Lasting Insecticide Research Articles

Insecticide resistance in Anopheles arabiensis in Sudan: temporal trends and underlying mechanisms.

BackgroundMalaria vector control in Sudan relies mainly on indoor residual spraying (IRS) and the use of long lasting insecticide treated bed nets (LLINs). Monitoring insecticide resistance in the main Sudanese malaria vector, Anopheles arabiensis, is essential for planning and implementing an effective vector control program in this country.MethodsWHO susceptibility tests were used to monitor resistance to insecticides from all four WHO-approved classes of insecticide at four sentinel sites in Gezira state over a three year period. Insecticide resistance mechanisms were studied using PCR and microarray analyses.ResultsWHO susceptibility tests showed that Anopheles arabiensis from all sites were fully susceptible to bendiocarb and fenitrothion for the duration of the study (2008–2011). However, resistance to DDT and pyrethroids was detected at three sites, with strong seasonal variations evident at all sites. The 1014 F kdr allele was significantly associated with resistance to pyrethroids and DDT (P < 0.001) with extremely high effects sizes (OR > 7 in allelic tests). The 1014S allele was not detected in any of the populations tested. Microarray analysis of the permethrin-resistant population of An. arabiensis from Wad Medani identified a number of metabolic genes that were significantly over-transcribed in the field-collected resistant samples when compared to the susceptible Sudanese An. arabiensis Dongola strain. These included CYP6M2 and CYP6P3, two genes previously implicated in pyrethroid resistance in Anopheles gambiae s.s, and the epsilon-class glutathione-S-transferase, GSTe4.ConclusionsThese data suggest that both target-site mechanisms and metabolic mechanisms play an important role in conferring pyrethroid resistance in An. arabiensis from Sudan. Identification in An. arabiensis of candidate loci that have been implicated in the resistance phenotype in An. gambiae requires further investigation to confirm the role of these genes.

Commodity utilization of malaria intervention and control tool: Access and utilization of long lasting insecticide net in rural communities of Imeko-Afon and Odeda local government area of Ogun state, Nigeria

Background: Long lasting insecticide net (LLIN) is one of the major tools utilized in the control and prevention of malaria across all age groups. Aim: This study compared the accessibility and usage patterns of LLIN in rural communities of Odeda and Imeko-Afon local government areas (LGAs). Materials and Methods: Three villages were selected each from Odeda and Imeko-Afon LGAs using the simple random sampling method. Questionnaires were administered to the head of households, and personal information was collected from individual member of the family. Descriptive analysis was used to summarize important variables. Results: A total of 140 households participated in the study, 70 from each LGA. Of the households surveyed, 87.1% have LLIN in Imeko-Afon LGA and was significantly higher (P = 0.0000) compared to 60% in Odeda LGA (P = 0.000). However, 96.7% and 95.2% of households in Imeko-Afon and Odeda LGAs respectively acquired the LLIN free from the government. The utilization rate by househeads the night prior the study was 72.1% and 57.1% in Imeko-Afon and Odeda LGA respectively (P = 0.115). Of the total respondents, only 47.9% in Imeko-Afon and 32.4% in Odeda sleep under the net everyday (P = 0.000) and 22.9% and 62.1% respectively in both LGAs do not sleep under LLIN (P = 0.000). There was a significant difference (P = 0.000) in the number of respondents that sleep under LLIN every day between the two LGAs. Reason for not sleeping under net was majorly heat. Conclusion: There is a need for more awareness and health education on proper utilization and maintenance of LLIN to enhance the effectiveness of the net.

Analysis of the Cost of Malaria in Children and Use of Insecticide-treated Bednets in Africa

We examine the direct and indirect costs of malaria in children under five years and the benefit of investing in long lasting insecticide treated mosquito nets as a preventative policy strategy in 18 African countries. The results indicate that the use of mosquito treated nets can induce a 6.2 percent reduction in outpatient costs, a 6.6 percent reduction in inpatient treatment costs, a 6.3 percent reduction in productivity losses, and a 22.6 percent reduction in disability adjusted life years (DALY), all on an annual basis.

