Insecticide-treated net use before and after mass distribution in a fishing community along Lake Victoria, Kenya: successes and unavoidable pitfalls

Evaluation of a financial incentive intervention on malaria prevalence among the residents in Lake Victoria basin, Kenya: study protocol for a cluster-randomized controlled trial

BACKGROUND

In the Lake Victoria basin of western Kenya, malaria remains highly endemic despite high coverage of interventions such as mass distribution of long-lasting insecticidal nets (LLIN), indoor residual spraying (IRS) programs, and improvement of availability and accessibility of rapid diagnostic tests (RDT) and artemisinin-based combination therapy (ACT) at community healthcare facilities. We hypothesize that one major cause of the residual transmission is the lack of motivation among residents for malaria prevention and early treatment.

METHODS

This study will aim to develop a demand-side policy tool to encourage local residents' active malaria prevention and early treatment-seeking behaviors. We examine the causal impact of a financial incentive intervention complemented with malaria education to residents in malaria-prone areas. A cluster-randomized controlled trial is designed to assess the effect of the financial incentive intervention on reducing malaria prevalence in residents of Suba South in Homa Bay County, Kenya. The intervention includes two components. The first component is the introduction of a financial incentive scheme tied to negative RDT results for malaria infection among the target population. This study is an attempt to promote behavioral changes in the residents by providing them with monetary incentives. The project has two different forms of incentive schemes. One is a conditional cash transfer (CCT) that offers a small reward (200 Ksh) for non-infected subjects during the follow-up survey, and the other is a lottery incentive scheme (LIS) that gives a lottery with a 10% chance of winning a large reward (2000 Ksh) instead of the small reward. The second component is a knowledge enhancement with animated tablet-based malaria educational material (EDU) developed by the research team. It complements the incentive scheme by providing the appropriate knowledge to the residents for malaria elimination. We evaluate the intervention's impact on the residents' malaria prevalence using a cluster-randomized control trial.

DISCUSSION

A policy tool to encourage active malaria prevention and early treatment to residents in Suba South, examined in this trial, may benefit other malaria-endemic counties and be incorporated as part of Kenya's national malaria elimination strategy.

TRIAL REGISTRATION

UMIN000047728. Registered on 29th July 2022.

Evaluation of the protective efficacy of Olyset®Plus ceiling net on reducing malaria prevalence in children in Lake Victoria Basin, Kenya: study protocol for a cluster-randomized controlled trial

BACKGROUND

In the Lake Victoria Basin of western Kenya, malaria remains highly endemic despite high coverage of interventions such as insecticide-impregnated long-lasting insecticidal nets (LLIN). The malaria-protective effect of LLINs is hampered by insecticide resistance in Anopheles vectors and its repurposing by the community. Ceiling nets and LLIN with synergist piperonyl butoxide (PBO-LLIN) are novel tools that can overcome the problems of behavioral variation of net use and metabolic resistance to insecticide, respectively. The two have been shown to reduce malaria prevalence when used independently. Integration of these two tools (i.e., ceiling nets made with PBO-LLIN or Olyset®Plus ceiling nets) appears promising in further reducing the malaria burden.

METHODS

A cluster-randomized controlled trial is designed to assess the effect of Olyset®Plus ceiling nets on reducing malaria prevalence in children on Mfangano Island in Homa Bay County, where malaria transmission is moderate. Olyset®Plus ceiling nets will be installed in 1315 residential structures. Malaria parasitological, entomological, and serological indicators will be measured for 12 months to compare the effectiveness of this new intervention against conventional LLIN in the control arm.

DISCUSSION

Wider adoption of Olyset®Plus ceiling nets to complement existing interventions may benefit other malaria-endemic counties and be incorporated as part of Kenya's national malaria elimination strategy.

TRIAL REGISTRATION

UMIN Clinical Trials Registry UMIN000045079. Registered on 4 August 2021.

Insecticide-treated bed net use and associated factors among households having under-five children in East Africa: a multilevel binary logistic regression analysis

BACKGROUND

Even though malaria is preventable, it remains the leading cause of under-five morbidity and mortality in low-and middle-income countries. Despite the World Health Organization (WHO) recommendations, its advantage, and its free-of-cost access, the utilization of insecticide-treated nets (ITN) is still low in East Africa. Therefore, this study aimed to assess ITN use and associated factors among households having under-five children in East Africa.

