Bed Net Coverage Research Articles

Coverage, use and maintenance of bed nets and related influence factors in Kachin Special Region II, northeastern Myanmar.

BackgroundMyanmar is one of the 31 highest burden malaria countries worldwide. Scaling up the appropriate use of insecticide-treated nets (ITNs) is a national policy for malaria prevention and control. However, the data on use, influencing factors and maintenance of bed nets is still lack among the population in Kachin Special Region II (KR2), Northeastern Myanmar.MethodsThe study combined a quantitative household questionnaire survey and qualitative direct observation of households. A Chi-squared test was used to compare the percentages of ownership, coverage, and rates of use of bed nets. Additionally, multivariate logistic regression analysis (MVLRA) was used to analyse factors that influence the use of bed nets. Finally, covariance compared the mean calibrated hole indexes (MCHI) across potential influence variables.ResultsThe bed net to person ratio was 1:1.96 (i.e., more than one net for every two people). The long-lasting insecticidal net (LLIN) to person ratio was 1: 2.52. Also, the percentage of households that owned at least one bed net was 99.7 % (666/688). Some 3262 (97.3 %) residents slept under bed nets the prior night, 2551 (76.1 %) of which slept under ITNs/LLINs the prior night (SUITNPN). The poorest families, those with thatched roofing, those who use agriculture as their main source of family income, household heads who knew that mosquitoes transmit malaria and those who used bed nets to prevent malaria, were significantly more likely to be in the SUITNPN group. However, residents in lowlands, and foothills were significantly less likely to be SUITNPNs. Finally, head of household attitude towards fixing bed nets influenced MCHI (F = 8.09, P = 0.0046).ConclusionsThe coverage and usage rates of bed nets were high, especially among children, and pregnant women. Family wealth index, geographical zones, household roofing, source of family income, household head’s knowledge of malaria transmission and of using bed nets as tools for malaria prevention are all independent factors which influence use of ITNs/LLINs in KR2. Maintaining high coverage, and use rate of bed nets should be a priority for the war-torn population of KR2 to ensure equity and human rights.

Baseline malaria vector transmission dynamics in communities in Ahafo mining area in Ghana.

BackgroundMalaria vector dynamics are relevant prior to commencement of mining activities. A baseline entomology survey was conducted in Asutifi and Tano (referred to as Ahafo) in the Brong-Ahafo geo-political region of Ghana during preparatory stages for mining by Newmont Ghana Gold Limited.MethodsBetween November 2006 and August 2007, eight Centre for Disease Control light traps were set daily (Monday-Friday) to collect mosquitoes. Traps were hanged in rooms that were selected from a pool of 1,100 randomly selected houses. Types of materials used in construction of houses were recorded and mosquito prevention measures were assessed from occupants.ResultsA total of 5,393 mosquitoes were caught that comprised Anopheles gambiae (64.8%), Anopheles funestus (4.2%), as well as Culicines, comprising of Culex (30.4%) and Aedes species (0.6%). The entomological inoculation rate in Asutifi (279 infective bites/person/month) and Tano (487 infective bites/person/month) demonstrate relatively high malaria transmission in Ahafo. The presence or absence of Anopheles vectors in rooms was influenced by the type of roofing material (OR 2.33, 95%CI: 1.29-4.22, p = 0.01) as well as the presence of eaves gaps (OR 1.80, 95%CI: 1.37-2.37, p < 0.01). It was also associated with bed net availability in the room (OR 1.39, 95%CI: 1.08-1.80, p = 0.01). Over 80% of the houses were roofed with corrugated zinc sheets. Over 60% of the houses in Ahafo had no eaves gaps to give access to mosquito entry and exit into rooms and mosquito bed net coverage was over 50%. Other measures used in preventing mosquito bites included; coil (22.1%), insecticide spray (9.4%), repellent cream (4.0%) and smoky fires (1.1%), contributed minimally to individual mosquito preventive measures in impact areas. Similarly, levels of protection; coil (16.9%), insecticide spray (2.8%) and repellent cream (0.3%) for the non-impact areas, depict low individual prevention measures.ConclusionsThe survey identified areas where intensified vector control activities would be beneficial. It also demonstrates that transmission in Asutifi and Tano is high even before the commencement of mining operations. This study serves as baseline information to assess impact of mining activities in relation to future vector control interventions.

Fine resolution mapping of population age-structures for health and development applications.