Facing the Resistance Crisis in Malaria Control by Developing and Evaluating 'Resistance-Breaking' Products

Prevention of malaria is best achieved by controlling the mosquito vector which, today in Africa relies almost entirely on the use of residual insecticides inside the home. Wide scale implementation of tools such as indoor residual spraying (IRS) and long lasting insecticide impregnated bednets (LLINs) have led to impressive decreases in malaria transmission in some regions and these interventions are the cornerstone of malaria control programmes in most African countries. These two interventions are largely reliant on a single class of insecticides, the pyrethroids. Only pyrethroids can be used to treat bednets and, although four insecticide classes are approved by the World Health Organisation for use in IRS, the vast majority of programmes spray with pyrethroids. An inevitable consequence of the scale up of malaria control has been the emergence of insecticide resistance in the Anopheles vectors. Pyrethroid resistance was first detected in Anopheles gambiae in West Africa in 1993 and remained relatively rare until the end of the twentieth century. But in the past 10 years reports of pyrethroid resistance in the major African malaria vectors have escalated. Action must be taken to ensure that this resistance does not compromise malaria control. The AvecNet project (www.avecnet.eu) was established in 2011, with funding from the European Union Framework 7 programme, with the goal of developing new or improved mosquito control tools to complement existing interventions and control insecticide resistant populations. Some of the key activities and outputs from this project are described.

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

IntroductionMalaria 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.MethodsMulti-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.ResultsSixty 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.ConclusionCoverage 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.

IMPACT OF ENLIGHTENMENT AND MONITORING ON THE USE OF LONG LASTING INSECTICIDE NETS FOR MALARIA PREVENTION AMONG CHILDREN UNDER FIVE YEARS IN A RURAL COMMUNITY IN ABEOKUTA, NIGERIA

The female Anopheles mosquito is the vector for human malaria and bites man mostly from 5pm to 7am, with maximum intensity between 10pm and 4am. This provides the basis for the use of Long Lasting Insecticide Nets (LLIN). A study to assess the impact of enlightenment, advocacy and monitoring on LLIN use for children under five years was conducted in Olugbo. A total of two hundred (200) children under five years were recruited into the study. Ethical clearance was received from the Ogun State Ministry of Health. Pre-tested questionnaires were administered to the respondents and blood samples were collected for malaria test before and after provision(Pre and Post intervention) of LLIN. The blood samples were analyzed at the laboratory using the QBC Malaria Test and ParaLens system. The subjects were divided into two groups of study (group that received LLIN, enlightenment on the importance of LLIN and assisted with LLIN hanging) and Control (group that merely received the LLIN without enlightenment or assistance). The subjects in the study group were monitored between 1600hrs to 2000hrs thrice a week. The pre intervention study result shows that the prevalence of malaria infection was 70% and 56% amongst the study and Control group respectively. The post intervention blood samples screening reveals that the prevalence of infection in the study group was 13% with low parasite density. In the Control group, however, the prevalence of infection was 60% and 38.33% of those infected had high parasite density. There is a significant difference (P<0.05) in malaria parasitaemia between both groups post intervention. This study shows that distribution of LLINs alone is not sufficient to reduce malaria morbidity and recommends that enlightenment and assistance with hanging of LLINs should form an integral part of mass distribution of LLINs by government and donor agencies.