METHODS

The most recent Demographic and Health Survey (DHS) datasets of East African countries were used. A total of 174,411 weighted samples was used for analysis. Given the hierarchical nature of DHS data, a multilevel binary logistic regression model was fitted to identify factors associated with ITN use. Four models were fitted and a model with the lowest deviance value was chosen as the best-fitted model for the data. Variables with a p-value < 0.2 in the bivariable analysis were considered for the multivariable analysis. In the multivariable multilevel binary logistic regression analysis, the Adjusted Odds Ratio (AOR) with the 95% Confidence Interval (CI) was reported to declare the statistical significance and strength of association.

RESULTS

In this study, the proportion of ITN use among households having under-five children in East Africa was 46.32% (95% CI 46.08%, 46.55%), ranging from 11.8% in Zimbabwe to 70.03% in Rwanda. In the multivariable analysis, being in the age group 25-34 years, married, widowed, and divorced, primary and post-primary education, wealthy households, having a lower household size, many under-five children, having media exposure, and male-headed households were associated with higher odds of ITN use. Moreover, respondents from a rural place of residence, communities with a higher level of media exposure, communities with lower poverty levels, and communities with higher education levels had higher odds of ITN use.

CONCLUSION

In this study, the proportion of ITN use was relatively low. Both individual and community-level factors were associated with ITN use. Therefore, giving attention, especially to those who had no formal education, the poor, younger age groups, and households with the large family size is advisable to increase awareness about ITN use. Moreover, media campaigns regarding ITN use should be strengthened.

Ideational factors associated with consistent use of insecticide-treated nets: a multi-country, multilevel analysis

BACKGROUND

Malaria remains a major cause of morbidity and mortality in sub-Saharan Africa. Using insecticide-treated nets (ITNs) every night, year-round is critical to maximize protection against malaria. This study describes sociodemographic, psychosocial, and household factors associated with consistent ITN use in Cameroon, Côte d'Ivoire and Sierra Leone.

METHODS

Cross-sectional household surveys employed similar sampling procedures, data collection tools, and methods in three countries. The survey sample was nationally representative in Côte d'Ivoire, representative of the North and Far North regions in Cameroon, and representative of Bo and Port Loko districts in Sierra Leone. Analysis used multilevel logistic regression and sociodemographic, ideational, and household independent variables among households with at least one ITN to identify correlates of consistent ITN use, defined as sleeping under an ITN every night the preceding week.

FINDINGS

Consistent ITN use in Côte d'Ivoire was 65.4%, 72.6% in Cameroon, and 77.1% in Sierra Leone. While several sociodemographic and ideational variables were correlated with consistent ITN use, these varied across countries. Multilevel logistic regression results showed perceived self-efficacy to use ITNs and positive attitudes towards ITN use were variables associated with consistent use in all three countries. The perception of ITN use as a community norm was positively linked with consistent use in Cameroon and Côte d'Ivoire but was not significant in Sierra Leone. Perceived vulnerability to malaria was positively linked with consistent use in Cameroon and Sierra Leone but negatively correlated with the outcome in Côte d'Ivoire. Household net sufficiency was strongly and positively associated with consistent use in all three countries. Finally, the findings revealed strong clustering at the household and enumeration area (EA) levels, suggesting similarities in net use among respondents of the same EA and in the same household.

CONCLUSIONS

There are similarities and differences in the variables associated with consistent ITN use across the three countries and several ideational variables are significant. The findings suggest that a social and behaviour change strategy based on the ideation model is relevant for increasing consistent ITN use and can inform specific strategies for each context. Finally, ensuring household net sufficiency is essential.

Risk Factors Associated with Diarrheal Episodes in an Agricultural Community in Nam Dinh Province, Vietnam: A Prospective Cohort Study

In Vietnam, data on the risk factors for diarrhea at the community level remain sparse. This study aimed to provide an overview of diarrheal diseases in an agricultural community in Vietnam, targeting all age groups. Specifically, we investigated the incidence of diarrheal disease at the community level and described the potential risk factors associated with diarrheal diseases. In this prospective cohort study, a total of 1508 residents were enrolled during the 54-week study period in northern Vietnam. The observed diarrheal incidence per person-year was 0.51 episodes. For children aged <5 years, the incidence per person-year was 0.81 episodes. Unexpectedly, the frequency of diarrhea was significantly higher among participants who used tap water for drinking than among participants who used rainwater. Participants who used a flush toilet had less frequent diarrhea than those who used a pit latrine. The potential risk factors for diarrhea included the source of water used in daily life, drinking water, and type of toilet. However, the direct reason for the association between potential risk factors and diarrhea was not clear. The infection routes of diarrheal pathogens in the environment remain to be investigated at this study site.