The age-group composition of populations varies considerably across the world, and obtaining accurate, spatially detailed estimates of numbers of children under 5 years is important in designing vaccination strategies, educational planning or maternal healthcare delivery. Traditionally, such estimates are derived from population censuses, but these can often be unreliable, outdated and of coarse resolution for resource-poor settings. Focusing on Nigeria, we use nationally representative household surveys and their cluster locations to predict the proportion of the under-five population in 1 × 1 km using a Bayesian hierarchical spatio-temporal model. Results showed that land cover, travel time to major settlements, night-time lights and vegetation index were good predictors and that accounting for fine-scale variation, rather than assuming a uniform proportion of under 5 year olds can result in significant differences in health metrics. The largest gaps in estimated bednet and vaccination coverage were in Kano, Katsina and Jigawa. Geolocated household surveys are a valuable resource for providing detailed, contemporary and regularly updated population age-structure data in the absence of recent census data. By combining these with covariate layers, age-structure maps of unprecedented detail can be produced to guide the targeting of interventions in resource-poor settings.

The use of mediation analysis to assess the effects of a behaviour change communication strategy on bed net ideation and household universal coverage in Tanzania.

BackgroundSBCC campaigns are designed to act on cognitive, social and emotional factors at the individual or community level. The combination of these factors, referred to as ‘ideation’, play a role in determining behaviour by reinforcing and confirming decisions about a particular health topic. This study introduces ideation theory and mediation analysis as a way to evaluate the impact of a malaria SBCC campaign in Tanzania, to determine whether exposure to a communication programme influenced universal coverage through mediating ideational variables.MethodsA household survey in three districts where community change agents (CCAs) were active was conducted to collect information on ITN use, number of ITNs in the household, and perceptions about ITN use and ownership. Variables relating to attitudes and beliefs were combined to make ‘net ideation’. Using an ideational framework, a mediation analysis was conducted to see the impact exposure to a CCA only, mass media and community (M & C) messaging only, or exposure to both, had on household universal coverage, through the mediating variable net ideation.ResultsAll three levels of exposure (CCA, M & C messaging, or exposure to both) were significantly associated with increased net ideation (CCA: 0.283, 95% CI: 0.136-0.429, p-value: <0.001; M & C: 0.128, 95% CI: 0.032-0.334, p-value: 0.018; both: 0.376, 95% CI: 0.170-0.580, p-value: <0.001). Net ideation also significantly increased the odds of having universal coverage (CCAOR: 1.265, 95% CI: 1.118-1.433, p-value: <0.001; M & COR: 1.264, 95% CI: 1.117-1.432, p-value: <0.001, bothOR: 1.260, 95% CI: 1.114-1.428, p-value: <0.001). There were no significant direct effects between any exposure and universal coverage when controlling for net ideation.ConclusionsThe results of this study indicate that mediation analysis is an applicable new tool to assess SBCC campaigns. Ideation as a mediator of the effects of communication exposure on household universal coverage has implications for designing SBCC to support both mass and continuous distribution efforts, since both heavily rely on consumer participation to obtain and maintain ITNs. Such systems can be strengthened by SBCC programming, generating demand through improving social norms about net ownership and use, perceived benefits of nets, and other behavioural constructs.

Households with Insufficient Bednets in a Village with Sufficient Bednets: Evaluation of Household Bednet Coverage Using Bednet Distribution Index in Xepon District, Lao PDR.

In Lao PDR, the National Malaria Control Program (NMCP) evaluates bednet coverage, often at the village level, using a coverage target of one net per 2.5 (or fewer) persons in a given population. However, in villages that meet the target, not all households necessarily meet the target or utilize all available bednets. This study explored households that fell short of the target and household utilization of bednets in villages that met the target of bednet coverage set by the NMCP. The person per net ratio (PPNR), which is defined as the population divided by the number of available bednets in a household/village, was used to determine whether a household/village met the NMCP target. Using a household survey, we collected and analyzed the data of 635 households in 17 villages in Xepon district in 2012. Households that fell short of the target (households with a PPNR of > 2.5 or no bednet) existed in every village. The proportion of these households differed greatly among the villages, ranging from 3.4–50%, with some households falling far short. Of the 635 households, 275 (43.5%) had at least one bednet that was not being used on the night preceding the survey and 131 (20.6%) had at least two. In conclusion, in villages that met the NMCP target, a considerable number of households fell short of the target, and the available bednets were not fully utilized in many of the surveyed households.

Quantifying the impact of decay in bed-net efficacy on malaria transmission

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 in 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 R0, 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 R0 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.