The Influence of Social Factors towards Resurgent Malaria and its Mitigation Using Sri Lanka as a Case-study

Social factors of malaria were examined using the case-study of malaria incidence in Sri Lanka. Sri Lanka has currently achieved eradication of malaria but as it is a small island, developing country, it is vulnerable to climate change threats. Therefore the social influences, host immunity, anti-malarial resistance, prosperity and travel, were investigated with particular reference to potential climate change-induced malaria. Development of immunity depends on the intensity and stability of transmission within the region. Although Sri Lanka recently eradicated malaria, it was previously considered a region of low to moderate transmission, with most individual inoculation resulting in infection and disease at all ages. Self-medication when unrequired is particularly significant in contributing to the global issue of anti-malarial resistance. Despite known drug resistance, distribution continues to be widespread due to low over-the-counter cost and rapid relief of symptoms. Poverty promotes transmission of malaria and in turn malaria impedes economic growth. Malaria imposes economic loss beyond direct medical costs and associated effects to macroenomic costs by impacts on worker productivity, school children performance, etc. However improved economic growth is insufficient to eradicate malaria e.g. Oman. Air travel is a vital factor in malaria transmission due to conveyance of asymptomatic carriers from endemic to non-endemic countries, leading to outbreaks of epidemic malaria. Incidence of imported malaria has been observed mainly due to lapse or absence of prophylaxis. The management of malaria was examined under the categories of public healthcare services and mitigation measures. Mitigation measures were evaluated in relation to social factors, to determine their efficacy in the event of resurgent malaria. Mitigation techniques of prominence were anti-malarial therapy, Indoor Residual Spraying, Insecticide Treated Nets and Long Lasting Insecticide Treated Nets and lastly environmental management. Malaria is borne out of multiple risks; both environmental (i.e. climate change and environmental degradation) and social (i.e. anti-malarial resistance, migration and poverty). As observed in Sri Lanka, strong political commitment in prioritising malaria control with sustained resource allocation is vital to eliminate malaria. A multi-measure approach cross cutting public health care services and malaria interventions has proven effective despite some evident climate change impacts

English

Malaria in pregnancy is a significant contributor to adverse pregnancy outcome. In low resource setting of India to contain malaria in the vast chloroquine resistant endemic zone LLIN (Long lasting insecticide treated Nets) has been introduced as an intervention to prevent malarial morbidity and mortality in the population among anemic pregnant women in malarias zone is quite high, oral ferrous ascorbate has an edge over commonly available ferrous sulfate to rectify Anemia with least side effect in those pregnant women. INTRODUCTION: Malaria in pregnancy is an important public health problem that affects 25 million pregnant women in endemic zones of world and contributes heavily on maternal and infant morbidity and mortality. Acquired immunity in endemic zones is compromised in pregnant state. Maternal Anemia (70%) still birth, premature birth and LBW are adverse outcome in pregnant women in endemic zones of Malaria, especially in chloroquine resistant areas. Although in 2004 WHO recommended prophylactic two doses of sulfadoxine pyrimethamine (Ref-5) in 2nd trimester of pregnancy in endemic zones, sub optimal drug adherence and increasing sulfadoxine pyrimethamine resistance has stood as an obstacle for Malaria containment. Now effect of long lasting insecticide net (LLIN) insecticide treated net (ITN) is being promoted through UNICEF and Govt. in endemic zones resistant to chloroquine chemoprophylaxis. Here is a camp based study in one heavily affected Malarias zone of Odisha on effect of LLIN in pregnant women and effect of Oral ferrous Ascorbate in improving the anaemic status of pregnant women in malarious zone. MATERIALS & METHODS: Ramagiri PHC was selected for study as it comes under Intensive Falciparum zone of Koraput district, API-32 in 2012. A pre-camp advertisement in the area was performed. A three member doctor team along with four paramedical assistants, one lab technician and two Divine Life Society volunteers were employed for the camp and 100 nos. of Antenatal cases were registered out of which only 50 cases were randomly studied whose socio economic status was noted to be poor. Antenatal check up Height of Uterus, Abdominal girth/ Wt, BP, HB, urine ALB, splenic examination and Cervical smear and peripheral blood smear were studied. In all cases MP was studied by thick blood sample. Hemoglobin was instantly estimated by hemocue instrument (HB301) after finger prick. Only 10 cases gave their consent for vaginal cytology inspite of maintenance of privacy in presence of a female attendant. Ferrous sulfate 45 tab and Ferrous Ascorbate (Elferri xt supplied by Svizera Health Care - Constituent Per tab Ferrous Ascorbate 100 mg, Folic Acid-1.5 mg, Zinc -22.5 mg ) 45 tabs were given on alternate making them Group 'A' and Group 'B' respectively. HB was reestimated after 45 days in both groups by same