A preliminary study on designing a cluster randomized control trial of two new mosquito nets to prevent malaria parasite infection

BACKGROUND

Although long-lasting insecticidal nets (LLINs) are the most effective tool for preventing malaria parasite transmission, the nets have some limitations. For example, the increase of LLIN use has induced the rapid expansion of mosquito insecticide resistance. More than two persons often share one net, which increases the infection risk. To overcome these problems, two new mosquito nets were developed, one incorporating piperonyl butoxide and another covering ceilings and open eaves. We designed a cluster randomized controlled trial (cRCT) to evaluate these nets based on the information provided in the present preliminary study.

RESULTS

Nearly 75% of the anopheline population in the study area in western Kenya was Anopheles gambiae s. l., and the remaining was Anopheles funestus s. l. More female anophelines were recorded in the western part of the study area. The number of anophelines increased with rainfall. We planned to have 80% power to detect a 50% reduction in female anophelines between the control group and each intervention group. The between-cluster coefficient of variance was 0.192. As the number of clusters was limited to 4 due to the size of the study area, the estimated cluster size was 7 spray catches with an alpha of 0.05. Of 1619 children tested, 626 (48%) were Plasmodium falciparum positive using a rapid diagnostic test (RDT). The prevalence was higher in the northwestern part of the study area. The number of children who slept under bed nets was 929 (71%). The P. falciparum RDT-positive prevalence (RDTpfPR) of net users was 45%, and that of non-users was 55% (OR 0.73; 95% CI 0.56, 0.95). Using 45% RDTpfPR of net users, we expected each intervention to reduce prevalence by 50%. The intracluster correlation coefficient was 0.053. With 80% power and an alpha of 0.05, the estimated cluster size was 116 children. Based on the distribution of children, we modified the boundaries of the clusters and established 300-m buffer zones along the boundaries to minimize a spillover effect.

CONCLUSIONS

The cRCT study design is feasible. As the number of clusters is limited, we will apply a two-stage procedure with the baseline data to evaluate each intervention.

Protective effects of Olyset® Net on Plasmodium falciparum infection after three years of distribution in western Kenya

Background

Several types of insecticides, treating technologies and materials are available for long-lasting insecticide-treated nets (LLINs). The variations may result in different efficacies against mosquitoes and correspondingly infection risks for the Plasmodium falciparum malaria parasite. This cross-sectional study investigated whether infection risk varied among children who slept under different LLIN brands in rural villages of western Kenya.

Methods

Children sleeping under various types of LLINs were tested for P. falciparum infection using a diagnostic polymerase chain reaction (PCR) assay. Data were collected for other potential factors associated with infection risk: sleeping location (with bed/without bed), number of persons sharing the same net, dwelling wall material, gap of eaves (open/close), proportional hole index, socio-economic status, and density of indoor resting anophelines. Bed-net efficacy against the Anopheles gambiae susceptible strain was estimated using the WHO cone test and the tunnel test. The residual insecticide content on nets was measured.

Results

Seven LLIN brands were identified, and deltamethrin-based DawaPlus® 2.0 was the most popular (48%) followed by permethrin-based Olyset® Net (28%). The former LLIN was distributed in the area about six months before the present study was conducted, and the latter net was distributed at least three years before. Of 254 children analysed, P. falciparum PCR-positive prevalence was 58% for DawaPlus® 2.0 users and 38% for Olyset® users. The multiple regression analysis revealed that the difference was statistically significant (adjusted OR: 0.67, 95% credible interval: 0.45–0.97), whereas the confounders were not statistically important. Among randomly selected net samples, all DawaPlus® 2.0 (n = 20) and 95% of Olyset® (n = 19) passed either the cone test or the tunnel test.

Conclusions

Olyset® was more effective in reducing infection risk compared with DawaPlus® 2.0. Although the data from the present study were too limited to explain the mechanism clearly, the results suggest that the characteristics of the former brand are more suitable for the conditions, such as vector species composition, of the study area.

