken sheds sprayed with insecticide, compared to pheromone-less controls. Furthermore, a ten-fold increase in the amount of sex pheromone released from test sheds increased the number of females attracted and subsequently killed. Treating sheds with insecticide alone resulted in a significant decrease in numbers of males attracted to sheds (compared to pre-spraying levels), and a near significant decrease in numbers of females. However, this effect was reversed through addition of synthetic pheromone at the time of insecticide spraying, leading to an increase in number of flies attracted post-treatment. In field trials of commercially available different coloured sticky traps, yellow traps caught more males than blue traps when placed in chicken sheds. In addition, yellow traps fitted with 10 pheromone lures caught significantly more males than pheromone-less controls. However, while female sand flies showed a preference for both blue and yellow pheromone traps sticky traps over white traps in the laboratory, neither colour caught significant numbers of females in chicken sheds, either with or without pheromone. Conclusions We conclude that synthetic pheromone could currently be most effectively

Determination of the predictive factors of long-lasting insecticide-treated net ownership and utilisation in the Bamenda Health District of Cameroon.

PubMed

Fokam, Eric B; Kindzeka, Germaine F; Ngimuh, Leonard; Dzi, Kevin T J; Wanji, Samuel

2017-03-16

Malaria is a serious health concern in Africa. In Cameroon, an endemic country where malaria remains a major public health problem, several control measures have been put in place among which the use of insecticide-treated bednets (LLINs/ITNs) is considered one of the core vector control strategies. However, the greatest challenges include ownership and utilisation by individuals and households. Factors such as age, marital status, gender, education and occupation of the household head, household size, knowledge of bednets, socioeconomic status, and environmental factors have been suggested to have an impact on bednet ownership and utilisation in different settings. The present study sought to determine bednet ownership and utilisation rates and to assess the impact of predictive factors on bednet ownership and use in the Bamenda Health District (BHD) of Cameroon. A cross-sectional study involving 384 households was conducted in six health areas in the BHD. A structured and semi-structured questionnaire was used to collect data on demographic and household characteristics as well as information on their bednet ownership and utilisation. Descriptive statistics, bivariate and multivariate logistic regression analysis were performed. Frequency of bednet ownership was relatively high (63.5%) with LLINs being most abundant (91.9%); the majority of households (87.7%) obtained their bednets during the 2011 free distribution campaign. Utilisation was relatively high (69.3%), with negligence (29.3%) and heat discomfort (26.7%) accounting most for non-usage of bednets. Children less than 5 years (63%) and pregnant women (60%) most often used these nets. Households headed by a married couple, those with older household heads, household with smaller size (5-12 persons), and knowledge of bednets (good knowledge) had positive impacts on bednet ownership (p < 0.05). The gender of the household head (males), their educational level, environmental conditions (presence of

Free mass distribution of long lasting insecticidal nets lead to high levels of LLIN access and use in Madagascar, 2010: A cross-sectional observational study

PubMed Central

Butts, Jessica; Ranaivoharimina, Harilala; Cotte, Annett H.; Ramarosandratana, Benjamin; Rabarijaona, Henintsoa; Tuseo, Luciano; Chang, Michelle; Vanden Eng, Jodi

2017-01-01

Background Madagascar conducted the first two phases of a national free mass distribution campaign of long-lasting insecticidal nets (LLINs) during a political crisis in 2009 aiming to achieve coverage of two LLINs per household as part of the National Malaria Control Strategy. The campaign targeted households in 19 out of 91 total health districts. Methods A community-based cross-sectional household survey using a three-stage cluster sample design was conducted four months post campaign to assess LLIN ownership, access and use. Multivariable logistic regression analysis was used to identify factors associated with household LLIN access and individual LLIN use. Results A total of 2211 households were surveyed representing 8867 people. At least one LLIN was present in 93.5% (95% confidence interval [CI], 91.6–95.5%) of households and 74.8% (95% CI, 71.0–78.6%) owned at least two LLINs. Access measured as the proportion of the population that could potentially be covered by household-owned LLINs was 77.2% (77.2% (95% CI, 72.9–81.3%) and LLIN use by all individuals was 84.2% (95% CI, 81.2–87.2%). LLIN use was associated with knowledge of insecticide treated net use to prevent malaria (OR = 3.58, 95% CI, 1.85–6.94), household ownership of more LLINs (OR 2.82, 95% CI 1.85–4.3), presence of children under five (OR = 2.05, 95% CI, 1.67–2.51), having traveled to the distribution point and receiving information about hanging a bednet (OR = 1.56, 95% CI, 1.41–1.74), and having received a post-campaign visit by a community mobilizer (OR = 1.75, 95% CI, 1.26–2.43). Lower LLIN use was associated with increasing household size (OR = 0.81 95% CI 0.77–0.85) and number of sleeping spaces (OR = 0.55, 95% CI, 0.44–0.68). Conclusions A large scale free mass LLIN distribution campaign was feasible and effective at achieving high LLIN access and use in Madagascar. Campaign process indicators highlighted potential areas for strengthening implementation to optimize

When intensity of deltamethrin resistance in Anopheles gambiae s.l. leads to loss of Long Lasting Insecticidal Nets bio-efficacy: a case study in north Cameroon.

PubMed

Etang, Josiane; Pennetier, Cédric; Piameu, Michael; Bouraima, Aziz; Chandre, Fabrice; Awono-Ambene, Parfait; Marc, Coosemans; Corbel, Vincent

2016-03-08

In Cameroon, insecticide resistance in Anopheles (An.) gambiae s.l. has been reported in several foci, prompting further investigations on associated patterns of Long-Lasting Insecticidal Nets (LLINs) bio-efficacy. The current study, conducted from June to August 2011, explored the intensity of deltamethrin resistance in An. gambiae s.l. from Pitoa and its impact on the residual bio-efficacy of LifeNet, a LLIN with deltamethrin incorporated into polypropylene nets (PND). Two-four days old females An. gambiae s.l. reared from larval collections in Pitoa were tested for susceptibility to DDT, permethrin and deltamethrin, using standard World Health Organization (WHO) tube assays. Intensity of deltamethrin resistance was explored using WHO tube assays, but across six working concentrations from 0.001 % to 0.5 %. Bio-efficacy of unwashed and washed PND was assessed using WHO cone test. Species identification and kdr 1014 genotyping were performed on mosquito samples that were not exposed to insecticides, using PCR-RFLP and HOLA methods respectively. The Kisumu reference susceptible strain of An. gambiae s.s. was used for comparisons. A total of 1895 An. gambiae s.l. specimens from Pitoa were used for resistance and PND bio-efficacy testing. This mosquito population was resistant to DDT, permethrin and deltamethrin, with 18-40 min knockdown times for 50 % of tested mosquitoes and 59-77 % mortality. Deltamethrin Resistance Ratio compared with the Kisumu strain was estimated at ≥500 fold. LifeNets were effective against the susceptible Kisumu (100 % knockdown (KD60min) and mortality) and the resistant Pitoa samples (95 % KD60min, 83-95 % mortality). However, the bio-efficacy gradually dropped against the Pitoa samples when nets were washed (X (2) = 35.887, df = 8, p < 0.001), and fell under the WHO efficacy threshold (80 % mortality and/or 95 % KD60min) between 10 and 15 washes. The Pitoa samples were composed of three sibling species: An. arabiensis (132

The effect of insecticide-treated bed nets on the incidence and prevalence of malaria in children in an area of unstable seasonal transmission in western Myanmar

PubMed Central

2013-01-01

Background Insecticide-treated bed nets (ITN) reduce malaria morbidity and mortality consistently in Africa, but their benefits have been less consistent in Asia. This study’s objective was to evaluate the malaria protective efficacy of village-wide usage of ITN in Western Myanmar and estimate the cost-effectiveness of ITN compared with extending early diagnosis and treatment services. Methods A cluster-randomized controlled trial was conducted in Rakhine State to assess the efficacy of ITNs in preventing malaria and anaemia in children and their secondary effects on nutrition and development. The data were aggregated for each village to obtain cluster-level infection rates. In total 8,175 children under 10 years of age were followed up for 10 months, which included the main malaria transmission period. The incidence and prevalence of Plasmodium falciparum and Plasmodium vivax infections, and the biting behaviour of Anopheles mosquitoes in the area were studied concurrently. The trial data along with costs for current recommended treatment practices were modelled to estimate the cost-effectiveness of ITNs compared with, or in addition to extending the coverage of early diagnosis and treatment services. Results In aggregate, malaria infections, spleen rates, haemoglobin concentrations, and weight for height, did not differ significantly during the study period between villages with and without ITNs, with a weighted mean difference of −2.6 P. falciparum episodes per 1,000 weeks at risk (95% Confidence Interval −7 to 1.8). In areas with a higher incidence of malaria there was some evidence ITN protective efficacy. The economic analysis indicated that, despite the uncertainty and variability in their protective efficacy in the different study sites, ITN could still be cost-effective, but not if they displaced funding for early diagnosis and effective treatment which is substantially more cost-effective. Conclusion In Western Myanmar deployment of ITNs did not

Treating Cattle to Protect People? Impact of Footbath Insecticide Treatment on Tsetse Density in Chad

PubMed Central

Ndeledje, Noël; Bouyer, Jérémy; Stachurski, Frédéric; Grimaud, Patrice; Belem, Adrien Marie Gaston; Molélé Mbaïndingatoloum, Fidèle; Bengaly, Zakaria; Oumar Alfaroukh, Idriss; Cecchi, Guiliano; Lancelot, Renaud

2013-01-01

Background In Chad, several species of tsetse flies (Genus: Glossina ) transmit African animal trypanosomoses (AAT), which represents a major obstacle to cattle rearing, and sleeping sickness, which impacts public health. After the failure of past interventions to eradicate tsetse, the government of Chad is now looking for other approaches that integrate cost-effective intervention techniques, which can be applied by the stake holders to control tsetse-transmitted trypanosomoses in a sustainable manner. The present study thus attempted to assess the efficacy of restricted application of insecticides to cattle leg extremities using footbaths for controlling Glossina m. submorsitans, G . tachinoides and G . f . fuscipes in southern Chad. Methodology/Principal Findings Two sites were included, one close to the historical human African trypanosomiasis (HAT) focus of Moundou and the other to the active foci of Bodo and Moissala. At both sites, a treated and an untreated herd were compared. In the treatment sites, cattle were treated on a regular basis using a formulation of deltamethrin 0.005% (67 to 98 cattle were treated in one of the sites and 88 to 102 in the other one). For each herd, tsetse densities were monthly monitored using 7 biconical traps set along the river and beside the cattle pen from February to December 2009. The impact of footbath treatment on tsetse populations was strong (p < 10-3) with a reduction of 80% in total tsetse catches by the end of the 6-month footbath treatment. Conclusions/Significance The impact of footbath treatment as a vector control tool within an integrated strategy to manage AAT and HAT is discussed in the framework of the “One Health” concept. Like other techniques based on the treatment of cattle, this technology should be used under controlled conditions, in order to avoid the development of insecticide and acaricide resistance in tsetse and tick populations, respectively. PMID:23799148

Malaria control under the Taliban regime: insecticide-treated net purchasing, coverage, and usage among men and women in eastern Afghanistan.

PubMed

Howard, Natasha; Shafi, Ahmad; Jones, Caroline; Rowland, Mark

2010-01-06

Scaling up insecticide-treated mosquito net (ITN) coverage is a key malaria control strategy even in conflict-affected countries 12. Socio-economic factors influence access to ITNs whether subsidized or provided free to users. This study examines reported ITN purchasing, coverage, and usage in eastern Afghanistan and explores women's access to health information during the Taliban regime (1996-2001). This strengthens the knowledge base on household-level health choices in complex-emergency settings. Fifteen focus group discussions (FGDs) and thirty in-depth interviews were conducted with men and women from ITN-owning and non-owning households. FGDs included rank ordering, pile sorting and focused discussion of malaria knowledge and ITN purchasing. Interviews explored general health issues, prevention and treatment practices, and women's malaria knowledge and concerns. Seven key informant interviews with health-related workers and a concurrent survey of 200 ITN-owning and 214 non-owning households were used to clarify or quantify findings. Malaria knowledge was similar among men and women and ITN owners and non-owners. Women reported obtaining health information through a variety of sources including clinic staff, their husbands who had easier access to information, and particularly female peers. Most participants considered ITNs very desirable, though not usually household necessities. ITN owners reported more household assets than non-owners. Male ITN owners and non-owners ranked rugs and ITNs as most desired, while women ranked personal assets such as jewellery highest. While men were primarily responsible for household decision-making and purchasing, older women exerted considerable influence. Widow-led and landless households reported most difficulties purchasing ITNs. Most participants wanted to buy ITNs only if they could cover all household members. When not possible, preferential usage was given to women and children. Despite restricted access to health

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis

PubMed Central

2012-01-01

Background Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Methods Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. Results The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. Conclusions The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both

The use of insecticide-treated nets for reducing malaria morbidity among children aged 6-59 months, in an area of high malaria transmission in central Côte d'Ivoire

PubMed Central

2010-01-01

Background Long-lasting insecticidal nets (LLINs) are an important tool for controlling malaria. Much attention has been devoted to determine both the effect of LLINs on the reduction of Plasmodium infection rate and on clinically-confirmed malaria cases in sub-Saharan Africa. We carried out an epidemiological study to investigate whether LLINs impact on Plasmodium prevalence rate and the proportion of clinically-confirmed malaria cases, in five villages in the district of Toumodi, central Côte d'Ivoire. Methods From April 2007 to November 2008, a community-based malaria control programme was implemented in the study villages, which involved large-scale distribution of LLINs, and training and sensitization activities within the community. We determined the effect of this programme on Plasmodium prevalence rate, clinically-confirmed malaria cases and proportion of high parasitaemia rates in children aged 6-59 months through a series of cross-sectional surveys starting in April 2007 and repeated once every 6 months. Results We observed a significant decrease in the mean P. falciparum prevalence rate from April 2007 to April 2008 (p = 0.029). An opposite trend was observed from November 2007 to November 2008 when P. falciparum prevalence rate increased significantly (p = 0.003). Highly significant decreases in the proportions of clinical malaria cases were observed between April 2007 and April 2008 (p < 0.001), and between November 2007 and November 2008 (p = 0.001). Conclusions Large-scale distribution of LLINs, accompanied by training and sensitization activities, significantly reduced Plasmodium prevalence rates among young children in the first year of the project, whereas overall clinical malaria rates dropped over the entire 18-month project period. A decrease in community motivation to sleep under bed nets, perhaps along with changing patterns of malaria transmission, might explain the observed increase in the Plasmodium prevalence rate between November 2007

The Effect of Single or Repeated Home Visits on the Hanging and Use of Insecticide-Treated Mosquito Nets following a Mass Distribution Campaign - A Cluster Randomized, Controlled Trial

PubMed Central

Kilian, Albert; Balayo, Connie; Feldman, Mitra; Koenker, Hannah; Lokko, Kojo; Ashton, Ruth A.; Bruce, Jane; Lynch, Matthew; Boulay, Marc

2015-01-01

Background Study objective was to evaluate the effectiveness of commonly used post-campaign hang-up visits on the hanging and use of campaign nets. Methods A cluster-randomized trial was carried out in Uganda following an ITN distribution campaign. Five clusters (parishes, consisting of ∼11 villages each) were randomly selected for each of the three study arms with between 7,534 and 9,401 households per arm. Arm 1 received one hang-up visit, while Arm 2 received two visits by volunteers four and seven months after the campaign. Visits consisted of assistance hanging the net and education on net use. The control arm was only exposed to messages during the campaign itself. Three cross-sectional surveys with a two-stage cluster sampling design, representative of the study populations, were carried out to capture the two key outcome variables of net hanging and ITN use. Sample size was calculated to detect at least a 15 percentage-points change in net use, and was 1811 at endline. The analysis used an intention-to-treat approach. Findings Both hanging and use of ITN increased during follow-up in a similar way in all three study arms. The proportion of the population using an ITN the previous night was 64.0% (95% CI 60.8, 67.2), for one additional visit, 68.2% (63.8, 72.2) for two visits and 64.0% (59.4, 68.5) for the control. The proportion of households with all campaign nets hanging increased from 55.7% to 72.5% at endline (p<0.0005 for trend), with no difference between study arms. Financial cost per household visited was estimated as USD 2.33 for the first visit and USD 2.24 for the second. Conclusions Behavior change communication provided during the campaign or through other channels was sufficient to induce high levels of net hanging and use and additional “hang-up” activities were not cost-effective. PMID:25774676

Towards achieving Abuja targets: identifying and addressing barriers to access and use of insecticides treated nets among the poorest populations in Kenya.

PubMed

Chuma, Jane; Okungu, Vincent; Ntwiga, Janet; Molyneux, Catherine

2010-03-16

Ensuring that the poor and vulnerable population benefit from malaria control interventions remains a challenge for malaria endemic countries. Until recently, ownership and use of insecticides treated nets (ITNs) in most countries was low and inequitable, although coverage has increased in countries where free ITN distribution is integrated into mass vaccination campaigns. In Kenya, free ITNs were distributed to children aged below five years in 2006 through two mass campaigns. High and equitable coverage were reported after the campaigns in some districts, although national level coverage remained low, suggesting that understanding barriers to access remains important. This study was conducted to explore barriers to ownership and use of ITNs among the poorest populations before and after the mass campaigns, to identify strategies for improving coverage, and to make recommendations on how increased coverage levels can be sustained. The study was conducted in the poorest areas of four malaria endemic districts in Kenya. Multiple data collection methods were applied including: cross-sectional surveys (n = 708 households), 24 focus group discussions and semi-structured interviews with 70 ITN suppliers. Affordability was reported as a major barrier to access but non-financial barriers were also shown to be important determinants. On the demand side key barriers to access included: mismatch between the types of ITNs supplied through interventions and community preferences; perceptions and beliefs on illness causes; physical location of suppliers and; distrust in free delivery and in the distribution agencies. Key barriers on the supply side included: distance from manufacturers; limited acceptability of ITNs provided through interventions; crowding out of the commercial sector and the price. Infrastructure, information and communication played a central role in promoting or hindering access. Significant resources have been directed towards addressing affordability

Field trial on a novel control method for the dengue vector, Aedes aegypti by the systematic use of Olyset® Net and pyriproxyfen in Southern Vietnam

PubMed Central

2013-01-01

Background Jars, tanks, and drums provide favorable rearing/breeding sites for Aedes aegypti in Vietnam. However, the use of insecticides to control mosquitoes at such breeding sites has not been approved in Vietnam since they are also often sources of drinking water, making larval vector control difficult. Mosquito nets pre-treated with long-lasting insecticide treated nets (LLITNs) form an effective measure for malaria control. We examined changes in the abundance of immature Aedes aegypti to evaluate the efficacy of covering ceramic jars with lids comprising one type of LLITN, Olyset® Net, in inhibiting oviposition by adult females, and to evaluate the effect of treating other breeding containers, such as flower vases, inside and around the outside of houses with a slow-release pyriproxyfen formulation to kill pupae. Methods We selected 313 households for the trial and 363 households for the control in Tan Chanh, Long An province, Vietnam. In the trial area, Olyset® Net lids were used to cover five major types of water container (ceramic jars, cylindrical concrete tanks, other concrete tanks, plastic drums, and plastic buckets), while pyriproxyfen was used to treat flower vases and ant traps. We also monitored dengue virus transmission by measuring anti-dengue IgM and IgG levels in healthy residents in both control and trial areas to estimate the effectiveness of Olyset® Net at controlling the dengue vector, Aedes aegypti. Results The container-index and house-index for immature Ae. aegypti fell steeply one month after treatment in the trial area. Lids with Olyset® Net that fit container openings clearly seemed to reduce the presence of immature Ae. aegypti as the density of pupae decreased 1 month after treatment in the trial area. Pyriproxyfen was also effective at killing pupae in the water containers in the trial area. Although the dengue seroconversion rate was not influenced by Olyset® Net, it was lower in two-five year old children when compared to

The Effect of Indoor Residual Spraying on the Prevalence of Malaria Parasite Infection, Clinical Malaria and Anemia in an Area of Perennial Transmission and Moderate Coverage of Insecticide Treated Nets in Western Kenya

PubMed Central

Gimnig, John E.; Otieno, Peter; Were, Vincent; Marwanga, Doris; Abong’o, Daisy; Wiegand, Ryan; Williamson, John; Wolkon, Adam; Zhou, Ying; Bayoh, M. Nabie; Lobo, Neil F.; Laserson, Kayla; Kariuki, Simon; Hamel, Mary J.

2016-01-01

Background Insecticide treated nets (ITNs) and indoor residual spraying (IRS) have been scaled up for malaria prevention in sub-Saharan Africa. However, there are few studies on the benefit of implementing IRS in areas with moderate to high coverage of ITNs. We evaluated the impact of an IRS program on malaria related outcomes in western Kenya, an area of intense perennial malaria transmission and moderate ITN coverage (55–65% use of any net the previous night). Methods The Kenya Division of Malaria Control, with support from the US President’s Malaria Initiative, conducted IRS in one lowland endemic district with moderate coverage of ITNs. Surveys were conducted in the IRS district and a neighboring district before IRS, after one round of IRS in July-Sept 2008 and after a second round of IRS in April-May 2009. IRS was conducted with pyrethroid insecticides. At each survey, 30 clusters were selected for sampling and within each cluster, 12 compounds were randomly selected. The primary outcomes measured in all residents of selected compounds included malaria parasitemia, clinical malaria (P. falciparum infection plus history of fever) and anemia (Hb<8) of all residents in randomly selected compounds. At each survey round, individuals from the IRS district were matched to those from the non-IRS district using propensity scores and multivariate logistic regression models were constructed based on the matched dataset. Results At baseline and after one round of IRS, there were no differences between the two districts in the prevalence of malaria parasitemia, clinical malaria or anemia. After two rounds of IRS, the prevalence of malaria parasitemia was 6.4% in the IRS district compared to 16.7% in the comparison district (OR = 0.36, 95% CI = 0.22–0.59, p<0.001). The prevalence of clinical malaria was also lower in the IRS district (1.8% vs. 4.9%, OR = 0.37, 95% CI = 0.20–0.68, p = 0.001). The prevalence of anemia was lower in the IRS district but only in children

Demand and willingness-to-pay for bed nets in Tanzania: results from a choice experiment.

PubMed

Gingrich, Chris D; Ricotta, Emily; Kahwa, Amos; Kahabuka, Catherine; Koenker, Hannah

2017-07-14

Universal coverage campaigns for long-lasting insecticide-treated nets do not always reach the goal of one net for every two household members, and even when ownership of at least one net per household is high, many households may not own enough nets. The retail market provides these households options for replacing or increasing the number of nets they own with products that best fit their needs since a variety of net shapes, sizes, and colours are available. Hence, it is important to understand the factors affecting private net demand. This study explores private demand for nets in Tanzania using a discrete choice experiment. The experiment provides participants the option to buy nets with their own money, and thus should prove more accurate than a hypothetical survey of net preferences. Nearly 800 participants sampled in two regions showed an overall strong demand for nets, with 40% choosing to buy a net across all seven combinations of net prices and characteristics such as size, shape, and insecticide treatment. Only 8% of all participants chose not to buy a single net. A key factor influencing demand was whether a participant's household currently owned sufficient nets for all members, with rural participants showing lower net coverage and greater demand than urban participants. Both poor and less poor households showed strong evidence of making purchase decisions based on more than price alone. Mean willingness-to-pay values for a net started at US$1.10 and grew by US$0.50-1.40 for various attributes such as rectangular shape, large size, and insecticide treatment. The impact of price on demand was negative but small, with elasticity values between -0.25 and -0.45. The results suggest that private demand for nets in Tanzania could potentially supplement future coverage campaigns. Net manufacturers and retailers should advertise and promote consumers' preferred net attributes to improve sales and further expand net access and coverage. To overcome household

Insecticide Treated Camouflage Sceening Reduces Sand Fly Numbers in Leishmania-Endemic Regions in Kenya

USDA-ARS?s Scientific Manuscript database

Current U.S. military operations in deserts face persistent threats from sand flies that transmit human Leishmania. In this study we investigated the efficacy of artificial barriers treated with residual insecticide to potentially reduce the risk of human infection from leishmaniasis by reducing the...

Feasibility and acceptability of insecticide-treated plastic sheeting (ITPS) for vector control in Papua New Guinea

PubMed Central

2012-01-01

Background This study assessed the feasibility and acceptability of utilizing insecticide-treated plastic sheeting (ITPS) as a malaria control intervention in Papua New Guinea (PNG). Methods ZeroVector® ITPS was installed in 40 homes across four study sites representing a cross section of malaria transmission risk and housing style. Structured questionnaires were completed at the time of ITPS installation (n=40) and at four weeks post installation (n=40) with the household head. Similarly, group interviews with the male and/or female household heads were completed at installation (n=5) and four-week follow-up (n=4). Results ZeroVector® ITPS was successfully installed in a range of homes employing traditional and/or modern building materials in PNG. The ITPS installations remained intact over the course of the four-week trial period and were highly acceptable to both male and female household heads. No dissatisfaction with the ITPS product was reported at four-week follow-up; however, the installation process was time consuming, participants reported a reduction in mosquito net use following ITPS installation and many participants expressed concern about the longevity of ITPS over the longer term. Conclusion ZeroVector® ITPS installation is feasible and highly acceptable in a diverse range of PNG contexts and is likely to be favourably received as a vector control intervention if accessible en masse. A longer-term evaluation is required before firm policy or public health decisions can be made regarding the potential application of ITPS in the national malaria control programme. The positive study findings suggest a longer-term evaluation of this promising malaria control intervention warrants consideration. PMID:23046535

Short and long term evaluation of the efficiency of PermaNet® 2.0 bed net against environmental factors and washing using bioassay tests

PubMed Central

Kayedi, Mohammad Hassan; Khamisabadi, Kiumars; Haghdoost, Ali Akbar; Kayedi, Zohreh; Fallahi, Shirzad; Abdali, Nargess

2017-01-01

ABSTRACT The aim of the present study was to examine the resistance of PermaNet® 2.0 bed nets against repeated washing and environmental factors by using bioassay tests. After 5, 15 and 21 washings with detergents and by using bioassay tests, the resistance of 40 PermaNet® 2.0 bed nets was compared with that of 40 bed nets conventionally treated with one K-O tablet. To examine the long-term resistance, 31 PermaNet® 2.0 bed nets were also distributed among villagers, and were re-collected to perform bioassay tests after 1, 2 and 5 years. In the first phase of this study, the insecticidal effect of the conventionally-treated nets significantly decreased due to repeated washings (P < 0.001); however, it was not significant regarding PermaNet® 2.0 bed nets (P = 0.92 in continuous exposure and P = 0.12 in mortality tests). In the long-term phase of this study, the time required for knockdown of PermaNet® 2.0 increased over the first 2 years and then decreased. In addition, the mortality rate decreased over the first 2 years and then increased. In conclusion, it seems that the technique used by the manufacturer for impregnation of PermaNet® 2.0 bed nets has an acceptable efficiency in comparison with conventional techniques. PMID:28423093

Status of Insecticide Resistance in Papua New Guinea: An Update from Nation-Wide Monitoring of Anopheles Mosquitoes.

PubMed

Koimbu, Gussy; Czeher, Cyrille; Katusele, Michelle; Sakur, Muker; Kilepak, Lemen; Tandrapah, Anthony; Hetzel, Manuel W; Pulford, Justin; Robinson, Leanne; Karl, Stephan

2018-01-01

Insecticide resistance (IR) monitoring is an important component of vector-borne disease control. The last assessment of IR in Papua New Guinea (PNG) was conducted in 2010. Since then, vector populations have been exposed to higher levels of pyrethroids with the continued nation-wide distribution of insecticide-treated nets. Here, we provide an update on phenotypic IR in four highly malaria-endemic areas of PNG. IR against deltamethrin, lambda-cyhalothrin, and dichlorodiphenyltrichloroethane was assessed using World Health Organization bioassays. A total of 108 bioassays for each insecticide were conducted screening 2,290 adult female anopheline mosquitoes. No phenotypic resistance was observed. Bioassay parameters agreed well with those observed in other studies that used the same assays and insecticides. These results indicate that the three tested insecticides are still universally effective in PNG. Continued IR monitoring (every 1-2 years) in PNG is recommended to detect reduced susceptibility early and adjust guidelines to prevent widespread resistance.

Cost-effectiveness analysis of vaccinating children in Malawi with RTS,S vaccines in comparison with long-lasting insecticide-treated nets.

PubMed

Seo, Mikyung Kelly; Baker, Peter; Ngo, Karen Ngoc-Lan

2014-02-24

New RTS,S malaria vaccines may soon be licensed, yet its cost-effectiveness is unknown. Before the widespread introduction of RTS,S vaccines, cost-effectiveness studies are needed to help inform governments in resource-poor settings about how best to prioritize between the new vaccine and existing malaria interventions. A Markov model simulated malaria progression in a hypothetical Malawian birth cohort. Parameters were based on published data. Three strategies were compared: no intervention, vaccination at one year, and long-lasting, insecticide-treated nets (LLINs) at birth. Both health service and societal perspectives were explored. Health outcomes were measured in disability-adjusted life years (DALYs) averted and costed in 2012 US$. Incremental cost-effectiveness ratios (ICERs) were calculated and extensive sensitivity analyses were conducted. Three times GDP per capita ($1,095) per DALY averted was used for a cost-effectiveness threshold, whilst one times GDP ($365) was considered 'very cost-effective'. From a societal perspective the vaccine strategy was dominant. It averted 0.11 more DALYs than LLINs and 0.372 more DALYs than the no intervention strategy per person, while costing $10.04 less than LLINs and $59.74 less than no intervention. From a health service perspective the vaccine's ICER was $145.03 per DALY averted, and thus can be considered very cost-effective. The results were robust to changes in all variables except the vaccine and LLINs' duration of efficacy. Vaccines remained cost-effective even at the lowest assumed efficacy levels of 49.6% (mild malaria) and 14.2% (severe malaria), and the highest price of $15. However, from a societal perspective, if the vaccine duration efficacy was set below 2.69 years or the LLIN duration of efficacy was greater than 4.24 years then LLINs became the more cost-effective strategy. The results showed that vaccinating Malawian children with RTS,S vaccines was very cost-effective from both a societal and a

Evaluating the efficacy of biological and conventional insecticides with the new 'MCD bottle' bioassay.

PubMed

Sternberg, Eleanore D; Waite, Jessica L; Thomas, Matthew B

2014-12-16

Control of mosquitoes requires the ability to evaluate new insecticides and to monitor resistance to existing insecticides. Monitoring tools should be flexible and low cost so that they can be deployed in remote, resource poor areas. Ideally, a bioassay should be able to simulate transient contact between mosquitoes and insecticides, and it should allow for excito-repellency and avoidance behaviour in mosquitoes. Presented here is a new bioassay, which has been designed to meet these criteria. This bioassay was developed as part of the Mosquito Contamination Device (MCD) project and, therefore, is referred to as the MCD bottle bioassay. Presented here are two experiments that serve as a proof-of-concept for the MCD bottle bioassay. The experiments used four insecticide products, ranging from fast-acting, permethrin-treated, long-lasting insecticide nets (LLINs) that are already widely used for malaria vector control, to the slower acting entomopathogenic fungus, Beauveria bassiana, that is currently being evaluated as a prospective biological insecticide. The first experiment used the MCD bottle to test the effect of four different insecticides on Anopheles stephensi with a range of exposure times (1 minute, 3 minutes, 1 hour). The second experiment is a direct comparison of the MCD bottle and World Health Organization (WHO) cone bioassay that tests a subset of the insecticides (a piece of LLIN and a piece of netting coated with B. bassiana spores) and a further reduced exposure time (5 seconds) against both An. stephensi and Anopheles gambiae. Immediate knockdown and mortality after 24 hours were assessed using logistic regression and daily survival was assessed using Cox proportional hazards models. Across both experiments, fungus performed much more consistently than the chemical insecticides but measuring the effect of fungus required monitoring of mosquito mortality over several days to a week. Qualitatively, the MCD bottle and WHO cone performed comparably

Analysing and recommending options for maintaining universal coverage with long-lasting insecticidal nets: the case of Tanzania in 2011

PubMed Central

2013-01-01

Background Tanzania achieved universal coverage with long-lasting insecticidal nets (LLINs) in October 2011, after three years of free mass net distribution campaigns and is now faced with the challenge of maintaining high coverage as nets wear out and the population grows. A process of exploring options for a continuous or “Keep-Up” distribution system was initiated in early 2011. This paper presents for the first time a comprehensive national process to review the major considerations, findings and recommendations for the implementation of a new strategy. Methods Stakeholder meetings and site visits were conducted in five locations in Tanzania to garner stakeholder input on the proposed distribution systems. Coverage levels for LLINs and their decline over time were modelled using NetCALC software, taking realistic net decay rates, current demographic profiles and other relevant parameters into consideration. Costs of the different distribution systems were estimated using local data. Results LLIN delivery was considered via mass campaigns, Antenatal Care-Expanded Programme on Immunization (ANC/EPI), community-based distribution, schools, the commercial sector and different combinations of the above. Most approaches appeared unlikely to maintain universal coverage when used alone. Mass campaigns, even when combined with a continuation of the Tanzania National Voucher Scheme (TNVS), would produce large temporal fluctuations in coverage levels; over 10 years this strategy would require 63.3 million LLINs and a total cost of $444 million USD. Community mechanisms, while able to deliver the required numbers of LLINs, would require a massive scale-up in monitoring, evaluation and supervision systems to ensure accurate application of identification criteria at the community level. School-based approaches combined with the existing TNVS would reach most Tanzanian households and deliver 65.4 million LLINs over 10 years at a total cost of $449 million USD and ensure

Malaria infection in mosquitoes decreases the personal protection offered by permethrin-treated bednets.

PubMed

Thiévent, Kevin; Hofer, Lorenz; Rapp, Elise; Tambwe, Mgeni Mohamed; Moore, Sarah; Koella, Jacob C

2018-05-04

Insecticides targeting adult mosquitoes are the main way of controlling malaria. They work not only by killing mosquitoes, but also by repelling and irritating them. Indeed their repellent action gives valuable personal protection against biting mosquitoes. In the context of malaria control this personal protection is especially relevant when mosquitoes are infectious, whereas to protect the community we would prefer that the mosquitoes that are not yet infectious are killed (so, not repelled) by the insecticide. As the infectious stage of malaria parasites increases the motivation of mosquitoes to bite, we predicted that it would also change their behavioural response to insecticides. With two systems, a laboratory isolate of the rodent malaria Plasmodium berghei infecting Anopheles gambiae and several isolates of P. falciparum obtained from schoolchildren in Tanzania that infected Anopheles arabiensis, we found that mosquitoes harbouring the infectious stage (the sporozoites) of the parasite were less repelled by permethrin-treated nets than uninfected ones. Our results suggest that, at least in the laboratory, malaria infection decreases the personal protection offered by insecticide-treated nets at the stage where the personal protection is most valuable. Further studies must investigate whether these results hold true in the field and whether the less effective personal protection can be balanced by increased community protection.

