Untreated Nets Research Articles

How equitable is bed net ownership and utilisation in Tanzania? A practical application of the principles of horizontal and vertical equity

BackgroundStudies show that the burden of malaria remains huge particularly in low-income settings. Although effective malaria control measures such as insecticide-treated nets (ITNs) have been promoted, relatively little is known about their equity dimension. Understanding variations in their use in low-income settings is important for scaling up malaria control programmes particularly ITNs. The objective of this paper is to measure the extent and causes of inequalities in the ownership and utilisation of bed nets across socioeconomic groups (SEGs) and age groups in Tanga District, north-eastern Tanzania.MethodsA questionnaire was administered to heads of 1,603 households from rural and urban areas. Households were categorized into SEGs using both an asset-based wealth index and education level of the household head. Concentration indices and regression-based measures of inequality were computed to analyse both vertical and horizontal inequalities in ownership and utilisation of bed nets. Focus Group Discussions (FGDs) were used to explore community perspectives on the causes of inequalities.ResultsUse of ITNs remained appallingly low compared to the RBM target of 80% coverage. Inequalities in ownership of ITNs and all nets combined were significantly pro-rich and were much more pronounced in rural areas. FGDs revealed that lack of money was the key factor for not using ITNs followed by negative perceptions about the effect of insecticides on the health of users. Household SES, living within the urban areas and being under-five were positively associated with bed net ownership and/or utilisation.ConclusionThe results highlight the need for mass distribution of ITN; a community-wide programme to treat all untreated nets and to promote the use of Long-Lasting Insecticidal nets (LLINs) or longer-lasting treatment of nets. The rural population and under-fives should be targeted through highly subsidised schemes and mass distribution of free nets. Public campaigns are also needed to encourage people to use treated nets and mitigate negative perceptions about insecticides.

Field Evaluation of Olyset Nets: A Long-Lasting Insecticidal Net Against Malaria VectorsAnopheles culicifaciesandAnopheles fluviatilisin a Hyperendemic Tribal Area of Orissa, India

A village-scale trial was conducted on the efficacy of Olyset nets: a long-lasting insecticidal net (LLIN) factory treated with 2% wt:wt permethrin against malaria vectors Anopheles culicifacies Giles and Anopheles fluviatilis James, 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 clusters. Baseline studies showed that both vector species were 100% susceptible to permethrin. Results of wash resistance and bioefficacy of Olyset nets showed 100% mortality in An. culicifacies up to 11 washings, whereas 100% mortality was observed in An. fluviatilis even after 20 washings. The median knock-down time for these species ranged between 4.55-6.00 and 4.45-5.45 min, respectively, during 1 yr of intervention. In the Olyset net study area, there was a significant reduction of 80.6, 94.1, and 76.7% in the entry rate of An. culicifacies, An. fluviatilis, and other anopheline species, respectively, with an overall reduction of 63.5% in total mosquitoes. Floor sheet collections in houses with Olyset nets indicated 39% immediate mortality in total mosquitoes. The overall feeding success rate of mosquitoes in the trial village was only 18.0% in comparison to 44.2 and 79.1% in villages with untreated nets and no nets, respectively. A significant reduction was also recorded in parity rate and human blood index of vector species in the Olyset net area. This study showed that Olyset nets are an effective personal protection tool that can be used in a community-based intervention program.