Dynamic modelling of personal protection control strategies for vector-borne disease limits the role of diversity amplification

Personal protection measures, such as bed nets and repellents, are important tools for the suppression of vector-borne diseases like malaria and Zika, and the ability of health agencies to distribute protection and encourage its use plays an important role in the efficacy of community-wide disease management strategies. Recent modelling studies have shown that a counterintuitive diversity-driven amplification in community-wide disease levels can result from a population's partial adoption of personal protection measures, potentially to the detriment of disease management efforts. This finding, however, may overestimate the negative impact of partial personal protection as a result of implicit restrictive model assumptions regarding host compliance, access to and longevity of protection measures. We establish a new modelling methodology for incorporating community-wide personal protection distribution programmes in vector-borne disease systems which flexibly accounts for compliance, access, longevity and control strategies by way of a flow between protected and unprotected populations. Our methodology yields large reductions in the severity and occurrence of amplification effects as compared to existing models.

Age and gender trends in insecticide-treated net use in sub-Saharan Africa: a multi-country analysis

Background

The degree to which insecticide-treated net (ITN) supply accounts for age and gender disparities in ITN use among household members is unknown. This study explores the role of household ITN supply in the variation in ITN use among household members in sub-Saharan Africa.

Methods

Data was from Malaria Indicator Surveys or Demographic and Health Surveys collected between 2011 and 2016 from 29 countries in sub-Saharan Africa. The main outcome was ITN use the previous night. Other key variables included ITN supply (nets/household members), age and gender of household members. Analytical methods included logistic regressions and meta-regression.

Results

Across countries, the median (range) of the percentage of households with enough ITNs was 30.7% (8.5–62.0%). Crude analysis showed a sinusoidal pattern in ITN use across age groups of household members, peaking at 0–4 years and again around 30–40 years and dipping among people between 5–14 and 50+ years. This sinusoidal pattern was more pronounced in households with not enough ITNs compared to those with enough ITNs. ITN use tended to be higher in females than males in households with not enough ITNs while use was comparable among females and males in households with enough ITNs. After adjusting for wealth quintile, residence and region, among households with not enough ITNs in all countries, the odds of ITN use were consistently higher among children under 5 years and non-pregnant women 15–49 years. Meta-regressions showed that across all countries, the mean adjusted odds ratio (aOR) of ITN use among children under 5 years, pregnant and non-pregnant women aged 15–49 years and people 50 years and above was significantly higher than among men aged 15–49 years. Among these household members, the relationship was attenuated when there were enough ITNs in the household (dropping 0.26–0.59 points) after adjusting for geographical zone, household ITN supply, population ITN access, and ITN use:access ratio. There was no significant difference in mean aOR of ITN use among school-aged children compared to men aged 15–49 years, regardless of household ITN supply.

Conclusions

This study demonstrated that having enough ITNs in the household increases level of use and decreases existing disparities between age and gender groups. ITN distribution via mass campaigns and continuous distribution channels should be enhanced as needed to ensure that households have enough ITNs for all members, including men and school-aged children.

Antimalarial bednet protection of children disappears when shared by three or more people in a high transmission setting of western Kenya

A sizeable proportion of households is forced to share single long-lasting insecticide treated net (LLIN). However, the relationship between increasing numbers of people sharing a net and the risk for Plasmodium infection is unclear. This study revealed whether risk for Plasmodium falciparum infection is associated with the number of people sharing a LLIN in a holoendemic area of Kenya. Children ⩽5 years of age were tested for P. falciparum infection using polymerase chain reaction. Of 558 children surveyed, 293 (52.5%) tested positive for parasitaemia. Four hundred and fifty-eight (82.1%) reported sleeping under a LLIN. Of those, the number of people sharing a net with the sampled child ranged from 1 to 5 (median = 2). Children using a net alone or with one other person were at lower risk than non-users (OR = 0.29, 95% CI 0.10-0.82 and OR = 0.47, 95% CI 0.22-0.97, respectively). On the other hand, there was no significant difference between non-users and children sharing a net with two (OR = 0.88, 95% CI 0.44-1.77) or more other persons (OR = 0.75, 95% CI 0.32-1.72). LLINs are effective in protecting against Plasmodium infection in children when used alone or with one other person compared with not using them. Public health professionals should inform caretakers of the risks of too many people sharing a net.