Rapid Increase in Ownership and Use of Long-Lasting Insecticidal Nets and Decrease in Prevalence of Malaria in Three Regional States of Ethiopia (2006-2007)

PubMed Central

Shargie, Estifanos Biru; Ngondi, Jeremiah; Graves, Patricia M.; Getachew, Asefaw; Hwang, Jimee; Gebre, Teshome; Mosher, Aryc W.; Ceccato, Pietro; Endeshaw, Tekola; Jima, Daddi; Tadesse, Zerihun; Tenaw, Eskindir; Reithinger, Richard; Emerson, Paul M.; Richards, Frank O.; Ghebreyesus, Tedros Adhanom

2010-01-01

Following recent large scale-up of malaria control interventions in Ethiopia, this study aimed to compare ownership and use of long-lasting insecticidal nets (LLIN), and the change in malaria prevalence using two population-based household surveys in three regions of the country. Each survey used multistage cluster random sampling with 25 households per cluster. Household net ownership tripled from 19.6% in 2006 to 68.4% in 2007, with mean LLIN per household increasing from 0.3 to 1.2. Net use overall more than doubled from 15.3% to 34.5%, but in households owning LLIN, use declined from 71.7% to 48.3%. Parasitemia declined from 4.1% to 0.4%. Large scale-up of net ownership over a short period of time was possible. However, a large increase in net ownership was not necessarily mirrored directly by increased net use. Better targeting of nets to malaria-risk areas and sustained behavioural change communication are needed to increase and maintain net use. PMID:20936103

The impact of insecticide-treated school uniforms on dengue infections in school-aged children: study protocol for a randomised controlled trial in Thailand

PubMed Central

2012-01-01

Background There is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence. Methods A randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7–18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons. Discussion Practical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed. Trial registration clinicaltrial.gov. Registration number: NCT01563640 PMID:23153360

The Presence of Flour Affects the Efficacy of Aerosolized Insecticides used to Treat the Red Flour Beetle, Tribolium castaneum

PubMed Central

Toews, Michael D.; Campbell, James F.; Arthur, Franklin H.

2010-01-01

Experiments were conducted in tightly sealed pilot scale warehouses to assess the efficacy of common aerosolized insecticides on all life stages of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) when exposed in dishes containing 0 to 2 g of wheat flour either under pallets or out in the open. Petri dishes containing 0, 0.1, 1, or 2 g of flour were prepared with 25 eggs, 3rd instars, pupae, or adults and then immediately treated with aerosolized solvent, Pyrethrins, or esfenvalerate. Twenty-four h after insecticide exposure, the dishes were brought to the laboratory and placed in a growth chamber and held for a 3 day moribund (knockdown) assessment and a 21 day mortality assessment. Mortality in untreated controls was generally less than 10%, with the exception of the 21 day counts of adults and eggs. Solvent-treated replications followed similar trends, except that additional mortality was observed in exposed larvae and pupae. In the insecticide-treated dishes, mortality of T. castaneum provisioned with flour generally showed a linear decrease with increasing flour deposits. Regardless of life stage, mortality did not exceed 60% when individuals were exposed in petri dishes containing 2 g of flour. Exposure location also made a significant difference in observed mortality. While mortality never exceeded 75% in dishes positioned under pallets, there was never less than 80% mortality in dishes exposed in the open. Although there was a perceptible increase in mortality with esfenvalerate compared to Pyrethrins, these differences were considerably less than the variation observed among flour deposits. The study suggests that sanitation and preparation prior to aerosol insecticide treatments were more important than choice of a particular insecticide. PMID:21268701

Which family members use the best nets? An analysis of the condition of mosquito nets and their distribution within households in Tanzania.

PubMed

Tsuang, Angela; Lines, Jo; Hanson, Kara

2010-07-22

Household ownership of insecticide-treated mosquito nets (ITNs) is increasing, and coverage targets have been revised to address universal coverage with ITNs. However, many households do not have enough nets to cover everyone, and the nets available vary in physical condition and insecticide treatment status. Since 2004, the Government of Tanzania has been implementing the Tanzania National Voucher Scheme (TNVS), which distributes vouchers for ITNs through antenatal clinics to target pregnant women and their infants. This analysis aimed to determine the following: (1) coverage patterns of bed nets within households according to physical condition and treatment status; (2) who might be at risk if mosquitoes were diverted from occupants of untreated nets to those not using nets? (3) the degree to which those at highest risk of malaria use the most protective nets. Data from the 2006 TNVS household survey were analysed to assess within-household distribution of net use. The associations between net characteristics and net user were also evaluated. Multivariate analysis was applied to the relationship between the number of holes per net and user characteristics while adjusting for confounders. In households with a net:person ratio better than 1:4 (one net for every four household members), more than 80% of the people in such households reported using a net the previous night. ITNs were most likely to be used by infants, young children (1-4 y), and women of childbearing age; they were least likely to be used by older women (>or=50 y), older children (5-14 y), and adult men. The nets used by infants and women of childbearing age were in better-than-average physical condition; the nets used by older women and older children were in worse-than-average condition; while young children and adult men used nets in intermediate (average) condition. When adjusted for confounders, the nets used by young and older children had more holes than nets used by infants. Infants and other

Costs and effects of two public sector delivery channels for long-lasting insecticidal nets in Uganda.

PubMed

Kolaczinski, Jan H; Kolaczinski, Kate; Kyabayinze, Daniel; Strachan, Daniel; Temperley, Matilda; Wijayanandana, Nayantara; Kilian, Albert

2010-04-20

In Uganda, long-lasting insecticidal nets (LLIN) have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC) services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda. Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY). These effects were calculated for the total number of LLINs delivered and for those retained and used. After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja) and 99% (ANC Adjumani) were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja). Economic cost for ANC distribution were considerably higher (USD 2.27) compared to campaign costs (USD 1.23) in Adjumani. Targeted campaigns and routine ANC services can both achieve high LLIN retention and use among

Assessing Insecticide Hazard to Bumble Bees Foraging on Flowering Weeds in Treated Lawns

PubMed Central

Larson, Jonathan L.; Redmond, Carl T.; Potter, Daniel A.

2013-01-01

Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees. PMID:23776667

Assessing insecticide hazard to bumble bees foraging on flowering weeds in treated lawns.

PubMed

Larson, Jonathan L; Redmond, Carl T; Potter, Daniel A

2013-01-01

Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees.

Country-level operational implementation of the Global Plan for Insecticide Resistance Management

PubMed Central

Hemingway, Janet; Vontas, John; Poupardin, Rodolphe; Raman, Jaishree; Lines, Jo; Schwabe, Chris; Matias, Abrahan; Kleinschmidt, Immo

2013-01-01

Malaria control is reliant on the use of long-lasting pyrethroid-impregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs. PMID:23696658

Country-level operational implementation of the Global Plan for Insecticide Resistance Management.

PubMed

Hemingway, Janet; Vontas, John; Poupardin, Rodolphe; Raman, Jaishree; Lines, Jo; Schwabe, Chris; Matias, Abrahan; Kleinschmidt, Immo

2013-06-04

Malaria control is reliant on the use of long-lasting pyrethroid-impregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs.

Examining the impact of larval source management and insecticide-treated nets using a spatial agent-based model of Anopheles gambiae and a landscape generator tool

PubMed Central

2013-01-01

Background Agent-based models (ABMs) have been used to estimate the effects of malaria-control interventions. Early studies have shown the efficacy of larval source management (LSM) and insecticide-treated nets (ITNs) as vector-control interventions, applied both in isolation and in combination. However, the robustness of results can be affected by several important modelling assumptions, including the type of boundary used for landscapes, and the number of replicated simulation runs reported in results. Selection of the ITN coverage definition may also affect the predictive findings. Hence, by replication, independent verification of prior findings of published models bears special importance. Methods A spatially-explicit entomological ABM of Anopheles gambiae is used to simulate the resource-seeking process of mosquitoes in grid-based landscapes. To explore LSM and replicate results of an earlier LSM study, the original landscapes and scenarios are replicated by using a landscape generator tool, and 1,800 replicated simulations are run using absorbing and non-absorbing boundaries. To explore ITNs and evaluate the relative impacts of the different ITN coverage schemes, the settings of an earlier ITN study are replicated, the coverage schemes are defined and simulated, and 9,000 replicated simulations for three ITN parameters (coverage, repellence and mortality) are run. To evaluate LSM and ITNs in combination, landscapes with varying densities of houses and human populations are generated, and 12,000 simulations are run. Results General agreement with an earlier LSM study is observed when an absorbing boundary is used. However, using a non-absorbing boundary produces significantly different results, which may be attributed to the unrealistic killing effect of an absorbing boundary. Abundance cannot be completely suppressed by removing aquatic habitats within 300 m of houses. Also, with density-dependent oviposition, removal of insufficient number of aquatic

Explaining variation in adult Anopheles indoor resting abundance: the relative effects of larval habitat proximity and insecticide-treated bed net use.

PubMed

McCann, Robert S; Messina, Joseph P; MacFarlane, David W; Bayoh, M Nabie; Gimnig, John E; Giorgi, Emanuele; Walker, Edward D

2017-07-17

Spatial determinants of malaria risk within communities are associated with heterogeneity of exposure to vector mosquitoes. The abundance of adult malaria vectors inside people's houses, where most transmission takes place, should be associated with several factors: proximity of houses to larval habitats, structural characteristics of houses, indoor use of vector control tools containing insecticides, and human behavioural and environmental factors in and near houses. While most previous studies have assessed the association of larval habitat proximity in landscapes with relatively low densities of larval habitats, in this study these relationships were analysed in a region of rural, lowland western Kenya with high larval habitat density. 525 houses were sampled for indoor-resting mosquitoes across an 8 by 8 km study area using the pyrethrum spray catch method. A predictive model of larval habitat location in this landscape, previously verified, provided derivations of indices of larval habitat proximity to houses. Using geostatistical regression models, the association of larval habitat proximity, long-lasting insecticidal nets (LLIN) use, house structural characteristics (wall type, roof type), and peridomestic variables (cooking in the house, cattle near the house, number of people sleeping in the house) with mosquito abundance in houses was quantified. Vector abundance was low (mean, 1.1 adult Anopheles per house). Proximity of larval habitats was a strong predictor of Anopheles abundance. Houses without an LLIN had more female Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus than houses where some people used an LLIN (rate ratios, 95% CI 0.87, 0.85-0.89; 0.84, 0.82-0.86; 0.38, 0.37-0.40) and houses where everyone used an LLIN (RR, 95% CI 0.49, 0.48-0.50; 0.39, 0.39-0.40; 0.60, 0.58-0.61). Cooking in the house also reduced Anopheles abundance across all species. The number of people sleeping in the house, presence of cattle near the house

Long-Lasting Insecticidal Nets Are Synergistic with Mass Drug Administration for Interruption of Lymphatic Filariasis Transmission in Nigeria

PubMed Central

Eigege, Abel; Miri, Emmanuel; Sallau, Adamu; Umaru, John; Mafuyai, Hayward; Chuwang, Yohanna S.; Danjuma, Goshit; Danboyi, Jacob; Adelamo, Solomon E.; Mancha, Bulus S.; Okoeguale, Bridget; Patterson, Amy E.; Rakers, Lindsay; Richards, Frank O.

2013-01-01

In central Nigeria Anopheles mosquitoes transmit malaria and lymphatic filariasis (LF). The strategy used for interrupting LF transmission in this area is annual mass drug administration (MDA) with albendazole and ivermectin, but after 8 years of MDA, entomological evaluations in sentinel villages showed continued low-grade mosquito infection rates of 0.32%. After long-lasting insecticidal net (LLIN) distribution by the national malaria program in late 2010, however, we were no longer able to detect infected vectors over a 24-month period. This is evidence that LLINs are synergistic with MDA in interrupting LF transmission. PMID:24205421

Physical condition and maintenance of mosquito bed nets in Kwale County, coastal Kenya

PubMed Central

2013-01-01

Background Despite the extensive ownership and use of insecticide-treated nets (ITNs) over the last decade, the effective lifespan of these nets, especially their physical integrity, under true operational conditions is not well-understood. Usefulness of nets declines primarily due to physical damage or loss of insecticidal activity. Methods A community based cross-sectional survey was used to determine the physical condition and to identify predictors of poor physical condition for bed nets owned by individuals from communities in Kwale County, coastal Kenya. A proportionate hole index (pHI) was used as a standard measure, and the cut-offs for an ‘effective net’ (offer substantial protection against mosquito bites) and ‘ineffective nets’ (offer little or no protection against mosquito bites) were determined (pHI ≤88 (about ≤500 cm2 of holes surface area) and pHI of >88 (≥500 cm2 of holes surface area), respectively). Results The vast majority (78%) of the surveyed nets had some holes. The median pHI was 92 (range: 1–2,980). Overall, half of the nets were categorized as ‘effective nets’ or ‘serviceable nets’. Physical deterioration of nets was associated with higher use and washing frequency. Young children and older children were found to use ineffective bed nets significantly more often than infants, while the physical integrity of nets owned by pregnant women was similar to those owned by infants. Estuarine environment inhabitants owned nets with the worst physical condition, while nets owned by the coastal slope inhabitants were in fairly good physical condition. The results suggest that bed nets are optimally utilized when they are new and physically intact. Thereafter, bed net utilization decreases gradually with increasing physical deterioration, with most net owners withdrawing physically damaged nets from routine use. This withdrawal commonly happens following 1.5 years of use, making bed net use the most important predictor of

Insecticide-Treated Nets Utilization and Associated Factors among under-5 Years Old Children in Mirab-Abaya District, Gamo-Gofa Zone, Ethiopia.

PubMed

Admasie, Amha; Zemba, Amanuel; Paulos, Wondimagegn

2018-01-01

Malaria can be prevented using cost-effective interventions. It can be prevented at large via the use of insecticide-treated mosquito nets (ITNs). The use of ITNs decreases malaria mortality rates by 55% in under-5 years old children in Africa, Ethiopia, realizing the effectiveness, scaling up distribution and utilization of ITNs to cover 100% of children less than 5 years of age. However, little is known about ITNs utilization and factors associated with the utilization in under-5 years old children in the study area yet. The purpose of this study was to assess the level and associated factors of ITNs utilization in under-5 years old children among households with under-5 years old children of Mirab Abaya District, Gamo Gofa Zone, Ethiopia. A community-based cross-sectional study was conducted during August-September, 2016. Six study Kebeles were identified by simple random sampling technique and 398 households with at least one under-5 years old children were selected by random sampling technique using computer generated random numbers from health post family folders. Structured, interviewer questionnaire was administered to mothers or care givers of the children. Data were entered to Epi Info Version 3.5 and analyzed in SPSS version 21 statistical software. Bivariate and multivariate logistic regression analysis was done. P -value <0.05 and odds ratio with 95% confidence interval were used for the determination of associations between dependent and predictor variables. Results were presented in narrations, tables, and graph. Among 398 under-5 years old children assessed, the majority, 362 (91.0%) of them had access to ITN, but only 137 (37.2%) of the child had ITNs utilization during the previous night prior to the survey. Households with age of mothers or caretakers 31-44 years, AOR = 0.03, 95% CI (0.01-0.07) and ≥45 years of age; AOR = 0.05, 95% CI (0.01-0.58); households with family size ≤5 members, AOR = 11.23, 95% CI (4

Markets, voucher subsidies and free nets combine to achieve high bed net coverage in rural Tanzania.

PubMed

Khatib, Rashid A; Killeen, Gerry F; Abdulla, Salim M K; Kahigwa, Elizeus; McElroy, Peter D; Gerrets, Rene P M; Mshinda, Hassan; Mwita, Alex; Kachur, S Patrick

2008-06-02

Tanzania has a well-developed network of commercial ITN retailers. In 2004, the government introduced a voucher subsidy for pregnant women and, in mid 2005, helped distribute free nets to under-fives in small number of districts, including Rufiji on the southern coast, during a child health campaign. Contributions of these multiple insecticide-treated net delivery strategies existing at the same time and place to coverage in a poor rural community were assessed. Cross-sectional household survey in 6,331 members of randomly selected 1,752 households of 31 rural villages of Demographic Surveillance System in Rufiji district, Southern Tanzania was conducted in 2006. A questionnaire was administered to every consenting respondent about net use, treatment status and delivery mechanism. Net use was 62.7% overall, 87.2% amongst infants (0 to 1 year), 81.8% amongst young children (>1 to 5 years), 54.5% amongst older children (6 to 15 years) and 59.6% amongst adults (>15 years). 30.2% of all nets had been treated six months prior to interview. The biggest source of nets used by infants was purchase from the private sector with a voucher subsidy (41.8%). Half of nets used by young children (50.0%) and over a third of those used by older children (37.2%) were obtained free of charge through the vaccination campaign. The largest source of nets amongst the population overall was commercial purchase (45.1% use) and was the primary means for protecting adults (60.2% use). All delivery mechanisms, especially sale of nets at full market price, under-served the poorest but no difference in equity was observed between voucher-subsidized and freely distributed nets. All three delivery strategies enabled a poor rural community to achieve net coverage high enough to yield both personal and community level protection for the entire population. Each of them reached their relevant target group and free nets only temporarily suppressed the net market, illustrating that in this setting that

The impact of a hybrid social marketing intervention on inequities in access, ownership and use of insecticide-treated nets.

PubMed

Agha, Sohail; Van Rossem, Ronan; Stallworthy, Guy; Kusanthan, Thankian

2007-01-29

An ITN intervention was initiated in three predominantly rural districts of Eastern Province, Zambia, that lacked commercial distribution and communication infrastructures. Social marketing techniques were used for product and message development. Public sector clinics and village-based volunteers promoted and distributed subsidized ITNs priced at 2.5 dollars per net. A study was conducted to assess the effects of the intervention on inequities in knowledge, access, ownership and use of ITNs. A post-test only quasi-experimental study design was used to compare intervention and comparison districts. A total of 2,986 respondents were interviewed. Survey respondents were grouped into four socio-economic (SES) categories: low, medium-low, medium and high. Knowledge, access, ownership and use indicators are compared. Concentration index scores are calculated. Interactions between intervention status and SES help determine how different SES groups benefited from the intervention. Although overall use of nets remained relatively low, post-test data show that knowledge, access, ownership and use of mosquito nets was higher in intervention districts. A decline in SES inequity in access to nets occurred in intervention districts, resulting from a disproportionately greater increase in access among the low SES group. Declines in SES inequities in net ownership and use of nets were associated with the intervention. The largest increases in net ownership and use occurred among medium and high SES categories. Increasing access to nets among the poorest respondents in rural areas may not lead to increases in net use unless the price of nets is no longer a barrier to their purchase.

Reproduction by an altricial songbird, the red-winged blackbird, in fields treated with the organophosphate insecticide fenthion

USGS Publications Warehouse

Powell, G.V.N.

1984-01-01

(1) Breeding red-winged blackbirds were used as a model to study the effects of a single application of an organophosphate insecticide, fenthion, on reproduction of altricial songbirds..... (2) The insecticide had no significant effect on frequency of nest abandonment, clutch size, hatching success, or fledgling success..... (3) Growth rates of young nestlings were lower in nests on one of two treated areas, but overall growth rates of survivors were not significantly different from controls in nests on nearby unsprayed areas....(4) The insecticide had no measured effect on male spatial organization....(5) Measures of abundance of the principal nestling food item, noctuid larvae, showed that one application of the msecticide significantly reduced the abundance of the food supply, but the reduction of food supply did not result in a decrease in nestling growth rates or fledgling success.

Impact of long-lasting, insecticidal nets on anaemia and prevalence of Plasmodium falciparum among children under five years in areas with highly resistant malaria vectors.

PubMed

Tokponnon, Filémon T; Ogouyémi, Aurore Hounto; Sissinto, Yolande; Sovi, Arthur; Gnanguenon, Virgile; Cornélie, Sylvie; Adéothy, Adicath Adéola; Ossè, Razaki; Wakpo, Abel; Gbénou, Dina; Oke, Mariam; Kinde-Gazard, Dorothée; Kleinschmidt, Immo; Akogbeto, Martin C; Massougbodji, Achille

2014-03-01

The widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN-based interventions and perhaps reverse progress in reducing malaria morbidity. To prevent such difficulty, it is important to know the real impact of resistance in the effectiveness of mosquito nets. Therefore, an assessment of LLIN efficacy was conducted in malaria prevention among children in high and low resistance areas. The study was conducted in four rural districts and included 32 villages categorized as low or high resistance areas in Plateau Department, south-western Benin. Larvae collection was conducted to measure vector susceptibility to deltamethrin and knockdown resistance (kdr) frequency. In each resistance area, around 500 children were selected to measure the prevalence of malaria infection as well as the prevalence of anaemia associated with the use of LLINs. Observed mortalities of Anopheles gambiae s.s population exposed to deltamethrin ranged from 19 to 96%. Knockdown resistance frequency was between 38 and 84%. The prevalence of malaria infection in children under five years was 22.4% (19.9-25.1). This prevalence was 17.3% (14.2-20.9) in areas of high resistance and 27.1% (23.5-31.1) in areas of low resistance (p=0.04). Eight on ten children that were aged six - 30 months against seven on ten of those aged 31-59 months were anaemic. The anaemia observed in the six to 30-month old children was significantly higher than in the 31-59 month old children (p=0.00) but no difference associated with resistance areas was observed (p=0.35). The net use rate was 71%. The risk of having malaria was significantly reduced (p<0.05) with LLIN use in both low and high resistance areas. The preventive effect of LLINs in high resistance areas was 60% (95% CI: 40-70), and was significantly higher than that observed in low resistance areas (p<0.05). The results of this study showed that the

Clustering of host-seeking activity of Anopheles gambiae mosquitoes at the top surface of a human-baited bed net

PubMed Central

2013-01-01

Background Knowledge of the interactions between mosquitoes and humans, and how vector control interventions affect them, is sparse. A study exploring host-seeking behaviour at a human-occupied bed net, a key event in such interactions, is reported here. Methods Host-seeking female Anopheles gambiae activity was studied using a human-baited ‘sticky-net’ (a bed net without insecticide, coated with non-setting adhesive) to trap mosquitoes. The numbers and distribution of mosquitoes captured on each surface of the bed net were recorded and analysed using non-parametric statistical methods and random effects regression analysis. To confirm sticky-net reliability, the experiment was repeated using a pitched sticky-net (tilted sides converging at apex, i.e., neither horizontal nor vertical). The capture efficiency of horizontal and vertical sticky surfaces were compared, and the potential repellency of the adhesive was investigated. Results In a semi-field experiment, more mosquitoes were caught on the top (74-87%) than on the sides of the net (p < 0.001). In laboratory experiments, more mosquitoes were caught on the top than on the sides in human-baited tests (p < 0.001), significantly different to unbaited controls (p < 0.001) where most mosquitoes were on the sides (p = 0.047). In both experiments, approximately 70% of mosquitoes captured on the top surface were clustered within a 90 × 90 cm (or lesser) area directly above the head and chest (p < 0.001). In pitched net tests, similar clustering occurred over the sleeper’s head and chest in baited tests only (p < 0.001). Capture rates at horizontal and vertical surfaces were not significantly different and the sticky-net was not repellent. Conclusion This study demonstrated that An. gambiae activity occurs predominantly within a limited area of the top surface of bed nets. The results provide support for the two-in-one bed net design for managing pyrethroid-resistant vector populations

Mathematical evaluation of community level impact of combining bed nets and indoor residual spraying upon malaria transmission in areas where the main vectors are Anopheles arabiensis mosquitoes.

PubMed

Okumu, Fredros O; Kiware, Samson S; Moore, Sarah J; Killeen, Gerry F

2013-01-16

Indoor residual insecticide spraying (IRS) and long-lasting insecticide treated nets (LLINs) are commonly used together even though evidence that such combinations confer greater protection against malaria than either method alone is inconsistent. A deterministic model of mosquito life cycle processes was adapted to allow parameterization with results from experimental hut trials of various combinations of untreated nets or LLINs (Olyset, PermaNet 2.0, Icon Life nets) with IRS (pirimiphos methyl, lambda cyhalothrin, DDT), in a setting where vector populations are dominated by Anopheles arabiensis, so that community level impact upon malaria transmission at high coverage could be predicted. Intact untreated nets alone provide equivalent personal protection to all three LLINs. Relative to IRS plus untreated nets, community level protection is slightly higher when Olyset or PermaNet 2.0 nets are added onto IRS with pirimiphos methyl or lambda cyhalothrin but not DDT, and when Icon Life nets supplement any of the IRS insecticides. Adding IRS onto any net modestly enhances communal protection when pirimiphos methyl is sprayed, while spraying lambda cyhalothrin enhances protection for untreated nets but not LLINs. Addition of DDT reduces communal protection when added to LLINs. Where transmission is mediated primarily by An. arabiensis, adding IRS to high LLIN coverage provides only modest incremental benefit (e.g. when an organophosphate like pirimiphos methyl is used), but can be redundant (e.g. when a pyrethroid like lambda cyhalothin is used) or even regressive (e.g. when DDT is used for the IRS). Relative to IRS plus untreated nets, supplementing IRS with LLINs will only modestly improve community protection. Beyond the physical protection that intact nets provide, additional protection against transmission by An. arabiensis conferred by insecticides will be remarkably small, regardless of whether they are delivered as LLINs or IRS. The insecticidal action of LLINs

Insecticide treated curtains and residual insecticide treatment to control Aedes aegypti: An acceptability study in Santiago de Cuba.

PubMed

Pérez, Dennis; Van der Stuyft, Patrick; Toledo, María Eugenia; Ceballos, Enrique; Fabré, Francisco; Lefèvre, Pierre

2018-01-01

Within the context of a field trial conducted by the Cuban vector control program (AaCP), we assessed acceptability of insecticide-treated curtains (ITCs) and residual insecticide treatment (RIT) with deltamethrin by the community. We also assessed the potential influence of interviewees' risk perceptions for getting dengue and disease severity. We embedded a qualitative study using in-depth interviews in a cluster randomized trial (CRT) testing the effectiveness of ITCs and RIT in Santiago de Cuba. In-depth interviews (N = 38) were conducted four and twelve months after deployment of the tools with people who accepted the tools, who stopped using them and who did not accept the tools. Data analysis was deductive. Main reasons for accepting ITCs at the start of the trial were perceived efficacy and not being harmful to health. Constraints linked to manufacturer instructions were the main reason for not using ITCs. People stopped using the ITCs due to perceived allergy, toxicity and low efficacy. Few heads of households refused RIT despite the noting reasons for rejection, such as allergy, health hazard and toxicity. Positive opinions of the vector control program influenced acceptability of both tools. However, frequent insecticide fogging as part of routine AaCP vector control actions diminished perceived efficacy of both tools and, therefore, acceptability. Fifty percent of interviewees did feel at risk for getting dengue and considered dengue a severe disease. However, this did not appear to influence acceptability of ITCs or RIT. Acceptability of ITCs and RIT was linked to acceptability of AaCP routine vector control activities. However, uptake and use were not always an indication of acceptability. Factors leading to acceptability may be best identified using qualitative methods, but more research is needed on the concept of acceptability and its measurement.

Long-lasting insecticidal net source, ownership and use in the context of universal coverage: a household survey in eastern Rwanda.

PubMed

Kateera, Fredrick; Ingabire, Chantal M; Hakizimana, Emmanuel; Rulisa, Alexis; Karinda, Parfait; Grobusch, Martin P; Mutesa, Leon; van Vugt, Michèle; Mens, Petra F

2015-10-06

Universal long-lasting insecticidal net (LLIN) coverage (ULC) has reduced malaria morbidity and mortality across Africa. Although information is available on bed net use in specific groups, such as pregnant women and children under 5 years, there is paucity of data on their use among the general population. Bed net source, ownership and determinants of use among individuals from households in an eastern Rwanda community 8 months after a ULC were characterized. Using household-based, interviewer-administered questionnaires and interviewer-direct observations, data on bed net source, ownership and key determinants of net use, including demographics, socio-economic status indicators, house structure characteristics, as well as of bed net quantity, type and integrity, were collected from 1400 randomly selected households. Univariate and mixed effects logistic regression modelling was done to assess for determinants of bed net use. A total of 1410 households and 6598 individuals were included in the study. Overall, the proportion of households with at least one net was 92 % while bed net usage was reported among 72 % of household members. Of the households surveyed, a total ownership of 2768 nets was reported, of which about 96 % were reportedly LLINs received from the ULC. By interviewer-physical observation, 88 % of the nets owned were of the LLIN type with the remaining 12 % did not carry any mark to enable type recognition. The odds of bed net use were significantly lower among males and individuals: from households of low socio-economic status, from households with nets, from households reporting use of ≥two sleeping spaces, and those reporting to have not slept on a bed. In this study, despite high a bed net coverage, over 25 % of members reported not to have slept under a bed net the night before the survey. Males were particularly less likely to use bed nets even where nets were available. Household socio-economic status, number of bed nets and type

Gender differences in the use of insecticide-treated nets after a universal free distribution campaign in Kano State, Nigeria: post-campaign survey results.

PubMed

Garley, Ashley E; Ivanovich, Elizabeth; Eckert, Erin; Negroustoueva, Svetlana; Ye, Yazoume

2013-04-10

Recent expansion in insecticide-treated net (ITN) distribution strategies range from targeting pregnant women and children under five and distributing ITN at antenatal care and immunization programmes, to providing free distribution campaigns to cover an entire population. These changes in strategy raise issues of disparities, such as equity of access and equality in ITN use among different groups, including females and males. Analysis is needed to assess the effects of gender on uptake of key malaria control interventions. A recent post-universal free ITN distribution campaign survey in Kano State, Nigeria offered an opportunity to look at gender effects on ITN use. A post-campaign survey was conducted three to five months after the campaign in Kano State, Nigeria from 19 October to 4 November, 2009, on a random sample of 4,602 individuals. The survey was carried out using a questionnaire adapted from the Malaria Indicator Survey. Using binary logistic regression, controlling for several covariates, the authors assessed gender effects on ITN use among individuals living in households with at least one ITN. The survey showed that household ITN ownership increased more than 10-fold, from 6% before to 71% after the campaign. There was no significant difference between the proportion of females and males living in households with at least one ITN. However, a higher percentage of females used ITNs compared to males (57.2% vs 48.8%). After controlling for several covariates, females remained more likely to use ITNs compared to males (OR: 1.5, 95% CI: 1.3-1.7). Adolescent boys remained the least likely group to use an ITN. This study reveals gender disparity in ITN use, with males less likely to use ITNs particularly among ages 15-25 years. The uptake of the intervention among the most at-risk group (females) is higher than males, which may be reflective of earlier strategies for malaria interventions. Further research is needed to identify whether gender disparities

Genetic variation associated with increased insecticide resistance in the malaria mosquito, Anopheles coluzzii.

PubMed

Main, Bradley J; Everitt, Amanda; Cornel, Anthony J; Hormozdiari, Fereydoun; Lanzaro, Gregory C

2018-04-04

Malaria mortality rates in sub-Saharan Africa have declined significantly in recent years as a result of increased insecticide-treated bed net (ITN) usage. A major challenge to further progress is the emergence and spread of insecticide resistance alleles in the Anopheles mosquito vectors, like An. coluzzii. A non-synonymous mutation in the para voltage-gated sodium channel gene reduces pyrethroid-binding affinity, resulting in knockdown resistance (kdr). Metabolic mechanisms of insecticide resistance involving detoxification genes like cytochrome P450 genes, carboxylesterases, and glutathione S-transferases are also important. As some gene activity is tissue-specific and/or environmentally induced, gene regulatory variation may be overlooked when comparing expression from whole mosquito bodies under standard rearing conditions. We detected complex insecticide resistance in a 2014 An. coluzzii colony from southern Mali using bottle bioassays. Additional bioassays involving recombinant genotypes from a cross with a relatively susceptible 1995 An. coluzzii colony from Mali confirmed the importance of kdr and associated increased permethrin resistance to the CYP9K1 locus on the X chromosome. Significant differential expression of CYP9K1 was not observed among these colonies in Malpighian tubules. However, the P450 gene CYP6Z1 was overexpressed in resistant individuals following sublethal permethrin exposure and the carboxylesterase gene COEAE5G was constitutively overexpressed. The significant P450-related insecticide resistance observed in the 2014 An. coluzzii colony indicates that ITNs treated with the P450 inhibitor piperonyl butoxide (PBO) would be more effective in this region. The known insecticide resistance gene CYP6Z1 was differentially expressed exclusively in the context of sublethal permethrin exposure, highlighting the importance of tissue-specificity and environmental conditions in gene expression studies. The increased activity of the carboxylesterase

Determinants of household demand for bed nets in a rural area of southern Mozambique

PubMed Central

Chase, Claire; Sicuri, Elisa; Sacoor, Charfudin; Nhalungo, Delino; Nhacolo, Ariel; Alonso, Pedro L; Menéndez, Clara

2009-01-01

Background A key to making insecticide-treated nets (ITNs) a long-term, sustainable solution to the spread of malaria is understanding what drives their purchase and use. Few studies have analysed the determinants of demand for bed nets for malaria prevention at the household level, and in particular, how demand for nets compares with demand for other mosquito prevention methods. Methods This study uses a household survey to assess the determinants of demand for bed nets in an area of endemic malaria transmission in rural, southern Mozambique. The study looks at willingness to pay (WTP) for bed nets, net ownership, usage, and past purchase behaviour, alongside expenditure and frequency of use of alternate methods for malaria prevention. Results While overall net ownership in the sample is low, the evidence fails to suggest that poorer households are less likely to own bed nets, when controlling for covariates, nor does the likelihood of receiving a free net depend on socioeconomic status (SES). Formal schooling and market knowledge seem to indicate higher average willingness to pay, while use of alternate methods for malaria prevention, and receipt of Indoor Residual Spraying (IRS) are found to decrease demand for bed nets. Conclusion For long-term sustainability of ITNs to be realized, results suggest that either full or partial subsidies may be necessary in some contexts to encourage households to obtain and use nets. Given the possible substitution effects of combined malaria control interventions, and the danger of not taking into consideration household preferences for malaria prevention, successful malaria control campaigns should invest a portion of their funds towards educating recipients of IRS and users of other preventive methods on the importance of net use even in the absence of mosquitoes. PMID:19527505

The paradigm of eave tubes: scaling up house improvement and optimizing insecticide delivery against disease-transmitting mosquitoes.