Dynamics of Forest Malaria Transmission in Balaghat District, Madhya Pradesh, India

BackgroundAn epidemiological and entomological study was carried out in Balaghat district, Madhya Pradesh, India to understand the dynamics of forest malaria transmission in a difficult and hard to reach area where indoor residual spray and insecticide treated nets were used for vector control.MethodsThis community based cross-sectional study was undertaken from January 2010 to December 2012 in Baihar and Birsa Community Health Centres of district Balaghat for screening malaria cases. Entomological surveillance included indoor resting collections, pyrethrum spray catches and light trap catches. Anophelines were assayed by ELISA for detection of Plasmodium circumsporozoite protein.Findings Plasmodium falciparum infection accounted for >80% of all infections. P. vivax 16.5%, P. malariae 0.75% and remaining were mixed infections of P. falciparum, P. vivax and P. malariae. More than, 30% infections were found in infants under 6 months of age. Overall, an increasing trend in malaria positivity was observed from 2010 to 2012 (chi-square for trend = 663.55; P<0.0001). Twenty five Anopheles culicifacies (sibling species C, D and E) were positive for circumsporozoite protein of P. falciparum (44%) and P. vivax (56%). Additionally, 2 An. fluviatilis, were found positive for P. falciparum and 1 for P. vivax (sibling species S and T). An. fluviatilis sibling species T was found as vector in forest villages for the first time in India.ConclusionThese results showed that the study villages are experiencing almost perennial malaria transmission inspite of indoor residual spray and insecticide treated nets. Therefore, there is a need for new indoor residual insecticides which has longer residual life or complete coverage of population with long lasting insecticide treated nets or both indoor residual spray and long lasting bed nets for effective vector control. There is a need to undertake a well designed case control study to evaluate the efficacy of these interventions.

Post intervention assessment of long lasting insecticde nets (LLINs) distributed in Kano metropolis, Kano state, Nigeria

Kano state hasdistributed about 4,137,464 Long Lasting Insecticide Treated Net (LLINs) in2009 being one of the main malaria vector control strategy developed by theNigeria Federal Ministry of Health (FMOH) which is in line with Roll BackMalaria. The objective of the study was to evaluate the effectiveness of LLINsin use and to evaluate the knowledge, attitude and practice of some net usersin Kano metropolis. The effectiveness of LLINs distributed in the year 2009 inKano metropolis in Kano State, Northern Nigeria was evaluated using a clustersample technique A Cone bioassay with laboratory reared Anopheles wereperformed. Knockdown after 60 minutes and mortality after 24 hours following 3minutes exposure were evaluated. A total of 210 households were administeredwith two hundred and five (205) respondents 97.6% indicated the knowledge aboutLLINs while five (5) respondents were not aware. Similarly, one hundred andninety- eight respondents (94.3%) strongly believed that the washing of LLINsdoes not reduce the preventive role of LLINs. Very high and consistentknockdown and mortality in all replicates was found. The outcome on the use ofLLINs reflects the effective use of LLINs among the respondents with twohundred and eight respondents (99%). Respondent still holds some reservation onthe use of LLINs, one hundred and five respondents (54.8%) believes it causesheat. It has been observed that the respondents reply does not rely mostly onLLINs despite by their believe in the efficacy of it rather, 41.4% of thepeople that participated in the research still resort to the use of spray and26.2% uses smoke to prevent mosquito bite. It can be concluded from the findings that respondents were fully awareof long lasting insecticide net and they agree that it is effective against thevector causing malaria parasite and other insects though some of them havereservation on the use of smoke and indoor residual spray to prevent mosquitoesbite. Considering that the nets are expected to be effective for three years ormore years, it is reasonable to conclude that the nets were effective inpreventing mosquito bites based on the knock-down and exposure mortalityresults.