Global, regional, and national incidence and mortality for HIV, tuberculosis, and malaria during 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013

The Millennium Declaration in 2000 brought special global attention to HIV, tuberculosis, and malaria through the formulation of Millennium Development Goal (MDG) 6. The Global Burden of Disease 2013 study provides a consistent and comprehensive approach to disease estimation for between 1990 and 2013, and an opportunity to assess whether accelerated progress has occured since the Millennium Declaration. To estimate incidence and mortality for HIV, we used the UNAIDS Spectrum model appropriately modified based on a systematic review of available studies of mortality with and without antiretroviral therapy (ART). For concentrated epidemics, we calibrated Spectrum models to fit vital registration data corrected for misclassification of HIV deaths. In generalised epidemics, we minimised a loss function to select epidemic curves most consistent with prevalence data and demographic data for all-cause mortality. We analysed counterfactual scenarios for HIV to assess years of life saved through prevention of mother-to-child transmission (PMTCT) and ART. For tuberculosis, we analysed vital registration and verbal autopsy data to estimate mortality using cause of death ensemble modelling. We analysed data for corrected case-notifications, expert opinions on the case-detection rate, prevalence surveys, and estimated cause-specific mortality using Bayesian meta-regression to generate consistent trends in all parameters. We analysed malaria mortality and incidence using an updated cause of death database, a systematic analysis of verbal autopsy validation studies for malaria, and recent studies (2010-13) of incidence, drug resistance, and coverage of insecticide-treated bednets. Globally in 2013, there were 1·8 million new HIV infections (95% uncertainty interval 1·7 million to 2·1 million), 29·2 million prevalent HIV cases (28·1 to 31·7), and 1·3 million HIV deaths (1·3 to 1·5). At the peak of the epidemic in 2005, HIV caused 1·7 million deaths (1·6 million to 1·9 million). Concentrated epidemics in Latin America and eastern Europe are substantially smaller than previously estimated. Through interventions including PMTCT and ART, 19·1 million life-years (16·6 million to 21·5 million) have been saved, 70·3% (65·4 to 76·1) in developing countries. From 2000 to 2011, the ratio of development assistance for health for HIV to years of life saved through intervention was US$4498 in developing countries. Including in HIV-positive individuals, all-form tuberculosis incidence was 7·5 million (7·4 million to 7·7 million), prevalence was 11·9 million (11·6 million to 12·2 million), and number of deaths was 1·4 million (1·3 million to 1·5 million) in 2013. In the same year and in only individuals who were HIV-negative, all-form tuberculosis incidence was 7·1 million (6·9 million to 7·3 million), prevalence was 11·2 million (10·8 million to 11·6 million), and number of deaths was 1·3 million (1·2 million to 1·4 million). Annualised rates of change (ARC) for incidence, prevalence, and death became negative after 2000. Tuberculosis in HIV-negative individuals disproportionately occurs in men and boys (versus women and girls); 64·0% of cases (63·6 to 64·3) and 64·7% of deaths (60·8 to 70·3). Globally, malaria cases and deaths grew rapidly from 1990 reaching a peak of 232 million cases (143 million to 387 million) in 2003 and 1·2 million deaths (1·1 million to 1·4 million) in 2004. Since 2004, child deaths from malaria in sub-Saharan Africa have decreased by 31·5% (15·7 to 44·1). Outside of Africa, malaria mortality has been steadily decreasing since 1990. Our estimates of the number of people living with HIV are 18·7% smaller than UNAIDS's estimates in 2012. The number of people living with malaria is larger than estimated by WHO. The number of people living with HIV, tuberculosis, or malaria have all decreased since 2000. At the global level, upward trends for malaria and HIV deaths have been reversed and declines in tuberculosis deaths have accelerated. 101 countries (74 of which are developing) still have increasing HIV incidence. Substantial progress since the Millennium Declaration is an encouraging sign of the effect of global action. Bill & Melinda Gates Foundation.

Challenges in universal coverage and utilization of insecticide-treated bed nets in migrant plantation workers in Myanmar.