PubMed

Okumu, Fredros

2017-05-19

Control of mosquito-borne diseases is greatly compromised by spread of insecticide resistance, high implementation costs and sub-optimal compliance among users. Improved housing has potential to reduce malaria transmission nearly as much as long-lasting insecticide-treated nets (LLINs), while also preventing other arthropod-borne diseases and improving overall well-being. Yet, it is hardly promoted as mainstream intervention, partly because of high costs, minimal communal benefits to people in non-improved houses, and low scalability. By exploiting biological observations of mosquito behaviours around dwellings, scientists have developed a new approach that integrates effective vector control into housing developments. The technique involves blocking eave spaces in local houses, leaving a few cylindrical holes into which plastic tubes with insecticide-laden electrostatic nettings are inserted. Where houses already have blocked eaves, these cylindrical holes are drilled and the tubes inserted. The eave tube technology, as it is called, is an innovative new approach for implementing housing improvements, by creating a new scalable product that can be integrated in houses during or after construction. It takes away insecticides from proximity of users, and instead puts them where mosquitoes are most likely to enter houses, thereby reducing insecticidal exposure among household occupants, while maximizing exposure of mosquitoes. This way, lower quantities of insecticides are used, better house ventilation achieved, intervention costs reduced, and mass communal benefits achieved even were vectors are resistant to similar insecticides when delivered conventionally. There are however still some critical pieces missing, notably epidemiological, social and economic evidence that the above assertions are true and sustainable. Besides, there also some technical limitations to be considered, namely: (1) need for extensive house modifications before eave tubes are inserted, (2

Investigating a Non-Mesh Mosquito Net among Outdoor Sleeping Nomadic Communities in Kenya

PubMed Central

Gore-Langton, Georgia R.; Mungai, James; Alenwi, Nfornuh; Abagira, Abdullahi; Bicknell, Owen M.; Harrison, Rebecca E.; Hassan, Farah Amin; Munga, Stephen; Eves, Katie; Juma, Elizabeth; Allan, Richard

2015-01-01

Rising reports of exophagic malaria vectors make even more pressing the need for alternatives to traditional, mesh, long-lasting insecticidal nets (LLINs) designed for indoor sleeping and often inadequate in the protection of outdoor-sleeping populations. This study tests and evaluates the retention, utilization, and durability of novel, non-mesh nets designed for outdoor use. Longitudinal, cross-sectional surveys were conducted, the physical condition of nets was assessed, and bio-efficacy and insecticide content were tested. At 22 months, retention was 98.0%; 97.1% of nets fell within the World Health Organization (WHO) category of being in “good” condition; none were in the “torn” category. At 18 months post-distribution, 100% of nets had at least WHO Pesticide Evaluation Scheme (WHOPES)-acceptable levels of insecticide, this proportion was 66.7% at 22 months. This novel mosquito net has the potential to provide a durable and context-specific tool to prevent malaria among traditionally hard-to-protect and highly vulnerable populations. PMID:26416107

Assessing healthcare providers' knowledge and practices relating to insecticide-treated nets and the prevention of malaria in Ghana, Laos, Senegal and Tanzania.

PubMed

Hoffman, Steven J; Guindon, G Emmanuel; Lavis, John N; Ndossi, Godwin D; Osei, Eric J A; Sidibe, Mintou Fall; Boupha, Boungnong

2011-12-13

Research evidence is not always being disseminated to healthcare providers who need it to inform their clinical practice. This can result in the provision of ineffective services and an inefficient use of resources, the implications of which might be felt particularly acutely in low- and middle-income countries. Malaria prevention is a particularly compelling domain to study evidence/practice gaps given the proven efficacy, cost-effectiveness and disappointing utilization of insecticide-treated nets (ITNs). This study compares what is known about ITNs to the related knowledge and practices of healthcare providers in four low- and middle-income countries. A new questionnaire was developed, pilot tested, translated and administered to 497 healthcare providers in Ghana (140), Laos (136), Senegal (100) and Tanzania (121). Ten questions tested participants' knowledge and clinical practice related to malaria prevention. Additional questions addressed their individual characteristics, working context and research-related activities. Ordinal logistic regressions with knowledge and practices as the dependent variable were conducted in addition to descriptive statistics. The survey achieved a 75% response rate (372/497) across Ghana (107/140), Laos (136/136), Senegal (51/100) and Tanzania (78/121). Few participating healthcare providers correctly answered all five knowledge questions about ITNs (13%) or self-reported performing all five clinical practices according to established evidence (2%). Statistically significant factors associated with higher knowledge within each country included: 1) training in acquiring systematic reviews through the Cochrane Library (OR 2.48, 95% CI 1.30-4.73); and 2) ability to read and write English well or very well (OR 1.69, 95% CI 1.05-2.70). Statistically significant factors associated with better clinical practices within each country include: 1) reading scientific journals from their own country (OR 1.67, 95% CI 1.10-2.54); 2) working

Community point distribution of insecticide-treated bed nets and community health worker hang-up visits in rural Zambia: a decision-focused evaluation.

PubMed

Wang, Paul; Connor, Alison L; Joudeh, Ammar S; Steinberg, Jeffrey; Ndhlovu, Ketty; Siyolwe, Musanda; Ntebeka, Bristol; Chibuye, Benjamin; Hamainza, Busiku

2016-03-03

In 2013, the Zambian Ministry of Health through its National Malaria Control Programme distributed over two million insecticide-treated bed nets (ITNs) in four provinces using a door-to-door distribution strategy, and more than 6 million ITNs were allocated to be distributed in 2014. This study was commissioned to measure attendance rates at a community point distribution and to examine the impact of follow-up community health worker (CHW) hang-up visits on short and medium-term ITN retention and usage with a view of informing optimal ITN distribution strategy in Zambia. Households received ITNs at community point distributions conducted in three rural communities in Rufunsa District, Zambia. Households were then randomly allocated into five groups to receive CHW visits to hang any unhung ITNs at different intervals: 1-3, 5-7, 10-12, 15-17 days, and no hang-up visit. Follow-up surveys were conducted among all households at 7-11 weeks after distribution and at 5-6 months after distribution to measure short- and medium-term household retention and usage of ITNs. Of the 560 pre-registered households, 540 (96.4 %) attended the community point distribution. Self-installation of ITNs by households increased over the first 10 days after the community point distribution. Retention levels remained high over time with 90.2 % of distributed ITNs still in the household at 7-11 weeks and 85.7 % at 5-6 months. Retention did not differ between households that received a CHW visit and those that did not. At 7-11 weeks, households had an average of 73.8 % of sleeping spaces covered compared to 80.3 % at 5-6 months. On average, 65.6 % of distributed ITNs were hanging at 7-11 weeks compared to 63.1 % at 5-6 months. While a CHW hang-up visit was associated with increased usage at 7-11 weeks, this difference was no longer apparent at 5-6 months. This evaluation revealed that (1) the community point distributions achieved high attendance rates followed by acceptable rates of short

Widespread mosquito net fishing in the Barotse floodplain: Evidence from qualitative interviews

PubMed Central

Mulenga, Angela; Reid, Robert

2018-01-01

Background The insecticide-treated mosquito net (ITN) is a crucial component of malaria control programs, and has prevented many malaria cases and deaths due to scale up. ITNs also serve effectively as fishing nets and various sources have reported use of ITNs for fishing. This article examines how widespread the practice of mosquito net fishing with ITNs is. Methods We conducted in-depth interviews with fishery personnel and traditional leadership from the Barotse Royal Establishment in Western Province, Zambia, to better understand the presence or absence of the use of ITNs as fishing nets. We then coded the interviews for themes through content analysis. Additionally we conducted a desk review of survey data to show trends in malaria indicators, nutritional status of the population and fish consumption. Results All those interviewed reported that ITNs are regularly used for fishing in Western Zambia and the misuse is widespread. Concurrently those interviewed reported declines in fish catches both in terms of quantity and quality leading to threatened food security in the area. In addition to unsustainable fishing practices those interviewed referenced drought and population pressure as reasons for fishery decline. Malaria indicators do not show a trend in declining malaria transmission, fish consumption has dropped dramatically and nutritional status has not improved over time. Conclusions Despite the misuse of the ITNs for fishing all those interviewed maintained that ITN distribution should continue. Donors, control programs and scientists should realize that misuse of ITNs as fishing nets is a current problem for malaria control and potentially for food security that needs to be addressed. PMID:29719003

Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial

PubMed Central

Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

2015-01-01

Background Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. Methods A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4–6 weeks after the second intervention (March to April 2014). Results Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Conclusions Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. PMID:25604762

Impact of operational effectiveness of long-lasting insecticidal nets (LLINs) on malaria transmission in pyrethroid-resistant areas

PubMed Central

2013-01-01

Background A dynamic study on the transmission of malaria was conducted in two areas (R+ area: Low resistance area; R+++ area: High resistance area) in the department of Plateau in South Eastern Benin, where the population is protected by Long Lasting Insecticidal Nets (LLINs). The aim of this study was to determine if the resistance of malaria vectors to insecticides has an impact on their behavior and on the effectiveness of LLINs in the reduction of malaria transmission. Methods Populations of Anopheles gambiae s.l. were sampled monthly by human landing catch in the two areas to evaluate human biting rates (HBR). Collected mosquitoes were identified morphologically and female Anopheles mosquitoes were tested for the presence of Plasmodium falciparum antigen as assessed using ELISA. The entomological inoculation rate (EIR) was also calculated (EIR = HBR x sporozoitic index [S]). We estimated the parity rate by dissecting the females of An. gambiae. Finally, window catch and spray catch were conducted in order to assess the blood feeding rate and the exophily rate of vectors. Results After 6 months of tracking the mosquito's behavior in contact with the LLINs (Olyset) in R+++ and R+ areas, the entomological indicators of the transmission of malaria (parity rate and sporozoitic index) were similar in the two areas. Also, An. gambiae populations showed the same susceptibility to P. falciparum in both R+ and R+++ areas. The EIR and the exophily rate are higher in R+ area than in R+++ area. But the blood-feeding rate is lower in R+ area comparing to R+++. Conclusion The highest entomological inoculation rate observed in R+ area is mostly due to the strong aggressive density of An. gambiae recorded in one of the study localities. On the other hand, the highest exophily rate and the low blood-feeding rate recorded in R+ area compared to R+++ area are not due to the resistance status of An. gambiae, but due to the differences in distribution and availability of

Use of insecticide-treated school uniforms for prevention of dengue in schoolchildren: a cost-effectiveness analysis.

PubMed

Tozan, Yesim; Ratanawong, Pitcha; Louis, Valérie R; Kittayapong, Pattamaporn; Wilder-Smith, Annelies

2014-01-01

Dengue-related illness is a leading cause of hospitalization and death, particularly among children. Practical, acceptable and affordable measures are urgently needed to protect this age group. Schools where children spend most of their day is proposed as an ideal setting to implement preventive strategies against day-biting Aedes mosquitoes. The use of insecticide-treated school uniforms is a promising strategy currently under investigation. Using a decision-analytic model, we evaluated the cost-effectiveness of the use of insecticide-treated school uniforms for prevention of dengue, compared with a "do-nothing" alternative, in schoolchildren from the societal perspective. We explored how the potential economic value of the intervention varied under various scenarios of intervention effectiveness and cost, as well as dengue infection risk in school-aged children, using data specific to Thailand. At an average dengue incidence rate of 5.8% per year in school-aged children, the intervention was cost-effective (ICER≤$16,440) in a variety of scenarios when the intervention cost per child was $5.3 or less and the intervention effectiveness was 50% or higher. In fact, the intervention was cost saving (ICER<0) in all scenarios in which the intervention cost per child was $2.9 or less per year and the intervention effectiveness was 50% or higher. The results suggested that this intervention would be of no interest to Thai policy makers when the intervention cost per child was $10.6 or higher per year regardless of intervention effectiveness (ICER>$16,440). Our results present the potential economic value of the use of insecticide-treated uniforms for prevention of dengue in schoolchildren in a typical dengue endemic setting and highlight the urgent need for additional research on this intervention.

Wealth, mother's education and physical access as determinants of retail sector net use in rural Kenya

PubMed Central

2006-01-01

Background Insecticide-treated bed nets (ITN) provide real hope for the reduction of the malaria burden across Africa. Understanding factors that determine access to ITN is crucial to debates surrounding the optimal delivery systems. The influence of homestead wealth on use of nets purchased from the retail sector is well documented, however, the competing influence of mother's education and physical access to net providers is less well understood. Methods Between December 2004 and January 2005, a random sample of 72 rural communities was selected across four Kenyan districts. Demographic, assets, education and net use data were collected at homestead, mother and child (aged < 5 years) levels. An assets-based wealth index was developed using principal components analysis, travel time to net sources was modelled using geographic information systems, and factors influencing the use of retail sector nets explored using a multivariable logistic regression model. Results Homestead heads and guardians of 3,755 children < 5 years of age were interviewed. Approximately 15% (562) of children slept under a net the night before the interview; 58% (327) of the nets used were purchased from the retail sector. Homestead wealth (adjusted OR = 10.17, 95% CI = 5.45–18.98), travel time to nearest market centres (adjusted OR = 0.51, 95% CI = 0.37–0.72) and mother's education (adjusted OR = 2.92, 95% CI = 1.93–4.41) were significantly associated with use of retail sector nets by children aged less than 5 years. Conclusion Approaches to promoting access to nets through the retail sector disadvantage poor and remote communities where mothers are less well educated. PMID:16436216

Lantos-Hyde United States Government Malaria Strategy, 2009-2014

DTIC Science & Technology

2010-04-25

Long lasting insecticide -treated nets (LLINs); • Indoor residual spraying (IRS) with insecticides ; • Intermittent preventive treatment of...measures: insecticide -treated mosquito nets (ITNs); indoor residual spraying (IRS) of insecticides ; artemisinin-based combination therapy (ACTs); and...is national policy. Indoor residual spraying : Between 2005 and 2009, PMI supported the introduction or

Rural households at risk of malaria did not own sufficient insecticide treated nets at Dabat HDSS site: evidence from a cross sectional re-census.

PubMed

Muchie, Kindie Fentahun; Alemu, Kassahun; Tariku, Amare; Tsegaye, Adino Tesfahun; Abebe, Solomon Mekonnen; Yitayal, Mezgebu; Awoke, Tadesse; Biks, Gashaw Andargie

2017-11-21

Malaria is the leading cause of disease burden across the world, especially in African countries. Ethiopia has designed a five year (2011-2015) plan to cover 100% of the households in malarious areas with one insecticide treated net (ITN) for every two persons, and to raise consistent ITN utilization to at least 80%. However, evidence on ownership of ITN among malarious rural households in northwest Ethiopia is quite limited. Hence, the present study aimed at assessing ownership of ITN and associated factors among rural households at risk of malaria at Dabat Health and Demographic Surveillance System site, northwest Ethiopia. A cross sectional re-census was carried out in Dabat Health and Demographic Surveillance System site during peak malaria seasons from October to December, 2014. Data for 15,088 households at Dabat Health and Demographic Surveillance System site were used for the analysis. Descriptive measures and binary logistic regression were carried out. Among those who owned at least one ITN, 53.4% were living at an altitude >2500 m above sea level. However, out of households living at an altitude <2000 m above sea level, 15.8% (95% CI 14.4%, 17.3%) owned ITN at an average of 4.3 ± 2.1 persons per ITN. Of these, 69.5% (95% CI 64.7%, 74.1%) used the ITN. Among utilizing households at malarious areas, 23.7% prioritized pregnant women and 31.4% children to use ITN. The availability of radio receiver/mobile (AOR 1.60, 95%CI 1.08, 2.35) and secondary/above educational status of household member (AOR 1.54, 95%CI 1.19, 2.04) were predictors of ownership of ITN. Rural households at risk of malaria did not own a sufficient number of ITN though the utilization is promising. Moreover, prioritizing children and pregnant women to sleep under ITN remains public health problems. Programmers, partners and implementers should consider tailored intervention strategy stratified by altitude in distributing ITN. ITN distribution should also be accompanied by using

To assess whether indoor residual spraying can provide additional protection against clinical malaria over current best practice of long-lasting insecticidal mosquito nets in The Gambia: study protocol for a two-armed cluster-randomised trial

PubMed Central

2011-01-01

Background Recently, there has been mounting interest in scaling-up vector control against malaria in Africa. It needs to be determined if indoor residual spraying (IRS with DDT) will provide significant marginal protection against malaria over current best practice of long-lasting insecticidal nets (LLINs) and prompt treatment in a controlled trial, given that DDT is currently the most persistent insecticide for IRS. Methods A 2 armed cluster-randomised controlled trial will be conducted to assess whether DDT IRS and LLINs combined provide better protection against clinical malaria in children than LLINs alone in rural Gambia. Each cluster will be a village, or a group of small adjacent villages; all clusters will receive LLINs and half will receive IRS in addition. Study children, aged 6 months to 13 years, will be enrolled from all clusters and followed for clinical malaria using passive case detection to estimate malaria incidence for 2 malaria transmission seasons in 2010 and 2011. This will be the primary endpoint. Exposure to malaria parasites will be assessed using light and exit traps followed by detection of Anopheles gambiae species and sporozoite infection. Study children will be surveyed at the end of each transmission season to estimate the prevalence of Plasmodium falciparum infection and the prevalence of anaemia. Discussion Practical issues concerning intervention implementation, as well as the potential benefits and risks of the study, are discussed. Trial Registration ISRCTN01738840 - Spraying And Nets Towards malaria Elimination (SANTE) PMID:21663656

Insecticide susceptibility of Anopheles stephensi to DDT and current insecticides in an elimination area in Iran.

PubMed

Zare, Mehdi; Soleimani-Ahmadi, Moussa; Davoodi, Sayed Hossein; Sanei-Dehkordi, Alireza

2016-11-04

Iran has recently initiated a malaria elimination program with emphasis on vector control strategies which are heavily reliant on indoor residual spraying and long-lasting insecticidal nets. Insecticide resistance seriously threatens the efficacy of vector control strategies. This study was conducted to determine the insecticide susceptibility of Anopheles stephensi to DDT and current insecticides in Jask county as an active malaria focus in southeastern Iran. In this study, the anopheline larvae were collected from different aquatic habitats in Jask county and transported to insectarium, fed with sugar and then 3-day-old adults were used for susceptibility tests. WHO insecticide susceptibility tests were performed with DDT (4 %), malathion (5 %), lambda-cyhalothrin (0.05 %), deltamethrin (0.05 %) and permethrin (0.75 %). The field strain of An. stephensi was found resistant to DDT and lambda-cyhalothrin. The LT 50 values for DDT and lambda-cyhalothrin in this species were 130.25, and 37.71 min, respectively. Moreover, An. stephensi was completely susceptible to malathion and permethrin and tolerant to deltamethrin. The present study results confirm the resistance of the major malaria vector, An. stephensi, to DDT and lambda-cyhalothrin, and tolerance to deltamethrin, which could gradually increase and spread into other malaria endemic areas. Thus, there is a need for regular monitoring of insecticide resistance in order to select suitable insecticides for vector control interventions towards malaria elimination.

Long-term trends in Anopheles gambiae insecticide resistance in Côte d'Ivoire.

PubMed

Edi, Constant A V; Koudou, Benjamin G; Bellai, Louise; Adja, Akre M; Chouaibou, Mouhamadou; Bonfoh, Bassirou; Barry, Sarah J E; Johnson, Paul C D; Müller, Pie; Dongus, Stefan; N'Goran, Eliezer K; Ranson, Hilary; Weetman, David

2014-11-28

Malaria control is heavily dependent on the use of insecticides that target adult mosquito vectors via insecticide treated nets (ITNs) or indoor residual spraying (IRS). Four classes of insecticide are approved for IRS but only pyrethroids are available for ITNs. The rapid rise in insecticide resistance in African malaria vectors has raised alarms about the sustainability of existing malaria control activities. This problem might be particularly acute in Côte d'Ivoire where resistance to all four insecticide classes has recently been recorded. Here we investigate temporal trends in insecticide resistance across the ecological zones of Côte d'Ivoire to determine whether apparent pan-African patterns of increasing resistance are detectable and consistent across insecticides and areas. We combined data on insecticide resistance from a literature review, and bioassays conducted on field-caught Anopheles gambiae mosquitoes for the four WHO-approved insecticide classes for ITN/IRS. The data were then mapped using Geographical Information Systems (GIS) and the IR mapper tool to provide spatial and temporal distribution data on insecticide resistance in An. gambiae sensu lato from Côte d'Ivoire between 1993 and 2014. Bioassay mortality decreased over time for all insecticide classes, though with significant spatiotemporal variation, such that stronger declines were observed in the southern ecological zone for DDT and pyrethroids than in the central zone, but with an apparently opposite effect for the carbamate and organophosphate. Variation in relative abundance of the molecular forms, coupled with dramatic increase in kdr 1014F frequency in M forms (An. coluzzii) seems likely to be a contributory factor to these patterns. Although records of resistance across insecticide classes have become more common, the number of classes tested in studies has also increased, precluding a conclusion that multiple resistance has also increased. Our analyses attempted synthesis of 22�

Social marketing and the fight against malaria in Africa: population services international (PSI) and insecticide treated nets (ITNS).

PubMed

Omona, Julius

2009-12-01

This textual analyses on Social marketing, Insecticide Treated Nets (ITNs) and Population Services International (PSI) were undertaken to achieve two objectives: (a) to contribute to the continuing debate and search for a better strategy for combating malaria in sub-Saharan Africa; and (b) to contribute to theory building on social marketing. The analyses revealed that Malaria has reached an epidemic proportion and despite major inroads by PSI in combating malaria on the principles of social marketing, the strategies of pricing and segmentation of the clients are not appropriate for Sub-Saharan African countries that are mired in absolute poverty where majority of the rural communities eke a living on less than a dollar per day and the health sector does not receive priority attention from policy makers and politicians. The descriptive statistics and a one sample t test for the sampled countries suggest that sub-Saharan countries have not even met the hypothesized 5% investment of their GDP on health, compared to their counterparts, the developed countries, who are all above this figure. The null hypothesis that there is no significant different between the population and the sample means of both developed and a developing country in their investments in the health sector was also tested and rejected. Though the elements in some of the existent models and theories of social marketing such as Health Belief Model, Theory of Reasoned Action, Social Cognitive Theory and Trans-theoretical Models all attempt to advocate for elimination of constraints and barriers to effective access to a service or product, PSI is adamant to these and try to generalize these principles in all contexts, including in Sub-Saharan Africa. The African scenario, where about 90% of Malaria related deaths cases in the world occur, demands more than what these theories present. Accordingly, it was concluded that however good intentioned social marketing is, in the case of ITNs in this region, it

Decrease of insecticide resistance over generations without exposure to insecticides in Nilaparvata lugens (Hemipteran: Delphacidae).

PubMed

Yang, Yajun; Dong, Biqin; Xu, Hongxing; Zheng, Xusong; Tian, Junce; Heong, Kongleun; Lu, Zhongxian

2014-08-01

The brown planthopper, Nilaparvata lugens (Stål), is one of the most important insect pests on paddy rice in tropical and temperate Asia. Overuse and misuse of insecticides have resulted in the development of high resistance to many different insecticides in this pest. Studies were conducted to evaluate the change of resistance level to four insecticides over 15 generations without any exposure to insecticides in brown planthopper. After 15 generations' rearing without exposure to insecticide, brown planthopper could reverse the resistance to imidacloprid, chlorpyrifos, fipronil, and fenobucarb. The range and style of resistance reversal of brown planthopper differed when treated with four different insecticides. To monitor potential changes in insect physiological responses, we measured the activity of each of the three selected enzymes, including acetylcholinesterases (AChE), general esterases (EST), and glutathione S-transferases. After multiple generations' rearing without exposure to insecticide, AChE and EST activities of brown planthopper declined with the increased generations, suggesting that the brown planthopper population adjusted activities of EST and AChE to adapt to the non-insecticide environment. These findings suggest that the reducing, temporary stop, or rotation of insecticide application could be incorporated into the brown planthopper management.

The economics of social marketing: the case of mosquito nets in Tanzania.

PubMed

Kikumbih, Nassor; Hanson, Kara; Mills, Anne; Mponda, Hadji; Schellenberg, Joanna Armstrong

2005-01-01

There is a growing appreciation of the role of the private sector in expanding the use of key health interventions. At the policy level, this has raised questions about how public sector resources can best be used to encourage the private sector in order to achieve public health impact. Social marketing has increasingly been used to distribute public health products in developing countries. The Kilombero and Ulanga Insecticide-Treated Net Project (KINET) project used a social marketing approach in two districts of Tanzania to stimulate the development of the market for insecticide-treated mosquito nets (ITNs) for malaria control. Using evidence from household surveys, focus group discussions and a costing study in the intervention area and a control area, this paper examines two issues: (1) How does social marketing affect the market for ITNs, where this is described in terms of price and coverage levels; and (2) What does the added cost of social marketing "buy" in terms of coverage and equity, compared with an unassisted commercial sector model? It appears that supply improved in both areas, although there was a greater increase in supply in the intervention area. However, the main impact of social marketing on the market for nets was to shift demand in the intervention district, leading to a higher coverage market outcome. While social marketing was more costly per net distributed than the unassisted commercial sector, higher overall levels of coverage were achieved in the social marketing area together with higher coverage of the lowest socioeconomic group, of pregnant women and children under 5 years, and of those living on the periphery of their villages. These findings are interpreted in the context of Tanzania's national plan for scaling up ITNs.

Net use, care and repair practices following a universal distribution campaign in Mali.

PubMed

Leonard, Lori; Diop, Samba; Doumbia, Seydou; Sadou, Aboubacar; Mihigo, Jules; Koenker, Hannah; Berthe, Sara; Monroe, April; Bertram, Kathryn; Weber, Rachel

2014-11-18

The Government of Mali and the President's Malaria Initiative conducted a long-lasting, insecticidal net (LLIN) distribution campaign in April 2011 in the Sikasso region of Mali, with the aim of universal coverage, defined as one insecticide-treated net for every two persons. This study examines how households in post- and pre-campaign regions value and care for nets. The study was conducted in October 2012 in Sikasso and Kayes in the southeast and western regions of Mali, respectively. The regions were purposively selected to allow for comparison between areas that had already had a mass distribution campaign (Sikasso) and areas that had not yet had a mass distribution campaign (Kayes). Study sites and households were randomly selected. Sleeping space questionnaires and structured interviews with household heads were conducted to obtain information on net use, perceived value of free nets in relation to other malaria prevention activities, and net care and repair practices. The study included 40 households, split evenly across the two regions. Forty interviews were conducted with household heads and 151 sleeping spaces were inventoried using the sleeping space questionnaire. Nets obtained through the free distribution were reported to be highly valued in comparison to other malaria prevention strategies. Overall, net ownership and use were higher among households in areas that had already experienced a mass distribution. While participants reported using and valuing these nets, care and repair practices varied. National net use is high in Mali, and comparatively higher in the region covered by the universal distribution campaign than in the region not yet covered. While the Government of Mali and implementing partners have made strides to ensure high net coverage, some gaps remain related to communication messaging of correct and consistent net use throughout the year, and on improving net care and repair behaviour. By focusing on these areas as well as improved

The Economic Value of Long-Lasting Insecticidal Nets and Indoor Residual Spraying Implementation in Mozambique

PubMed Central

Lee, Bruce Y.; Bartsch, Sarah M.; Stone, Nathan T. B.; Zhang, Shufang; Brown, Shawn T.; Chatterjee, Chandrani; DePasse, Jay V.; Zenkov, Eli; Briët, Olivier J. T.; Mendis, Chandana; Viisainen, Kirsi; Candrinho, Baltazar; Colborn, James

2017-01-01

Malaria-endemic countries have to decide how much of their limited resources for vector control to allocate toward implementing long-lasting insecticidal nets (LLINs) versus indoor residual spraying (IRS). To help the Mozambique Ministry of Health use an evidence-based approach to determine funding allocation toward various malaria control strategies, the Global Fund convened the Mozambique Modeling Working Group which then used JANUS, a software platform that includes integrated computational economic, operational, and clinical outcome models that can link with different transmission models (in this case, OpenMalaria) to determine the economic value of vector control strategies. Any increase in LLINs (from 80% baseline coverage) or IRS (from 80% baseline coverage) would be cost-effective (incremental cost-effectiveness ratios ≤ $114/disability-adjusted life year averted). However, LLIN coverage increases tend to be more cost-effective than similar IRS coverage increases, except where both pyrethroid resistance is high and LLIN usage is low. In high-transmission northern regions, increasing LLIN coverage would be more cost-effective than increasing IRS coverage. In medium-transmission central regions, changing from LLINs to IRS would be more costly and less effective. In low-transmission southern regions, LLINs were more costly and less effective than IRS, due to low LLIN usage. In regions where LLINs are more cost-effective than IRS, it is worth considering prioritizing LLIN coverage and use. However, IRS may have an important role in insecticide resistance management and epidemic control. Malaria intervention campaigns are not a one-size-fits-all solution, and tailored approaches are necessary to account for the heterogeneity of malaria epidemiology. PMID:28719286

The Economic Value of Long-Lasting Insecticidal Nets and Indoor Residual Spraying Implementation in Mozambique.

PubMed

Lee, Bruce Y; Bartsch, Sarah M; Stone, Nathan T B; Zhang, Shufang; Brown, Shawn T; Chatterjee, Chandrani; DePasse, Jay V; Zenkov, Eli; Briët, Olivier J T; Mendis, Chandana; Viisainen, Kirsi; Candrinho, Baltazar; Colborn, James

2017-06-01

AbstractMalaria-endemic countries have to decide how much of their limited resources for vector control to allocate toward implementing long-lasting insecticidal nets (LLINs) versus indoor residual spraying (IRS). To help the Mozambique Ministry of Health use an evidence-based approach to determine funding allocation toward various malaria control strategies, the Global Fund convened the Mozambique Modeling Working Group which then used JANUS, a software platform that includes integrated computational economic, operational, and clinical outcome models that can link with different transmission models (in this case, OpenMalaria) to determine the economic value of vector control strategies. Any increase in LLINs (from 80% baseline coverage) or IRS (from 80% baseline coverage) would be cost-effective (incremental cost-effectiveness ratios ≤ $114/disability-adjusted life year averted). However, LLIN coverage increases tend to be more cost-effective than similar IRS coverage increases, except where both pyrethroid resistance is high and LLIN usage is low. In high-transmission northern regions, increasing LLIN coverage would be more cost-effective than increasing IRS coverage. In medium-transmission central regions, changing from LLINs to IRS would be more costly and less effective. In low-transmission southern regions, LLINs were more costly and less effective than IRS, due to low LLIN usage. In regions where LLINs are more cost-effective than IRS, it is worth considering prioritizing LLIN coverage and use. However, IRS may have an important role in insecticide resistance management and epidemic control. Malaria intervention campaigns are not a one-size-fits-all solution, and tailored approaches are necessary to account for the heterogeneity of malaria epidemiology.

Status of pyrethroid resistance in Anopheles gambiae s. s. M form prior to the scaling up of Long Lasting Insecticidal Nets (LLINs) in Adzopé, Eastern Côte d’Ivoire

PubMed Central

2012-01-01

Background The growing development of pyrethroid resistance constitutes a serious threat to malaria control programmes and if measures are not taken in time, resistance may compromise control efforts in the foreseeable future. Prior to Long Lasting Insecticidal Nets (LLINs) distribution in Eastern Cote d’Ivoire, we conducted bioassays to inform the National Malaria Control Programme of the resistance status of the main malaria vector, Anopheles gambiae s. s. and the need for close surveillance of resistance. Methods Larvae of An. gambiae s. s. were collected in two areas of Adzopé (Port-Bouët and Tsassodji) and reared to adults. WHO susceptibility tests with impregnated filter papers were carried out to detect resistance to three pyrethroids commonly used to develop LLINs: permethrin 1%, deltamethrin 0.05% and lambda-cyhalothrin 0.05%. Molecular assays were conducted to detect M and S forms and the L1014F kdr allele in individual mosquitoes. Results Resistance, at various degrees was detected in both areas of Adzopé. Overall, populations of An. gambiae at both sites surveyed showed equivalent frequency of the L1014F kdr allele (0.67) but for all tested pyrethroids, there were significantly higher survival rates for mosquitoes from Tsassodji (32–58%) than those from Port-Bouët (3–32%) (p < 0.001), indicating the implication of resistance mechanisms other than kdr alone. During the survey period (May–June) in this forested area of Côte d’Ivoire, An. gambiae s. s. found were exclusively of the M form and were apparently selected for pyrethroid resistance through agricultural and household usage of insecticides. Conclusion Prior to LLINs scaling up in Eastern Côte d’Ivoire, resistance was largely present at various levels in An. gambiae. Underlying mechanisms included the high frequency of the L1014F kdr mutation and other unidentified components, probably metabolic detoxifiers. Their impact on the efficacy of the planned strategy (LLINs) in the

Validation of a multi-residue method to determine deltamethrin and alpha-cypermethrin in mosquito nets by gas chromatography with electron capture detection (GC-μECD)

PubMed Central

2013-01-01

Background Nowadays long-lasting insecticidal mosquito nets (LNs) are frequently used around the world to protect people against malaria vectors. As they contain insecticide, laboratory control is needed to check whether the content of the active ingredient follows the conditions of the manufacturer and also if the active ingredient is still present after some time of use. For this purpose, an analytical method had to be developed. The fact that LNs include a range of polymers for the yarn and use coated or incorporated technologies for the active ingredient, it is a challenge to find only one analytical method determining the active ingredient in LNs, which takes into account both impregnation technologies. Some methods are provided by international organizations but are limited by the determination of only one pesticide per method. The aim of this study was to optimize a short time extraction method for deltamethrin and alpha-cypermethrin from coated and incorporated mosquito nets and also to detect both insecticides in one analytical run, using gas chromatography with electron capture detection (GC-μECD). Methods Based on the literature, the most suitable solvent and the adequate extraction process for the insecticides used for net making were identified and adapted for the new multi-residue method. Results The validation data of the multi-residue method to determine deltamethrin and alpha-cypermethrin in mosquito nets by GC-μECD are given. Depending on the concentration of the active ingredient spiked on the nets, the mean recovery for alpha-cypermethrin ranged between 86% and 107% with a relative standard deviation below 3.5%. For deltamethrin it ranged between 90% and 108% with a relative standard deviation also below 3.5%. The limit of detection is 0.009 g.a.i/kg of net (0.3 mg a.i./m2 of net) both for alpha-cypermethrin and deltamethrin. Conclusions Data obtained are excellent. A 30 minutes reflux extraction method with xylene was developed to determine

Laboratory evaluation of lambda-cyhalothrin a microencapsulated formulation on mosquito nets for control of vector mosquitos.