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

BackgroundMass 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.MethodsA 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.ResultsResults 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.ConclusionsWhere pre-campaign coverage levels established by a household survey are below 40% we recommend that planners do not take such LLINs into account and instead plan a blanket mass distribution. At pre-campaign coverage levels above 40%, campaign planners should make explicit consideration of the cost and feasibility of accounting for existing LLINs before planning blanket mass distributions. Planners should also consider restricting the coverage estimates used for this decision to only include nets under two years of age in order to ensure that old and damaged nets do not compose too large a fraction of existing net coverage.

Effectiveness and Compliance of Long Lasting Insecticide Nets (LLINs) on Malaria Parasitemia among Pregnant Women attending Antenatal Clinics in Port Harcourt, Rivers State

Effectiveness and Compliance of Long Lasting Insecticide Nets (LLINs) on Malaria Parasitemia among Pregnant Women attending Antenatal Clinics in Port Harcourt, Rivers State

Effectiveness and Compliance of Long Lasting Insecticide Nets (LLINs) on Malaria Parasitemia among Pregnant Women attending Antenatal Clinics in Port Harcourt, Rivers State

Aim: To determine the effectiveness and compliance of Long Lasting Insecticide Nets (LLINs) on malaria parasitaemia among pregnant women attending antenatal clinics. Study Design:Cross sectional study. Place and Duration of Study:Rivers State, Nigeria, between April and September 2011. Methodology: Thick and thin blood films were made and stained using parasitological standard procedures to identify malaria parasites. Questionnaires were distributed to collect personal data of the pregnant women examined. Data gotten was analyzed with Chi-square test of significance. Results: A total of 400 pr egnant women were examined, 317(79%) used LLINs with 29(9.1%) positive formalaria parasites while 83(21%) did not use LLINs with 75 (90.4%) positive for malaria parasites (P<0.05). Pregnant women in their first, second and third trimesters that used LLINs had prevalence rates of 5.3%, 12.2% and 11.5% respectively

Post-intervention assessment of long-lasting insecticide nets (LLINs) distributed in the Kano metropolis, Kano State, Nigeria

Kano state has distributed about 4,137,464 Long Lasting Insecticide Nets (LLINs) in 2009 being one of the main malariavector control strategy developed by the Nigeria Federal Ministry of Health(FMOH) in line with Roll Back Malaria. The objective of the study was to evaluate the effectiveness of LLINs in use, the knowledge, attitude and practicesof some net users inthe Kano metropolis. A Cone bioassay with laboratory reared Anopheles was performed. Knock down after 60 minutes and mortality after 24 hours followed with a 3 minutes exposure were evaluated. A total of 210 households were administered with a structured questionnaire on two hundred and five (205) respondents (97.6%) indicated knowledge about LLINs while five (5) respondents (2.4%) were not aware. Very high and consistent knockdown and mortality in all 5 replicates were found. Respondent still holds some reservation on the use of LLINs, and one hundred and five respondents (54.8%) believed it causes heat. The respondents replied that they did not rely mostly on LLINs, despite their beliefs in the efficacy of it rather. 41.4% of the people that participated in the research still resorted to use of aerosols and 26.2% use smoke screens to prevent mosquito bites. It can be concluded from the findings that respondents were aware of long lasting insecticide net and agreed on its effectiveness against the vector of malaria parasite and other insects, with some having reservations on the use of smoke screens and indoor residual insecticide sprays to prevent mosquitobites. Considering that the nets are expected tobe effective for three years or more years, it is reasonable to conclude that the nets were effective in preventing mosquito bites based on the knock-down and exposure mortality results obtained during this study.