BackgroundHigh coverage of the bed nets can reduce mortality and morbidity of mosquito-borne diseases including malaria. Although the migrant workers are at high risk of malaria, there are many hidden challenges in universal coverage and utilization of the insecticide-treated nets (ITNs) in this populations.MethodsCross sectional study was conducted in 170 migrant workers in palm oil plantation sites in Tanintharyi Region and 175 in rubber plantation sites in Mon State. A multistage stratified cluster sampling was applied to select the participants. During household visit, face-to-face interviews using structured pre-coded, pre tested questionnaires and direct observation on installation of the bed nets was conducted. Two focus group discussions in each site were done by sample stratified purposive sampling method mainly focused on effective utilization of bed nets.ResultsAmong them, 332 (96.2%) had a bed net and 284 (82.3%) had an ITN, while 204 (59.1%) had unused extranets. Among the ITNs users, 28.9% reported problems including insecticide smell (56.9%), dizziness (20.2%), headache (12.8%) and itchiness (9.2%). More than 75% received ITNs from health authorities and NGOs free-of-charge. More than 70% wanted to buy a net but they were unaffordable for 64% of them. On observation, only five families could show no bed net, but 80% showed 1–3 ITNs. Consistent utilization in all seasons was noted in 189 (53.1%), that was higher in palm oil plantation than rubber plantation workers (p = 0.0001) due to the nature of the work at night. Perceived malaria risk was also significantly higher ITNs consistent users than non-users (p = 0.0004) and better willingness to buy an ITN by themselves (p = 0.0005). They said that effectiveness of the ITNs was reduced after 6 months and 2–3 times washing. They wished to receive more durable smooth nets with small holes in lace. Misuses of the ITNs such as use the nets for animals and fishing, were also noted.ConclusionThere should be efforts to improve effective utilization of ITNs by continuous mass free distribution, durability monitoring, surveillance of insecticide resistance of the vector and behaviour change interventions in migrant plantation workers.

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

BackgroundUniversal 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 <five years was carried out, prior to a planned fill-in campaign to achieve universal LLIN coverage. This survey was conducted after the targeted distribution in central Uganda to assess progress in LLIN ownership and usage among children <five years.MethodsA two-stage, cluster-sample, cross-sectional household survey was carried out in early 2011 in Central region districts surveyed during the 2009 Malaria Indicator Survey (MIS). In the first sampling stage, 30 enumeration areas (EAs) were selected and all households were enumerated. Within each sampled EA, 20 households were randomly selected for interview using two questionnaires: a household questionnaire and a woman’s questionnaire for all women aged 15-49 years, both modified from the MIS.ResultsWhen compared to 2009 MIS results, household ownership of at least one LLIN increased by 47%, from 22 to 69% after the targeted campaign. LLIN use among children <five years increased by 40%, from 11 to 51%. Households with a child <six years old at the time of the survey, a proxy for those targeted, were significantly more likely to have received a campaign bed 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%.ConclusionsThe first phase of the campaign led to substantial increases in both LLIN ownership and equitable use among children <five years in the Central region. However, access to an LLIN within the household was still low after the first phase of the campaign, indicating the need for the universal fill-in campaign.

Impacts of insecticide treated bed nets on Anopheles gambiae s.l. populations in Mbita district and Suba district, Western Kenya

BackgroundAbundance and species composition of sympatric malaria vector species are the important factors governing transmission intensity. A widespread insecticidal bed net coverage may replace endophagic species with exophagic species. However, unique local environments also influence a vector population. This study examined the impacts of insecticidal bed nets on An. gambiae s.l populations in Mbita District and Suba District.MethodsThe species compositions of An. gambiae s.l. larvae were compared between 1997, 2009 and 2010 and between geographical areas. The abundance and species composition of An. gambiae s.l. females resting indoors were compared between 1999, 2008 and 2010 and between geographical areas. Bed net coverage was also examined temporally and spatially, and its relationships with vector abundance and species composition were examined.ResultsThe relative abundance of An. gambiae s.s. larvae was 31.4% in 1997, decreasing to 7.5% in 2008 and 0.3% in 2010. The density of indoor resting An. gambiae s.l. females decreased by nearly 95%, and the relative abundance of An. gambiae s.s. females decreased from 90.6% to 60.7% and 72.4% in 2008 and 2010, respectively. However, the species composition of indoor resting An. gambiae s.l. females changed little in the island villages, and An. gambiae s.s. remained dominant in the western part of the study area. The density of house resting females was negatively associated with the number of bed nets in a retrospective analysis, but the effect of bed nets on species composition was not significant in both retrospective and cross-sectional analyses.ConclusionAn increase in bed net coverage does not necessarily replace endophilic species with exophilic species. The effect of bed nets on An. gambiae s.l. populations varies spatially, and locally unique environments are likely to influence the species composition.