PubMed

Vythilingam, I; Zainal, A R; Hamidah, T

1999-03-01

Two formulations of lambda-cyhalothrin (EC-Emulsion concentrate and MC-Microencapsulated) were impregnated into bednets made of polyethylene and polyester. The nets were treated at a dosage of 15 mg/m2. For bioassay of insecticidal efficacy, female Anopheles maculatus and Aedes aegypti were exposed to the nets for two minutes and mortality was scored 24 hours later. The nets were also tested after repeated washings with water and with soap and water. Microencapsulated (2.5CS) formulation was more effective than emulsion concentrate (2.5EC) formulation on both net materials--polyethylene and polyester. Repeated washing with water and soap reduces the efficacy of all bednet treatment combinations. Microencapsulated formulation on polyethylene gave best results; it could sustain up to five washes with water and two with soap and water.

Value of Neonicotinoid Insecticide Seed Treatments in Mid-South Corn (Zea mays) Production Systems.

PubMed

North, J H; Gore, J; Catchot, A L; Stewart, S D; Lorenz, G M; Musser, F R; Cook, D R; Kerns, D L; Leonard, B R; Dodds, D M

2018-02-09

Neonicotinoid seed treatments are one of several effective control options used in corn, Zea mays L., production in the Mid-South for early season insect pests. An analysis was performed on 91 insecticide seed treatment trials from Arkansas, Louisiana, Mississippi, and Tennessee to determine the value of neonicotinoids in corn production systems. The analysis compared neonicotinoid insecticide treated seed plus a fungicide to seed only with the same fungicide. When analyzed by state, corn yields were significantly higher when neonicotinoid seed treatments were used compared to fungicide only treated seed in Louisiana and Mississippi. Corn seed treated with neonicotinoid seed treatments yielded 111, 1,093, 416, and 140 kg/ha, higher than fungicide only treatments for Arkansas, Louisiana, Mississippi, and Tennessee, respectively. Across all states, neonicotinoid seed treatments resulted in a 700 kg/ha advantage compared to fungicide only treated corn seed. Net returns for corn treated with neonicotinoid seed treatment were $1,446/ha compared with $1,390/ha for fungicide only treated corn seed across the Mid-South. Economic returns for neonicotinoid seed treated corn were significantly greater than fungicide-only-treated corn seed in 8 out of 14 yr. When analyzed by state, economic returns for neonicotinoid seed treatments were significantly greater than fungicide-only-treated seed in Louisiana. In some areas, dependent on year, neonicotinoid seed treatments provide significant yield and economic benefits in Mid-South corn. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Insecticide treated bednet strategy in rural settings: can we exploit women's decision making power?

PubMed

Tilak, Rina; Tilak, V W; Bhalwar, R

2007-01-01

Use of insecticide treated bednets in prevention of malaria is a widely propagated global strategy, however, its use has been reported to be influenced and limited by many variables especially gender bias. A cross sectional field epidemiological study was conducted in a rural setting with two outcome variables, 'Bednet use'(primary outcome variable) and 'Women's Decision Making Power' which were studied in reference to various predictor variables. Analysis reveals a significant effect on the primary outcome variable 'Bednet use' of the predictor variables- age, occupation, bednet purchase decision, women's decision making power, husband's education and knowledge about malaria and its prevention. The study recommends IEC on treated bednets to be disseminated through TV targeting the elderly women who have better decision making power and mobilizing younger women who were found to prefer bednets for prevention of mosquito bites for optimizing the use of treated bednets in similar settings.

Residual mosquito barrier treatments on U.S. military camouflage netting in a southern California desert environment.

PubMed

Britch, Seth C; Linthicum, Kenneth J; Wynn, Wayne W; Walker, Todd W; Farooq, Muhammad; Smith, Vincent L; Robinson, Cathy A; Lothrop, Branka B; Snelling, Melissa; Gutierrez, Arturo; Lothrop, Hugh D

2010-08-01

Treating perimeters of vegetation with residual insecticides for protection from mosquito vectors has potential for U.S. military force health protection. However, for current U.S. military operations in hot-arid environments with little or no vegetation, residual applications on portable artificial materials may be a viable alternative. We evaluated bifenthrin residual treatments of U.S. military camouflage netting under hot-arid field conditions in a desert area in southern California exposed to abundant wild Culex tarsalis mosquitoes. We assessed the ability of the treatment to reduce the numbers of mosquitoes penetrating perimeters of netting and reaching CO2-baited mosquito traps. Treated camouflage netting barriers reduced mosquitoes by > or = 50% for 7-14 days and by 20-35% for 21-28 days compared to untreated barriers. Although reductions may be translated into reductions in risk of exposure to mosquito-borne diseases, we emphasize that barrier treatments should be a component in a suite of insect control measures to be effective.

A household randomized, controlled trial of the efficacy of 0.03% transfluthrin coils alone and in combination with long-lasting insecticidal nets on the incidence of Plasmodium falciparum and Plasmodium vivax malaria in Western Yunnan Province, China.

PubMed

Hill, Nigel; Zhou, Hong Ning; Wang, Piyu; Guo, Xiaofang; Carneiro, Ilona; Moore, Sarah J

2014-05-31

Mosquito coils are the most commonly used household insecticidal product in the world with sales exceeding 50 billion coils, used by two billion people worldwide annually. Despite strong evidence that coils prevent mosquito bites a systematic review concluded that there is no evidence that burning mosquito coils prevents malaria acquisition. Therefore, the current trial was designed to measure and compare prevention of malaria infection by mosquito coils or long-lasting insecticidal net (LLIN) or a combination of the two in Yunnan, China in the Greater Mekong sub-region. A four-arm single blind household-randomized design was chosen as coils emanate insecticide throughout the household. Households enrolled at baseline were randomly allocated by the lottery method to one of the four intervention arms: (i) nothing, (ii) 0.03% transfluthrin coils alone, (iii) deltamethrin long-lasting insecticide treated nets, (LLINs) alone or (iv) a combination of transfluthrin coils and deltamethrin LLINs. All household members were recruited to the study, with only those households excluded with pregnant or breastfeeding mothers, members with chest complaints or allergies or members that regularly slept away from home. The main outcome of interest was Plasmodium falciparum malaria prevalence detected by rapid diagnostic tests (RDTs) during six repeated monthly cross-sectional surveys. The secondary outcome of interest was the effect on Plasmodium vivax prevalence detected in the same way. A total of 2,052 households were recruited into the study, comprising 7,341 individuals The odds ratios of testing positive by RDT with P. falciparum or P. vivax were >75% lower for all intervention arms compared with the control arm. Coils alone provided 77% protection (95% CI: 50%-89%), LLINs provided 91% protection (95% CI: 72%-97%) and the combination of coils and LLINs provided 94% protection (95% CI: 77%-99%) against P. falciparum compared with the control arm. There was no statistically

Use of bed nets and factors that influence bed net use among Jinuo Ethnic Minority in southern China.

PubMed

Xu, Jian-wei; Liao, Yuan-mei; Liu, Hui; Nie, Ren-hua; Havumaki, Joshua

2014-01-01

Insecticide-treated nets (ITNs) are an integral part of vector control recommendations for malaria elimination in China. This study investigated the extent to which bed nets were used and which factors influence bed net use among Jinuo Ethnic Minority in China-Myanmar-Laos border areas. This study combined a quantitative household questionnaire survey and qualitative semi-structured in-depth interviews (SDI). Questionnaires were administered to 352 heads of households. SDIs were given to 20 key informants. The bed net to person ratio was 1∶2.1 (i.e., nearly one net for every two people), however only 169 (48.0%) households owned at least one net and 623 (47.2%) residents slept under bed nets the prior night. The percentages of residents who regularly slept under nets (RSUN) and slept under nets the prior night (SUNPN) were similar (48.0% vs. 47.2%, P>0.05), however the percentage correct use of nets (CUN) was significantly lower (34.5%, P<0.0001). The annual cash income per person (ACIP) was an independent factor that influenced bed net use (P<0.0001), where families with an ACIP of CNY10000 or more were much more likely to use nets. House type was strongly associated with bed net use (OR: 4.71, 95% CI: 2.81, 7.91; P<0.0001), where those with traditional wood walls and terracotta roofs were significantly more likely to use nets, and the head of household's knowledge was an independent factor (OR: 5.04, 95% CI: 2.72, 9.35; P<0.0001), where those who knew bed nets prevent malaria were significantly more likely to use nets too. High bed net availability does not necessarily mean higher coverage or bed net use. Household income, house type and knowledge of the ability of bed nets to prevent malaria are all independent factors that influence bed net use among Jinuo Ethnic Minority.

Navy Entomologists Assist CDC’s Fight Against Malaria

DTIC Science & Technology

2013-01-01

long - lasting insec- ticide treated bed nets (LLINs): 2) indoor residual spraying (IRS) of living quarters using long - lasting residual ... insecticide susceptible malaria mosquitoes for residual insecticide testing of IRS sprayed walls and long lasting insecticide -treated bed nets . which is...the Navy Entomology Center of Excellence sprays panels, made of materials

The impact of six insecticides commonly used in control of agricultural pests on the generalist predator Hippodamia convergens (Coleoptera: Coccinellidae).

PubMed

Santos, Kenia Fernanda Aguiar; Zanuzo Zanardi, Odimar; de Morais, Matheus Rovere; Jacob, Cynthia Renata Oliveira; de Oliveira, Monique Bárbara; Yamamoto, Pedro Takao

2017-11-01

Hippodamia convergens is an important predator found in different agroecosystems. We evaluated the impacts of six insecticides on eggs, larvae and adults of this predator. For eggs, all insecticides reduced larval hatching rates, but did not affect egg duration. Chlorpyrifos and phosmet reduced larval survival; and chlorpyrifos, etofenprox and phosmet prolonged the larva development time. The survival and duration of pupae were not affected by all insecticides tested. Chlorpyrifos reduced fecundity, fertility and longevity when eggs were sprayed. For first-instar larvae, chlorpyrifos, etofenprox, phosmet and imidacloprid caused 100% mortality, while azadirachtin and thiamethoxam caused 35.0 and 52.7% mortality, respectively. However, azadirachtin and thiamethoxam did not affect the other biological parameters of the predator. In adults, chlorpyrifos, etofenprox and phosmet reduced adult survival. Chlorpyrifos, etofenprox, and phosmet reduced fecundity and longevity, but did not affect fertility. Azadirachtin, imidacloprid and thiamethoxam did not affect fecundity, fertility or longevity. Based on demographic parameters, all insecticides reduced the net reproductive rate (R o ), intrinsic rate of increase (r) and finite rate of increase (λ) of the predator when eggs were treated directly. Azadirachtin, chlorpyrifos, etofenprox and phosmet increased the mean generation time (T), while the effects of imidacloprid and thiamethoxam were similar to the control. When first-instar larvae were treated, azadirachtin and thiamethoxam reduced the R o , r and λ. Thiamethoxam increased the T value, while the effects of the other insecticides were similar to the control. These insecticides should be used with caution, in order to reduce their harmful effects on the predator in agroecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sulfadoxine-Pyrimethamine-Based Intermittent Preventive Treatment, Bed Net Use, and Antenatal Care during Pregnancy: Demographic Trends and Impact on the Health of Newborns in the Kassena Nankana District, Northeastern Ghana

DTIC Science & Technology

2010-01-01

treatment for uncomplicated malaria, whether confirmed, or suspected, in 2004 and SIP- based IPTp was introduced in 2005.1•3 Indoor residual spray - ing...emigrations recorded. Although many women may have been using long - lasting ITNs during pregnancy, this quality of the bed nets could not be determined with...care, provision and wide use of insecticide -treated bed nets (ITNs), and intensified health education. Ghana readily adopted and began implementa

The effect of insecticide-treated bed nets on the incidence and prevalence of malaria in children in an area of unstable seasonal transmission in western Myanmar.

PubMed

Smithuis, Frank M; Kyaw, Moe Kyaw; Phe, U Ohn; van der Broek, Ingrid; Katterman, Nina; Rogers, Colin; Almeida, Patrick; Kager, Piet A; Stepniewska, Kasia; Lubell, Yoel; Simpson, Julie A; White, Nicholas J

2013-10-11

Insecticide-treated bed nets (ITN) reduce malaria morbidity and mortality consistently in Africa, but their benefits have been less consistent in Asia. This study's objective was to evaluate the malaria protective efficacy of village-wide usage of ITN in Western Myanmar and estimate the cost-effectiveness of ITN compared with extending early diagnosis and treatment services. A cluster-randomized controlled trial was conducted in Rakhine State to assess the efficacy of ITNs in preventing malaria and anaemia in children and their secondary effects on nutrition and development. The data were aggregated for each village to obtain cluster-level infection rates. In total 8,175 children under 10 years of age were followed up for 10 months, which included the main malaria transmission period. The incidence and prevalence of Plasmodium falciparum and Plasmodium vivax infections, and the biting behaviour of Anopheles mosquitoes in the area were studied concurrently. The trial data along with costs for current recommended treatment practices were modelled to estimate the cost-effectiveness of ITNs compared with, or in addition to extending the coverage of early diagnosis and treatment services. In aggregate, malaria infections, spleen rates, haemoglobin concentrations, and weight for height, did not differ significantly during the study period between villages with and without ITNs, with a weighted mean difference of -2.6 P. falciparum episodes per 1,000 weeks at risk (95% Confidence Interval -7 to 1.8). In areas with a higher incidence of malaria there was some evidence ITN protective efficacy. The economic analysis indicated that, despite the uncertainty and variability in their protective efficacy in the different study sites, ITN could still be cost-effective, but not if they displaced funding for early diagnosis and effective treatment which is substantially more cost-effective. In Western Myanmar deployment of ITNs did not provide consistent protection against malaria

Field and in vitro insecticidal efficacy of alphacypermethrin-treated high density polyethylene mesh against Culicoides biting midges in South Africa.

PubMed

Page, P C; Labuschagne, K; Venter, G J; Schoeman, J P; Guthrie, A J

2014-06-16

The efficacy of untreated and alphacypermethrin-treated high density polyethylene (HDPE) mesh against Culicoides biting midges (Diptera: Ceratopogonidae) was determined using Onderstepoort downdraught black light traps and a contact bioassay. Three traps were operated overnight in four replicates of a 3×3 randomised Latin square design near horses under South African field conditions. Both the untreated and alphacypermethrin-treated HDPE mesh significantly (P<0.05) reduced the numbers of Culicoides midges, predominantly Culicoides (Avaritia) imicola Kieffer, collected in the light traps by 4.2 and 7.2 times, respectively. A repellent effect of the alphacypermethrin-treated mesh was not confirmed because the number of midges collected in the light traps with untreated and alphacypermethrin-treated HDPE mesh was not significantly different (P=0.656). Bioassay of the insecticidal contact efficacy indicated median C. imicola mortality of 100% from 30 and 10 min following exposure to the alphacypermethrin-treated HDPE mesh for 1 or 3 min, respectively. In the bioassay, mortality was significantly higher (P=0.016) at 5 min post exposure in the midges exposed to the alphacypermethrin-treated mesh for 3 min (74.8%) compared to the 1 min exposure group (59.5%). The HDPE mesh could be used to reduce exposure of housed animals to Culicoides midges, specifically C. imicola, and viruses transmitted by these midges. Mesh treated with alphacypermethrin had the additional benefit of a rapid insecticidal effect on C. imicola. Copyright © 2014 Elsevier B.V. All rights reserved.

Combining fungal biopesticides and insecticide-treated bednets to enhance malaria control.

PubMed

Hancock, Penelope A

2009-10-01

In developing strategies to control malaria vectors, there is increased interest in biological methods that do not cause instant vector mortality, but have sublethal and lethal effects at different ages and stages in the mosquito life cycle. These techniques, particularly if integrated with other vector control interventions, may produce substantial reductions in malaria transmission due to the total effect of alterations to multiple life history parameters at relevant points in the life-cycle and transmission-cycle of the vector. To quantify this effect, an analytically tractable gonotrophic cycle model of mosquito-malaria interactions is developed that unites existing continuous and discrete feeding cycle approaches. As a case study, the combined use of fungal biopesticides and insecticide treated bednets (ITNs) is considered. Low values of the equilibrium EIR and human prevalence were obtained when fungal biopesticides and ITNs were combined, even for scenarios where each intervention acting alone had relatively little impact. The effect of the combined interventions on the equilibrium EIR was at least as strong as the multiplicative effect of both interventions. For scenarios representing difficult conditions for malaria control, due to high transmission intensity and widespread insecticide resistance, the effect of the combined interventions on the equilibrium EIR was greater than the multiplicative effect, as a result of synergistic interactions between the interventions. Fungal biopesticide application was found to be most effective when ITN coverage was high, producing significant reductions in equilibrium prevalence for low levels of biopesticide coverage. By incorporating biological mechanisms relevant to vectorial capacity, continuous-time vector population models can increase their applicability to integrated vector management.

Factors Associated with Correct and Consistent Insecticide Treated Curtain Use in Iquitos, Peru

PubMed Central

Scott, Thomas W.; Elder, John P.; Alexander, Neal; Halsey, Eric S.; McCall, Philip J.

2016-01-01

Dengue is an arthropod-borne virus of great public health importance, and control of its mosquito vectors is currently the only available method for prevention. Previous research has suggested that insecticide treated curtains (ITCs) can lower dengue vector infestations in houses. This observational study investigated individual and household-level socio-demographic factors associated with correct and consistent use of ITCs in Iquitos, Peru. A baseline knowledge, attitudes, and practices (KAP) survey was administered to 1,333 study participants, and ITCs were then distributed to 593 households as part of a cluster-randomized trial. Follow up KAP surveys and ITC-monitoring checklists were conducted at 9, 18, and 27 months post-ITC distribution. At 9 months post-distribution, almost 70% of ITCs were hanging properly (e.g. hanging fully extended or tied up), particularly those hung on walls compared to other locations. Proper ITC hanging dropped at 18 months to 45.7%. The odds of hanging ITCs correctly and consistently were significantly greater among those participants who were housewives, knew three or more correct symptoms of dengue and at least one correct treatment for dengue, knew a relative or close friend who had had dengue, had children sleeping under a mosquito net, or perceived a change in the amount of mosquitoes in the home. Additionally, the odds of recommending ITCs in the future were significantly greater among those who perceived a change in the amount of mosquitoes in the home (e.g. perceived the ITCs to be effective). Despite various challenges associated with the sustained effectiveness of the selected ITCs, almost half of the ITCs were still hanging at 18 months, suggesting a feasible vector control strategy for sustained community use. PMID:26967157

Synergy between Repellents and Organophosphates on Bed Nets: Efficacy and Behavioural Response of Natural Free-Flying An. gambiae Mosquitoes

PubMed Central

Pennetier, Cédric; Costantini, Carlo; Corbel, Vincent; Licciardi, Séverine; Dabiré, Roch K.; Lapied, Bruno; Chandre, Fabrice; Hougard, Jean-Marc

2009-01-01

Background Chemicals are used on bed nets in order to prevent infected bites and to kill aggressive malaria vectors. Because pyrethroid resistance has become widespread in the main malaria vectors, research for alternative active ingredients becomes urgent. Mixing a repellent and a non-pyrethroid insecticide seemed to be a promising tool as mixtures in the laboratory showed the same features as pyrethroids. Methodology/Principal Findings We present here the results of two trials run against free-flying Anopheles gambiae populations comparing the effects of two insect repellents (either DEET or KBR 3023, also known as icaridin) and an organophosphate insecticide at low-doses (pirimiphos-methyl, PM) used alone and in combination on bed nets. We showed that mixtures of PM and the repellents induced higher exophily, blood feeding inhibition and mortality among wild susceptible and resistant malaria vectors than compounds used alone. Nevertheless the synergistic interactions are only involved in the high mortality induced by the two mixtures. Conclusion These field trials argue in favour of the strategy of mixing repellent and organophosphate on bed nets to better control resistant malaria vectors. PMID:19936249

Discovery of Species-selective and Resistance-breaking Anticholinesterase Insecticides for the Malaria Mosquito

PubMed Central

Carlier, Paul R.; Bloomquist, Jeffrey R.; Totrov, Max; Li, Jianyong

2017-01-01

Great reductions in malaria mortality have been accomplished in the last 15 years, in part due to the widespread roll-out of insecticide-treated bednets across sub-Saharan Africa. To date, these nets only employ pyrethroids, insecticides that target the voltage-gated sodium ion channel of the malaria vector, Anopheles gambiae. Due to the growing emergence of An. gambiae strains that are resistant to pyrethroids, there is an urgent need to develop new public health insecticides that engage a different target and possess low mammalian toxicity. In this review, we will describe efforts to develop highly species-specific and resistance-breaking inhibitors of An. gambiae acetylcholinesterase (AgAChE). These efforts have been greatly aided by advances in knowledge of the structure of the enzyme, and two major inhibitor design strategies have been explored. Since AgAChE possesses an unpaired Cys residue not present in mammalian AChE, a logical strategy to achieve selective inhibition involves design of compounds that could ligate that Cys. A second strategy involves the design of new molecules to target the catalytic serine of the enzyme. Here the challenge is not only to achieve high inhibition selectivity vs human AChE, but also to demonstrate toxicity to An. gambiae that carry the G119S resistance mutation of AgAChE. The advances made and challenges remaining will be presented. This review is part of the special issue “Insecticide Mode of Action: From Insect to Mammalian Toxicity. PMID:28176636

Evaluation of a universal long-lasting insecticidal net (LLIN) distribution campaign in Ghana: cost effectiveness of distribution and hang-up activities

PubMed Central

2014-01-01

Background Between May 2010 and October 2012, approximately 12.5 million long-lasting insecticidal nets (LLINs) were distributed through a national universal mass distribution campaign in Ghana. The campaign included pre-registration of persons and sleeping places, door-to-door distribution of LLINs with ‘hang-up’ activities by volunteers and post-distribution ‘keep-up’ behaviour change communication activities. Hang-up activities were included to encourage high and sustained use. Methods The cost and cost-effectiveness of the LLIN Campaign were evaluated using a before-after design in three regions: Brong Ahafo, Central and Western. The incremental cost effectiveness of the ‘hang-up’ component was estimated using reported variation in the implementation of hang-up activities and LLIN use. Economic costs were estimated from a societal perspective assuming LLINs would be replaced after three years, and included the time of unpaid volunteers and household contributions given to volunteers. Results Across the three regions, 3.6 million campaign LLINs were distributed, and 45.5% of households reported the LLINs received were hung-up by a volunteer. The financial cost of the campaign was USD 6.51 per LLIN delivered. The average annual economic cost was USD 2.90 per LLIN delivered and USD 6,619 per additional child death averted by the campaign. The cost-effectiveness of the campaign was sensitive to the price, lifespan and protective efficacy of LLINs. Hang-up activities constituted 7% of the annual economic cost, though the additional financial cost was modest given the use of volunteers. LLIN use was greater in households in which one or more campaign LLINs were hung by a volunteer (OR = 1.57; 95% CI = 1.09, 2.27; p = 0.02). The additional economic cost of the hang-up activities was USD 0.23 per LLIN delivered, and achieved a net saving per LLIN used and per death averted. Conclusion In this campaign, hang-up activities were estimated to be net

Insecticide Resistance in Fleas.

PubMed

Rust, Michael K

2016-03-17

Fleas are the major ectoparasite of cats, dogs, and rodents worldwide and potential vectors of animal diseases. In the past two decades the majority of new control treatments have been either topically applied or orally administered to the host. Most reports concerning the development of insecticide resistance deal with the cat flea, Ctenocephalides felis felis. Historically, insecticide resistance has developed to many of the insecticides used to control fleas in the environment including carbamates, organophosphates, and pyrethroids. Product failures have been reported with some of the new topical treatments, but actual resistance has not yet been demonstrated. Failures have often been attributed to operational factors such as failure to adequately treat the pet and follow label directions. With the addition of so many new chemistries additional monitoring of flea populations is needed.

An exploratory qualitative study on perceptions about mosquito bed nets in the Niger Delta: what are the barriers to sustained use?

PubMed Central

Galvin, Kathleen T; Petford, Nick; Ajose, Frances; Davies, Dai

2011-01-01

Background: The effectiveness of malaria control programs is determined by an array of complex factors, including the acceptability and sustained use of preventative measures such as the bed net. A small-scale exploratory study was conducted in several locations in the Niger Delta region, Nigeria, to discover barriers against the use of bed nets, in the context of a current drive to scale up net use in Nigeria. Methods: A qualitative approach with a convenience sample was used. One to one interviews with mostly male adult volunteers were undertaken which explored typical living and sleeping arrangements, and perceptions about and barriers against the use of the mosquito prevention bed net. Results: Several key issues emerged from the qualitative data. Bed nets were not reported as widely used in this small sample. The reasons reported for lack of use included issues of convenience, especially net set up and dismantling; potential hazard and safety concerns; issues related to typical family composition and nature of accommodation; humid weather conditions; and perceptions of cost and effectiveness. Most barriers to net use concerned issues about everyday practical living and sleeping arrangements and perceptions about comfort. Interviewees identified were aware of malaria infection risks, but several also indicated certain beliefs that were barriers to net use. Conclusions: Successful control of malaria and scale up of insecticide-treated net coverage relies on community perceptions and practice. This small study has illuminated a number of important everyday life issues, which remain barriers to sustained net use, and has clarified further questions to be considered in net design and in future research studies. The study highlights the need for further research on the human concerns that contribute to sustained use of nets or, conversely, present significant barriers to their use. PMID:21544249

Large-scale implementation of disease control programmes: a cost-effectiveness analysis of long-lasting insecticide-treated bed net distribution channels in a malaria-endemic area of western Kenya-a study protocol.

PubMed

Gama, Elvis; Were, Vincent; Ouma, Peter; Desai, Meghna; Niessen, Louis; Buff, Ann M; Kariuki, Simon

2016-11-21

Historically, Kenya has used various distribution models for long-lasting insecticide-treated bed nets (LLINs) with variable results in population coverage. The models presently vary widely in scale, target population and strategy. There is limited information to determine the best combination of distribution models, which will lead to sustained high coverage and are operationally efficient and cost-effective. Standardised cost information is needed in combination with programme effectiveness estimates to judge the efficiency of LLIN distribution models and options for improvement in implementing malaria control programmes. The study aims to address the information gap, estimating distribution cost and the effectiveness of different LLIN distribution models, and comparing them in an economic evaluation. Evaluation of cost and coverage will be determined for 5 different distribution models in Busia County, an area of perennial malaria transmission in western Kenya. Cost data will be collected retrospectively from health facilities, the Ministry of Health, donors and distributors. Programme-effectiveness data, defined as the number of people with access to an LLIN per 1000 population, will be collected through triangulation of data from a nationally representative, cross-sectional malaria survey, a cross-sectional survey administered to a subsample of beneficiaries in Busia County and LLIN distributors' records. Descriptive statistics and regression analysis will be used for the evaluation. A cost-effectiveness analysis will be performed from a health-systems perspective, and cost-effectiveness ratios will be calculated using bootstrapping techniques. The study has been evaluated and approved by Kenya Medical Research Institute, Scientific and Ethical Review Unit (SERU number 2997). All participants will provide written informed consent. The findings of this economic evaluation will be disseminated through peer-reviewed publications. Published by the BMJ Publishing

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis.

PubMed

Briët, Olivier J T; Hardy, Diggory; Smith, Thomas A

2012-01-13

Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both before and during intervention

Decreasing proportion of Anopheles darlingi biting outdoors between long-lasting insecticidal net distributions in peri-Iquitos, Amazonian Peru.

PubMed

Prussing, Catharine; Moreno, Marta; Saavedra, Marlon P; Bickersmith, Sara A; Gamboa, Dionicia; Alava, Freddy; Schlichting, Carl D; Emerson, Kevin J; Vinetz, Joseph M; Conn, Jan E

2018-02-20

In Loreto Department, Peru, a successful 2005-2010 malaria control programme (known as PAMAFRO) included massive distribution of long-lasting insecticidal nets (LLINs). Additional local distribution of LLINs occurred in individual villages, but not between 2012 and 2015. A 2011-2012 study of the primary regional malaria vector Anopheles darlingi detected a trend of increased exophagy compared with pre-PAMAFRO behaviour. For the present study, An. darlingi were collected in three villages in Loreto in 2013-2015 to test two hypotheses: (1) that between LLIN distributions, An. darlingi reverted to pre-intervention biting behaviour; and, (2) that there are separate sub-populations of An. darlingi in Loreto with distinct biting behaviour. In 2013-2015 An. darlingi were collected by human landing catch during the rainy and dry seasons in the villages of Lupuna and Cahuide. The abundance of An. darlingi varied substantially across years, villages and time periods, and there was a twofold decrease in the ratio of exophagic:endophagic An. darlingi over the study period. Unexpectedly, there was evidence of a rainy season population decline in An. darlingi. Plasmodium-infected An. darlingi were detected indoors and outdoors throughout the night, and the monthly An. darlingi human biting rate was correlated with the number of malaria cases. Using nextRAD genotyping-by-sequencing, 162 exophagic and endophagic An. darlingi collected at different times during the night were genotyped at 1021 loci. Based on model-based and non-model-based analyses, all genotyped An. darlingi belonged to a homogeneous population, with no evidence for genetic differentiation by biting location or time. This study identified a decreasing proportion of exophagic An. darlingi in two villages in the years between LLIN distributions. As there was no evidence for genetic differentiation between endophagic and exophagic An. darlingi, this shift in biting behaviour may be the result of behavioural

Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico.

PubMed

Che-Mendoza, Azael; Guillermo-May, Guillermo; Herrera-Bojórquez, Josué; Barrera-Pérez, Mario; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Arredondo-Jiménez, Juan I; Sánchez-Tejeda, Gustavo; Vazquez-Prokopec, Gonzalo; Ranson, Hilary; Lenhart, Audrey; Sommerfeld, Johannes; McCall, Philip J; Kroeger, Axel; Manrique-Saide, Pablo

2015-02-01

Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Field trial on a novel control method for the dengue vector, Aedes aegypti by the systematic use of Olyset® Net and pyriproxyfen in Southern Vietnam.

PubMed

Tsunoda, Takashi; Kawada, Hitoshi; Huynh, Trang T T; Luu, Loan Le; Le, San Hoang; Tran, Huu Ngoc; Vu, Huong Thi Que; Le, Hieu Minh; Hasebe, Futoshi; Tsuzuki, Ataru; Takagi, Masahiro

2013-01-11

Jars, tanks, and drums provide favorable rearing/breeding sites for Aedes aegypti in Vietnam. However, the use of insecticides to control mosquitoes at such breeding sites has not been approved in Vietnam since they are also often sources of drinking water, making larval vector control difficult. Mosquito nets pre-treated with long-lasting insecticide treated nets (LLITNs) form an effective measure for malaria control. We examined changes in the abundance of immature Aedes aegypti to evaluate the efficacy of covering ceramic jars with lids comprising one type of LLITN, Olyset® Net, in inhibiting oviposition by adult females, and to evaluate the effect of treating other breeding containers, such as flower vases, inside and around the outside of houses with a slow-release pyriproxyfen formulation to kill pupae. We selected 313 households for the trial and 363 households for the control in Tan Chanh, Long An province, Vietnam. In the trial area, Olyset® Net lids were used to cover five major types of water container (ceramic jars, cylindrical concrete tanks, other concrete tanks, plastic drums, and plastic buckets), while pyriproxyfen was used to treat flower vases and ant traps. We also monitored dengue virus transmission by measuring anti-dengue IgM and IgG levels in healthy residents in both control and trial areas to estimate the effectiveness of Olyset® Net at controlling the dengue vector, Aedes aegypti. The container-index and house-index for immature Ae. aegypti fell steeply one month after treatment in the trial area. Lids with Olyset® Net that fit container openings clearly seemed to reduce the presence of immature Ae. aegypti as the density of pupae decreased 1 month after treatment in the trial area. Pyriproxyfen was also effective at killing pupae in the water containers in the trial area. Although the dengue seroconversion rate was not influenced by Olyset® Net, it was lower in two-five year old children when compared to older children and adults in

Reports of long-lasting insecticidal bed nets catching on fire: a threat to bed net users and to successful malaria control?

PubMed Central

2014-01-01

Background One of the control tools to reduce malaria transmission is the use of LLINs. However, several studies show that household bed net use is quite low. A study was developed to better understand the cultural factors that might explain these gaps in Benin. One reason mentioned is that bed nets can catch on fire and cause harm. This paper presents a summary of these findings, their analysis and the ensuing issues. Methods This anthropological study is based on an inductive qualitative approach, including 91 semi-structured interviews conducted from July 2011 to March 2012 in a health district in Southern Benin. Results Fifty-six persons stated that bed nets can catch on fire but do not always refer to specific facts. However, 34 of the 56 people narrate specific events they heard or experienced. 39 accounts were geographically located and situated in time, with various details. In 27 situations, people were burned, for which 12 people reportedly died. Discussion The disparity between these results and the dearth of bibliographic documentation in the initial search prompted a more in-depth literature review: 16 contributions between 1994 and 2013 were found. Bed net fires were noted in 10 countries, but it is impossible to ascertain the frequency of such events. Moreover, bodily harm can be significant, and several cases of death attributed to bed net fires were noted. Conclusions Indisputably, the use of bed nets to reduce the impact of this terrible disease is an optimal control method. However, the perception that LLINs have a potentially negative effect hinders the use rate in the real world, at least for some. If some people fear the risk of fires, this possibility must be addressed during information and prevention sessions on malaria, with a communication strategy tailored to specific social contexts. Moreover, all possible measures should be taken to limit the harm suffered by individuals and their families. PMID:24972637

Knowledge, access and utilization of bed-nets among stable and seasonal migrants in an artemisinin resistance containment area of Myanmar.