Household possession, use and non-use of treated or untreated mosquito nets in two ecologically diverse regions of Nigeria – Niger Delta and Sahel Savannah

BackgroundCurrent use of treated mosquito nets for the prevention of malaria falls short of what is expected in sub-Saharan Africa (SSA), though research within the continent has indicated that the use of these commodities can reduce malaria morbidity by 50% and malaria mortality by 20%. Governments in sub-Sahara Africa are investing substantially in scaling-up treated mosquito net coverage for impact. However, certain significant factors still prevent the use of the treated mosquito nets, even among those who possess them. This survey examines household ownership as well as use and non-use of treated mosquito nets in Sahel Savannah and Niger Delta regions of Nigeria.MethodologyThis survey employed cross-sectional survey to collect data from households on coverage and use of mosquito nets, whether treated or not. Fever episodes in previous two weeks among children under the age of five were also recorded. The study took place in August 1 – 14 2007, just five months after the March distribution of treated mosquito nets, coinciding with the second raining period of the year and a time of high malaria transmission during the wet season. EPI INFO version 2003 was used in data analysis.ResultsThe survey covered 439 households with 2,521 persons including 739 under-fives, 585 women in reproductive age and 78 pregnant women in Niger Delta Region and Sahel Savannah Region. Of the 439 HHs, 232 had any mosquito nets. Significantly higher proportion of households in the Niger Delta Region had any treated or untreated mosquito nets than those in the Sahel Savannah Region. In the Niger Delta Region, the proportion of under-fives that had slept under treated nets the night before the survey exceeded those that slept under treated nets in the Sahel Savannah Region. Children under the age of five years in the Niger Delta Region were four times more likely to sleep under treated nets than those in the Sahel Savannah Region.ConclusionThis study found that despite the fact that treated nets were distributed widely across Nigeria, the use of this commodity was still very low in the Sahel Savannah region. Future campaigns should include more purposeful social and health education on the importance and advantages of the use of treated nets to save lives in the Sahel Savannah region of Nigeria.

Mosquitoes and bednets: testing the spatial positioning of insecticide on nets and the rationale behind combination insecticide treatments

The recent development of pyrethroid resistance of operational significance in Anopheles gambiae s.l. is a major threat to the control of malaria in West Africa. The so-called '2-in-1' bednet, in which the top of the net is treated with a non-pyrethroid insecticide and the sides with pyrethroid, has been proposed as a way of maintaining efficacy in the wake of such resistance. A host-seeking female Anopheles mosquito must contact both the top and sides of a '2-in-1' net, however, for such nets to be useful in resistance management. In the present study, the interaction between mosquitoes and insecticide-treated bednets (ITN) was explored by restricting the insecticide to particular surfaces of the nets (top only or sides only) and then testing these nets, untreated nets and nets treated on all their surfaces in experimental huts, under simulated field conditions. Over the 6-week trial, there was no significant difference in An. arabiensis mortality between nets treated with pyrethroid on the top only (39.2%), sides only (39.6%) and all surfaces (39.7%), thus indicating that a female An. arabiensis usually contacts both the top and sides of a bednet during its host-seeking behaviour. The data on blood-feeding indicated, however, that the insecticide used on the sides of the net may be more important in preventing mosquito biting than that on the top. These results support the rationale behind the '2-in-1' nets. Such nets may have advantages over the use of nets treated on all surfaces with a mixture of insecticides that includes a non-pyrethroid component. With the '2-in-1', the more toxic component can be deployed on the top of the net, away from human contact, while the more repellent pyrethroid can be restricted to the sides, to prevent blood-feeding. With the scaling-up of ITN coverage and the need to preserve pyrethroid efficacy, more consideration should be given to switching from pyrethroid-only nets to 'combination' nets that have been treated with a pyrethroid and another insecticide. Since the mosquitoes that act as malarial vectors may contact all surfaces of a bednet during their host-seeking, spatial heterogeneity in insecticide levels over the surface of a net may not reduce that net's overall efficacy. Nets with a rather uneven distribution of insecticide (such as those that might be produced using home-treatment insecticide kits) may therefore be no less effective, prior to washing, than nets with a more even distribution of insecticide (such as long-lasting insecticidal nets produced under factory conditions).