An adjusted bed net coverage indicator with estimations for 23 African countries

BackgroundMany studies have assessed the level of bed net coverage in populations at risk of malaria infection. These revealed large variations in bed net use across countries, regions and social strata. Such studies are often aimed at identifying populations with low access to bed nets that should be prioritized in future interventions. However, often spatial differences in malaria endemicity are not taken into account. By ignoring variability in malaria endemicity, these studies prioritize populations with little access to bed nets, even if these happen to live in low endemicity areas. Conversely, populations living in regions with high malaria endemicity will receive a lower priority once a seizable proportion is protected by bed nets. Adequately assigning priorities requires accounting for both the current level of bed net coverage and the local malaria endemicity. Indeed, as shown here for 23 African countries, there is no correlation between the level of bed net coverage and the level of malaria endemicity in a region. Therefore, the need for future interventions can not be assessed based on current bed net coverage alone. This paper proposes the Adjusted Bed net Coverage (ABC) statistic as a measure taking into account both local malaria endemicity and the level of bed net coverage. The measure allows setting priorities for future interventions taking into account both local malaria endemicity and bed net coverage.MethodsA mathematical formulation of the ABC as a weighted difference of bed net coverage and malaria endemicity is presented. The formulation is parameterized based on a model of malaria epidemiology (Smith et al. Trends Parasitol 25:511-516, 2009). By parameterizing the ABC based on this model, the ABC as used in this paper is proxy for the steady-state malaria burden given the current level of bed net coverage. Data on the bed net coverage in under five year olds and malaria endemicity in 23 Sub-Saharan countries is used to show that the ABC prioritizes different populations than the level of bed net coverage by itself. Data from the following countries was used: Angola, Burkina Faso, Burundi, Cameroon, Congo Democratic Republic, Ethiopia, Ghana, Guinea, Kenya, Liberia, Madagascar, Malawi, Mali, Mozambique, Namibia, Nigeria, Rwanda, Senegal, Sierra Leone, Tanzania, Uganda, Zambia and Zimbabwe. The priority order given by the ABC and the bed net coverage are compared at the countries’ level, the first level administrative divisions and for five different wealth quintiles.ResultsBoth at national level and at the level of the administrative divisions the ABC suggests a different priority order for selecting countries and divisions for future interventions. When taking into account malaria endemicity, measures assessing equality in access to bed nets across wealth quintiles, such as slopes of inequality, are prone to change. This suggests that when assessing inequality in access to bed nets one should take into account the local malaria endemicity for populations from different wealth quintiles.ConclusionAccounting for malaria endemicity highlights different countries, regions and socio-economic strata for future intervention than the bed net coverage by itself. Therefore, care should be taken to factor out any effects of local malaria endemicity in assessing bed net coverage and in prioritizing populations for further scale-up of bed net coverage. The ABC is proposed as a simple means to do this that is derived from an existing model of malaria epidemiology.

Declining burden of malaria over two decades in a rural community of Muheza district, north-eastern Tanzania

BackgroundThe recently reported declining burden of malaria in some African countries has been attributed to scaling-up of different interventions although in some areas, these changes started before implementation of major interventions. This study assessed the long-term trends of malaria burden for 20 years (1992–2012) in Magoda and for 15 years in Mpapayu village of Muheza district, north-eastern Tanzania, in relation to different interventions as well as changing national malaria control policies.MethodsRepeated cross-sectional surveys recruited individuals aged 0 – 19 years from the two villages whereby blood smears were collected for detection of malaria parasites by microscopy. Prevalence of Plasmodium falciparum infections and other indices of malaria burden (prevalence of anaemia, splenomegaly and gametocytes) were compared across the years and between the study villages. Major interventions deployed including a mobile clinic, bed nets and other research activities, and changes in national malaria control policies were also marked.ResultsIn Magoda, the prevalence of P. falciparum infections initially decreased between 1992 and 1996 (from 83.5 to 62.0%), stabilized between 1996 and 1997, and further declined to 34.4% in 2004. A temporary increase between 2004 and 2008 was followed by a progressive decline to 7.2% in 2012, which is more than 10-fold decrease since 1992. In Mpapayu (from 1998), the highest prevalence was 81.5% in 1999 and it decreased to 25% in 2004. After a slight increase in 2008, a steady decline followed, reaching <5% from 2011 onwards. Bed net usage was high in both villages from 1999 to 2004 (≥88%) but it decreased between 2008 and 2012 (range, 28% - 68%). After adjusting for the effects of bed nets, age, fever and year of study, the risk of P. falciparum infections decreased significantly by ≥97% in both villages between 1999 and 2012 (p < 0.001). The prevalence of splenomegaly (>40% to <1%) and gametocytes (23% to <1%) also decreased in both villages.Discussion and conclusionsA remarkable decline in the burden of malaria occurred between 1992 and 2012 and the initial decline (1992 – 2004) was most likely due to deployment of interventions, such as bed nets, and better services through research activities. Apart from changes of drug policies, the steady decline observed from 2008 occurred when bed net coverage was low suggesting that other factors contributed to the most recent pattern. These results suggest that continued monitoring is required to determine causes of the changing malaria epidemiology and also to monitor the progress towards maintaining low malaria transmission and reaching related millennium development goals.