PubMed

Phyo Than, Wint; Oo, Tin; Wai, Khin Thet; Thi, Aung; Owiti, Philip; Kumar, Binay; Deepak Shewade, Hemant; Zachariah, Rony

2017-09-14

Myanmar lies in the Greater Mekong sub-region of South-East Asia faced with the challenge of emerging resistance to artemisinin combination therapies (ACT). Migrant populations are more likely than others to spread ACT resistance. A vital intervention to reduce malaria transmission, resistance spread and eliminate malaria is the use of bed nets. Among seasonal and stable migrants in an artemisinin resistance containment region of Myanmar, we compared a) their household characteristics, b) contact with health workers and information material, and c) household knowledge, access and utilization of bed nets. Secondary data from community-based surveys on 2484 migrant workers (2013 and 2014, Bago Region) were analyzed of which 37% were seasonal migrants. Bed net access and utilization were assessed using a) availability of at least one bed net per household, and b) one bed net per two persons, and c) proportion of household members who slept under abed net during the previous night (Indicator targets = 100%). Over 70% of all migrants were from unstable work settings with short transitory stays. Average household size was five (range 1-25) and almost half of all households had children under-five years. Roughly 10 % of migrants were night-time workers. Less than 40% of households had contact with health workers and less than 30% had exposure to information education and communication (IEC) materials, the latter being significantly lower among seasonal migrants. About 70% of households were aware of the importance of insecticide-treated bed-nets/long-lasting insecticidal nets (ITNs/LLINs), but knowledge on insecticide impregnation and retreatment of ITNs was poor (< 10%). Although over 95% of households had access to at least one bed net, the number with one bed net per two persons was grossly inadequate (13% for stable migrants and 9% for seasonal migrants, P = 0.001). About half of all household members slept under a bed net during the previous night. This study

Factors associated with mosquito net use by individuals in households owning nets in Ethiopia

PubMed Central

2011-01-01

Background Ownership of insecticidal mosquito nets has dramatically increased in Ethiopia since 2006, but the proportion of persons with access to such nets who use them has declined. It is important to understand individual level net use factors in the context of the home to modify programmes so as to maximize net use. Methods Generalized linear latent and mixed models (GLLAMM) were used to investigate net use using individual level data from people living in net-owning households from two surveys in Ethiopia: baseline 2006 included 12,678 individuals from 2,468 households and a sub-sample of the Malaria Indicator Survey (MIS) in 2007 included 14,663 individuals from 3,353 households. Individual factors (age, sex, pregnancy); net factors (condition, age, net density); household factors (number of rooms [2006] or sleeping spaces [2007], IRS, women's knowledge and school attendance [2007 only], wealth, altitude); and cluster level factors (rural or urban) were investigated in univariate and multi-variable models for each survey. Results In 2006, increased net use was associated with: age 25-49 years (adjusted (a) OR = 1.4, 95% confidence interval (CI) 1.2-1.7) compared to children U5; female gender (aOR = 1.4; 95% CI 1.2-1.5); fewer nets with holes (Ptrend = 0.002); and increasing net density (Ptrend < 0.001). Reduced net use was associated with: age 5-24 years (aOR = 0.2; 95% CI 0.2-0.3). In 2007, increased net use was associated with: female gender (aOR = 1.3; 95% CI 1.1-1.6); fewer nets with holes (aOR [all nets in HH good] = 1.6; 95% CI 1.2-2.1); increasing net density (Ptrend < 0.001); increased women's malaria knowledge (Ptrend < 0.001); and urban clusters (aOR = 2.5; 95% CI 1.5-4.1). Reduced net use was associated with: age 5-24 years (aOR = 0.3; 95% CI 0.2-0.4); number of sleeping spaces (aOR [per additional space] = 0.6, 95% CI 0.5-0.7); more old nets (aOR [all nets in HH older than 12 months] = 0.5; 95% CI 0.3-0.7); and increasing household altitude

Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique.

PubMed

Faulde, Michael K; Nehring, Oliver

2012-08-01

New and improved strategies for malaria control and prevention are urgently needed. As a contribution to an optimized personal protection strategy, a novel long-lasting insecticide and repellent-treated net (LLIRN) has been designed by binding combinations of permethrin plus N,N-diethyl-m-toluamide (DEET), or insect repellent 3535 (IR3535), and etofenprox plus DEET, onto fibres of bed net fabric employing a new multi-layer polymer-coating technique. Protective repellent efficacy, toxicological effectiveness and residual activity of 12 LLIRN types have been evaluated by laboratory testing against adult Aedes aegypti. The novel multi-layer LLIRN design allowed simultaneous embedding at concentrations up to 5,930 mg/m(2) for DEET, 3,408 mg/m(2) for IR3535, 2,296 mg/m(2) for permethrin and 2,349 mg/m(2) for etofenprox, respectively. IR3535 layers prevented co-binding of additional pyrethroid-containing polymer layers, thus making pyrethroids plus DEET LLIRNs an ideal combination. All LLIRNs revealed synergistic insecticidal effects which, when measured against concentration controls of the isolated compounds, were significant in all LLIRN types designed. DEET in DEET plus permethrin LLIRNs significantly (p < 0.0001) reduced the concentration-dependent permethrin 100 % knockdown (KD) time from 55 to 75 %, the corresponding 100 % kill time (p < 0.0001) from 55 to 64 %. DEET in DEET plus etofenprox LLIRNs reduced the dose-specific 100 % knockdown (KD) time of etofenprox from 42 to 50 % (p = 0.004), the 100 % kill time from 25 to 38 % (p < 0.0001). Permethrin or etofenprox did not influence spatial repellency of DEET or IR3535 on LLIRNs. Vice versa, DEET and IR3535 increased spatial and excitatory repellency and reduced landing and probing frequency on LLIRNs resulting in strongly enhanced biting protection, even at low concentrations. One hundred percent biting and probing protection of stored LLIRNs was preserved for 83 weeks with the 5,930 mg/m(2) DEET

Effectiveness and equity of the Tanzania National Voucher Scheme for mosquito nets over 10 years of implementation.

PubMed

Kramer, Karen; Mandike, Renata; Nathan, Rose; Mohamed, Ally; Lynch, Matthew; Brown, Nick; Mnzava, Ally; Rimisho, Wilhelmina; Lengeler, Christian

2017-06-15

The Tanzania National Voucher Scheme (TNVS) was a public private partnership managed by the Ministry of Health that provided pregnant women and infants with highly subsidized (long-lasting) insecticide-treated nets between 2004 and 2014. It was implemented in the context of the National Insecticide Treated Nets (NATNETS) Programme and was the main keep up strategy for vulnerable populations. The programme design was adjusted considerably over time to incorporate new evidence, shifting public health policies, and changing donor priorities. Three TNVS models can be distinguished: (1) the fixed discount; (2) the fixed top-up; (3) the hybrid voucher model. The changes improved equity and effectiveness, but also had a profound effect on how the programme was managed and implemented. The TNVS reached the majority of beneficiaries with vouchers, and significantly increased household ownership and use of LLINs. While two mass distribution campaigns implemented between 2009 and 2011 achieved universal coverage and equity, the TNVS ensured continuous protection of the vulnerable populations before, during and after the campaigns. The TNVS stimulated and maintained a large national retail network which managed the LLIN supply chain. The effectiveness of the TNVS was a function of several interdependent factors, including the supply chain of vouchers through the public health system; the supply chain of nets in the commercial sector; the demand for nets from voucher recipients; management and risk mitigation measures; and the influence of global and donor objectives. The TNVS was a highly innovative and globally influential programme, which stimulated the thinking around effectively and equitably distributing ITNs, and contributed directly to the evolution of global policy. It was a fundamental component of the NATNETS programme which protected a malaria-vulnerable population for over a decade.

Field durability of the same type of long-lasting insecticidal net varies between regions in Nigeria due to differences in household behaviour and living conditions.

PubMed

Kilian, Albert; Koenker, Hannah; Obi, Emmanuel; Selby, Richmond A; Fotheringham, Megan; Lynch, Matthew

2015-03-24

With the recent publication of WHO-recommended methods to estimate net survival, comparative analyses from different areas have now become possible. With this in mind, a study was undertaken in Nigeria to compare the performance of a specific long-lasting insecticidal net (LLIN) product in three socio-ecologically different areas. In addition, the objective was to assess the feasibility of a retrospective study design for durability. In three states, Zamfara in the north, Nasarawa in the centre and Cross River in the south, four local government areas were selected one year after mass distribution of 100-denier polyester LLINs. From a representative sample of 300 households per site that had received campaign nets, an assessment of net survival was made based on rate of loss of nets and the physical condition of surviving nets measured by the proportionate hole index (pHI). Surveys were repeated after two and three years. Over the three-year period 98% of the targeted sample size of 3,720 households was obtained and 94% of the 5,669 campaign nets found were assessed for damage. With increasing time since distribution, recall of having received campaign nets dropped by 11-22% and only 31-87% of nets actually lost were reported. Using a recall bias adjustment, attrition rates were fairly similar in all three sites. The proportion of surviving nets in serviceable condition differed dramatically, however, resulting in an estimated median net survival of 3.0 years in Nasarawa, 4.5 years in Cross River and 4.7 years in Zamfara. Although repairs on damaged nets increased from around 10% at baseline to 21-38% after three years, the average pHI value for each of the four hole size categories did not differ between repaired and unrepaired nets. First, the differences observed in net survival are driven by living conditions and household behaviours and not the LLIN material. Second, recall bias in a retrospective durability study can be significant and while adjustments can

Reducing grain storage losses in developing countries

USDA-ARS?s Scientific Manuscript database

We investigated the use of insecticide-treated material and modified atmosphere storage for reducing insect damage in stored maize. Results showed that insecticide treated netting and insecticide treated seed bags protected grain from insect damage for up to nine months if the grain was free from i...

Examining the impact of larval source management and insecticide-treated nets using a spatial agent-based model of Anopheles gambiae and a landscape generator tool.

PubMed

Arifin, S M Niaz; Madey, Gregory R; Collins, Frank H

2013-08-21

Agent-based models (ABMs) have been used to estimate the effects of malaria-control interventions. Early studies have shown the efficacy of larval source management (LSM) and insecticide-treated nets (ITNs) as vector-control interventions, applied both in isolation and in combination. However, the robustness of results can be affected by several important modelling assumptions, including the type of boundary used for landscapes, and the number of replicated simulation runs reported in results. Selection of the ITN coverage definition may also affect the predictive findings. Hence, by replication, independent verification of prior findings of published models bears special importance. A spatially-explicit entomological ABM of Anopheles gambiae is used to simulate the resource-seeking process of mosquitoes in grid-based landscapes. To explore LSM and replicate results of an earlier LSM study, the original landscapes and scenarios are replicated by using a landscape generator tool, and 1,800 replicated simulations are run using absorbing and non-absorbing boundaries. To explore ITNs and evaluate the relative impacts of the different ITN coverage schemes, the settings of an earlier ITN study are replicated, the coverage schemes are defined and simulated, and 9,000 replicated simulations for three ITN parameters (coverage, repellence and mortality) are run. To evaluate LSM and ITNs in combination, landscapes with varying densities of houses and human populations are generated, and 12,000 simulations are run. General agreement with an earlier LSM study is observed when an absorbing boundary is used. However, using a non-absorbing boundary produces significantly different results, which may be attributed to the unrealistic killing effect of an absorbing boundary. Abundance cannot be completely suppressed by removing aquatic habitats within 300 m of houses. Also, with density-dependent oviposition, removal of insufficient number of aquatic habitats may prove counter

Selective insecticide-induced stimulation on fecundity and biochemical changes in Tryporyza incertulas (Lepidoptera: Pyralidae).

PubMed

Wang, Ai-Hua; Wu, Jin-Cai; Yu, Yue-Shu; Liu, Jing-Lan; Yue, Jiang-Fei; Wang, Mei-Yue

2005-08-01

The use of selective insecticides in rice, Oryza sativa L., fields often causes resurgence of nontarget pest insects. This study was conducted to investigate the effect of two selective insecticides, buprofezin and imidacloprid, on Tryporyza incertulas (Walker), a nontarget pest. After larval feeding on rice plants treated with each insecticide, fecundity, ovary protein content, and titer of juvenile hormone III (JHIII) in the resulting female moths were determined with 'Xiushui 63' rice susceptible to T. incertulas and 'Zhendao 2' moderately resistant to T. incertulas. The fecundity of females developed from larvae that fed on the insecticide-treated Xiushui 63 plants was stimulated compared with that of moths from larvae that fed on rice plants that were not treated with either insecticide. There was no stimulating effect in females from larvae that fed on insecticide-treated Zhendao 2 plants. The weight of fourth instars (final instars) that fed on the insecticide-treated Xiushui 63 rice plants was significantly greater than that of control, increasing by 50.3 and 46.7% for 60 and 112.5 g (AI) ha(-1) buprofezin, and by 23.7 and 19.5% for 15 and 37.5 g (AI) ha(-1) imidacloprid treatments, respectively. Ovary protein content in adult females developed from larvae that fed on the rice treated with the high dose of buprofezin was significantly higher than that in control. For the high and low doses of imidacloprid during the second instar, and the low dose of imidacloprid during the fourth instar, JHIII titers in female adults were also significantly higher than that in control, increasing by 152.81, 90.52, and 114.19%, respectively.

The Use of Mosquito Nets and the Prevalence of Plasmodium falciparum Infection in Rural South Central Somalia

PubMed Central

Noor, Abdisalan M.; Moloney, Grainne; Borle, Mohamed; Fegan, Greg W.; Shewchuk, Tanya; Snow, Robert W.

2008-01-01

Background There have been resurgent efforts in Africa to estimate the public health impact of malaria control interventions such as insecticide treated nets (ITNs) following substantial investments in scaling-up coverage in the last five years. Little is known, however, on the effectiveness of ITN in areas of Africa that support low transmission. This hinders the accurate estimation of impact of ITN use on disease burden and its cost-effectiveness in low transmission settings. Methods and Principal Findings Using a stratified two-stage cluster sample design, four cross-sectional studies were undertaken between March-June 2007 across three livelihood groups in an area of low intensity malaria transmission in South Central Somalia. Information on bed net use; age; and sex of all participants were recorded. A finger prick blood sample was taken from participants to examine for parasitaemia. Mantel-Haenzel methods were used to measure the effect of net use on parasitaemia adjusting for livelihood; age; and sex. A total of 10,587 individuals of all ages were seen of which 10,359 provided full information. Overall net use and parasite prevalence were 12.4% and 15.7% respectively. Age-specific protective effectiveness (PE) of bed net ranged from 39% among <5 years to 72% among 5–14 years old. Overall PE of bed nets was 54% (95% confidence interval 44%–63%) after adjusting for livelihood; sex; and age. Conclusions and Significance Bed nets confer high protection against parasite infection in South Central Somalia. In such areas where baseline transmission is low, however, the absolute reductions in parasitaemia due to wide-scale net use will be relatively small raising questions on the cost-effectiveness of covering millions of people living in such settings in Africa with nets. Further understanding of the progress of disease upon infection against the cost of averting its consequent burden in low transmission areas of Africa is therefore required. PMID:18461178

[Comparative behaviour studies in horses infested with flying insects treated with insecticide or repellent substances].

PubMed

Sünder, Ulrich; Moors, Eva; Hagemann, Kristina; Gauly, Matthias

2011-01-01

The aim of this study was to estimate the effects of flying insects (Order Diptera) on the behaviour of grazing horses in relation to the use of insecticide and repellent substances. The investigations were done between June and August in 2008 in 3 periods of 7 days each. As insecticide and repellent two substances were used: "Well-care emulsion" (Co. Essex Tierarznei, München, GER) containing Permethrin and "Bremsen-Frei-Plus" (Co. Dr. Schaette AG, Bad Waldsee, GER) based on etheric oils. Both groups were compared with a non treated control group in a crossover-design. Each group (n = 3-5) was used alternately as control and treatment group. Several climate parameters were taken during the study. Furthermore, the number of insects per animal was estimated at certain times. Once per observation period insects were caught using Malaise traps and differentiated by species. The proportion of horse relevant species of the genera Diptera, especially Culex pipiens and Musca autumnalis, caught was 9% on an average. There was no correlation between the number of Tabanidae caught in the Malaise traps and the number observed near by the horses. Behaviour parameters like tailswishing, headshaking, stamping, skintwitching, snapping at the body, and moving were observed more frequently with increasing insect infestation. When horses were infested with a high number of flying insects, feeding activity was significant lower, whereas locomotion activity was significant higher. Both substances had positive effects for about 50 hours after application with no apparent difference between the substances. However, a lower frequency of headshaking and tailswishing could be observed in the Permethrin treated horses.

User-determined end of net life in Senegal: a qualitative assessment of decision-making related to the retirement of expired nets

PubMed Central

2013-01-01

Background Procurement and distribution of long-lasting insecticidal nets (LLINs) in the African region has decreased from 145 million in 2010 to 66 million nets in 2012. As resources for LLIN distribution appear to stagnate, it is important to understand the users’ perception of the life span of a net and at what point and why they stop using it. In order to get the most value out of distributed nets and to ensure that they are used for as long as possible, programmes must communicate to users about how to assess useful net life and how to extend it. Methods Data were collected from 114 respondents who participated in 56 in-depth interviews (IDIs) and eight focus group discussions (FGDs) in August 2012 in eight regions in Senegal. Households were eligible for the study if they owned at least one net and had an available household member over the age of 18. Data were coded by a team of four coders in ATLAS.ti using a primarily deductive approach. Results Respondents reported assessing useful net life using the following criteria: the age of net, the number and size of holes and the presence of mosquitoes in the net at night. If they had the means to do so, many respondents preferred the acquisition of a new net rather than the continued use of a very torn net. However, respondents would preferentially use newer nets, saving older, but useable nets for the future or sharing them with family or friends. Participants reported observing alternative uses of nets, primarily for nets that were considered expired. Conclusions The results indicate that decisions regarding the end of net life vary among community members in Senegal, but are primarily related to net integrity. Additional research is needed into user-determined end of net life as well as care and repair behaviours, which could extend useful net life. The results from this study and from future research on this topic should be used to understand current behaviours and develop communication programmes to

Neonicotinoid Insecticides Alter Induced Defenses and Increase Susceptibility to Spider Mites in Distantly Related Crop Plants

PubMed Central

Szczepaniec, Adrianna; Raupp, Michael J.; Parker, Roy D.; Kerns, David; Eubanks, Micky D.

2013-01-01

Background Chemical suppression of arthropod herbivores is the most common approach to plant protection. Insecticides, however, can cause unintended, adverse consequences for non-target organisms. Previous studies focused on the effects of pesticides on target and non-target pests, predatory arthropods, and concomitant ecological disruptions. Little research, however, has focused on the direct effects of insecticides on plants. Here we demonstrate that applications of neonicotinoid insecticides, one of the most important insecticide classes worldwide, suppress expression of important plant defense genes, alter levels of phytohormones involved in plant defense, and decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari: Tetranychidae), in multiple, distantly related crop plants. Methodology/Principal Findings Using cotton (Gossypium hirsutum), corn (Zea mays) and tomato (Solanum lycopersicum) plants, we show that transcription of phenylalanine amonia lyase, coenzyme A ligase, trypsin protease inhibitor and chitinase are suppressed and concentrations of the phytohormone OPDA and salicylic acid were altered by neonicotinoid insecticides. Consequently, the population growth of spider mites increased from 30% to over 100% on neonicotinoid-treated plants in the greenhouse and by nearly 200% in the field experiment. Conclusions/Significance Our findings are important because applications of neonicotinoid insecticides have been associated with outbreaks of spider mites in several unrelated plant species. More importantly, this is the first study to document insecticide-mediated disruption of plant defenses and link it to increased population growth of a non-target herbivore. This study adds to growing evidence that bioactive agrochemicals can have unanticipated ecological effects and suggests that the direct effects of insecticides on plant defenses should be considered when the ecological costs of insecticides are evaluated. PMID

Feasibility and acceptability of insecticide-treated plastic sheeting (ITPS) for vector control in Papua New Guinea.

PubMed

Pulford, Justin; Tandrapah, Anthony; Atkinson, Jo-An; Kaupa, Brown; Russell, Tanya; Hetzel, Manuel W

2012-10-09

This study assessed the feasibility and acceptability of utilizing insecticide-treated plastic sheeting (ITPS) as a malaria control intervention in Papua New Guinea (PNG). ZeroVector® ITPS was installed in 40 homes across four study sites representing a cross section of malaria transmission risk and housing style. Structured questionnaires were completed at the time of ITPS installation (n=40) and at four weeks post installation (n=40) with the household head. Similarly, group interviews with the male and/or female household heads were completed at installation (n=5) and four-week follow-up (n=4). ZeroVector® ITPS was successfully installed in a range of homes employing traditional and/or modern building materials in PNG. The ITPS installations remained intact over the course of the four-week trial period and were highly acceptable to both male and female household heads. No dissatisfaction with the ITPS product was reported at four-week follow-up; however, the installation process was time consuming, participants reported a reduction in mosquito net use following ITPS installation and many participants expressed concern about the longevity of ITPS over the longer term. ZeroVector® ITPS installation is feasible and highly acceptable in a diverse range of PNG contexts and is likely to be favourably received as a vector control intervention if accessible en masse. A longer-term evaluation is required before firm policy or public health decisions can be made regarding the potential application of ITPS in the national malaria control programme. The positive study findings suggest a longer-term evaluation of this promising malaria control intervention warrants consideration.

The effect of long-lasting insecticidal water container covers on field populations of Aedes aegypti (L.) mosquitoes in Cambodia.

PubMed

Seng, Chang Moh; Setha, To; Nealon, Joshua; Chantha, Ngan; Socheat, Doung; Nathan, Michael B

2008-12-01

Dengue in Cambodia is mainly transmitted by Aedes aegypti (L.) mosquitoes that primarily breed in large, concrete jars (> or =200 liters) used for the storage of water for domestic use. Following a preliminary risk assessment, long-lasting insecticidal netting (LN) treated with deltamethrin was incorporated into the design of the covers for these jars. Their effect on immature and adult female populations of Ae. aegypti in six villages in a peri-urban area of Cambodia were compared with populations in six nearby control villages before and for 22 weeks after distribution of the jar covers. There were significantly fewer pupae per house in intervention villages than in control villages (6.6 and 31.9, respectively, p<0.01). Fewer pupae were recovered from intervention houses than from control houses at every post-intervention assessment. Two weeks after the intervention, the average number of indoor resting female Ae. aegypti per house in the intervention villages had declined approximately three-fold, whereas in the controls there was only a slight reduction (16%). The magnitude of the difference between the two areas diminished over time, which contact bioassays confirmed was likely due to a gradual reduction of insecticidal effect of the jar covers. In the study area, insecticide-treated covers for large concrete water storage jars were efficacious for controlling Ae. aegypti in the protected water jars and with a demonstrable effect on adult densities and survival. Further studies of this targeted container strategy in Cambodia, and elsewhere, are recommended. However, improvements in technology that would extend the duration of insecticidal effectiveness of LN materials may be needed for the development of cost-effective public health applications.

Bed Net Durability Assessments: Exploring a Composite Measure of Net Damage

PubMed Central

Vanden Eng, Jodi L.; Chan, Adeline; Abílio, Ana Paula; Wolkon, Adam; Ponce de Leon, Gabriel; Gimnig, John; Morgan, Juliette

2015-01-01

Background The durability of Long Lasting Insecticidal Nets (LLINs) in field conditions is of great importance for malaria prevention and control efforts; however, the physical integrity of the net fabric is not well understood making it challenging to determine overall effectiveness of nets as they age. The 2011 World Health Organization Pesticide Evaluation Scheme (WHOPES) guidelines provide a simple, standardized method using a proportional hole index (PHI) for assessing net damage with the intent to provide national malaria control programs with guidelines to assess the useful life of LLINS and estimate the rate of replacement. Methods We evaluated the utility of the PHI measure using 409 LLINs collected over three years in Nampula Province, Mozambique following a mass distribution campaign in 2008. For each LLIN the diameter and distance from the bottom of the net were recorded for every hole. Holes were classified into four size categories and a PHI was calculated following WHOPES guidelines. We investigate how the size, shape, and location of holes influence the PHI. The areas of the WHOPES defined categories were compared to circular and elliptical areas based on approximate shape and actual measured axes of each hole and the PHI was compared to cumulative damaged surface area of the LLIN. Results The damaged area of small, medium, large, and extra-large holes was overestimated using the WHOPES categories compared to elliptical areas using the actual measured axes. Similar results were found when comparing to circular areas except for extra-large holes which were underestimated. (Wilcoxon signed rank test of differences p< 0.0001 for all sizes). Approximating holes as circular overestimated hole surface area by 1.5 to 2 times or more. There was a significant difference in the mean number of holes < 0.5 cm by brand and there were more holes of all sizes on the bottom of nets than the top. For a range of hypothetical PHI thresholds used to designate a �

The association between household bed net ownership and all-cause child mortality in Madagascar.

PubMed

Meekers, Dominique; Yukich, Joshua O

2016-09-17

Malaria continues to be an important cause of morbidity and mortality in Madagascar. It has been estimated that the malaria burden costs Madagascar over $52 million annually in terms of treatment costs, lost productivity and prevention expenses. One of the key malaria prevention strategies of the Government of Madagascar consists of large-scale mass distribution campaigns of long-lasting insecticide-treated bed nets (LLIN). Although there is ample evidence that child mortality has decreased in Madagascar, it is unclear whether increases in LLIN ownership have contributed to this decline. This study analyses multiple recent cross-sectional survey data sets to examine the association between household bed net ownership and all-cause child mortality. Data on household-level bed net ownership confirm that the percentage of households that own one or more bed nets increased substantially following the 2009 and 2010 mass LLIN distribution campaigns. Additionally, all-cause child mortality in Madagascar has declined during the period 2008-2013. Bed net ownership was associated with a 22 % reduction in the all-cause child mortality hazard in Madagascar. Mass bed net distributions contributed strongly to the overall decline in child mortality in Madagascar during the period 2008-2013. However, the decline was not solely attributable to increases in bed net coverage, and nets alone were not able to eliminate most of the child mortality hazard across the island.

Deltamethrin-incorporated nets as an integrated pest management tool for the invasive Halyomorpha halys (Hemiptera: Pentatomidae)

USDA-ARS?s Scientific Manuscript database

Long-lasting insecticide nets (LLINs), which have insecticide incorporated within the fibers, have been widely used for the control of malaria and other insect-vectored diseases. Only recently have researchers begun exploring their use for control of agricultural pests. In this study, we evaluated...

Micro-Loans, Insecticide-Treated Bednets, and Malaria: Evidence from a Randomized Controlled Trial in Orissa, India.

PubMed

Tarozzi, Alessandro; Mahajan, Aprajit; Blackburn, Brian; Kopf, Dan; Krishnan, Lakshmi; Yoong, Joanne

2014-07-01

We describe findings from the first large-scale cluster randomized controlled trial in a developing country that evaluates the uptake of a health-protecting technology, insecticide-treated bednets (ITNs), through micro-consumer loans, as compared to free distribution and control conditions. Despite a relatively high price, 52 percent of sample households purchased ITNs, highlighting the role of liquidity constraints in explaining earlier low adoption rates. We find mixed evidence of improvements in malaria indices. We interpret the results and their implications within the debate about cost sharing, sustainability and liquidity constraints in public health initiatives in developing countries.

“People will say that I am proud”: a qualitative study of barriers to bed net use away from home in four Ugandan districts

PubMed Central

2014-01-01

Background Despite increased access and ownership, barriers to insecticide-treated bed net (ITN) use persist. While barriers within the home have been well documented, the challenges to net use when sleeping away from home remain relatively unexplored. This study examines common situations in which people sleep away from home and the barriers to ITN use in those situations. Methods To explore these issues, a group of researchers conducted 28 in-depth interviews and four focus groups amongst adults from net-owning households in four Ugandan districts. Results In addition to sleeping outside during hot season, participants identified social events, livelihood activities, and times of difficulty as circumstances in which large numbers of people sleep away from home. Associated challenges to ITN use included social barriers such as fear of appearing proud, logistical barriers such as not having a place to hang a net, and resource limitations such as not having an extra net with which to travel. Social disapproval emerged as an important barrier to ITN use in public settings. Conclusions Unique barriers to ITN use exist when people spend the night away from home. It is essential to identify and address these barriers in order to reduce malaria exposure in such situations. For events like funerals or religious “crusades” where large numbers of people sleep away from home, alternative approaches, such as spatial repellents may be more appropriate than ITNs. Additional research is required to identify the acceptability and feasibility of alternative prevention strategies in situations where ITNs are unlikely to be effective. PMID:24602371

Insecticide Exposures on Commercial Aircraft: A Literature Review and Screening Level Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddalena, Randy I.; McKone, Thomas E.

2008-10-01

The objective of this project was to provide initial estimates of the relationship between insecticide use on passenger aircraft and exposure levels present in the cabin environment. The work was initially divided into three tasks including 1) a review of insecticide application practices in commercial aircraft, 2) exploratory measurements of insecticide concentrations in treated aircraft and 3) screening level exposure modeling. Task 1 gathered information that is needed to assess the time-concentration history of insecticides in the airline cabin. The literature review focused on application practices, information about the cabin environment and existing measurements of exposure concentrations following treatment. Informationmore » from the airlines was not available for estimating insecticide application rates in the U.S. domestic fleet or for understanding how frequently equipment rotate into domestic routes following insecticide treatment. However, the World Health Organization (WHO) recommends several methods for treating aircraft with insecticide. Although there is evidence that these WHO guidelines may not always be followed, and that practices vary by airline, destination, and/or applicator company, the guidelines in combination with information related to other indoor environments provides a plausible basis for estimating insecticide loading rates on aircraft. The review also found that while measurements of exposure concentrations following simulated aerosol applications are available, measurements following residual treatment of aircraft or applications in domestic aircraft are lacking. Task 2 focused on developing an approach to monitor exposure concentrations in aircraft using a combination of active and passive sampling methods. An existing active sampling approach was intended to provide data immediately following treatment while a passive sampler was developed to provide wider coverage of the fleet over longer sampling periods. The passive

Impact of PermaNet 3.0 on entomological indices in an area of pyrethroid resistant Anopheles gambiae in south-western Nigeria

PubMed Central

2014-01-01

Background PermaNet® 3.0 is an insecticide synergist-combination long-lasting insecticidal net designed to have increased efficacy against malaria vectors with metabolic resistance, even when combined with kdr. The current study reports on the impact of this improved tool on entomological indices in an area with pyrethroid-resistant malaria vectors in Nigeria. Methods Baseline entomological indices across eight villages in Remo North LGA of Ogun State provided the basis for selection of three villages (Ilara, Irolu and Ijesa) for comparing the efficacy of PermaNet® 3.0 (PN3.0), PermaNet® 2.0 (PN2.0) and untreated polyester nets as a control (UTC). In each case, nets were distributed to cover all sleeping spaces and were evaluated for insecticidal activity on a 3-monthly basis. Collection of mosquitoes was conducted monthly via window traps and indoor resting catches. The arithmetic means of mosquito catches per house, entomological inoculation rates before and during the intervention were compared as well as three other outcome parameters: the mean mosquito blood feeding rate, mean mortality and mean parity rates. Results Anopheles gambiae s.l. was the main malaria vector in the three villages, accounting for >98% of the Anopheles population and found in appreciable numbers for 6–7 months. Deltamethrin, permethrin and lambdacyhalothrin resistance were confirmed at Ilara, Irolu and Ijesa. The kdr mutation was the sole resistance mechanism at Ilara, whereas kdr plus P450-based metabolic mechanisms were detected at Irolu and Ijesa. Bioassays repeated on domestically used PN 2.0 and PN 3.0 showed persistent optimal (100%) bio-efficacy for both net types after the 3rd, 6th, 9th and 12th month following net distribution. The use of PN 3.0 significantly reduced mosquito densities with a ‘mass killing’ effect inside houses. Households with PN 3.0 also showed reduced blood feeding as well as lower mosquito parity and sporozoite rates compared to the PN 2.0 and the

How Much Does Malaria Vector Control Quality Matter: The Epidemiological Impact of Holed Nets and Inadequate Indoor Residual Spraying

PubMed Central

Rehman, Andrea M.; Coleman, Mike; Schwabe, Christopher; Baltazar, Giovanna; Matias, Abrahan; Roncon Gomes, Irina; Yellott, Lee; Aragon, Cynthia; Nseng Nchama, Gloria; Mzilahowa, Themba; Rowland, Mark; Kleinschmidt, Immo

2011-01-01

Background Insecticide treated nets (ITN) and indoor residual spraying (IRS) are the two pillars of malaria vector control in Africa, but both interventions are beset by quality and coverage concerns. Data from three control programs were used to investigate the impact of: 1) the physical deterioration of ITNs, and 2) inadequate IRS spray coverage, on their respective protective effectiveness. Methods Malaria indicator surveys were carried out in 2009 and 2010 in Bioko Island, mainland Equatorial Guinea and Malawi to monitor infection with P.falciparum in children, mosquito net use, net condition and spray status of houses. Nets were classified by their condition. The association between infection and quality and coverage of interventions was investigated. Results There was reduced odds of infection with P.falciparum in children sleeping under ITNs that were intact (Odds ratio (OR): 0.65, 95% CI: 0.55–0.77 and OR: 0.81, 95% CI: 0.56–1.18 in Equatorial Guinea and in Malawi respectively), but the protective effect became less with increasingly worse condition of the net. There was evidence for a linear trend in infection per category increase in deterioration of nets. In Equatorial Guinea IRS offered protection to those in sprayed and unsprayed houses alike when neighbourhood spray coverage was high (≥80%) compared to those living in areas of low IRS coverage (<20%), regardless of whether the house they lived in was sprayed or not (adjusted OR = 0.54, 95% CI 0.33–0.89). ITNs provided only personal protection, offering no protection to non users. Although similar effects were seen in Malawi, the evidence was much weaker than in Equatorial Guinea. Conclusions Universal coverage strategies should consider policies for repair and replacement of holed nets and promote the care of nets by their owners. IRS programs should ensure high spray coverage since inadequate coverage gives little or no protection at all. PMID:21559436

The impact of insecticide-treated school uniforms on dengue infections in school-aged children: study protocol for a randomised controlled trial in Thailand.

PubMed

Wilder-Smith, Annelies; Byass, Peter; Olanratmanee, Phanthip; Maskhao, Pongsri; Sringernyuang, Luechai; Logan, James G; Lindsay, Steve W; Banks, Sarah; Gubler, Duane; Louis, Valérie R; Tozan, Yesim; Kittayapong, Pattamaporn

2012-11-15

There is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence. A randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7-18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons. Practical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed. clinicaltrial.gov. NCT01563640.

The impact of insecticides management linked with resistance expression in Anopheles spp. populations.

PubMed

Silva, Guilherme Liberato da; Pereira, Thiago Nunes; Ferla, Noeli Juarez; Silva, Onilda Santos da

2016-06-01

The resistance of some species of Anopheles to chemical insecticides is spreading quickly throughout the world and has hindered the actions of prevention and control of malaria. The main mechanism responsible for resistance in these insects appears to be the target site known as knock-down resistance (kdr), which causes mutations in the sodium channel. Even so, many countries have made significant progress in the prevention of malaria, focusing largely on vector control through long-lasting insecticide nets (LLINs), indoor residual spraying and (IRS) of insecticides. The objective of this review is to contribute with information on the more applied insecticides for the control of the main vectors of malaria, its effects, and the different mechanisms of resistance. Currently it is necessary to look for others alternatives, e.g. biological control and products derived from plants and fungi, by using other organisms as a possible regulator of the populations of malaria vectors in critical outbreaks.