Spatial effects of mosquito bednets on child mortality

BackgroundInsecticide treated nets (ITN) have been proven to be an effective tool in reducing the burden of malaria. Few randomized clinical trials examined the spatial effect of ITNs on child mortality at a high coverage level, hence it is essential to better understand these effects in real-life situation with varying levels of coverage. We analyzed for the first time data from a large follow-up study in an area of high perennial malaria transmission in southern Tanzania to describe the spatial effects of bednets on all-cause child mortality.MethodsThe study was carried out between October 2001 and September 2003 in 25 villages in Kilombero Valley, southern Tanzania. Bayesian geostatistical models were fitted to assess the effect of different bednet density measures on child mortality adjusting for possible confounders.ResultsIn the multivariate model addressing potential confounding, the only measure significantly associated with child mortality was the bed net density at household level; we failed to observe additional community effect benefit from bed net coverage in the community.ConclusionIn this multiyear, 25 village assessment, despite substantial known inadequate insecticide-treatment for bed nets, the density of household bed net ownership was significantly associated with all cause child mortality reduction. The absence of community effect of bednets in our study area might be explained by (1) the small proportion of nets which are treated with insecticide, and (2) the relative homogeneity of coverage with nets in the area. To reduce malaria transmission for both users and non-users it is important to increase the ITNs and long-lasting nets coverage to at least the present untreated nets coverage.

Malaria vector control practices in an irrigated rice agro-ecosystem in central Kenya and implications for malaria control

BackgroundMalaria transmission in most agricultural ecosystems is complex and hence the need for developing a holistic malaria control strategy with adequate consideration of socio-economic factors driving transmission at community level. A cross-sectional household survey was conducted in an irrigated ecosystem with the aim of investigating vector control practices applied and factors affecting their application both at household and community level.MethodsFour villages representing the socio-economic, demographic and geographical diversity within the study area were purposefully selected. A total of 400 households were randomly sampled from the four study villages. Both semi-structured questionnaires and focus group discussions were used to gather both qualitative and quantitative data.ResultsThe results showed that malaria was perceived to be a major public health problem in the area and the role of the vector Anopheles mosquitoes in malaria transmission was generally recognized. More than 80% of respondents were aware of the major breeding sites of the vector. Reported personal protection methods applied to prevent mosquito bites included; use of treated bed nets (57%), untreated bed nets (35%), insecticide coils (21%), traditional methods such as burning of cow dung (8%), insecticide sprays (6%), and use of skin repellents (2%). However, 39% of respondents could not apply some of the known vector control methods due to unaffordability (50.5%), side effects (19.9%), perceived lack of effectiveness (16%), and lack of time to apply (2.6%). Lack of time was the main reason (56.3%) reported for non-application of environmental management practices, such as draining of stagnant water (77%) and clearing of vegetations along water canals (67%).ConclusionThe study provides relevant information necessary for the management, prevention and control of malaria in irrigated agro-ecosystems, where vectors of malaria are abundant and disease transmission is stable.

Socio-economic status is inversely related to bed net use in Gabon

BackgroundInsecticide-treated bed nets (ITNs) range among the most effective measures of malaria prophylaxis, yet their implementation level in sub-Saharan Africa is still low. The goal of this study was to investigate the influence of socio-economic factors on the use of bed nets by mothers in Gabon.MethodsA cross-sectional study was conducted completing pre-tested, interviewer-administered questionnaires exploring socioeconomic proxy measures with 397 mothers or guardians of young children. Respondents were grouped according to their socio-economic situation, using scores. The condition of the bed nets was evaluated during a home visit.ResultsSocio-economic factors of wellbeing were negatively associated with bed net use, such as living in a stone house (OR 0.26, 95% CI 0.14–0.48), running water in the house (OR 0.44, 95% CI 0.21–0.92), shower/flush toilet in the house (OR 0.39/0.34, 95% CI 0.21–0.75/0.16–0.73), ownership of a freezer (OR 0.50, 95% CI 0.26–0.96) and belonging to the highest group in the economic score (OR 0.32, 95% CI 0.15–0.67). In contrast, similar factors were positively associated with a good maintenance condition of the bed nets: higher monthly income (OR 5.64, 95% CI 2.41–13.19) and belonging to the highest group in the economic score (OR 2.55, 95% CI 1.19 – 5.45).ConclusionAmong the poorest families in Lambaréné the coverage with untreated nets (UTNs) is the highest, but the condition of these UTNs is the worst. To achieve a broad implementation of ITNs in Lambaréné, there is an urgent need for educational programmes as well as need-tailored marketing strategies for ITNs.