An epidemiological overview of malaria in Bangladesh

Bangladesh is one of the four major malaria-endemic countries in South-East Asia having approximately 34% of its population at risk of malaria. This paper aims at providing an overview of the malaria situation in this country. Relevant information was retrieved from published articles and reports in PubMed and Google Scholar. Malaria in Bangladesh is concentrated in 13 districts with a prevalence ranging between 3.1% and 36%, and is mostly caused by Plasmodium falciparum. Geographical conditions pose a potential risk for Plasmodium knowlesi malaria. Resistance to a number of drugs previously recommended for treatment has been reported. Low socio-economic status, poor schooling and close proximity to water bodies and forest areas comprise important risk factors. Despite the significant steps in Long Lasting Insecticide Net (LLIN)/Insecticide Treated Net (ITN) coverage in Bangladesh, there are still many challenges including the extension of malaria support to the remote areas of Bangladesh, where malaria prevalence is higher, and further improvements in the field of referral system and treatment.

Use of insecticide treated net and malaria preventive education: effect on malaria parasitemia among people living with AIDS in Nigeria, a cross-sectional study

BackgroundMalaria and HIV are major causes of morbidity and mortality in sub-Saharan Africa with both diseases highly endemic in Nigeria. This study was conducted to assess the effect of long lasting insecticide treated net (ITN) use and malaria preventive education on burden of malaria parasite among people living with AIDS (PLWHA) at Osogbo southwestern Nigeria.MethodA descriptive cross-sectional study of newly recruited consenting PLWHA that were screened consecutively for malaria, those positive were treated with artemisinin combination therapy. All PLWHA were educated about malaria infection, given ITN and followed up monthly for three months when they were rescreened for malaria infection. Data collected was analyzed using descriptive and inferential statistics.ResultA total of 392 (92%) PLWHA completed the study. Mean age of the respondents was 33 ± 11.6 years. They were 120 (31%) males and 272 (69%) females. Majority (80%) were married, over 33% completed secondary education while 21% had tertiary education. Most were traders (40%) and artisans (25%). About 60% had Plasmodium falciparum malaria parasitemia at baseline which drastically reduced to 5% at three months with ITN use and malaria prevention education.ConclusionMalaria is a major preventable condition among PLWHA. Preventive education and ITN use reduced malaria parasite burden among this population.

A systematic review of mosquito coils and passive emanators: defining recommendations for spatial repellency testing methodologies

Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS), long lasting insecticide treated nets (LLINs) and insecticide treated materials (ITMs). PubMed, (National Centre for Biotechnology Information (NCBI), U.S. National Library of Medicine, NIH), MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words “Mosquito coils” “Mosquito emanators” and “Spatial repellents”. It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose–response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP), which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control.

Decreased proportions of indoor feeding and endophily in Anopheles gambiae s.l. populations following the indoor residual spraying and insecticide-treated net interventions in Benin (West Africa)

BackgroundIn many parts of Africa as in Benin, the main strategies of vector control are based on the scaling-up of Long Lasting Insecticide Treated Nets (LLITNs) and indoor residual spraying (IRS). The need to understand the biological implications of IRS in large scale and full coverage of LLITNs is paramount. It is in this context that the present study was conducted. It aims to evaluate the effect of a large scale IRS using a non-pyrethroid insecticide and full coverage of deltamethrin treated nets on the behavior of An. gambiae s.l. in the intervention areas compared to untreated areas used as controls.MethodsMosquitoes were collected using human landing catches, pyrethrum spray catches and window exit traps to assess reduction of entry rate, endophily rate, endophagy rate and overall mortality rate in natural populations of An. gambiae s.l. before IRS and LLITNs intervention (2007) and after in 2008 and 2010.ResultsIn the IRS arm, endophily rate was 67.13% before intervention and 4.5% after intervention, whereas in the control arm it was stable at 51.67% (P > 0 .05). In the LLITN arm endophily rates also decreased after intervention. After the IRS, no gravid mosquitoes were collected from all treated localities, but LLITN performance was not that spectacular. The proportion of mosquitoes biting indoors in the IRS arm decreased from 67.09% before intervention to 42.85% after intervention, compared to a low but significant decrease (71.31% to 57. 46%) in the LLITN arm.The use of vector control tools and behavior of the host would be the main factors that modify the behavior of taking a human blood meal observed on An. gambiae s.l. inside human dwellings.ConclusionThe impact on the behavior of An. gambiae s.l. observed with the bendiocarb used in IRS was highly effective compared with the free distribution of LLITNs in terms of mortality and the decrease of proportions of indoor feeding. Despite this efficacy, there is a need for complementary tools and research of alternative strategy oriented on effective health education, and the use of powerful tools such as IRS, LLITNs, larviciding and repellents.