Decline in frequency of the 2La chromosomal inversion in Anopheles gambiae (s.s.) in Western Kenya: correlation with increase in ownership of insecticide-treated bed nets.

PubMed

Matoke-Muhia, Damaris; Gimnig, John E; Kamau, Luna; Shililu, Josephat; Bayoh, M Nabie; Walker, Edward D

2016-06-10

The 2La chromosomal inversion, a genetic polymorphism in An. gambiae (sensu stricto) (s.s.), is associated with adaptation to microclimatic differences in humidity and desiccation resistance and mosquito behaviors. Ownership of insecticide-treated bed nets (ITNs) for malaria control has increased markedly in western Kenya in the last 20 years. An increase in the frequency of ITNs indoors could select against house entering or indoor resting of Anopheles mosquitoes. Thus, the frequency of the 2La inversion is postulated to change in An. gambiae (s.s.) with the increase of ITN ownership over time. Anopheles gambiae mosquitoes were sampled between 1994 and 2011 using pyrethrum knockdown, bednet traps and human landing catches (HLC) from Asembo and Seme, western Kenya. The 2La inversion was detected by a PCR assay with primers designed for proximal breakpoints of the 2La/a and 2L+(a)/+(a) chromosomal conformation. Mosquitoes were tested for malaria parasite infection by sporozoite ELISA. The frequency of the 2La chromosomal inversion declined from 100 % of all chromosomes in 1994 to 17 % in 2005 and remained low through 2011 (21 %). ITN ownership increased from 0 to > 90 % of houses in the study area during this interval. The decline in the frequency of the 2La chromosomal inversion was significantly, negatively correlated with year (r = -0.93) and with increase in ITN ownership (r = -0.96). The frequency of the homo- and heterokaryotypes departed significantly from Hardy-Weinberg equilibrium, suggesting that 2La/a karyotype was under selection, earlier in its favor and later, against it. Precipitation and maximum monthly temperature did not vary over time, therefore there was no trend in climate that could account for the decline. There was no significant difference in frequency of the 2La inversion in An. gambiae (s.s.) females sampled indoors or outdoors in HCL in 2011, nor was there an association between the 2La inversion and infection with Plasmodium

How many holes is too many? A prototype tool for estimating mosquito entry risk into damaged bed nets.

PubMed

Sutcliffe, James; Ji, Xin; Yin, Shaoman

2017-08-01

Insecticide-treated bed nets (ITNs) have played an integral role in malaria reduction but how insecticide depletion and accumulating physical damage affect ITN performance is poorly understood. More accurate methods are needed to assess damage to bed nets so that they can be designed, deployed and replaced optimally. Video recordings of female Anopheles gambiae in near approach (1-½ cm) to occupied untreated rectangular bed nets in a laboratory study were used to quantify the amount of mosquito activity (appearances over time) around different parts of the net, the per-appearance probability of a mosquito coming close to holes of different sizes (hole encounter) and the per-encounter probability of mosquitoes passing through holes of different sizes (hole passage). Appearance frequency on different parts of the net reflected previously reported patterns: the area of the net under greatest mosquito pressure was the roof, followed by the bottom 30 cm of the sides, followed by the 30 cm area immediately above this, followed by the upper two-thirds of the sides. The ratio of activity in these areas was (respectively) 250:33:5:1. Per-appearance probability of hole encounter on all parts of the net was strongly predicted by a factor combining hole perimeter and area. Per-encounter probability of hole passage, in turn, was strongly predicted by hole width. For a given width, there was a 20% greater risk of passage through holes on the roof than holes on the sides. Appearance, encounter and passage predictors correspond to various mosquito behaviours that have previously been described and are combined into a prototype mosquito entry risk tool that predicts mosquito entry rates for nets with various amounts of damage. Scenarios that use the entry risk tool to test the recommendations of the WHOPES proportionate hole index (pHI) suggest that the pHI hole size categories and failure to account for hole location likely sometimes lead to incorrect conclusions about net

Behavioral Responses of the Common Bed Bug, Cimex lectularius, to Insecticide Dusts.

PubMed

Agnew, John L; Romero, Alvaro

2017-08-08

Bed bugs have reemerged recently as a serious and growing problem not only in North America but in many parts of the world. These insects have become the most challenging pest to control in urban environments. Residual insecticides are the most common methods used for bed bug control; however, insecticide resistance limits the efficacy of treatments. Desiccant dusts have emerged as a good option to provide a better residual effect for bed bug control. Several studies have focused on determining the efficacy of dust-based insecticides against bed bugs. However, behavioral responses of bed bugs to insecticide dusts could influence their efficacy. The behavioral responses of bed bugs to six insecticide dusts commonly used in the United States were evaluated with an advanced video tracking technique (Ethovision). Bed bugs took longer to make first contact with areas treated with the diatomaceous earth (DE)-based products MotherEarth D and Alpine than pyrethroid, pyrethrins or silica gel based products, DeltaDust, Tempo 1% Dust and CimeXa, respectively. Lower visitation rates of bed bugs were recorded for areas treated with MotherEarth D, Alpine and CimeXa than that of DeltaDust, Tempo 1% Dust, and Tri-Die Silica + Pyrethrum Dust. Bed bugs spent less time in areas treated with Tri-Die Dust, CimeXa, Alpine, and MotherEarth D than DeltaDust and Tempo 1% Dust, and they exhibited a reduction in locomotor parameters when crawling on areas treated with CimeXa and Alpine. The implications of these responses to bed bug control are discussed.

Behavioral Responses of the Common Bed Bug, Cimex lectularius, to Insecticide Dusts

PubMed Central

Agnew, John L.; Romero, Alvaro

2017-01-01

Bed bugs have reemerged recently as a serious and growing problem not only in North America but in many parts of the world. These insects have become the most challenging pest to control in urban environments. Residual insecticides are the most common methods used for bed bug control; however, insecticide resistance limits the efficacy of treatments. Desiccant dusts have emerged as a good option to provide a better residual effect for bed bug control. Several studies have focused on determining the efficacy of dust-based insecticides against bed bugs. However, behavioral responses of bed bugs to insecticide dusts could influence their efficacy. The behavioral responses of bed bugs to six insecticide dusts commonly used in the United States were evaluated with an advanced video tracking technique (Ethovision). Bed bugs took longer to make first contact with areas treated with the diatomaceous earth (DE)-based products MotherEarth D and Alpine than pyrethroid, pyrethrins or silica gel based products, DeltaDust, Tempo 1% Dust and CimeXa, respectively. Lower visitation rates of bed bugs were recorded for areas treated with MotherEarth D, Alpine and CimeXa than that of DeltaDust, Tempo 1% Dust, and Tri-Die Silica + Pyrethrum Dust. Bed bugs spent less time in areas treated with Tri-Die Dust, CimeXa, Alpine, and MotherEarth D than DeltaDust and Tempo 1% Dust, and they exhibited a reduction in locomotor parameters when crawling on areas treated with CimeXa and Alpine. The implications of these responses to bed bug control are discussed. PMID:28786920

The cost of routine Aedes aegypti control and of insecticide-treated curtain implementation.

PubMed

Baly, Alberto; Flessa, Steffen; Cote, Marilys; Thiramanus, Thirapong; Vanlerberghe, Veerle; Villegas, Elci; Jirarojwatana, Somchai; Van der Stuyft, Patrick

2011-05-01

Insecticide-treated curtains (ITCs) are promoted for controlling the Dengue vector Aedes aegypti. We assessed the cost of the routine Aedes control program (RACP) and the cost of ITC implementation through the RACP and health committees in Venezuela and through health volunteers in Thailand. The yearly cost of the RACP per household amounted to US$2.14 and $1.89, respectively. The ITC implementation cost over three times more, depending on the channel used. In Venezuela the RACP was the most efficient implementation-channel. It spent US$1.90 (95% confidence interval [CI]: 1.83; 1.97) per curtain distributed, of which 76.9% for the curtain itself. Implementation by health committees cost significantly (P = 0.02) more: US$2.32 (95% CI: 1.93; 2.61) of which 63% for the curtain. For ITC implementation to be at least as cost-effective as the RACP, at equal effectiveness and actual ITC prices, the attained curtain coverage and the adulticiding effect should last for 3 years.

Mechanistic modeling of insecticide risks to breeding birds in ...

EPA Pesticide Factsheets

Insecticide usage in the United States is ubiquitous in urban, suburban, and rural environments. In evaluating data for an insecticide registration application and for registration review, scientists at the United States Environmental Protection Agency (USEPA) assess the fate of the insecticide and the risk the insecticide poses to the environment and non-target wildlife. At the present time, current USEPA risk assessments do not include population-level endpoints. In this paper, we present a new mechanistic model, which allows risk assessors to estimate the effects of insecticide exposure on the survival and seasonal productivity of birds known to use agricultural fields during their breeding season. The new model was created from two existing USEPA avian risk assessment models, the Terrestrial Investigation Model (TIM v.3.0) and the Markov Chain Nest Productivity model (MCnest). The integrated TIM/MCnest model has been applied to assess the relative risk of 12 insecticides used to control corn pests on a suite of 31 avian species known to use cornfields in midwestern agroecosystems. The 12 insecticides that were assessed in this study are all used to treat major pests of corn (corn root worm borer, cutworm, and armyworm). After running the integrated TIM/MCnest model, we found extensive differences in risk to birds among insecticides, with chlorpyrifos and malathion (organophosphates) generally posing the greatest risk, and bifenthrin and ë-cyhalothrin (

Reported bed net ownership and use in social contacts is associated with uptake of bed nets for malaria prevention in pregnant women in Ghana.

PubMed

Ernst, Kacey C; Erly, Steven; Adusei, Charity; Bell, Melanie L; Kessie, David Komla; Biritwum-Nyarko, Alberta; Ehiri, John

2017-01-04

Despite progress made in the last decades, malaria persists as a pressing health issue in sub-Saharan Africa. Pregnant women are particularly vulnerable to infection and serious health outcomes for themselves and their unborn child. Risk can be mitigated through appropriate use of control measures such as insecticide-treated bed nets. Although social networks can influence uptake of preventive strategies, the role of social influence on bed net ownership has not been explored. During an evaluation of a bed net distribution programme, the influence of non-health care advisors on ownership and use of bed nets by pregnant women in Kumasi, Ghana was examined. Data were collected through in-person interviews with 300 pregnant women seeking antenatal care in an urban hospital in Kumasi, Ghana. Participants were asked about their bed net ownership, bed net use, and information about three personal contacts that they go to for pregnancy advice. Information about these advisors was combined into an influence score. Logistic regression models were used to determine the association between the score and bed net ownership. Those who owned a bed net were further assessed to determine if interpersonal influence was associated with self-reported sleeping under the bed net the previous night. Of the 294 women in the analysis, 229 (78%) reported owning bed nets. Of these bed net owners, 139 (61%) reported using a bed net the previous night. A dose response relationship was observed between the interpersonal influence score and bed net ownership and use. Compared to the lowest influence score, those with the highest influence score (>1 SD above the mean) were marginally more likely to own a bed net [OR = 2.37, 95% CI (0.87, 6.39)] and much more likely to use their bed net [5.38, 95% CI (1.89, 15.25)] after adjusting for other factors. Interpersonal influence appears to have modest impact on ownership and use of bed nets by pregnant women in an urban area of Ghana. Further

Insecticide exposure affects DNA and antioxidant enzymes activity in honey bee species Apis florea and A. dorsata: Evidence from Punjab, Pakistan.

PubMed

Hayat, Khizar; Afzal, Muhammad; Aqueel, Muhammad Anjum; Ali, Sajjad; Saeed, Muhammad Farhan; Khan, Qaiser M; Ashfaq, Muhammad; Damalas, Christos A

2018-09-01

Insecticide exposure can affect honey bees in agro-ecosystems, posing behavioral stresses that can lead to population decline. In this study, insecticide incidence, DNA damage, and antioxidant enzyme activity were studied in Apis florea and A. dorsata honey bee samples collected from insecticide-treated and insecticide-free areas of Punjab, Pakistan. Seven insecticides: chlorpyrifos, dimethoate, imidacloprid, phorate, emamectin, chlorfenapyr, and acetamiprid were detected in seven samples of A. florea and five samples of A. dorsata. In total, 12 samples (22.2%) of honey bees were found positive to insecticide presence out of 54 samples. The most frequently detected insecticide was chlorpyrifos, which was found in four samples (7.4%), with a concentration ranging from 0.01 to 0.05 μg/g and an average concentration 0.03 μg/g. The comet assay or single cell gel electrophoresis assay, a simple way to measure DNA strand breaks in eukaryotic cells, was used to microscopically find damage of DNA at the level of a single cell. Comet tail lengths of DNA in A. florea and A. dorsata samples from insecticide-treated areas were significantly higher (P < 0.05) than samples from insecticide-free areas. The highest comet tail length (19.28 ± 2.67 μm) was observed in DNA of A. dorsata from insecticide-treated areas, while the minimum one (3.18 ± 1.46 μm) was noted in A. dorsata from insecticide-free areas. Catalase (CAT) activity did not vary significantly between honey bee samples from insecticide-treated and insecticide-free areas, while glutathione S-transferase (GST) activity showed a significant reduction in response to insecticide exposure. Significant positive correlations were detected between enzyme activity and insecticide concentration in honey bee species from insecticide-treated areas compared with control groups. Toxicity from pesticide exposure at sub-lethal levels after application or from exposure to pesticide residues should not be

Impact of a mass media campaign on bed net use in Cameroon

PubMed Central

2013-01-01

Background In 2011, Cameroon and its health partners distributed over eight million free long-lasting insecticide treated nets (LLINs) in an effort to reduce the significant morbidity and mortality burden of malaria in the country. A national communications campaign was launched in July 2011 to ensure that as the nets were delivered, they would be used consistently to close a net use gap: only 51.6% of adults and 63.4% of their children in households with at least one net were sleeping under nets before the distribution. Even in households with at least one net for every two people, over 35% of adults were not sleeping under a net. Malaria No More (MNM) adapted its signature NightWatch communications programme to fit within the coordinated “KO Palu” (Knock Out Malaria) national campaign. This study evaluates the impact of KO Palu NightWatch activities (that is, the subset of KO Palu-branded communications that were funded by MNM’s NightWatch program) on bed net use. Methods Using national survey data collected at baseline (in March/April 2011, before the national LLIN distribution and KO Palu NightWatch launch) and post-intervention (March/April 2012), this study evaluates the impact of exposure to KO Palu NightWatch activities on last-night net use by Cameroonian adults and their children under five. First, a plausible case for causality was established by comparing net use in 2011 and 2012 and measuring exposure to KO Palu NightWatch; next, a propensity score matching (PSM) model was used to estimate the impact of exposure on net use by simulating a randomized control trial; finally, the model was tested for sensitivity to unmeasured factors. Results The PSM model estimated that among Cameroonians with at least one net in their household, exposure to KO Palu NightWatch activities was associated with a 6.6 percentage point increase in last-night net use among respondents (65.7% vs 59.1%, p < 0.05) and a 12.0 percentage point increase in last-night net

Effect of malaria transmission reduction by insecticide-treated bed nets (ITNs) on the genetic diversity of Plasmodium falciparum merozoite surface protein (MSP-1) and circumsporozoite (CSP) in western Kenya.

PubMed

Kariuki, Simon K; Njunge, James; Muia, Ann; Muluvi, Geofrey; Gatei, Wangeci; Ter Kuile, Feiko; Terlouw, Dianne J; Hawley, William A; Phillips-Howard, Penelope A; Nahlen, Bernard L; Lindblade, Kim A; Hamel, Mary J; Slutsker, Laurence; Shi, Ya Ping

2013-08-27

Although several studies have investigated the impact of reduced malaria transmission due to insecticide-treated bed nets (ITNs) on the patterns of morbidity and mortality, there is limited information on their effect on parasite diversity. Sequencing was used to investigate the effect of ITNs on polymorphisms in two genes encoding leading Plasmodium falciparum vaccine candidate antigens, the 19 kilodalton blood stage merozoite surface protein-1 (MSP-1(19kDa)) and the Th2R and Th3R T-cell epitopes of the pre-erythrocytic stage circumsporozoite protein (CSP) in a large community-based ITN trial site in western Kenya. The number and frequency of haplotypes as well as nucleotide and haplotype diversity were compared among parasites obtained from children <5 years old prior to the introduction of ITNs (1996) and after 5 years of high coverage ITN use (2001). A total of 12 MSP-1(19kDa) haplotypes were detected in 1996 and 2001. The Q-KSNG-L and E-KSNG-L haplotypes corresponding to the FVO and FUP strains of P. falciparum were the most prevalent (range 32-37%), with an overall haplotype diversity of > 0.7. No MSP-1(19kDa) 3D7 sequence-types were detected in 1996 and the frequency was less than 4% in 2001. The CSP Th2R and Th3R domains were highly polymorphic with a total of 26 and 14 haplotypes, respectively detected in 1996 and 34 and 13 haplotypes in 2001, with an overall haplotype diversity of > 0.9 and 0.75 respectively. The frequency of the most predominant Th2R and Th3R haplotypes was 14 and 36%, respectively. The frequency of Th2R and Th3R haplotypes corresponding to the 3D7 parasite strain was less than 4% at both time points. There was no significant difference in nucleotide and haplotype diversity in parasite isolates collected at both time points. High diversity in these two genes has been maintained overtime despite marked reductions in malaria transmission due to ITNs use. The frequency of 3D7 sequence-types was very low in this area. These findings provide

Insecticide use and crop selection in regions with high GM adoption rates

USDA-ARS?s Scientific Manuscript database

South Dakota has recently experienced a significant increase in the proportion of acres treated with insecticide. Unfortunately, data on insecticide usage by crop at the county level is not available. The following case study seeks to uncover the reasons for this increase by analyzing county-leve...

Assessment of coverage of preventive treatment and insecticide-treated mosquito nets in pregnant women attending antenatal care services in 11 districts in Mozambique in 2011: the critical role of supply chain.

PubMed

Salomão, Cristolde; Sacarlal, Jahit; Gudo, Eduardo Samo

2017-05-25

Malaria during pregnancy is associated with poor maternal and pregnancy outcome and the World Health Organization recommends the administration of intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) and distribution of insecticide-treated mosquito nets (ITNs) to all pregnant women attending antenatal care (ANC) services. This study was conducted with the aim to assess the uptake of IPTp and ITNs in pregnant women attending ANC services and correlate with ANC attendance and frequency of stock-outs in 22 health facilities Mozambique. A cross-sectional study was conducted between July and December 2011 in 22 health units in 11 districts situated in 11 provinces in Mozambique. Two health facilities were selected per district (one urban and one rural). Data were collected by reviewing logbooks of antenatal consultations as well as from monthly district reports. During the period under investigation, a total of 23,524 pregnant women attended their 1st antenatal care visits, of which 12,775 (54.3%) and 7581 (32.2%) received one and two doses of IPTp, respectively. In regard to ITNs, a total of 16,436 (69.9%) pregnant women received ITNs. Uptake of IPTp and ITNs by pregnant women at ANC services was higher in southern Mozambique and lower in districts situated in the northern part of the country. Stock-outs of SP and ITNs were reported in 50.0% (11/22) and 54.5% (12/22) of the health facilities, respectively. Coverage of IPTp and ITN in health facilities with stock-outs of SP and ITNs was much lower as compared to health facilities with no stock-outs. Altogether, data from this study shows that coverage of the 2nd dose of IPTp, as well as ITNs, was low in pregnant women attending ANC services in Mozambique. In addition, this data also shows that stock-outs of SP and ITNs were frequent and led to lower coverage of IPTp and ITN, representing a serious barrier for the accomplishment of targets. In conclusion, this study recommends that

Theoretical impact of insecticide-impregnated school uniforms on dengue incidence in Thai children

PubMed Central

Massad, Eduardo; Amaku, Marcos; Coutinho, Francisco Antonio Bezerra; Kittayapong, Pattamaporn; Wilder-Smith, Annelies

2013-01-01

Background Children carry the main burden of morbidity and mortality caused by dengue. Children spend a considerable amount of their day at school; hence strategies that reduce human–mosquito contact to protect against the day-biting habits of Aedes mosquitoes at schools, such as insecticide-impregnated uniforms, could be an effective prevention strategy. Methodology We used mathematical models to calculate the risk of dengue infection based on force of infection taking into account the estimated proportion of mosquito bites that occur in school and the proportion of school time that children wear the impregnated uniforms. Principal findings The use of insecticide-impregnated uniforms has efficacy varying from around 6% in the most pessimistic estimations, to 55% in the most optimistic scenarios simulated. Conclusions Reducing contact between mosquito bites and human hosts via insecticide-treated uniforms during school time is theoretically effective in reducing dengue incidence and may be a valuable additional tool for dengue control in school-aged children. The efficacy of this strategy, however, is dependent on the compliance of the target population in terms of proper and consistent wearing of uniforms and, perhaps more importantly, the proportion of bites inflicted by the Aedes population during school time. PMID:23541045

Community structure of ammonia-oxidizing archaea and ammonia-oxidizing bacteria in soil treated with the insecticide imidacloprid.

PubMed

Cycoń, Mariusz; Piotrowska-Seget, Zofia

2015-01-01

The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil using the denaturing gradient gel electrophoresis (DGGE) approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S) and the Shannon-Wiener index (H) values for soil treated with the field rate (FR) dosage of imidacloprid (1 mg/kg soil) showed no changes in measured indices for the AOA and AOB community members. In turn, the 10∗FR dosage of insecticide (10 mg/kg soil) negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4 (+), known as the most important factor which determines the contribution of these microorganisms to soil nitrification.

Community Structure of Ammonia-Oxidizing Archaea and Ammonia-Oxidizing Bacteria in Soil Treated with the Insecticide Imidacloprid

PubMed Central

Cycoń, Mariusz; Piotrowska-Seget, Zofia

2015-01-01

The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil using the denaturing gradient gel electrophoresis (DGGE) approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S) and the Shannon-Wiener index (H) values for soil treated with the field rate (FR) dosage of imidacloprid (1 mg/kg soil) showed no changes in measured indices for the AOA and AOB community members. In turn, the 10∗FR dosage of insecticide (10 mg/kg soil) negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4 +, known as the most important factor which determines the contribution of these microorganisms to soil nitrification. PMID:25705674

Insecticide solvents: interference with insecticidal action.

PubMed

Brattsten, L B; Wilkinson, C F

1977-06-10

Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.

Long-Lasting Insecticide Net Ownership, Access and Use in Southwest Ethiopia: A Community-Based Cross-Sectional Study

PubMed Central

Seyoum, Dinberu; Speybroeck, Niko; Duchateau, Luc; Brandt, Patrick; Rosas-Aguirre, Angel

2017-01-01

Introduction: A large proportion of the Ethiopian population (approximately 68%) lives in malaria risk areas. Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the malaria prevention and control strategy in the country. This study assessed the ownership, access and use of LLNs in the malaria endemic southwest Ethiopia. Methods: A community-based cross-sectional study was conducted in southwest Ethiopia during October–November 2015, including 836 households from sixteen villages around Gilgel-Gibe dam area. Indicators of ownership, access and use of LLINs were derived following the Roll Back Malaria (RBM) guidelines. Factors associated with failure for both LLIN access and use were analysed at household level using a multivariate logistic regression model. Results: The proportion of households with at least one LLIN was 82.7% (95% CI: 80.0, 85.1). However, only 68.9% (95% CI: 65.6, 71.9) had enough LLINs to cover all family members (with ≥one LLIN for every two persons). While 75.3% (95% CI: 68.4, 83.0) of the population was estimated to have accessed to LLINs, only 63.8% (95% CI: 62.3, 65.2) reported to have used a LLIN the previous night. The intra-household gap (i.e., households owning at least one LLIN, but unable to cover all family members) and the behavioral gap (i.e., household members who did not sleep under a LLIN despite having access to one) were 16.8% and 10.5%, respectively. Age, marital status and education of household heads, as well as household size and cooking using firewood were associated with the access to enough LLINs within households. Decreased access to LLINs at households was the main determinant for not achieving ≥80% household members sleeping under a LLIN the previous night. Other associated factors were household size and education level of household head. Conclusions: LLIN coverage levels in study villages remain below national targets of 100% for ownership and 80% for use. The access to

Long-Lasting Insecticide Net Ownership, Access and Use in Southwest Ethiopia: A Community-Based Cross-Sectional Study.

PubMed

Seyoum, Dinberu; Speybroeck, Niko; Duchateau, Luc; Brandt, Patrick; Rosas-Aguirre, Angel

2017-10-27

Introduction : A large proportion of the Ethiopian population (approximately 68%) lives in malaria risk areas. Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the malaria prevention and control strategy in the country. This study assessed the ownership, access and use of LLNs in the malaria endemic southwest Ethiopia. Methods: A community-based cross-sectional study was conducted in southwest Ethiopia during October-November 2015, including 836 households from sixteen villages around Gilgel-Gibe dam area. Indicators of ownership, access and use of LLINs were derived following the Roll Back Malaria (RBM) guidelines. Factors associated with failure for both LLIN access and use were analysed at household level using a multivariate logistic regression model. Results: The proportion of households with at least one LLIN was 82.7% (95% CI: 80.0, 85.1). However, only 68.9% (95% CI: 65.6, 71.9) had enough LLINs to cover all family members (with ≥one LLIN for every two persons). While 75.3% (95% CI: 68.4, 83.0) of the population was estimated to have accessed to LLINs, only 63.8% (95% CI: 62.3, 65.2) reported to have used a LLIN the previous night. The intra-household gap (i.e., households owning at least one LLIN, but unable to cover all family members) and the behavioral gap (i.e., household members who did not sleep under a LLIN despite having access to one) were 16.8% and 10.5%, respectively. Age, marital status and education of household heads, as well as household size and cooking using firewood were associated with the access to enough LLINs within households. Decreased access to LLINs at households was the main determinant for not achieving ≥80% household members sleeping under a LLIN the previous night. Other associated factors were household size and education level of household head. Conclusions: LLIN coverage levels in study villages remain below national targets of 100% for ownership and 80% for use. The access to

Serological Markers of Sand Fly Exposure to Evaluate Insecticidal Nets against Visceral Leishmaniasis in India and Nepal: A Cluster-Randomized Trial

PubMed Central

Gidwani, Kamlesh; Picado, Albert; Rijal, Suman; Singh, Shri Prakash; Roy, Lalita; Volfova, Vera; Andersen, Elisabeth Wreford; Uranw, Surendra; Ostyn, Bart; Sudarshan, Medhavi; Chakravarty, Jaya; Volf, Petr; Sundar, Shyam; Boelaert, Marleen; Rogers, Matthew Edward

2011-01-01

Background Visceral leishmaniasis is the world' second largest vector-borne parasitic killer and a neglected tropical disease, prevalent in poor communities. Long-lasting insecticidal nets (LNs) are a low cost proven vector intervention method for malaria control; however, their effectiveness against visceral leishmaniasis (VL) is unknown. This study quantified the effect of LNs on exposure to the sand fly vector of VL in India and Nepal during a two year community intervention trial. Methods As part of a paired-cluster randomized controlled clinical trial in VL-endemic regions of India and Nepal we tested the effect of LNs on sand fly biting by measuring the antibody response of subjects to the saliva of Leishmania donovani vector Phlebotomus argentipes and the sympatric (non-vector) Phlebotomus papatasi. Fifteen to 20 individuals above 15 years of age from 26 VL endemic clusters were asked to provide a blood sample at baseline, 12 and 24 months post-intervention. Results A total of 305 individuals were included in the study, 68 participants provided two blood samples and 237 gave three samples. A random effect linear regression model showed that cluster-wide distribution of LNs reduced exposure to P. argentipes by 12% at 12 months (effect 0.88; 95% CI 0.83–0.94) and 9% at 24 months (effect 0.91; 95% CI 0.80–1.02) in the intervention group compared to control adjusting for baseline values and pair. Similar results were obtained for P. papatasi. Conclusions This trial provides evidence that LNs have a limited effect on sand fly exposure in VL endemic communities in India and Nepal and supports the use of sand fly saliva antibodies as a marker to evaluate vector control interventions. PMID:21931871

Reduced ultraviolet light transmission increases insecticide longevity in protected culture raspberry production.

PubMed

Leach, Heather; Wise, John C; Isaacs, Rufus

2017-12-01

High tunnels are large protective structures used for season extension of many crops, including raspberries. These structures are often covered in plastic films to reduce and diffuse ultraviolet light transmission for pest and disease control, but this may also affect the photodegradation and efficacy of pesticides applied under these tunnels. We compared the residue levels of ten insecticides under three tunnel plastics with varying levels of UV transmission and open field conditions. Raspberry plants placed in research-scale tunnels were treated with insecticides and residues on fruit and foliage were monitored for one or two weeks in early 2015 and early and late 2016. Plastics that reduce UV transmission resulted in 50% greater residues of some insecticides compared to transparent plastics, and 60% compared to uncovered tunnels. This increased persistence of residues was evident within 1 day and remained consistently higher for up to 14 days. This pattern was demonstrated for multiple insecticides, including bifenthrin, esfenvalerate, imidacloprid, thiamethoxam, and spinosad. In contrast, the insecticide malathion degraded rapidly regardless of the plastic treatment, indicating less sensitivity to photodegradation. Bioassays using insecticide-treated leaves that were under UV-blocking plastic revealed higher mortality of the invasive fruit pest, Drosophila suzukii, compared to leaves that were uncovered. This indicates that the activity of pesticides under high tunnels covered in UV-reducing plastics may be prolonged, allowing for fewer insecticide applications and longer intervals between sprays. This information can be used to help optimize pest control in protected culture berry production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterizing the insecticide resistance of Anopheles gambiae in Mali.

PubMed

Cisse, Moussa B M; Keita, Chitan; Dicko, Abdourhamane; Dengela, Dereje; Coleman, Jane; Lucas, Bradford; Mihigo, Jules; Sadou, Aboubacar; Belemvire, Allison; George, Kristen; Fornadel, Christen; Beach, Raymond

2015-08-22

The impact of indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs), key components of the national malaria control strategy of Mali, is threatened by vector insecticide resistance. The objective of this study was to assess the level of insecticide resistance in Anopheles gambiae sensu lato populations from Mali against four classes of insecticide recommended for IRS: organochlorines (OCs), pyrethroids (PYs), carbamates (CAs) and organophosphates (OPs). Characterization of resistance was done in 13 sites across southern Mali and assessed presence and distribution of physiological mechanisms that included target-site modifications: knockdown resistance (kdr) and altered acetycholinesterase (AChE), and/or metabolic mechanisms: elevated esterases, glutathione S-transferases (GSTs), and monooxygenases. The World Health Organization (WHO) tube test was used to determine phenotypic resistance of An. gambiae s.l. to: dichlorodiphenyltrichloroethane (DDT) (OC), deltamethrin (PY), lambda-cyhalothrin (PY), bendiocarb (CA), and fenitrothion (OP). Identification of sibling species and presence of the ace-1 (R) and Leu-Phe kdr, resistance-associated mutations, were determined using polymerase chain reaction (PCR) technology. Biochemical assays were conducted to detect increased activity of GSTs, oxidases and esterases. Populations tested showed high levels of resistance to DDT in all 13 sites, as well as increased resistance to deltamethrin and lambda-cyhalothrin in 12 out of 13 sites. Resistance to fenitrothion and bendiocarb was detected in 1 and 4 out of 13 sites, respectively. Anopheles coluzzii, An. gambiae sensu stricto and Anopheles arabiensis were identified with high allelic frequencies of kdr in all sites where each of the species were found (13, 12 and 10 sites, respectively). Relatively low allelic frequencies of ace-1 (R) were detected in four sites where this assessment was conducted. Evidence of elevated insecticide metabolism, based on oxidase

Insecticide exposure impacts vector-parasite interactions in insecticide-resistant malaria vectors.

PubMed

Alout, Haoues; Djègbè, Innocent; Chandre, Fabrice; Djogbénou, Luc Salako; Dabiré, Roch Kounbobr; Corbel, Vincent; Cohuet, Anna

2014-07-07

Currently, there is a strong trend towards increasing insecticide-based vector control coverage in malaria endemic countries. The ecological consequence of insecticide applications has been mainly studied regarding the selection of resistance mechanisms; however, little is known about their impact on vector competence in mosquitoes responsible for malaria transmission. As they have limited toxicity to mosquitoes owing to the selection of resistance mechanisms, insecticides may also interact with pathogens developing in mosquitoes. In this study, we explored the impact of insecticide exposure on Plasmodium falciparum development in insecticide-resistant colonies of Anopheles gambiae s.s., homozygous for the ace-1 G119S mutation (Acerkis) or the kdr L1014F mutation (Kdrkis). Exposure to bendiocarb insecticide reduced the prevalence and intensity of P. falciparum oocysts developing in the infected midgut of the Acerkis strain, whereas exposure to dichlorodiphenyltrichloroethane reduced only the prevalence of P. falciparum infection in the Kdrkis strain. Thus, insecticide resistance leads to a selective pressure of insecticides on Plasmodium parasites, providing, to our knowledge, the first evidence of genotype by environment interactions on vector competence in a natural Anopheles-Plasmodium combination. Insecticide applications would affect the transmission of malaria in spite of resistance and would reduce to some degree the impact of insecticide resistance on malaria control interventions. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The Cost of Routine Aedes aegypti Control and of Insecticide-Treated Curtain Implementation

PubMed Central

Baly, Alberto; Flessa, Steffen; Cote, Marilys; Thiramanus, Thirapong; Vanlerberghe, Veerle; Villegas, Elci; Jirarojwatana, Somchai; Van der Stuyft, Patrick

2011-01-01

Insecticide-treated curtains (ITCs) are promoted for controlling the Dengue vector Aedes aegypti. We assessed the cost of the routine Aedes control program (RACP) and the cost of ITC implementation through the RACP and health committees in Venezuela and through health volunteers in Thailand. The yearly cost of the RACP per household amounted to US$2.14 and $1.89, respectively. The ITC implementation cost over three times more, depending on the channel used. In Venezuela the RACP was the most efficient implementation-channel. It spent US$1.90 (95% confidence interval [CI]: 1.83; 1.97) per curtain distributed, of which 76.9% for the curtain itself. Implementation by health committees cost significantly (P = 0.02) more: US$2.32 (95% CI: 1.93; 2.61) of which 63% for the curtain. For ITC implementation to be at least as cost-effective as the RACP, at equal effectiveness and actual ITC prices, the attained curtain coverage and the adulticiding effect should last for 3 years. PMID:21540384

A Cluster-Randomized Trial of Insecticide-Treated Curtains for Dengue Vector Control in Thailand

PubMed Central

Lenhart, Audrey; Trongtokit, Yuwadee; Alexander, Neal; Apiwathnasorn, Chamnarn; Satimai, Wichai; Vanlerberghe, Veerle; Van der Stuyft, Patrick; McCall, Philip J.