Modest additive effects of integrated vector control measures on malaria prevalence and transmission in western Kenya

BackgroundThe effect of integrating vector larval intervention on malaria transmission is unknown when insecticide-treated bed-net (ITN) coverage is very high, and the optimal indicator for intervention evaluation needs to be determined when transmission is low.MethodsA post hoc assignment of intervention-control cluster design was used to assess the added effect of both indoor residual spraying (IRS) and Bacillus-based larvicides (Bti) in addition to ITN in the western Kenyan highlands in 2010 and 2011. Cross-sectional, mass parasite screenings, adult vector populations, and cohort of active case surveillance (ACS) were conducted before and after the intervention in three study sites with two- to three-paired intervention-control clusters at each site each year. The effect of larviciding, IRS, ITNs and other determinants of malaria risk was assessed by means of mixed estimating methods.ResultsAverage ITN coverage increased from 41% in 2010 to 92% in 2011 in the study sites. IRS intervention had significant added impact on reducing vector density in 2010 but the impact was modest in 2011. The effect of IRS on reducing parasite prevalence was significant in 2011 but was seasonal specific in 2010. ITN was significantly associated with parasite densities in 2010 but IRS application was significantly correlated with reduced gametocyte density in 2011. IRS application reduced about half of the clinical malaria cases in 2010 and about one-third in 2011 compare to non-intervention areas.ConclusionCompared with a similar study conducted in 2005, the efficacy of the current integrated vector control with ITN, IRS, and Bti reduced three- to five-fold despite high ITN coverage, reflecting a modest added impact on malaria transmission. Additional strategies need to be developed to further reduce malaria transmission.

A mathematical model of the impact of present and future malaria vaccines

BackgroundWith the encouraging advent of new malaria vaccine candidates, mathematical modelling of expected impacts of present and future vaccines as part of multi-intervention strategies is especially relevant.MethodsThe impact of potential malaria vaccines is presented utilizing the EMOD model, a comprehensive model of the vector life cycle coupled to a detailed mechanistic representation of intra-host parasite and immune dynamics. Values of baseline transmission and vector feeding behaviour parameters are identified, for which local elimination is enabled by layering pre-erythrocytic vaccines of various efficacies on top of high and sustained insecticide-treated net coverage. The expected reduction in clinical cases is further explored in a scenario that targets children by adding a pre-erythrocytic vaccine to the EPI programme for newborns.ResultsAt high transmission, there is a minimal reduction in clinical disease cases, as the time to infection is only slightly delayed. At lower transmission, there is an accelerating community-level protection that has subtle dependences on heterogeneities in vector behaviour, ecology, and intervention coverage. At very low transmission, the trend reverses as many children are vaccinated to prevent few cases.ConclusionsThe maximum-impact setting is one in which the impact of increasing bed net coverage has saturated, vector feeding is primarily outdoors, and transmission is just above the threshold where small perturbations from a vaccine intervention result in large community benefits.

A need for better housing to further reduce indoor malaria transmission in areas with high bed net coverage

BackgroundThe suppression of indoor malaria transmission requires additional interventions that complement the use of insecticide treated nets (ITNs) and indoor residual spraying (IRS). Previous studies have examined the impact of house structure on malaria transmission in areas of low transmission. This study was conducted in a high transmission setting and presents further evidence about the association between specific house characteristics and the abundance of endophilic malaria vectors.MethodsMosquitoes were sampled using CDC light traps from 72 randomly selected houses in two villages on a monthly basis from 2008 to 2011 in rural Southern Tanzania. Generalized linear models using Poisson distributions were used to analyze the association of house characteristics (eave gaps, wall types, roof types, number of windows, rooms and doors, window screens, house size), number of occupants and ITN usage with mean catches of malaria vectors (An.gambiae s.l. and An. funestus).ResultsA total of 36490 female An. gambiae s.l. were collected in Namwawala village and 21266 in Idete village. As for An. funestus females, 2268 were collected in Namwawala and 3398 in Idete. Individually, each house factor had a statistically significant impact (p < 0.05) on the mean catches for An. gambiae s.l. but not An. funestus. A multivariate analysis indicated that the combined absence or presence of eaves, treated or untreated bed-nets, the number of house occupants, house size, netting over windows, and roof type were significantly related (p < 0.05) to An.gambiae s.l. and An. funestus house entry in both villages.ConclusionsDespite significant reductions in vector density and malaria transmission caused by high coverage of ITNs, high numbers of host-seeking malaria vectors are still found indoors due to house designs that favour mosquito entry. In addition to ITNs and IRS, significant efforts should focus on improving house design to prevent mosquito entry and eliminate indoor malaria transmission.