Prevention of lymphatic filariasis with insecticide-treated bednets in Cambodia

Potential risk factors for lymphatic filariasis (LF), including the failure to use insecticide-treated bednets (ITN), were studied in four north-eastern provinces of Cambodia, using 43 cases of LF and 248 apparently healthy controls who were matched with the cases in terms of age (+/-5 years), gender and village. The results of a univariate matched analysis indicated that lack of ITN [odds ratio (OR)=20.1; 95% confidence interval (CI)=2.2-182.4; P=0.008] and frequent overnight stays in forests or paddy fields outside the village (OR=3.6; CI=1.3-10.0; P=0.012) were the most important risk factors. In a multivariate matched analysis, frequent overnight stays outside the village combined with bednet use showed a clear dose-response relationship, with untreated nets offering significant protection during such stays but ITN offering significantly better protection. Even if villagers used ITN during such stays, they were significantly more likely to develop LF than villagers who did not travel (OR=5.0; CI=1.5-16.3; P=0.008), and if they used untreated or no nets while away they were even more likely than the non-travellers to develop the disease (OR=1413; CI=28.0-71,189; P<0.001). Taken together, these results provide further evidence for the importance of bednet use and their impregnation in the prevention of LF. At least in north-eastern Cambodia, the use of bednets and, preferably, ITN is particularly important during overnight stays outside the home village. In areas where LF is endemic, the sustained distribution of insecticide-treated bednets or hammock nets appears to be a very good idea.

An experimental hut evaluation of Olyset® nets against anopheline mosquitoes after seven years use in Tanzanian villages

BackgroundLong-lasting insecticidal nets (LLINs) are advocated by WHO for protection against malaria. Of the three brands of LLINs currently approved by WHO, Olyset® is the only one currently granted full recommendation. With this type of LLIN, the insecticide (permethrin) is incorporated into the polyethylene fibre during manufacture and diffuses from the core to the surface, thereby maintaining surface concentrations. It has not been determined for how long Olyset nets remain protective against mosquitoes in household use.MethodsExamples of Olyset nets, which had been in use in Tanzanian villages for seven years, were tested in experimental huts against naturally entering Anopheles gambiae and Anopheles funestus mosquitoes. Performance was compared with new Olyset nets, conventionally treated ITNs (either newly treated with alphacypermethrin or taken from local villages after 1.5 years of use) and untreated nets. All nets were artificially holed except for the seven-year Olyset nets, which had developed holes during prolonged domestic use.ResultsAnopheles funestus and An. gambiae in NE Tanzania are susceptible to pyrethroids. The new Olyset nets caused high mortality against An. funestus (73.9%) and An. gambiae (62.7%) in experimental huts. The seven-year Olyset nets caused 58.9% mortality against An. funestus and 40.0% mortality against An. gambiae. The freshly treated alphacypermethrin nets also caused high mortality against An. funestus (70.6%) and An. gambiae (72.0%); this decreased to 58.4% and 69.6% respectively after 1.5 years of use. The new Olyset nets inhibited blood-feeding by 40–50%. The 7 year Olyset nets showed no feeding inhibition over that shown by the untreated nets. The alphacypermethrin treated nets failed to inhibit blood-feeding after 1.5 years of use. However iHhhdn laboratory tunnel tests samples of all types of treated net including the 7 year Olyset inhibited blood-feeding by more than 95%.ConclusionAfter seven years of use Olyset nets were still strongly insecticidal. Mosquito mortality decreased by only 20–35% over this period. However, Olyset would not provide personal protection after seven years unless it was in good condition and all holes fully repaired.