2013-01-01

The efficacy of insecticide-treated window curtains (ITCs) for dengue vector control was evaluated in Thailand in a cluster-randomized controlled trial. A total of 2,037 houses in 26 clusters was randomized to receive the intervention or act as control (no treatment). Entomological surveys measured Aedes infestations (Breteau index, house index, container index, and pupae per person index) and oviposition indices (mean numbers of eggs laid in oviposition traps) immediately before and after intervention, and at 3-month intervals over 12 months. There were no consistent statistically significant differences in entomological indices between intervention and control clusters, although oviposition indices were lower (P < 0.01) in ITC clusters during the wet season. It is possible that the open housing structures in the study reduced the likelihood of mosquitoes making contact with ITCs. ITCs deployed in a region where this house design is common may be unsuitable for dengue vector control. PMID:23166195

Effectiveness of insecticide-treated and non-treated trap plants for the management of Frankliniella occidentalis (Thysanoptera: Thripidae) in greenhouse ornamentals.

PubMed

Buitenhuis, Rosemarije; Shipp, J Les; Jandricic, Sarah; Murphy, Graeme; Short, Mike

2007-09-01

The effectiveness of trap cropping as an integrated control strategy against western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), was explored in potted chrysanthemum, Dendranthema grandiflora (Tzvelev), greenhouse crops. The efficacy of flowering chrysanthemum trap plants, either treated with the insecticide spinosad or untreated, to regulate F. occidentalis populations was tested at different spatial scales (small cage, large cage and commercial greenhouse) and for different time periods (1 or 4 weeks). It was demonstrated that flowering chrysanthemums as trap plants lower the number of adult F. occidentalis in a vegetative chrysanthemum crop and, as a result, reduce crop damage. In the 4 week large-cage trial and the commercial trial, significant differences between the control and the trap plant treatments started to appear in the third week of the experiment. Larvae were only significantly reduced by the presence of trap plants in the 1 week small-cage trials. There were no significant differences between treatments with spinosad-treated and untreated trap plants in the number of F. occidentalis on the crop. This suggests that there was minimal movement of adult F. occidentalis back and forth between the trap plants and the crop to feed and oviposit. It is concluded that the trap plant strategy is a useful tool for integrated pest management against F. occidentalis in greenhouses. 2007 Crown in the right of Canada

Malaria epidemiology and economics: the effect of delayed immune acquisition on the cost-effectiveness of insecticide-treated bednets.

PubMed Central

Guyatt, H L; Snow, R W; Evans, D B

1999-01-01

An understanding of the epidemiology of a disease is central in evaluating the health impact and cost-effectiveness of control interventions. The epidemiology of life-threatening malaria is receiving renewed interest, with concerns that the implementation of preventive measures such as insecticide-treated bednets (ITNs) while protecting young children might in fact increase the risks of mortality and morbidity in older ages by delaying the acquisition of functional immunity. This paper aims to illustrate how a combined approach of epidemiology and economics can be used to (i) explore the long-term impact of changes in epidemiological profiles, and (ii) identify those variables that are critical in determining whether an intervention will be an efficient use of resources. The key parameters for determining effectiveness are the protective efficacy of ITNs (reduction in all-cause mortality), the malaria attributable mortality and the increased malaria-specific mortality risk due to delays in the acquisition of functional immunity. In particular, the analysis demonstrates that delayed immune acquisition is not a problem per se, but that the critical issue is whether it occurs immediately following the implementation of an ITN programme or whether it builds up slowly over time. In the 'worst case' scenario where ITNs immediately increase malaria-specific mortality due to reduced immunity, the intervention might actually cost lives. In other words, it might be better to not use ITNs. On the other hand, if reduced immunity takes two years to develop, ITNs would still fall into the category of excellent value for money compared to other health interventions, saving a year of life (YLL) at a cost of between US$25-30. These types of calculations are important in identifying the parameters which field researchers should be seeking to measure to address the important question of the net impact of delaying the acquisition of immunity through preventive control measures. PMID

Log bioassay of residual effectiveness of insecticides against bark beetles

Treesearch

Richard H. Smith

1982-01-01

Residual effectiveness of nine insecticides applied to bark was tested against western, mountain, and Jeffrey pine beetles. Ponderosa and Jeffrey pine trees were treated and logs cut from them 2 to 13 months later, and bioassayed with the three beetles. The insecticides were sprayed at the rate of 1 gal (3.8 l) per 40- or 80-ft² (3.6 or 7.2 m²) bark surface at varying...

Repellent-Treated Clothing

EPA Pesticide Factsheets

EPA regulates the pesticide permethrin to pre-treat clothing. We evaluate the safety and effectiveness of such insecticide uses, by exposure scenarios and risk assessment. Read and follow the label directions for use of permethrin-treated clothing.

Olyset Duo® (a Pyriproxyfen and Permethrin Mixture Net): An Experimental Hut Trial against Pyrethroid Resistant Anopheles gambiae and Culex quinquefasciatus in Southern Benin

PubMed Central

Ngufor, Corine; N’Guessan, Raphael; Fagbohoun, Josias; Odjo, Abibatou; Malone, David; Akogbeto, Martin; Rowland, Mark

2014-01-01

Background Alternative compounds which can complement pyrethroids on long-lasting insecticidal nets (LN) in the control of pyrethroid resistant malaria vectors are urgently needed. Pyriproxyfen (PPF), an insect growth regulator, reduces the fecundity and fertility of adult female mosquitoes. LNs containing a mixture of pyriproxyfen and pyrethroid could provide personal protection through the pyrethroid component and reduce vector abundance in the next generation through the sterilizing effect of pyriproxyfen. Method The efficacy of Olyset Duo, a newly developed mixture LN containing pyriproxyfen and permethrin, was evaluated in experimental huts in southern Benin against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus. Comparison was made with Olyset Net® (permethrin alone) and a LN with pyriproxyfen alone (PPF LN). Laboratory tunnel tests were performed to substantiate the findings in the experimental huts. Results Overall mortality of wild pyrethroid resistant An. gambiae s.s. was significantly higher with Olyset Duo than with Olyset Net (50% vs. 27%, P = 0.01). Olyset DUO was more protective than Olyset Net (71% vs. 3%, P<0.001). The oviposition rate of surviving blood-fed An. gambiae from the control hut was 37% whereas none of those from Olyset Duo and PPF LN huts laid eggs. The tunnel test results were consistent with the experimental hut results. Olyset Duo was more protective than Olyset Net in the huts against wild pyrethroid resistant Cx. quinquefasciatus although mortality rates of this species did not differ significantly between Olyset Net and Olyset Duo. There was no sterilizing effect on surviving blood-fed Cx. quinquefasciatus with the PPF-treated nets. Conclusion Olyset Duo was superior to Olyset Net in terms of personal protection and killing of pyrethroid resistant An. gambiae, and sterilized surviving blood-fed mosquitoes. Mixing pyrethroid and pyriproxyfen on a LN shows potential for malaria control and management of

The effect of holes in long-lasting insecticidal nets on malaria in Malawi: results from a case-control study.

PubMed

Minta, Anna A; Landman, Keren Z; Mwandama, Dyson A; Shah, Monica P; Eng, Jodi L Vanden; Sutcliffe, James F; Chisaka, Joseph; Lindblade, Kim A; Mathanga, Don P; Steinhardt, Laura C

2017-10-02

Long-lasting insecticidal nets (LLINs) are a cornerstone of malaria prevention. Holes develop in LLINs over time and compromise their physical integrity, but how holes affect malaria transmission risk is not well known. After a nationwide mass LLIN distribution in July 2012, a study was conducted to assess the relationship between LLIN damage and malaria. From March to September 2013, febrile children ages 6-59 months who consistently slept under LLINs (every night for 2 weeks before illness onset) were enrolled in a case-control study at Machinga District Hospital outpatient department. Cases were positive for Plasmodium falciparum asexual parasites by microscopy while controls were negative. Digital photographs of participants' LLINs were analysed using an image-processing programme to measure holes. Total hole area was classified by quartiles and according to the World Health Organization's proportionate hole index (pHI) cut-offs [< 79 cm 2 (good), 80-789 cm 2 (damaged), and > 790 cm 2 (too torn)]. Number of holes by location and size, and total hole area, were compared between case and control LLINs using non-parametric analyses and logistic regression. Of 248 LLINs analysed, 97 (39%) were from cases. Overall, 86% of LLINs had at least one hole. The median number of holes of any size was 9 [interquartile range (IQR) 3, 22], and most holes were located in the lower halves of the nets [median 7 (IQR 2, 16)]. There were no differences in number or location of holes between LLINs used by cases and controls. The median total hole area was 10 cm 2 (IQR 2, 125) for control LLINs and 8 cm 2 (IQR 2, 47) for case LLINs (p = 0.10). Based on pHI, 109 (72%) control LLINs and 83 (86%) case LLINs were in "good" condition. Multivariable modeling showed no association between total hole area and malaria, controlling for child age, caregiver education, and iron versus thatched roof houses. LLIN holes were not associated with increased odds of malaria in this study

Impact of permethrin-treated bed nets on entomologic indices in an area of intense year-round malaria transmission.

PubMed

Gimnig, John E; Vulule, John M; Lo, Terrence Q; Kamau, Luna; Kolczak, Margarette S; Phillips-Howard, Penelope A; Mathenge, Evan M; ter Kuile, Feiko O; Nahlen, Bernard L; Hightower, Allen W; Hawley, William A

2003-04-01

The effect of permethrin-treated bed nets (ITNs) on malaria vectors was studied as part of a large-scale, randomized, controlled trial in western Kenya. Indoor resting densities of fed Anopheles gambiae s.l. and An. funestus in intervention houses were 58.5% (P = 0.010) and 94.5% (P = 0.001) lower, respectively, compared with control houses. The sporozoite infection rate in An. gambiae s.l. was 0.8% in intervention areas compared with 3.4% (P = 0.026) in control areas, while the sporozoite infection rates in An. funestus were not significantly different between the two areas. We estimated the overall transmission of Plasmodium falciparum in intervention areas to be 90% lower than in control areas. Permethrin resistance was not detected during the study period. As measured by densities of An. gambiae s.l., the efficacy of bed nets decreased if one or more residents did not sleep under a net or if bed nets had not been re-treated within six months. These results indicate that ITNs are optimally effective if used every night and if permethrin is reapplied at least biannually.

Health impact and cost-effectiveness of a private sector bed net distribution: experimental evidence from Zambia

PubMed Central

2013-01-01

Background Relatively few programmes have attempted to actively engage the private sector in national malaria control efforts. This paper evaluates the health impact of a large-scale distribution of insecticide-treated nets (ITNs) conducted in partnership with a Zambian agribusiness, and its cost-effectiveness from the perspective of the National Malaria Control Programme (NMCP). Methods The study was designed as a cluster-randomized controlled trial. A list of 81,597 cotton farmers was obtained from Dunavant, a contract farming company in Zambia’s cotton sector, in December 2010. 39,963 (49%) were randomly selected to obtain one ITN each. Follow-up interviews were conducted with 438 farmers in the treatment and 458 farmers in the control group in June and July 2011. Treatment and control households were compared with respect to bed net ownership, bed net usage, self-reported fever, and self-reported confirmed malaria. Cost data was collected throughout the programme. Results The distribution effectively reached target beneficiaries, with approximately 95% of households in the treatment group reporting that they had received an ITN through the programme. The average increase in the fraction of household members sleeping under an ITN the night prior to the interview was 14.6 percentage points (p-value <0.001). Treatment was associated with a 42 percent reduction in the odds of self-reported fever (p-value <0.001) and with a 49 percent reduction in the odds of self-reported malaria (p-value 0.002). This was accomplished at a cost of approximately five US$ per ITN to Zambia’s NMCP. Conclusions The results illustrate that existing private sector networks can efficiently control malaria in remote rural regions. The intra-household allocation of ITNs distributed through this channel was comparable to that of ITNs received from other sources, and the health impact remained substantial. PMID:23506170

Widespread mosquito net fishing in the Barotse floodplain: Evidence from qualitative interviews.

PubMed

Larsen, David A; Welsh, Rick; Mulenga, Angela; Reid, Robert

2018-01-01

The insecticide-treated mosquito net (ITN) is a crucial component of malaria control programs, and has prevented many malaria cases and deaths due to scale up. ITNs also serve effectively as fishing nets and various sources have reported use of ITNs for fishing. This article examines how widespread the practice of mosquito net fishing with ITNs is. We conducted in-depth interviews with fishery personnel and traditional leadership from the Barotse Royal Establishment in Western Province, Zambia, to better understand the presence or absence of the use of ITNs as fishing nets. We then coded the interviews for themes through content analysis. Additionally we conducted a desk review of survey data to show trends in malaria indicators, nutritional status of the population and fish consumption. All those interviewed reported that ITNs are regularly used for fishing in Western Zambia and the misuse is widespread. Concurrently those interviewed reported declines in fish catches both in terms of quantity and quality leading to threatened food security in the area. In addition to unsustainable fishing practices those interviewed referenced drought and population pressure as reasons for fishery decline. Malaria indicators do not show a trend in declining malaria transmission, fish consumption has dropped dramatically and nutritional status has not improved over time. Despite the misuse of the ITNs for fishing all those interviewed maintained that ITN distribution should continue. Donors, control programs and scientists should realize that misuse of ITNs as fishing nets is a current problem for malaria control and potentially for food security that needs to be addressed.

Status of insecticide resistance in high-risk malaria provinces in Afghanistan.

PubMed

Ahmad, Mushtaq; Buhler, Cyril; Pignatelli, Patricia; Ranson, Hilary; Nahzat, Sami Mohammad; Naseem, Mohammad; Sabawoon, Muhammad Farooq; Siddiqi, Abdul Majeed; Vink, Martijn

2016-02-18

Insecticide resistance seriously threatens the efficacy of vector control interventions in malaria endemic countries. In Afghanistan, the status of insecticide resistance is largely unknown while distribution of long-lasting insecticidal nets has intensified in recent years. The main objective of this study was thus to measure the level of resistance to four classes of insecticides in provinces with medium to high risk of malaria transmission. Adult female mosquitoes were reared from larvae successively collected in the provinces of Nangarhar, Kunar, Badakhshan, Ghazni and Laghman from August to October 2014. WHO insecticide susceptibility tests were performed with DDT (4 %), malathion (5 %), bendiocarb (0.1 %), permethrin (0.75 %) and deltamethrin (0.05 %). In addition, the presence of kdr mutations was investigated in deltamethrin resistant and susceptible Anopheles stephensi mosquitoes collected in the eastern provinces of Nangarhar and Kunar. Analyses of mortality rates revealed emerging resistance against all four classes of insecticides in the provinces located east and south of the Hindu Kush mountain range. Resistance is observed in both An. stephensi and Anopheles culicifacies, the two dominant malaria vectors in these provinces. Anopheles superpictus in the northern province of Badakhshan shows a different pattern of susceptibility with suspected resistance observed only for deltamethrin and bendiocarb. Genotype analysis of knock down resistance (kdr) mutations at the voltage-gated channel gene from An. stephensi mosquitoes shows the presence of the known resistant alleles L1014S and L1014F. However, a significant fraction of deltamethrin-resistant mosquitoes were homozygous for the 1014L wild type allele indicating that other mechanisms must be considered to account for the observed pyrethroid resistance. This study confirms the importance of monitoring insecticide resistance for the development of an integrated vector management in Afghanistan. The

Patterns of insecticide resistance and knock down resistance (kdr) in malaria vectors An. arabiensis, An. coluzzii and An. gambiae from sympatric areas in Senegal.

PubMed

Niang, El Hadji Amadou; Konaté, Lassana; Diallo, Mawlouth; Faye, Ousmane; Dia, Ibrahima

2016-02-05

Malaria vector control in Africa relies on insecticides targeting adult mosquito vectors via insecticide treated nets or indoor residual spraying. Despite the proven efficacy of these strategies, the emergence and rapid rise in insecticide resistance in malaria vectors raises many concerns about their sustainability. Therefore, the monitoring of insecticide resistance is essential for resistance management strategies implementation. We investigated the kdr mutation frequencies in 20 sympatric sites of An. arabiensis Patton, An. coluzzii Coetzee & Wilkerson and An. gambiae Giles and its importance in malaria vector control by evaluating the susceptibility to insecticides in four representative sites in Senegal. Sibling species identification and kdr mutation detection were determined using polymerase chain reaction on mosquitoes collected using pyrethrum sprays collection in 20 sites belonging to two transects with differential insecticide selection pressure. The World Health Organization (WHO) tube test was used to determine phenotypic resistance of An. gambiae s.l. to DDT, deltamethrin, lambdacyholothrin, permethrin, bendiocarb and malathion in four representative sites. The L1014F kdr mutation was widely distributed and was predominant in An. gambiae in comparison to An. arabiensis and An. coluzzii. The bioassay tests showed a general trend with a resistance to DDT and pyrethroids and a susceptibility to organophosphate and carbamate according to WHO thresholds. For deltamethrin and permethrin, the two most used insecticides, no significant difference were observed either between the two transects or between mortality rates suggesting no differential selection pressures on malaria vectors. The study of the KD times showed similar trends as comparable levels of resistance were observed, the effect being more pronounced for permethrin. Our study showed a widespread resistance of malaria vectors to DDT and pyrethroids and a widespread distribution of the 1014F kdr

Insecticides for Suppression of Nylanderia fulva

PubMed Central

Oi, Faith; Oi, David; Mannion, Catharine

2017-01-01

Nylanderia fulva (Mayr) is an invasive ant that is a serious pest in the southern United States. Pest control operators and homeowners are challenged to manage pest populations below acceptable thresholds. Contact and bait insecticides are key components of an Integrated Pest Management (IPM) strategy, however, little is known about their efficacy. In repellency and efficacy bioassays, N. fulva were not completely repelled by any insecticide tested, although fewer ants crossed a surface treated with Temprid®. Few insecticides provided rapid control. Termidor® and Temprid® were the best performing with mean mortality of 100% in 13.4 and 19.0 days, respectively. In no-choice bait acceptance studies, it was shown that N. fulva generally had greater acceptance of carbohydrate-based ant baits (Advion®, InTiceTM (gel), and InTiceTM (granular)). However, mortality was low for the InTiceTM baits in a 7-day bioassay. Maxforce® Ant Killer Bait Gel and Advance® 375A in the spring and Maxforce® Complete in the summer and fall required the fewest days to reach 100% mortality. Bait active ingredients that resulted in the highest mortality were hydramethylnon and fipronil. These data on the efficacy of commercially available contact and bait insecticides provide valuable information to manage this invasive pest. PMID:28858251

Rainfastness of insecticides used to control Japanese beetle in blueberries.

PubMed

Hulbert, Daniel; Reeb, Pablo; Isaacs, Rufus; Vandervoort, Christine; Erhardt, Susan; Wise, John C

2012-10-01

Field-based bioassays were used to determine the relative impact of rainfall on the relative toxicity of four insecticides, phosmet, carbaryl, zeta-cypermethrin, or imidacloprid, from different chemical classes on adult Japanese beetles, Popillia japonica Newman, in highbush blueberries, Vaccinium corymbosum L. Bioassays were set up 24 h after spraying occurred and Japanese beetle condition was scored as alive, knockdown or immobile 1, 24, and 48 h after bioassay setup. All insecticides were significantly more toxic than the untreated control and zeta-cypermethrin consistently had the greatest toxic effect against the Japanese beetles. All insecticides experienced a decrease in efficacy after simulated rainfall onto treated blueberry shoots, although the efficacy of zeta-cypermethrin was the least affected by rainfall. This study will help blueberry growers make informed decisions on when reapplications of insecticides are needed in the field with the aim of improving integrated pest management (IPM).

Genetics, Synergists, and Age Affect Insecticide Sensitivity of the Honey Bee, Apis mellifera

PubMed Central

Rinkevich, Frank D.; Margotta, Joseph W.; Pittman, Jean M.; Danka, Robert G.; Tarver, Matthew R.; Ottea, James A.; Healy, Kristen B.

2015-01-01

The number of honey bee colonies in the United States has declined to half of its peak level in the 1940s, and colonies lost over the winter have reached levels that are becoming economically unstable. While the causes of these losses are numerous and the interaction between them is very complex, the role of insecticides has garnered much attention. As a result, there is a need to better understand the risk of insecticides to bees, leading to more studies on both toxicity and exposure. While much research has been conducted on insecticides and bees, there have been very limited studies to elucidate the role that bee genotype and age has on the toxicity of these insecticides. The goal of this study was to determine if there are differences in insecticide sensitivity between honey bees of different genetic backgrounds (Carniolan, Italian, and Russian stocks) and assess if insecticide sensitivity varies with age. We found that Italian bees were the most sensitive of these stocks to insecticides, but variation was largely dependent on the class of insecticide tested. There were almost no differences in organophosphate bioassays between honey bee stocks (<1-fold), moderate differences in pyrethroid bioassays (1.5 to 3-fold), and dramatic differences in neonicotinoid bioassays (3.4 to 33.3-fold). Synergism bioassays with piperonyl butoxide, amitraz, and coumaphos showed increased phenothrin sensitivity in all stocks and also demonstrated further physiological differences between stocks. In addition, as bees aged, the sensitivity to phenothrin significantly decreased, but the sensitivity to naled significantly increased. These results demonstrate the variation arising from the genetic background and physiological transitions in honey bees as they age. This information can be used to determine risk assessment, as well as establishing baseline data for future comparisons to explain the variation in toxicity differences for honey bees reported in the literature. PMID

Insecticide Control of Vector-Borne Diseases: When Is Insecticide Resistance a Problem?

PubMed Central

Rivero, Ana; Vézilier, Julien; Weill, Mylène; Read, Andrew F.; Gandon, Sylvain

2010-01-01

Many of the most dangerous human diseases are transmitted by insect vectors. After decades of repeated insecticide use, all of these vector species have demonstrated the capacity to evolve resistance to insecticides. Insecticide resistance is generally considered to undermine control of vector-transmitted diseases because it increases the number of vectors that survive the insecticide treatment. Disease control failure, however, need not follow from vector control failure. Here, we review evidence that insecticide resistance may have an impact on the quality of vectors and, specifically, on three key determinants of parasite transmission: vector longevity, competence, and behaviour. We argue that, in some instances, insecticide resistance is likely to result in a decrease in vector longevity, a decrease in infectiousness, or in a change in behaviour, all of which will reduce the vectorial capacity of the insect. If this effect is sufficiently large, the impact of insecticide resistance on disease management may not be as detrimental as previously thought. In other instances, however, insecticide resistance may have the opposite effect, increasing the insect's vectorial capacity, which may lead to a dramatic increase in the transmission of the disease and even to a higher prevalence than in the absence of insecticides. Either way—and there may be no simple generality—the consequence of the evolution of insecticide resistance for disease ecology deserves additional attention. PMID:20700451

ASSESSING LEVELS OF INTERMITTENT EXPOSURES OF CHILDRENTO FLEA CONTROL INSECTICIDES FROM THE FUR OF DOGS

EPA Science Inventory

There are reported insecticide residues present in food, water, and surfaces such as carpets treated for flea control. However, no studies (except those we currently have in place) have quantified the transferable flea control insecticide residues which occur on pets (the majo...

Mitochondrial impacts of insecticidal formate esters in insecticide-resistant and insecticide-susceptible Drosophila melanogaster.

PubMed

Song, Cheol; Scharf, Michael E

2009-06-01

Previous research on insecticidal formate esters in flies and mosquitoes has documented toxicity profiles, metabolism characteristics and neurological impacts. The research presented here investigated mitochondrial impacts of insecticidal formate esters and their hydrolyzed metabolite formic acid in the model dipteran insect Drosophila melanogaster Meig. These studies compared two Drosophila strains: an insecticide-susceptible strain (Canton-S) and a strain resistant by cytochrome P450 overexpression (Hikone-R). In initial studies investigating inhibition of mitochondrial cytochrome c oxidase, two proven insecticidal materials (hydramethylnon and sodium cyanide) caused significant inhibition. However, for insecticidal formate esters and formic acid, no significant inhibition was identified in either fly strain. Mitochondrial impacts of formate esters were then investigated further by tracking toxicant-induced cytochrome c release from mitochondria into the cytoplasm, a biomarker of apoptosis and neurological dysfunction. Formic acid and three positive control treatments (rotenone, antimycin A and sodium cyanide) induced cytochrome c release, verifying that formic acid is capable of causing mitochondrial disruption. However, when comparing formate ester hydrolysis and cytochrome c release between Drosophila strains, formic acid liberation was only weakly correlated with cytochrome c release in the susceptible Canton-S strain (r(2) = 0.70). The resistant Hikone-R strain showed no correlation (r(2) < 0.0001) between formate ester hydrolysis and cytochrome c release. The findings of this study provide confirmation of mitochondrial impacts by insecticidal formate esters and suggest links between mitochondrial disruption, respiratory inhibition, apoptosis and formate-ester-induced neurotoxicity.

Quantifying the impact of decay in bed-net efficacy on malaria transmission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ngonghala, Calistus N.; Del Valle, Sara Y.; Zhao, Ruijun

Insecticide-treated nets (ITNs) are at the forefront of malaria control programs and even though the percentage of households in sub-Saharan Africa that owned nets increased from 3% in 2000 to 53% in 2012, many children continue to die from malaria. The potential impact of ITNs on reducing malaria transmission is limited due to inconsistent or improper use, as well as physical decay in effectiveness. Most mathematical models for malaria transmission have assumed a fixed effectiveness rate for bed-nets, which can overestimate the impact of nets on malaria control. We develop a model for malaria spread that captures the decrease inmore » ITN effectiveness due to physical and chemical decay, as well as human behavior as a function of time. We perform uncertainty and sensitivity analyses to identify and rank parameters that play a critical role in malaria transmission. These analyses show that the basic reproduction number R 0, and the infectious human population are most sensitive to bed-net coverage and the biting rate of mosquitoes. Our results show the existence of a backward bifurcation for the case in which ITN efficacy is constant over time, which occurs for some range of parameters and is characterized by high malaria mortality in humans. This result implies that bringing R 0 to less than one is not enough for malaria elimination but rather additional efforts will be necessary to control the disease. For the case in which ITN efficacy decays over time, we determine coverage levels required to control malaria for different ITN efficacies and demonstrate that ITNs with longer useful lifespans perform better in malaria control. We conclude that malaria control programs should focus on increasing bed-net coverage, which can be achieved by enhancing malaria education and increasing bed-net distribution in malaria endemic regions.« less

Quantifying the impact of decay in bed-net efficacy on malaria transmission

DOE PAGES

Ngonghala, Calistus N.; Del Valle, Sara Y.; Zhao, Ruijun; ...

2014-08-23

Insecticide-treated nets (ITNs) are at the forefront of malaria control programs and even though the percentage of households in sub-Saharan Africa that owned nets increased from 3% in 2000 to 53% in 2012, many children continue to die from malaria. The potential impact of ITNs on reducing malaria transmission is limited due to inconsistent or improper use, as well as physical decay in effectiveness. Most mathematical models for malaria transmission have assumed a fixed effectiveness rate for bed-nets, which can overestimate the impact of nets on malaria control. We develop a model for malaria spread that captures the decrease inmore » ITN effectiveness due to physical and chemical decay, as well as human behavior as a function of time. We perform uncertainty and sensitivity analyses to identify and rank parameters that play a critical role in malaria transmission. These analyses show that the basic reproduction number R 0, and the infectious human population are most sensitive to bed-net coverage and the biting rate of mosquitoes. Our results show the existence of a backward bifurcation for the case in which ITN efficacy is constant over time, which occurs for some range of parameters and is characterized by high malaria mortality in humans. This result implies that bringing R 0 to less than one is not enough for malaria elimination but rather additional efforts will be necessary to control the disease. For the case in which ITN efficacy decays over time, we determine coverage levels required to control malaria for different ITN efficacies and demonstrate that ITNs with longer useful lifespans perform better in malaria control. We conclude that malaria control programs should focus on increasing bed-net coverage, which can be achieved by enhancing malaria education and increasing bed-net distribution in malaria endemic regions.« less

[Preliminary evaluation of the insecticide susceptibility in Anopheles gambiae and Culex quinquefasciatus from Lobito (Angola), using WHO standard assay].

PubMed

Toto, J C; Besnard, P; Le Mire, J; Almeida, D S I; Dos Santos, M A; Fortes, F; Foumane, V; Simard, F; Awono-Ambene, H P; Carnevale, P

2011-10-01

Field collections of the most common urban mosquito vectors Anopheles gambiae and Culex quinquefasciatus were carried out in June 2003, March 2004 and November 2005 to gather preliminary data on the insecticide susceptibility in mosquitoes from Lobito (Angola) using the WHO standard bioassays. Bioassays were performed on F0 adults emerging from the field larval collections and on unfed adults from landing catches on volunteers. Batches of mosquitoes from three selected locations (Alto Liro, San Jao and Bela Vista) were exposed for 1 hour to several insecticides such as DDT 4%, carbosulfan 0.4%, permethrin 1%, deltamethrin 0.05% and cyfluthrin 0.15%, in order to estimate the immediate knockdown times (kdT50 and kdT95) and the mortality rate after exposure. The results revealed that mosquito susceptibility to insecticides varied depending on the insecticide, the site and the period of collection. The main local malaria vector A. gambiae (both M and S forms) was basically resistant to DDT and susceptible to all pyrethoids, regardless of the period and the site of collections. The overall mortality rate due to DDT was 73% in Alto Liro, 89% in San Jao and varied depending on the period in Bela Vista between 95% in March 2004 and 100% in November 2005. The mortality due to pyrethoids was 100% at all locations, with the kdT50 and KdT95 times ranging between 9 and 16 minutes and between 18 and 29 minutes, respectively. Concerning the C. quinquefasciatus, populations from Yard and Caponte were resistant to all insecticides tested; the mortality rate was 40% with deltamethrin and 70% with permethrin, while no lethal effect was observed with DDT or carbosulfan. In conclusion, despite its probable high resistance to DDT, the main local malaria vector A. gambiae remained fully susceptible to pyrethroids. This could forecast a good biological efficacy of the scheduled vector control interventions in Angola, based on a large-scale distribution of long-lasting, insecticide-treated

Compatibility of endoparasitoid Hyposoter didymator (Hymenoptera: Ichneumonidae) protected stages with five selected insecticides.

PubMed

Medina, P; Morales, J J; Budia, F; Adan, A; Del Estal, P; Viñuela, E

2007-12-01

Hyposoter didymator (Thunberg) (Hymenoptera: Ichneumonidae) is a koinobiont endoparasitoid that emerges from the parasitization of economically important noctuid pests. H. didymator also is considered one of the most important native biocontrol agents of noctuids in Spain. Side effects of five insecticides with very different modes of action (fipronil, imidacloprid, natural pyrethrins + piperonyl butoxide, pymetrozine, and triflumuron) at the maximum field recommended rate in Spain were evaluated on H. didymator parasitizing Spodoptera littoralis (Boisduval) larvae and pupae of the endoparasitoid. Parasitized larvae were topically treated or ingested treated artificial diet. Parasitoid cocoons were topically treated. Host mortality when parasitized larvae were treated, as well as further development of the parasitoid surviving (e.g., percentage of cocoons spun, adult emergence, hosts attacked, and numbered progeny) were determined. Toxicity after treatment of parasitized larvae differed depending on the mode of exposure and insecticide. Fipronil was always highly toxic; imidacloprid killed all host insects by ingestion, but it was less toxic to both host and parasitoids, when administered topically; natural pyrethrins + piperonyl butoxide and triflumuron showed differing degrees of toxicity, and pymetrozine was harmless. Parasitoid cocoons provided effective protection against all the insecticides, except fipronil.

Pyrethroid Resistance Alters the Blood-Feeding Behavior in Puerto Rican Aedes aegypti Mosquitoes Exposed to Treated Fabric

USDA-ARS?s Scientific Manuscript database

Emerging insecticide resistance is a major issue for vector control; it decreases effectiveness of insecticides, thereby requiring greater quantities for comparable control with a net increase in risk of disease resurgence, product cost, and damage risk to the ecosystem. Pyrethroid resistance has b...

Transposable elements and insecticide resistance.

PubMed

Rostant, Wayne G; Wedell, Nina; Hosken, David J

2012-01-01

Transposable elements (TEs) are mobile DNA sequences that are able to copy themselves within a host genome. They were initially characterized as selfish genes because of documented or presumed costs to host fitness, but it has become increasingly clear that not all TEs reduce host fitness. A good example of TEs benefiting hosts is seen with insecticide resistance, where in a number of cases, TE insertions near specific genes confer resistance to these man-made products. This is particularly true of Accord and associated TEs in Drosophila melanogaster and Doc insertions in Drosophila simulans. The first of these insertions also has sexually antagonistic fitness effects in the absence of insecticides, and although the magnitude of this effect depends on the genetic background in which Accord finds itself, this represents an excellent example of intralocus sexual conflict where the precise allele involved is well characterized. We discuss this finding and the role of TEs in insecticide resistance. We also highlight areas for further research, including the need for surveys of the prevalence and fitness consequences of the Doc insertion and how Drosophila can be used as models to investigate resistance in pest species. Copyright © 2012 Elsevier Inc. All rights reserved.

Implementation strategies to increase access and demand of long-lasting insecticidal nets: a before-and-after study and scale-up process in Mozambique.

PubMed

Arroz, Jorge A H; Mendis, Chandana; Pinto, Liliana; Candrinho, Baltazar; Pinto, João; Martins, Maria do Rosário O

2017-10-25

The universal coverage bed nets campaign is a proven health intervention promoting increased access, ownership, and use of bed nets to reduce malaria burden. This article describes the intervention and implementation strategies that Mozambique carried out recently in order to improve access and increase demand for long-lasting insecticidal nets (LLINs). A before-and-after study with a control group was used during Stage I of the implementation process. The following strategies were tested in Stage I: (1) use of coupons during household registration; (2) use of stickers to identify the registered households; (3) new LLIN ascription formula (one LLIN for every two people). In Stage II, the following additional strategies were implemented: (4) mapping and micro-planning; (5) training; and (6) supervision. Odds ratio (OR) and 95% confidence interval (CI) were used to compare and establish differences between intervened and control districts in Stage I. Main outcomes were: percentage of LLINs distributed, percentage of target households benefited. In Stage I, 87.8% (302,648) of planned LLINs were distributed in the intervention districts compared to 77.1% (219,613) in the control districts [OR: 2.14 (95% CI 2.11-2.16)]. Stage I results also showed that 80.6% (110,453) of households received at least one LLIN in the intervention districts compared to 72.8% (87,636) in the control districts [OR: 1.56 (95% CI 1.53-1.59)]. In Stage II, 98.4% (3,536,839) of the allocated LLINs were delivered, covering 98.6% (1,353,827) of the registered households. Stage I results achieved better LLINs and household coverage in districts with the newly implemented strategies. The results of stage II were also encouraging. Additional strategies adaptation is required for a wide-country LLIN campaign.