Antenatal care visit attendance, intermittent preventive treatment and bed net use during pregnancy in Gabon

BackgroundThe World Health Organization (WHO) recommends that intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and insecticide treated bed nets (ITNs) must be provided during antenatal care (ANC) visits for malaria prevention during pregnancy. The aim of this study was to determine the level of ANC attendance and its relationship with IPTp-SP and bed net coverage in Gabonese pregnant women.MethodsThis was a cross-sectional survey performed in 2011 in sentinel sites for malaria: two ANC units (Melen and Owendo) and one delivery unit (CHL). A validated structured questionnaire was used to collect the following data: age, parity, history of the current pregnancy including gestational age at the interview, number of ANC visits already performed, date of first visit, use of malaria preventive measure and details on IPTp-SP administration.ResultsDuring the study, 1030 women were interviewed, 735 at their ANC visit and 295 at the delivery. Their median age was 24[20–29] years and 21.0% were primigravidae. More than 70.0% attended their first ANC visit during the second trimester. Among the 442 women who were at the end of their pregnancy, 71.5% had a correct attendance, at least four ANC visits, most frequently women with no education and older women; IPTp-SP was offered to 84.1% of them and 57.4% received at least two doses. The number of SP doses was correlated to the number of ANC visits. Bed net coverage was 59.0%, not associated with ANC attendance. Among the women with correct ANC attendance, only 49.5% had a complete IPTp-SP course associated with bed net use during pregnancy. In the site where SP administration was supervised, 80% had four ANC visits and 97.4% received a full 2-dose course of IPTp-SP.ConclusionsDespite a high level of correct ANC attendance in Gabon, the goal of 80% of women with 2-dose IPTp-SP during pregnancy is not achieved. Evaluations, training of health workers, as well as surveys from other areas of the country are needed to further measure the implementation and the impact of these strategies.

Impact of cyfluthrin (Solfac EW050) impregnated bed nets on malaria transmission in the city of Mbandjock : lessons for the nationwide distribution of long-lasting insecticidal nets (LLINs) in Cameroon

BackgroundInsecticide treated materials remain the mainstay for malaria prevention. The current study reports on the entomological impact of cyfluthrin impregnated bed nets on malaria transmission in Mbandjock, a semi urban locality in southern Cameroon. Several findings pertaining to the recent distribution of LLINs across Cameroon are discussed.MethodsMalaria transmission and vector bionomics were monitored before and after impregnated net coverage. Bed nets were distributed in Mbandjock, whereas the locality of Nkoteng was free of bed nets during the entire study period. January to June 1997 represented the period before bed net coverage and September 1997 to September 1998 was the period after bed net coverage. Adult mosquitoes were collected by human landing catches. Mosquito genus and species were identified with morphological and molecular diagnostic tools. Anopheline salivary glands and ovaries were dissected to determine female infectious status and parity rates respectively.ResultsA total of 6959 anophelines corresponding to 6029 in Mbandjock and 930 in Nkoteng were collected in the course of the study. Seven species were recorded in both cities : Anopheles coustani, An. funestus, An. gambiae sl, An. moucheti, An. ziemanni, An. nili and An. paludis. An. gambiae s.l. (>95% An. gambiae S molecular form) was the most abundant species representing 75.6% and 86.6% of the total anophelines caught in Mbandjock before and after bed net coverage respectively. The human biting rate (HBR) in Mbandjock decreased from 17 bites/human/night before bed net coverage to less than 4 bites/human/night during the first 7 months following impregnated bed net coverage. A significant decrease of mosquito parity rate was recorded when comparing the period before (52%) and after (46.5%) bed net distribution. The average infection rate of malaria vectors significantly decreased from 5.3% before to 1.8% after bed net coverage (p < 0.0001). The entomological inoculation rate in Mbandjock was reduced by 74% varying from 124.1 infected bites/human/year before bed net distribution, to 32.5 infected bites/human/year after bed net coverage. All entomological indexes were relatively stable in Nkoteng and no reduction of malaria transmission was recorded in this locality.ConclusionThe study confirms the effectiveness of cyfluthrin impregnated nets in reducing malaria transmission. Lessons from this study could be essential to draw guidelines for the management of the recent nationwide distribution of LLINs across Cameroon in 2011.