Knowledge on malaria transmission and its prevention among schoolchildren in Kyela District, South Western Tanzania

A school-based study was carried out to assess the knowledge on malaria and its prevention among children in Kyela District, south-western, Tanzania in August-September 2004. A total of 400 schoolchildren (age = 10-20 years) from four schools were selected. A structured questionnaire was used to collect data on knowledge on malaria transmission, methods of prevention, source of information and use of mosquito nets. More than 85% of the respondents were knowledgeable on malaria and preventive measures. Sources of information about malaria and its control were mainly from their teachers (47.4%), print materials (21.9%), family members (20.4%), television and radio (7.3%) and medical personnel (2.2.%). The perceived best control measures were untreated nets (32.1%), treated nets (21.4%), environmental management (25.7%) and burning mosquito coils and insect repellents (20.8%). Availability of mosquito nets was relatively high (70%), but only 38% of the pupils were using insecticide treated nets (ITNs). Low ITN use was due to its unavailability (57.5%), cost (35%) and foul smell and fear of side effects (7.5%). These findings suggest schoolchildren are aware about malaria and its prevention methods, but are not well-informed of the benefits of using ITNs. More education and advocacies on use of ITNs to parents and children is needed.

Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study

BackgroundAn important advantage of pyrethroid-treated nets over untreated nets is that once nets become worn or holed a pyrethroid treatment will normally restore protection. The capacity of pyrethroids to kill or irritate any mosquito that comes into contact with the net and prevent penetration of holes or feeding through the sides are the main reasons why treated nets continue to provide protection despite their condition deteriorating over time. Pyrethroid resistance is a growing problem among Anopheline and Culicine mosquitoes in many parts of Africa. When mosquitoes become resistant the capacity of treated nets to provide protection might be diminished, particularly when holed. An experimental hut trial against pyrethroid-resistant Culex quinquefasciatus was therefore undertaken in southern Benin using a series of intact and holed nets, both untreated and treated, to assess any loss of protection as nets deteriorate with use and time.ResultsThere was loss of protection when untreated nets became holed; the proportion of mosquitoes blood feeding increased from 36.2% when nets were intact to between 59.7% and 68.5% when nets were holed to differing extents. The proportion of mosquitoes blood feeding when treated nets were intact was 29.4% which increased to 43.6–57.4% when nets were holed. The greater the number of holes the greater the loss of protection regardless of whether nets were untreated or treated. Mosquito mortality in huts with untreated nets was 12.9–13.6%; treatment induced mortality was less than 12%. The exiting rate of mosquitoes into the verandas was higher in huts with intact nets.ConclusionAs nets deteriorate with use and become increasingly holed the capacity of pyrethroid treatments to restore protection is greatly diminished against resistant Culex quinquefasciatus mosquitoes.

The effects of washing and duration of use of long-lasting insecticidal nets (PermaNets) on insecticidal effectiveness

The use of insecticide-treated nets (ITNs) is one of the most feasible weapons available for malaria control in Africa today. One of the important requirements for ITN use is regular re-treatment at an appropriate time. As a response to the low re-treatment rate when the ITN users are expected to purchase insecticide and re-treat their nets, manufacturers have developed long-lasting insecticidal nets (LLIN) that are pre-treated in the factory, and are claimed to require no further treatment during their lifespan. A study was conducted to assess the possible effects of number of washings, frequency of washing and the duration of use on the effectiveness of PermaNets, a LLIN, against mosquitoes. The study was done for 9 months at Chekereni village, Northeastern Tanzania. The LLINs and untreated control nets were distributed to villagers in three groups. Group 1 nets were used without being washed for the whole study period. Group 2 nets received one wash per month, while group 3 received two washes per month. The effectiveness was assessed by contact bioassays using World Health Organization (WHO) bioassay cones. Mosquitoes were exposed to the netting for 3 min. The knock down and mortality was scored after 3 min and 24 h, respectively. Results showed that the number and frequency of washes had no significant effect on the efficacy for up to 18 washes. Similarly, we could not detect a significant effect of duration of use and conditions of use on the efficacy for up to 9 months. PermaNets caused short-lived irritation and sneezing but appear to be well accepted by the community in which the study was conducted.