A pre-intervention study of malaria vector abundance in Rio Muni, Equatorial Guinea: Their role in malaria transmission and the incidence of insecticide resistance alleles

PubMed Central

Ridl, Frances C; Bass, Chris; Torrez, Miguel; Govender, Dayanandan; Ramdeen, Varsha; Yellot, Lee; Edu, Amado Edjang; Schwabe, Christopher; Mohloai, Peter; Maharaj, Rajendra; Kleinschmidt, Immo

2008-01-01

Background Following the success of the malaria control intervention on the island of Bioko, malaria control by the use of indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLITN) was extended to Rio Muni, on the mainland part of Equatorial Guinea. This manuscript reports on the malaria vectors present and the incidence of insecticide resistant alleles prior to the onset of the programme. Methods Anopheles mosquitoes were captured daily using window traps at 30 sentinel sites in Rio Muni, from December 2006 to July 2007. The mosquitoes were identified to species and their sporozoite rates, knockdown resistance (kdr) and acetylcholinesterase (AChE) sensitivity measured, to define the role of vector species in malaria transmission and their potential susceptibility to insecticides. Results A total of 6,162 Anopheles mosquitoes were collected of which 4,808 were morphologically identified as Anopheles gambiae s.l., 120 Anopheles funestus, 1,069 Anopheles moucheti, and 165 Anopheles nili s.l.. Both M and S molecular forms of Anopheles gambiae s.s. and Anopheles melas were identified. Anopheles ovengensis and Anopheles carnevalei were the only two members of the An. nili group to be identified. Using the species-specific sporozoite rates and the average number of mosquitoes per night, the number of infective mosquitoes per trap per 100 nights for each species complex was calculated as a measure of transmission risk. Both kdr-w and kdr-e alleles were present in the S-form of An. gambiae s.s. (59% and 19% respectively) and at much lower frequencies in the M-form (9.7% and 1.8% respectively). The kdr-w and kdr-e alleles co-occurred in 103 S-form and 1 M-form specimens. No insensitive AChE was detected. Conclusion Anopheles gambiae s.s, a member of the Anopheles gambiae complex was shown to be the major vector in Rio Muni with the other three groups playing a relatively minor role in transmission. The demonstration of a high frequency of kdr alleles

The use of intermittent preventive treatment in pregnancy and insecticide-treated bed nets for malaria prevention by women of child-bearing age in eight districts in Malawi.

PubMed

Mwandama, Dyson; Gutman, Julie; Wolkon, Adam; Luka, Madalitso; Jafali, James; Ali, Doreen; Mathanga, Don P; Skarbinski, Jacek

2015-08-15

Intermittent preventive treatment in pregnancy (IPTp) and insecticide-treated bed nets (ITNs) can reduce the morbidity and mortality associated with malaria in pregnancy. Although the coverage for both IPTp and ITN use have been described in Malawi, the analysis of factors associated with IPTp receipt and ITN use is lacking. This analysis was conducted to assess IPTp and ITN use and predictors of use by women of child-bearing age (WOCBA). A two-stage cluster-sample cross-sectional survey was conducted April 16-30, 2009 in eight districts across Malawi. Information on receipt of two or more doses of IPTp, ITN ownership, and ITN use the night before the survey was collected. Multivariate logistic regression was used to assess predictors of IPTp and ITN use. Data were collected from 7407 households containing 6985 WOCBA and 3213 recently pregnant women (women who reported a completed pregnancy in the 2 years before the survey). Most recently pregnant women (96 %) had at least one antenatal care (ANC) clinic visit; 91 % reported receiving at least one dose of IPTp, and 72 % reported receiving two or more doses of IPTp. Women in Phalombe, Rumphi, and Lilongwe were more likely to receive two doses of IPTp than those in Blantyre [adjusted odds ratio (aOR) 2.5 (95 % CI 1.5-4.5), 2.5 (95 % CI 1.5-4.3), and 2.0 (95 % CI 1.2-3.1), respectively]. Educated women were more likely to have received IPTp compared to women with no education [aOR 1.6 (95 % CI 1.0-2.6) for those who completed primary school, aOR1.9 (95 % CI 1.1-3.3) for some secondary school, and aOR 4.1 (95 % CI 1.9-8.7) for completed secondary school or above], and women in the poorest socioeconomic status quintile were less likely to receive IPTp than those in the least poor quintile [aOR 0.68 (95 % CI 0.48-0.97)]. In all, 53 % of WOCBA used an ITN the previous night. Women in Nkhotkhota and Phalombe were less likely to have slept under an ITN the previous night compared to those in Blantyre [aOR 0.52 (95 % CI 0

Experiences with insecticide-treated curtains: a qualitative study in Iquitos, Peru.

PubMed

Paz-Soldan, Valerie A; Bauer, Karin M; Lenhart, Audrey; Cordova Lopez, Jhonny J; Elder, John P; Scott, Thomas W; McCall, Philip J; Kochel, Tadeusz J; Morrison, Amy C

2016-07-16

Dengue is an arthropod-borne viral disease responsible for approximately 400 million infections annually; the only available method of prevention is vector control. It has been previously demonstrated that insecticide treated curtains (ITCs) can lower dengue vector infestations in and around houses. As part of a larger trial examining whether ITCs could reduce dengue transmission in Iquitos, Peru, the objective of this study was to characterize the participants' experience with the ITCs using qualitative methods. Knowledge, attitudes, and practices (KAP) surveys (at baseline, and 9 and 27 months post-ITC distribution, with n = 593, 595 and 511, respectively), focus group discussions (at 6 and 12 months post-ITC distribution, with n = 18 and 33, respectively), and 11 one-on-one interviews (at 12 months post-distribution) were conducted with 605 participants who received ITCs as part of a cluster-randomized trial. Focus groups at 6 months post-ITC distribution revealed that individuals had observed their ITCs to function for approximately 3 months, after which they reported the ITCs were no longer working. Follow up revealed that the ITCs required re-treatment with insecticide at approximately 1 year post-distribution. Over half (55.3 %, n = 329) of participants at 9 months post-ITC distribution and over a third (34.8 %, n = 177) at 27 months post-ITC distribution reported perceiving a decrease in the number of mosquitoes in their home. The percentage of participants who would recommend ITCs to their family or friends in the future remained high throughout the study (94.3 %, n = 561 at 9 months and 94.6 %, n = 488 at 27 months post-distribution). When asked why, participants reported that ITCs were effective at reducing mosquitoes (81.6 and 37.8 %, at 9 and 27 months respectively), that they prevent dengue (5.7 and 51.2 %, at 9 and 27 months), that they are "beautiful" (5.9 and 3.1 %), as well as other reasons (6.9 and 2.5�

A Method for Evaluating Insecticide Efficacy against Bed Bug, Cimex lectularius, Eggs and First Instars.

PubMed

Campbell, Brittany E; Miller, Dini M

2017-03-15

Standard toxicity evaluations of insecticides against insect pests are primarily conducted on adult insects. Evaluations are based on a dose-response or concentration-response curve, where mortality increases as the dose or concentration of an insecticide is increased. Standard lethal concentration (LC50) and lethal dose (LD50) tests that result in 50% mortality of a test population can be challenging for evaluating toxicity of insecticides against non-adult insect life stages, such as eggs and early instar or nymphal stages. However, this information is essential for understanding insecticide efficacy in all bed bug life stages, which affects control and treatment efforts. This protocol uses a standard dipping bioassay modified for bed bug eggs and a contact insecticidal assay for treating nymphal first instars. These assays produce a concentration-response curve to further quantify LC50 values for insecticide evaluations.

Netting the malaria menace: Distribution and utilization of long-lasting insecticidal net in a malaria endemic area in Bankura, West Bengal.

PubMed

Mukhopadhyay, D K; Basu, S S; Roy, D; Das, N; Akbar, F; Sarkar, G N

2016-03-01

Long-lasting insecticidal net (LLIN) is considered to be a highly effective intervention against malaria under National Vector Borne Disease Control Programme in India. A cross-sectional study was undertaken to assess the coverage and utilization of LLIN and the factors related thereto. A survey of 1300 households was carried out in Ranibandh block of Bankura district in West Bengal, India, using lot quality assurance sampling (LQAS) method. Coverage/utilization of 80% was considered as minimum acceptable norm. The weighted sample size was calculated from each village of the block. The sociodemographic, economic information of the household along with the availability and use of LLIN was collected through interview and observation. In total, 7320 individuals including 840 children ≤ 5 yr were visited. Overall coverage of adequate LLIN was 65.4% (± 1.5%) and for children ≤ 5 yr, it was 60.5% (± 1.3%). Overall, 66.1% (± 1.4%) people of all ages and 63.7% (± 1.4%) children ≤ 5 yr slept under LLINs in the night before the survey. Out of 26 sub-centres, distribution of LLINs in 10 sub-centres was below the accepted norm, whereas utilization was sub-optimal in 19 sub-centres. In only 18.2% (± 0.5%) households, LLINs remained hanging during daytime. Poverty, caste, education, perception regarding malarial morbidity and preventive action of LLIN were associated significantly with the distribution of LLIN. Similarly, poverty (AOR = 2.14), threat perception regarding malarial morbidity (AOR = 1.51) and mortality (AOR = 2.52) were positively associated with the use of LLIN. Full utilization of bednets by under-fives of the households was higher in villages with sub-centres. Around two-third population of the study area was effectively covered with LLIN. Higher proportion of socially marginalized people received LLIN. Threat perception regarding malaria was directly associated with both receipt and use of LLIN. Behaviour change communication on utilization along

Insecticide susceptibility of Anopheles mosquitoes changes in response to variations in the larval environment.

PubMed

Owusu, Henry F; Chitnis, Nakul; Müller, Pie

2017-06-16

Insecticide resistance threatens the success achieved through vector control in reducing the burden of malaria. An understanding of insecticide resistance mechanisms would help to develop novel tools and strategies to restore the efficacy of insecticides. Although we have substantially improved our understanding of the genetic basis of insecticide resistance over the last decade, we still know little of how environmental variations influence the mosquito phenotype. Here, we measured how variations in larval rearing conditions change the insecticide susceptibility phenotype of adult Anopheles mosquitoes. Anopheles gambiae and A. stephensi larvae were bred under different combinations of temperature, population density and nutrition, and the emerging adults were exposed to permethrin. Mosquitoes bred under different conditions showed considerable changes in mortality rates and body weight, with nutrition being the major factor. Weight is a strong predictor of insecticide susceptibility and bigger mosquitoes are more likely to survive insecticide treatment. The changes can be substantial, such that the same mosquito colony may be considered fully susceptible or highly resistant when judged by World Health Organization discriminatory concentrations. The results shown here emphasise the importance of the environmental background in developing insecticide resistance phenotypes, and caution for the interpretation of data generated by insecticide susceptibility assays.

The importance of education to increase the use of bed nets in villages outside of Kinshasa, Democratic Republic of the Congo.

PubMed

Ndjinga, Julie K; Minakawa, Noboru

2010-10-12

Malaria is the most prominent disease in the Democratic Republic of the Congo (DRC), and long-lasting insecticide-treated nets (LLINs) have been distributed free of charge since 2006 to combat the disease. However, the success of this bed net campaign depends on sufficient bed net use in all age groups. This study was designed to examine the factors affecting bed net use in villages outside of Kinshasa. Two villages along the Congo River, totalling 142 households with 640 residents, were surveyed using a standard questionnaire. The interview determined the number, ages, and sexes of family members; the education level of the family head; the number, colour, and type of nets owned; and the number of nets used in the previous night. The size of house was also measured, and numbers of rooms and beds were recorded. These variables were examined to reveal important factors that affect bed net use. A total of 469 nets were counted, and nearly all nets were white LLINs. Of these nets, 229 (48.8%) nets were used by 284 (44.4%) residents. Bed nets were used by over 90% of children 5 to 15 years of age, whereas less than 50% of the residents in other age groups used bed nets. The important variables affecting bed net use were numbers of beds and rooms in the house and the education level of the family head of household. Education was the most important factor affecting bed net use in the villages outside Kinshasa. Development of an educational programme, particularly one directed toward parents, is necessary to reduce misconceptions and increase prevalence of bed net use among all age groups.

Mosquito repellents for malaria prevention

PubMed Central

Maia, Marta F; Kliner, Merav; Richardson, Marty; Lengeler, Christian; Moore, Sarah J

2018-01-01

Background Malaria is an important cause of illness and death across endemic regions. Considerable success against malaria has been achieved within the past decade mainly through long-lasting insecticide-treated nets (LLINs). However, elimination of the disease is proving difficult as current control methods do not protect against mosquitoes biting outdoors and when people are active. Repellents may provide a personal protection solution during these times. Objectives To assess the impact of topical repellents, insecticide-treated clothing, and spatial repellents on malaria transmission. Search methods We searched the following databases up to 26 June 2017: the Cochrane Infectious Diseases Group Specialized Register; the Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE; Embase; US AFPMB; CAB Abstracts; and LILACS. We also searched trial registration platforms and conference proceedings; and contacted organizations and companies for ongoing and unpublished trials. Selection criteria We included randomized controlled trials (RCTs) and cluster-randomized controlled trials of topical repellents proven to repel mosquitoes; permethrin-treated clothing; and spatial repellents such as mosquito coils. We included trials that investigated the use of repellents with or without LLINs, referred to as insecticide-treated nets. Data collection and analysis Two review authors independently reviewed trials for inclusion, extracted the data, and assessed the risk of bias. A third review author resolved any discrepancies. We analysed data by conducting meta-analysis and stratified by whether the trials had included LLINs. We combined results from cRCTs with individually RCTs by adjusting for clustering and presented results using forest plots. We used GRADE to assess the certainty of the evidence. Main results Eight cRCTs and two RCTs met the inclusion criteria. Six trials investigated topical repellents, two trials investigated insecticide-treated

Can Long-lasting Insecticide-treated Bednets with Holes Protect Children from Malaria?

PubMed

Nonaka, Daisuke; Maazou, Abani; Yamagata, Shigeo; Oumarou, Issofou; Uchida, Takako; Jg Yacouba, Honoré; Toma, Nami; Takeuchi, Rie; Kobayashi, Jun; Mizoue, Tetsuya

2014-09-01

Although long-lasting insecticide-treated bednets (LLINs) have been widely used for malaria control, little is known about how the condition of LLINs affects the risk of malaria infection. The objective of this cross-sectional study was to examine the association between the use of LLINs with holes and caregiver-reported malaria diagnosed in children under five years of age (U5). Data were collected in Boboye health district, Niger, in 2010. Surveyors conducted interviews and bednet inspections in 1,034 households. If a household had a U5 child, the surveyor asked the caregiver whether the child had experienced a fever episode in the past two weeks that entailed standard treatment for uncomplicated malaria at a healthcare facility. The authors analyzed the association between the use of LLINs with holes and caregiver-reported malaria episodes in U5 children using logistic regression, adjusted for possible confounders. Of the 1,165 children included in the analysis, approximately half (53.3%) used an intact LLIN while far fewer (10.6%) used a LLIN with holes. Compared to children using an intact LLIN, children using a LLIN with holes were significantly more likely to have a caregiver-reported malaria episode (8.7% vs. 17.1%; odds ratio: 2.23; 95% confidence interval: 1.24-4.01). In this study site, LLINs with holes were less protective than intact LLINs.

Insecticidal and sterilizing effect of Olyset Duo®, a permethrin and pyriproxyfen mixture net against pyrethroid-susceptible and -resistant strains of Anopheles gambiae s.s.: a release-recapture assay in experimental huts.

PubMed

Djènontin, Armel; Ahoua Alou, Ludovic P; Koffi, Alphonsine; Zogo, Barnabas; Duarte, Elves; N'Guessan, Raphael; Moiroux, Nicolas; Pennetier, Cédric

2015-01-01

In the context of the widespread distribution of pyrethroid resistance among malaria vectors, we did a release-recapture trial in experimental huts to investigate the insecticidal and sterilizing effects of a novel long-lasting net (LN), Olyset® Duo, incorporating a mixture of permethrin (PER) and the insect growth regulator (IGR), pyri-proxyfen (PPF). An LN containing PPF alone and a classic Olyset® Net were tested in parallel as positive controls. The effect of progressive number of holes (6, 30, or 150) that may accrue in nets over time was simulated. We used two laboratory Anopheles gambiae s.s. strains: the susceptible Kisumu strain and the pyrethroid-resistant VK-Per strain having solely kdr as resistance mechanism. The effect of these nets on the reproductive success of blood-fed females that survived the different LNs conditions was recorded. Regardless of the mosquito strain, the LNs containing PPF alone with as many as 30 holes drastically reduced the number of eggs laid by females succeeding in feeding, i.e. fecundity by 98% and egg hatching rate (fertility) by 93% relative to untreated control net. Very few of the resistant females blood fed and survived under the Olyset® Duo with similar number of holes (up to 30) but of these few, the inhibition of reproductive success was 100%. There was no evidence that the Olyset® Duo LN with 150 holes impacted fecundity or fertility of the resistant colony. The efficacy of Olyset® Duo is encouraging and clearly illustrates that this new net might be a promising tool for malaria transmission control and resistance management. © A. Djènontin et al., published by EDP Sciences, 2015.

Social Determinants of Long Lasting Insecticidal Hammock-Use Among the Ra-Glai Ethnic Minority in Vietnam: Implications for Forest Malaria Control

PubMed Central

Muela Ribera, Joan; Ngo Duc, Thang; van Bortel, Wim; Truong Ba, Nhat; Van, Ky Pham; Le Xuan, Hung; D'Alessandro, Umberto; Erhart, Annette

2012-01-01

Background Long-lasting insecticidal hammocks (LLIHs) are being evaluated as an additional malaria prevention tool in settings where standard control strategies have a limited impact. This is the case among the Ra-glai ethnic minority communities of Ninh Thuan, one of the forested and mountainous provinces of Central Vietnam where malaria morbidity persist due to the sylvatic nature of the main malaria vector An. dirus and the dependence of the population on the forest for subsistence - as is the case for many impoverished ethnic minorities in Southeast Asia. Methods A social science study was carried out ancillary to a community-based cluster randomized trial on the effectiveness of LLIHs to control forest malaria. The social science research strategy consisted of a mixed methods study triangulating qualitative data from focused ethnography and quantitative data collected during a malariometric cross-sectional survey on a random sample of 2,045 study participants. Results To meet work requirements during the labor intensive malaria transmission and rainy season, Ra-glai slash and burn farmers combine living in government supported villages along the road with a second home at their fields located in the forest. LLIH use was evaluated in both locations. During daytime, LLIH use at village level was reported by 69.3% of all respondents, and in forest fields this was 73.2%. In the evening, 54.1% used the LLIHs in the villages, while at the fields this was 20.7%. At night, LLIH use was minimal, regardless of the location (village 4.4%; forest 6.4%). Discussion Despite the free distribution of insecticide-treated nets (ITNs) and LLIHs, around half the local population remains largely unprotected when sleeping in their forest plot huts. In order to tackle forest malaria more effectively, control policies should explicitly target forest fields where ethnic minority farmers are more vulnerable to malaria. PMID:22253852

Implementing reduced-risk integrated pest management in fresh-market cabbage: improved net returns via scouting and timing of effective control.

PubMed

Burkness, Eric C; Hutchison, W D

2008-04-01

During 1998-2001, field studies were done to assess the efficacy of an integrated pest management (IPM) program using an action threshold and "reduced-risk" insecticides. The IPM program was compared with a conventional grower-based program. Program performance was evaluated based on management of Trichoplusia ni (Hiibner), Pieris (=Artogeia) rapae (L.), and Plutella xylostella (L.), as well as the economic impact of each program on net returns. The action threshold used in the IPM program consisted of 10% plants infested with T. ni larvae, based on previous small-plot experiment station trials. In all years of the study, the IPM program resulted in significantly lower percentages of plants infested than the conventional program or untreated check. The mean reduction in insecticide applications for the IPM program compared with the conventional program was 23.5%, whereas, on average, the costs of the IPM program were 46.0% higher than the conventional program. Pest reduction in the IPM program resulted in an average of 10.5% higher marketable yields than the conventional program. Percentages of marketable heads in the IPM program ranged from 82 to 99% and from 63 to 96% in the conventional program. Mean net returns for the IPM program exceeded the conventional program by $984.20/ha. These results indicated that the IPM program reduced insecticide use overall, even though costs of the IPM program, with either spinosad or indoxacarb, were sometimes higher. Overall, net returns of the IPM program were higher due to active pest scouting, improved application timing, and increases in marketable yield. Given the potential decrease in insecticide applications and increases in net profit resulting from this IPM program, additional analyses should be conducted to quantify the economic risk, or consistency of the results, to fully evaluate the benefits of the IPM program compared with a conventional program.

No Safety Net Required

ERIC Educational Resources Information Center

Benigni, Mark D.; Moylan, Maureen

2009-01-01

This article discusses the Berlin (Connecticut) High School's NET (Non-Traditional Educational Training) program. NET is a self-contained program that is composed of three components: academics, social and emotional support, and vocational training. Rather than treat students alike, the NET program tailors their high school experience to meet…

Pyrethroid resistance alters the blood-feeding behavior in Puerto Rican Aedes aegypti mosquitoes exposed to treated fabric

PubMed Central

Bloomquist, Jeffrey R.; Bernier, Ulrich R.

2017-01-01

Emerging insecticide resistance is a major issue for vector control. It decreases the effectiveness of insecticides, thereby requiring greater quantities for comparable control with a net increase in risk of disease resurgence, product cost, and damage risk to the ecosystem. Pyrethroid resistance has been documented in Puerto Rican populations of Aedes aegypti (L.) mosquitoes. In this study, topical toxicity of five insecticides (permethrin, etofenprox, deltamethrin, DDT, transfluthrin) was determined for susceptible (Orlando—ORL) and resistant (Puerto Rico—PR) strains of Ae. aegypti. Resistance ratios were calculated using LD50 values, and high resistance ratios for permethrin (112) and etofenprox (228) were observed for the Puerto Rico strain. Behavioral differences in blood-feeding activity for pyrethroid-resistant and pyrethroid-susceptible strains of Ae. aegypti when exposed to pyrethroid-treated cloth were also explored. Strains were exposed for 15 min to a range of concentrations of pyrethroid-treated uniform fabric in a cage that contained 60 female Ae. aegypti mosquitoes. Interestingly, the resistance ratios for blood-feeding were similar for permethrin (61) and etofenprox (70), but were lower than their respective resistance ratios for topical toxicity, suggesting that knockdown resistance was the primary mechanism of resistance in the blood feeding assays. Results showed a rightward shift in the dose-response curves for blood-feeding that indicated higher concentrations of pyrethroids were necessary to deter blood-feeding behavior in the pyrethroid-resistant Puerto Rican strain of Ae. aegypti. PMID:28931018

Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial.

PubMed

Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

2015-02-01

Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4-6 weeks after the second intervention (March to April 2014). Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Prevention of anaemia in pregnancy using insecticide-treated bednets and sulfadoxine-pyrimethamine in a highly malarious area of Kenya: a randomized controlled trial.

PubMed

Njagi, Joseph Kiambo; Magnussen, Pascal; Estambale, Benson; Ouma, John; Mugo, Benbolt

2003-01-01

To compare the effects of intermittent treatment with sulfadoxine-pyrimethamine (SP) given during the second and third trimester of pregnancy, the use of insecticide-treated nets (ITN), or the combination of both on haemoglobin (Hb) levels during pregnancy, a randomized, placebo-controlled intervention trial was conducted in a malaria-endemic area of western Kenya from July 1997 to September 1999. Primigravidae and secundigravidae were enrolled into the study and randomized into 4 intervention groups: (i) ITNs and SP, (ii) ITNs and placebo SP, (iii) SP alone, and (iv) placebo SP. All groups were offered case management and iron and folic acid supplementation. Seven hundred and fifty-two women were followed until delivery (53.2% were primigravidae and 46.8% secundigravidae). Among primigravidae in all the groups there was a significant improvement in Hb levels at delivery (107.6 g/L) compared with recruitment (101.9 g/L) (P < 0.006) with the greatest improvement in the combination ITNs + SP group. The protective efficacy of ITNs + SP on anaemia was 55.8% (95% CI 30.6-71.8), of SP alone 50.9% (95% CI 22.2-69.0), and of ITNs 41.6% (95% CI 9.8-62.3). Among secundigravidae, Hb levels were slightly lower at delivery compared with recruitment (P = 0.03). It was concluded that malaria is a major cause of anaemia in primigravidae but that other causes play a more significant role in secundigravidae, and that intermittent treatment with SP or use of ITNs benefits primigravidae more than secundigravidae.

Comparison of exclusion and imidacloprid for reduction of oviposition damage to young trees by periodical cicadas (Hemiptera: Cicadidae).

PubMed

Ahern, Robert G; Frank, Steven D; Raupp, Michael J

2005-12-01

Insecticides are traditionally used to control periodical cicadas (Homoptera: Cicadidae) and to reduce associated injury caused by oviposition. However, research has shown that conventional insecticides have low or variable season-long efficacy in reducing injury caused by cicadas. New systemic neonicotinoid insecticides provide excellent levels of control against a variety of sucking insects. We compared the efficacy of a neonicotinoid insecticide, imidacloprid, and a nonchemical control measure, netting, to reduce cicada injury. Netted trees sustained very little injury, whereas unprotected trees were heavily damaged. Fewer eggnests, scars, and flags were observed on trees treated with imidacloprid compared with unprotected trees; however, the hatching of cicada eggs was unaffected by imidacloprid.

The effect of small solar powered 'Bͻkͻͻ' net fans on mosquito net use: results from a randomized controlled cross-over trial in southern Ghana.

PubMed

Briët, Olivier J T; Yukich, Joshua O; Pfeiffer, Constanze; Miller, William; Jaeger, Mulako S; Khanna, Nitin; Oppong, Samuel; Nardini, Peter; Ahorlu, Collins K; Keating, Joseph

2017-01-03

Long-lasting insecticidal nets (LLINs) are ineffective malaria transmission prevention tools if they are unused. Discomfort due to heat is the most commonly reported reason for not using nets, but this problem is largely unaddressed. With increasing rural electrification and the dropping price of solar power, fans could improve comfort inside nets and be affordable to populations in malaria endemic areas. Here, results are presented from a pilot randomized controlled cross-over study testing the effect of fans on LLIN use. Eighty-three households from two rural communities in Greater Accra, Ghana, randomized into three groups, participated in a 10-month cross-over trial. After a screening survey to identify eligible households, all households received new LLINs. Bͻkͻͻ net fan systems (one fan per member) were given to households in Group 1 and water filters were given to households in Group 2. At mid-point, Group 1 and 2 crossed over interventions. Households in Group 1 and 2 participated in fortnightly surveys on households' practices related to nets, fans and water filters, while households in Group 3 were surveyed only at screening, mid-point and study end. Entomological and weather data were collected throughout the study. Analysis took both 'per protocol' (PP) and 'intention to treat' (ITT) approaches. The mid- and end-point survey data from Group 1 and 2 were analysed using Firth logistic regressions. Fortnightly survey data from all groups were analysed using logistic regressions with random effects. Provision of fans to households appeared to increase net use in this study. Although the increase in net use explained by fans was not significant in the primary analyses (ITT odds ratio 3.24, p > 0.01; PP odds ratio = 1.17, p > 0.01), it was significant in secondary PP analysis (odds ratio = 1.95, p < 0.01). Net use was high at screening and even higher after provision of new LLINs and with follow up. Fan use was 90-100% depending on the

[Malaria: knowledge, behaviour and practices among a rural population of Gossas, Senegal].

PubMed

Ndour, C T; Ba, O; Manga, N M; Fortes, M L; Nyamwasa, D; Sow, P S

2006-10-01

Malaria remains a major public health problem in Sub-Saharian Africa, in terms of morbidity and mortality rate. To assess the knowledge and behaviour of population regarding the transmission, the treatment and the prevention of malaria, we conducted a cluster sample household survey in Gossas, a rural District in Senegal, from May 2nd to May 6th 2005. A questionnaire that focused on socioeconomic conditions, beliefs, knowledge about and behavior toward antimalarial medication and the prevention means used was given to 480 household owners. Overall, 107 pregnant women and 1,201 children aged less than 5 years old lived within these household. More than a half of the household owners (51%) were illiterate and 25.2% ignored how malaria is transmitted. Fever was the most common symptom suggesting malaria (61%). In 46.1% of febrile cases, people did not seek for treatment from a physician. Home treatment of febrile episodes was based on paracetamol or aspirin (84%), chloroquine (13%) and cotrimoxazole (2.9%). Overall, the proportion of insecticide treated nets users were 22.7%. This percentage was 14.9% and 11.4% for pregnant women and children younger than 5 years old, respectively. People having radio sets, regular access to television, and people aware of the transmission route of malaria were more likely to use bed nets. In most cases, organic material burning was used as repellent against mosquitoes. The low prevalence of bed net use was most often explained by participants' limited accessibility to and by the high cost of insecticide-treated nets. Knowledge about malaria prevention and treatment is low in the rural district of Gossas. The rate of insecticide-treated-bed nets use in vulnerable people is very low, far from the Abuja meeting objective. A sensibilization program and a social marketing plan for insecticide-treated-bed nets could improve this situation.

Combining long-lasting insecticidal nets and indoor residual spraying for malaria prevention in Ethiopia: study protocol for a cluster randomized controlled trial.

PubMed

Deressa, Wakgari; Loha, Eskindir; Balkew, Meshesha; Hailu, Alemayehu; Gari, Taye; Kenea, Oljira; Overgaard, Hans J; Gebremichael, Teshome; Robberstad, Bjarne; Lindtjørn, Bernt

2016-01-12

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the main malaria prevention interventions in Ethiopia. There is conflicting evidence that the combined application of both interventions is better than either LLINs or IRS used alone. This trial aims to investigate whether the combination of LLINs (PermaNet 2.0, Vestergaard Frandsen, Lausanne, Switzerland) with IRS using propoxur will enhance the protective benefits and cost-effectiveness of the interventions against malaria and its effect on mosquito behavior, as compared to each intervention alone. This 2 x 2 factorial cluster randomized controlled trial is being carried out in the Adami Tullu district in south-central Ethiopia for about 116 weeks from September 2014 to December 2016. The trial is based on four arms: LLINs + IRS, LLINs alone, IRS alone and control. Villages (or clusters) will be the unit of randomization. The sample size includes 44 clusters per arm, with each cluster comprised of approximately 35 households (about 175 people). Prior to intervention, all households in the LLINs + IRS and LLINs alone arms will be provided with LLINs free of charge. Households in the LLINs + IRS and IRS alone arms will be sprayed with carbamate propoxur once a year just before the main malaria transmission season throughout the investigation. The primary outcome of this trial will be a malaria incidence based on the results of the rapid diagnostic tests in patients with a fever or history of fever attending health posts by passive case detection. Community-based surveys will be conducted each year to assess anemia among children 5-59 months old. In addition, community-based malaria prevalence surveys will be conducted each year on a representative sample of households during the main transmission season. The cost-effectiveness of the interventions and entomological studies will be simultaneously conducted. Analysis will be based on an intention-to-treat principle. This trial aims to

Assessment of Potential Sublethal Effects of Various Insecticides on Key Biological Traits of The Tobacco Whitefly, Bemisia tabaci

PubMed Central

He, Yuxian; Zhao, Jianwei; Zheng, Yu; Weng, Qiyong; Biondi, Antonio; Desneux, Nicolas; Wu, Kongming

2013-01-01

The tobacco whitefly Bemisia tabaci is one of the most devastating pests worldwide. Current management of B. tabaci relies upon the frequent applications of insecticides. In addition to direct mortality by typical acute toxicity (lethal effect), insecticides may also impair various key biological traits of the exposed insects through physiological and behavioral sublethal effects. Identifying and characterizing such effects could be crucial for understanding the global effects of insecticides on the pest and therefore for optimizing its management in the crops. We assessed the effects of sublethal and low-lethal concentrations of four widely used insecticides on the fecundity, honeydew excretion and feeding behavior of B. tabaci adults. The probing activity of the whiteflies feeding on treated cotton seedlings was recorded by an Electrical Penetration Graph (EPG). The results showed that imidacloprid and bifenthrin caused a reduction in phloem feeding even at sublethal concentrations. In addition, the honeydew excretions and fecundity levels of adults feeding on leaf discs treated with these concentrations were significantly lower than the untreated ones. While, sublethal concentrations of chlorpyrifos and carbosulfan did not affect feeding behavior, honeydew excretion and fecundity of the whitefly. We demonstrated an antifeedant effect of the imidacloprid and bifenthrin on B. tabaci, whereas behavioral changes in adults feeding on leaves treated with chlorpyrifos and carbosulfan were more likely caused by the direct effects of the insecticides on the insects' nervous system itself. Our results show that aside from the lethal effect, the sublethal concentration of imidacloprid and bifenthrin impairs the phloem feeding, i.e. the most important feeding trait in a plant protection perspective. Indeed, this antifeedant property would give these insecticides potential to control insect pests indirectly. Therefore, the behavioral effects of sublethal concentrations of

The effect of delivery mechanisms on the uptake of bed net re-impregnation in Kilifi District, Kenya.

PubMed

Snow, R W; McCabe, E; Mbogo, C N; Molyneux, C S; Some, E S; Mung'ala, V O; Nevill, C G

1999-03-01

The results of recently completed trials in Africa of insecticide-treated bed nets (ITBN) offer new possibilities for malaria control. These experimental trials aimed for high ITBN coverage combined with high re-treatment rates. Whilst necessary to understand protective efficacy, the approaches used to deliver the intervention provide few indications of what coverage of net re-treatment would be under operational conditions. Varied delivery and financing strategies have been proposed for the sustainable delivery of ITBNs and re-treatment programmes. Following the completion of a randomized, controlled trial on the Kenyan coast, a series of suitable delivery strategies were used to continue net re-treatment in the area. The trial adopted a bi-annual, house-to-house re-treatment schedule free of charge using research project staff and resulted in over 95% coverage of nets issued to children. During the year following the trial, sentinel dipping stations were situated throughout the community and household members informed of their position and opening times. This free re-treatment service achieved between 61-67% coverage of nets used by children for three years. In 1997 a social marketing approach, that introduced cost-retrieval, was used to deliver the net re-treatment services. The immediate result of this transition was that significantly fewer of the mothers who had used the previous re-treatment services adopted this revised approach and coverage declined to 7%. The future of new delivery services and their financing are discussed in the context of their likely impact upon previously defined protective efficacy and cost-effectiveness estimates.