Geographical Factors Affecting Bed Net Ownership, a Tool for the Elimination of Anopheles-Transmitted Lymphatic Filariasis in Hard-to-Reach Communities

Vector control, including the use of bed nets, is recommended as a possible strategy for eliminating lymphatic filariasis (LF) in post-conflict countries such as the Democratic Republic of Congo (DRC). This study examined the geographical factors that influence bed net ownership in DRC in order to identify hard-to-reach communities that need to be better targeted. In particular, urban/rural differences and the influence of population density, proximity to cities and health facilities, plus access to major transport networks were investigated. Demographic and Health Survey geo-referenced cluster level data were used to map bed net coverage (proportion of households with at least one of any type of bed net or at least one insecticide-treated net (ITN)), and ITN density (ITNs per person) for 260 clusters. Bivariate and multiple logistic or Poisson regression analyses were used to determine significant relationships. Overall, bed net (30%) and ITN (9%) coverage were very low with significant differences found between urban and rural clusters. In rural clusters, ITN coverage/density was positively correlated with population density (r = 0.25, 0.27 respectively, p<0.01), and negatively with the distance to the two largest cities, Kinshasa or Lubumbashi (r = −0.28, −0.30 respectively, p<0.0001). Further, ownership was significantly negatively correlated with distance to primary national roads and railways (all three measures), distance to main rivers (any bed net only) and distance to the nearest health facility (ITNs only). Logistic and Poisson regression models fitted to the rural cluster data indicated that, after controlling for measured covariates, ownership levels in the Bas-Congo province close to Kinshasa were much larger than that of other provinces. This was most noticeable when considering ITN coverage (odds ratio: 5.3, 95% CI: 3.67–7.70). This analysis provides key insights into the barriers of bed net ownership, which will help inform both LF and malaria bed net distribution campaigns as part of an integrated vector management strategy.

Studies on Knowledge, Attitude and Practices in Malaria Endemic Tribal Areas of Bihar and Jharkhand, India

Knowledge, attitude and practices (KAP) in tribal and rural population of four malaria endemic districts in Bihar and Jharkhand states in respect of malaria were studied. The results of this study showed that most of the respondents (92.5%) were known to malaria and aware of the common symptoms of malaria (82.4%) like fever, shivering and cold etc. However, considerable (28.4%) number was not aware that malaria is caused by mosquito bite. Knowledge about resting sites of malaria vectors was good as 48.8% respondents reported cattle sheds, 32.4% respondents reported human dwellings and 15% damp dark places. Most of the respondents were not aware of mosquito breeding associated with clean water bodies. The attitude of respondents towards vector control programme was very poor as 67.8% respondents lost faith in DDT spraying because of its ineffectiveness in controlling the mosquito nuisance. More than two third of respondents were regular user of treated bed nets and it was considered the best option for protection from malaria and mosquito bite. Proper health education is warranted to increase community knowledge and awareness in local language at the individual and community level to promote malaria prevention, to enhance the IRS coverage and use of bed nets for successful malaria control. Insecticide spray may be more acceptable to the communities, if appropriate and more effective insecticide is being used.

Beyond buzzing: mosquito watching stimulates malaria bednet use—a household-based cluster-randomized controlled assessor blind educational trial

Malaria remains a severe health problem in Sub-Saharan Africa, with approximately one million deaths and 365 million cases each year. In terms of malaria control, insecticide-treated bednets are an effective tool, and many organizations have distributed free or highly subsidized bednets in malaria endemic areas. Nevertheless, some recipients do not use bednets because of social, environmental or cultural factors. Making vulnerable populations aware of the presence of mosquitoes may improve bednet use among people owning but not using a bednet. We hypothesized that showing freshly collected mosquitoes from the vicinity could improve bednet use in households owning but not using bednets. To test this hypothesis, we applied a household-based cluster-randomized controlled assessor blind educational trial. Indirect observation of mosquitoes, via educational leaflets, produced no change in bednet use, while showing freshly captured mosquitoes led to a 13-fold increase in bednet use. Our results suggest that direct observation of freshly captured mosquitoes can encourage bednet use and may potentially improve effective bednet coverage for malaria control and elimination.