Population Preference of Net Texture prior to Bed Net Trial in Kala-Azar–Endemic Areas

Prior to a community-based efficacy trial of long-lasting insecticidal nets (LLINs) in the prevention of visceral leishmaniasis (VL; also called kala-azar), a pilot study on preference of tools was held in endemic areas of India and Nepal in September 2005.LLINs made of polyester and polyethylene were distributed to 60 participants, who used the nets sequentially for 7 d. Acceptability and preference were evaluated via indirect indicators through questionnaires at three defined time points before and after use of the LLINs and through focus group discussions (FGDs). In the latter, preferences for color and size were also assessed. Untreated bed nets were owned by 87% of the households prior to the study. All users liked textures of both LLIN types after 7 d of use, but had a slight preference for those made of polyester if they were to recommend a LLIN to relatives or friends (p<0.05), mainly because of their relatively greater softness in comparison to polyethylene LLINs. Users reported that both net types reduced mosquito bites and number of insects, including sand fly (bhusana; genus Phlebotomus), inside the house. Side effects were minor and disappeared quickly.The large-scale intervention trial considered the preferences of the study population to decide on the best tool of intervention—light-blue, rectangular, polyester LLINs of different sizes.

Delivery systems for insecticide treated and untreated mosquito nets in Africa: categorization and outcomes achieved

Coverage of insecticide-treated nets (ITNs) in sub-Saharan Africa is still low despite their proven efficacy, effectiveness and cost-effectiveness. Delivery systems for ITNs have been hotly debated, but there has been no structured approach to assessing their relative effectiveness. This paper aims to: propose a categorization of ITN and mosquito net delivery systems; classify existing systems according to this categorization; critique coverage measures reported; synthesize evidence about the levels of coverage achieved by each system; and identify current analytical gaps and future priorities. We undertook a systematic review of published papers complemented by grey literature from projects and programmes. A 4-by-3 matrix was developed of delivery sector and cost to end user. Delivery systems were placed in the matrix based on project descriptions. Coverage and equity of coverage outcomes of the identified delivery systems were assessed for consistency with standard Roll Back Malaria (RBM) coverage indicators. These were placed in the matrix for comparison of outcomes by ITN delivery category. Only 17 references with coverage data were identified, and amongst these there was variation from the RBM indicators. We identified three sets of coverage data where delivery and surveys to assess coverage of target groups were at national scale: public-free delivery in Togo; mixed-partially subsidized delivery in Malawi, and private-unsubsidized delivery in The Gambia. The highest level of household ownership was achieved through public-free delivery (62.5%), whilst use by pregnant women and by children under 5 was highest through private-unsubsidized delivery (67.2 and 67.7%, respectively). There are no comparative studies of delivery systems for ITNs from which definitive evidence can be drawn, so conclusions on the relative merits of different delivery systems and levels of subsidy cannot be made. Development of methods of attributing household-level outcomes to specific delivery systems would aid in providing this evidence base. As countries scale-up efforts to deliver ITNs, our matrix provides an analytical tool for developing a comprehensive mapping of systems and outcomes. To guide strategic decision-making, cross-country and cross-regional comparisons of the outcomes of systems are needed to facilitate an analysis of the influence of contextual factors.