Maintaining effective mass drug administration for lymphatic filariasis through in-process monitoring in Sierra Leone

BackgroundSince 2007 Sierra Leone has conducted mass drug administration (MDA) for the elimination of lymphatic filariasis (LF) implemented by unpaid community health volunteers (CHVs). Other health campaigns such as Mother and Child Health Weeks (MCHW) pay for services to be implemented at community level and these persons are then known as community health workers (CHWs). In 2010, the LF MDA in the 12 districts of the Southern, Northern and Eastern Provinces un-expectantly coincided with universal distribution of Long Lasting Insecticide Treated Nets (LLITNs) during the MCHW. In-process monitoring of LF MDA was performed to ensure effective coverage was attained in hard to reach sites (HTR) in both urban and rural locations where vulnerable populations reside.MethodsIndependent monitors interviewed individuals eligible for LF MDA and tallied those who recalled having taken ivermectin and albendazole, calculated program coverage and reported results daily by phone. Monitoring of coverage in HTR sites in the 4 most rapidly urbanizing towns was performed after 4 weeks of LF MDA and again after 8 weeks throughout all 12 districts. End process monitoring was performed in randomly selected HTR sites not previously sampled throughout all 12 districts and compared to coverage calculated from the pre-MDA census and reported treatments.ResultsOnly one town had reached effective program coverage (≥80%) after 4 weeks following which CHWs were recruited for LF MDA in all district headquarter towns. After 8 weeks only 4 of 12 districts had reached effective coverage so LF MDA was extended for a further month in all districts. By 12 weeks effective program coverage had been reached in all districts except Port Loko and there was no significant difference between those interviewed in communities versus households or by sex. Effective epidemiological coverage (≥65%) was reported in all districts and overall was significantly higher in males versus females.ConclusionsThe challenges to LF MDA included the late delivery in country of ivermectin, the availability and motivation of unpaid CHVs, concurrent LLITN distribution and the MCHW, remuneration for CHWs, rapid urbanization and employment seeking population migrations. 'In process' monitoring ensured modifications of LF MDA were made in a timely manner to ensure effective coverage was finally attained even in HTR locations.

Bioassay evaluation on the efficacy of α–cypermethrin impregnated into long lasting insecticide treated nets using Anopheles stephensi

ObjectiveTo evaluate the bioefficacy of α-cypermethrin impregnated into long lasting insecticide treated nets (LLITNs-INTERCEPTOR®) against main malaria vector, Anopheles stephensi (An. stephensi). MethodsThe effectiveness of bed net impregnated with α-cypermethrin (INTERCEPTOR®) with washing was evaluated. The washing procedure and bioassay tests were carried out according to the WHO-recommended methods. Malaria vector, An. stephensi was exposed to impregnated bed net for three minutes and then mortality measured after 24 h recovery period. Knockdown was also measured according to the logarithmic times. ResultsResult of cone bioassay method showed that bioefficacy of α-cypermethrin decreased from 100% in unwashed to 15% in 20 washes. KT50 was measure as one minute in one wash and increased to 40 min in 20 washes. DiscussionFindings of this study provide guideline for malaria vector control authorities and people using pyrethroid-impregnated bed nets.