A preliminary test of the protective efficacy of permethrin-treated bed nets in an area of Anopheles gambiae metabolic resistance to pyrethroids in north Cameroon

A trial of permethrin-treated nets (PTNs) versus untreated nets (UTNs) was conducted in Pitoa (north Cameroon), where the main malaria vectors, Anopheles gambiae s.l. and Anopheles arabiensis, show metabolic-based permethrin resistance. The deterrent effect of permethrin greatly reduced A. gambiae biting rate inside rooms where PTNs were installed. After 3 months of net use, malaria reinfection rate was significantly lower in children sleeping under a PTN, but no such effect was observed after 6 months. Parasitaemia was not significantly different between the two arms. These findings suggest good, although transitory, personal protection against malaria conferred by PTNs in an area of metabolic-based permethrin resistance.

EFFICACY OF PERMANET® 2.0 AGAINST ANOPHELES CULICIFACIES AND ANOPHELES STEPHENSI, MALARIA VECTORS IN INDIA

Bioefficacy of PermaNet was evaluated in both the laboratory and field against Anopheles culicifacies and An. stephensi, major malaria vectors in India. Contact bioassays were carried out after repeated washings and ring net bioassays to determine the median knockdown time of mosquitoes. Three villages were selected for the field trial: in the 1st village PermaNets were distributed, in the 2nd village untreated nets were distributed, and the 3rd village was a control. Entomological data were collected using standard procedures. The PermaNet contact bioassays showed high mortality (>80%) even after 20 washes against both the vector species. The median knockdown time of An. culicifacies and An. stephensi was 392 and 480 sec when exposed to fresh PermaNets and 472 and 986 sec when exposed to PermaNets that had been washed 20 times, respectively. PermaNets showed high efficacy in reducing the person-vector contact as evidenced by reduced person-hour density in the PermaNet village. Long-term field trials are indicated to test the impact of use of PermaNets in controlling malaria.

Deltamethrin‐impregnated bednets reduce human landing rates of sandfly vector Lutzomyia longipalpis in Amazon households

The entomological efficacy of using 25% deltamethrin EC insecticide-treated bednets (ITNs) was evaluated against the sandfly Lutzomyia longipalpis Lutz and Neiva (Diptera: Psychodidae), the principal vector of zoonotic visceral leishmaniasis (ZVL) in Latin America. A crossover field study in Amazon Brazil (Marajó Island, Pará State) demonstrated that, compared with untreated nets, the insecticide increased the barrier effect of nets by 39% (95% confidence interval [CI] 34-44%), reduced human landing rates by 80% (95% CI 62-90%) and increased the 24-h mortality rate from 0% to 98% (95% CI 93-99%) inside ITNs. The presence of an ITN also reduced the human landing rate on unprotected persons outside the net in the same room by 56% (95% CI 52-59%), and increased 24-h mortality to 68% (95% CI 62-73%) compared to 0.4% (0.1-2.0%) in untreated houses. The reduction in human landing rates in ITN rooms was associated with a doubling in the proportion of sandflies alighting on walls compared with that in untreated rooms, which was attributed to insecticide-induced excito-repellency. There was no evidence that sandflies were diverted onto unprotected hosts. Human landing catches inside houses peaked between 19.00 hours and 23.00 hours and declined steadily to zero at 02.00 hours and thereafter. House-to-house questionnaires established that only 34% of households owned at least one net (median two, range 1-8), only 20% of the population slept under a net (33% of 0-5-year-old children), and the majority (73%) of the population slept in hammocks. Combined data pertaining to sleeping times for children and sandfly activity period indicate that > 50% of sandfly bites inside houses, and substantially more outside houses, were taken before a third of children were potentially protected by a net. This study demonstrates the clear entomological efficacy of ITNs against Lu. longipalpis in this endemic region. The effectiveness of ITNs at preventing ZVL infection and disease has still to be evaluated.

Insecticide-Treated Nets for the Prevention of Malaria in Pregnancy: A Systematic Review of Randomised Controlled Trials

BackgroundProtection from malaria with insecticide-treated bednets (ITNs) during pregnancy is widely advocated, but evidence of benefit has been inconsistent. We undertook a systematic review of randomised trials.Methods and FindingsThree cluster-randomised and two individually randomised trials met the inclusion criteria; four from Africa (n = 6,418) and one from Thailand (n = 223). In Africa, ITNs compared to no nets increased mean birth weight by 55 g (95% confidence interval [CI] 21–88), reduced low birth weight by 23% (relative risk [RR] 0.77, 95% CI 0.61–0.98), and reduced miscarriages/stillbirths by 33% (RR 0.67, 0.47–0.97) in the first few pregnancies. Placental parasitaemia was reduced by 23% in all gravidae (RR 0.77, 0.66–0.90). The effects were apparent in the cluster-randomised trials and the one individually randomised trial in Africa. The trial in Thailand, which randomised individuals to ITNs or untreated nets, showed reductions in anaemia and fetal loss in all gravidae, but not reductions in clinical malaria or low birth weight.ConclusionsITNs used throughout pregnancy or from mid-pregnancy onwards have a beneficial impact on pregnancy outcome in malaria-endemic Africa in the first few pregnancies. The potential impact of ITNs in pregnant women and their newborns in malaria regions outside Africa requires further research.

The use of anitmalaria drugs and insecticide treated nets in Ile-Ife, Nigeria

The Roll Back Malaria Initiative (RBMI) is aimed at halving the malaria mortality in the year 2010 using prompt diagnosis and treatment of malaria and the use of Insecticide Treated Nets (ITNs). This is a cross sectional study of children aged 1 month to 14 years with confirmed malaria to assess the burden of malaria and to evaluate the home use of anti-malarial drugs and ITNs among children with malaria in Ile Ife, Nigeria. Of the total of 1047 children seen, 190 (18.1%) had malaria and were surveyed. Complications were present among 74 (38.9%) children and a significantly higher of the under-fives had complications (p by Fisher's exact test = 0.0018). Chloroquine was administered to 63 (67.0%) children within the first 24 hours of the illness although only 25 (26.6%) children had the correct dosage. One hundred and fifty three (80.5%) were aware of the use of untreated bed nets in preventing malaria while 38 (20.0%) and 4 (2.1%) were aware of ITNs and used ITNs respectively. The awareness of ITNs increased with increasing maternal education. Awareness of the parents about ITNs and their use are poor. Health education on appropriate antimalarial drug use and ITN use should be intensified. ITNs should be made more widely available.

Using schoolchildren's reports of bed net use monitored by schoolteachers as a proxy of community coverage in malaria endemic areas of Uganda

Community-based information on the delivery and use of health interventions is important to monitor the effectiveness of the Roll Back Malaria programme. However, community surveys to determine coverage for insecticide-treated bed nets are time-consuming and costly. We wanted to assess whether schoolchildren's reports of household ownership of a bed net and coverage among high-risk groups monitored by schoolteachers through a questionnaire could be used as a proxy of household ownership of bed net and coverage at community level, for routine monitoring of malaria control programmes. 3602 schoolchildren in 39 randomly selected schools and 2798 heads of households in 39 villages were interviewed about their use of either insecticide-treated or untreated bed nets. The overall household ownership of any kind of bed net was 35% in school surveys and 31% in household surveys (P < 0.001). Household ownership of insecticide-treated nets was 23% and 22%, respectively (P = 0.4); household ownership of untreated nets was 15% and 9%, respectively (P < 0.001). There was significant correlation between estimates of any bed net and treated net ownership based on household surveys and estimates based on school surveys (P < 0.01 for both). In areas with high school attendance rates, schoolchildren's report of bed net use monitored by schoolteachers through a questionnaire could give a good approximation of household ownership of bed net at community level with about +/-5% difference between community and school surveys. However, further operational research is required to investigate how the feasibility of large-scale implementation might be, by sending the questionnaire to the schools through routine channels and by independent handling by the school administration and teachers.