Factors associated with caregivers' consistency of use of bed nets in Nigeria: a multilevel multinomial analysis of survey data

Background

Malaria remains endemic in Nigeria despite programmes and policies put in place toward malaria elimination. Long-lasting insecticidal nets have been documented to offer protection from malaria by preventing mosquito bites. While many studies have examined the factors associated with the use of bed nets in Nigeria and across Africa, little information is available on the factors associated with consistency of use of bed nets.

Methods

The data for this study were derived from a household survey conducted in three states in Nigeria (Akwa Ibom, Kebbi and Nasarawa) between July and September 2015 by the Health Communication Capacity Collaborative, a 5-year cooperative agreement supported by the United States Agency for International Development and the US President’s Malaria initiative and led by the Johns Hopkins Center for Communication Programs. The analysis was limited to a total of 3884 men and women selected from 2863 households with at least one bed net. Multilevel multinomial logistic regression was used to assess the factors associated with consistency of use of bed nets.

Results

The findings revealed 43.2% of the respondents use bed nets every night, while 38.4% use bed nets most nights. The factors associated with using a bed net every night rather than rarely or never using a bed net included sociodemographic and household variables (age, gender, religion, household size, net density, and household wealth), ideational variables (perceptions about severity, susceptibility, self-efficacy to use nets, and response-efficacy of bed net; awareness of place of purchase; willingness to pay for bed nets; attitudes towards net use; and descriptive norm about nets), and state of residence. The three study states differ significantly in terms of most of the independent variables included in the estimated model.

Conclusions

The study recommends that efforts designed to promote consistent use of bed nets should be state-specific and include strategies targeting ideational variables. Furthermore, given the significance of unmeasured heterogeneity at the cluster level, strategies to engage and mobilize the community, such as community dialogue, home visits and engaging community leadership, are relevant.

Long-lasting insecticidal net (LLIN) ownership, use and cost of implementation after a mass distribution campaign in Kasaï Occidental Province, Democratic Republic of Congo

Background

Long-lasting insecticidal nets (LLIN) are a highly effective means for preventing malaria infection and reducing associated morbidity and mortality. Mass free distribution campaigns have been shown to rapidly increase LLIN ownership and use. Around 3.5 million LLINs were distributed free of charge in the Kasaï Occidental Province in the Democratic Republic of Congo (DRC) in September–October 2014, using two different approaches, a fixed delivery strategy and a door-to-door strategy including hang-up activities.

Methods

Repeated community-based cross-sectional surveys were conducted 2 months before and six months after the mass distribution. Descriptive statistics were used to measure changes in key malaria household indicators. LLIN ownership and use were compared between delivery strategies. Univariate and multivariate logistic regression analyses were used to identify factors associated with LLIN use before and after the mass distribution. A comparative financial cost analysis between the fixed delivery and door-to-door distribution strategies was carried out from the provider’s perspective.

Results

Household ownership of at least one LLIN increased from 39.4% pre-campaign to 91.4% post-campaign and LLIN universal coverage, measured as the proportion of households with at least one LLIN for every two people increased from 4.1 to 41.1%. Population access to LLIN within the household increased from 22.2 to 80.7%, while overall LLIN use increased from 18.0 to 68.3%. Higher LLIN ownership was achieved with the fixed delivery strategy compared with the door-to-door (92.5% [95% CI 90.2–94.4%] versus 85.2% [95% CI 78.5–90.0%]), while distribution strategy did not have a significant impact on LLIN use (69.6% [95% CI 63.1–75.5%] versus 65.7% [95% CI 52.7–76.7%]). Malaria prevalence among children aged 6–59 months was 44.8% post-campaign. Living in a household with sufficient numbers of LLIN to cover all members was the strongest determinant of LLIN use. The total financial cost per LLIN distributed was 6.58 USD for the fixed distribution strategy and 6.61 USD for the door-to-door strategy.

Conclusions

The mass distribution campaign was effective for rapidly increasing LLIN ownership and use. These gains need to be sustained for long-term reduction in malaria burden. The fixed delivery strategy achieved a higher LLIN coverage at lower delivery cost compared with the door-to-door strategy and seems to be a better distribution strategy in the context of the present study setting.

A Longitudinal Analysis of Mosquito Net Ownership and Use in an Indigenous Batwa Population after a Targeted Distribution

Major efforts for malaria prevention programs have gone into scaling up ownership and use of insecticidal mosquito nets, particularly in sub-Saharan Africa where the malaria burden is high. Socioeconomic inequities in access to long lasting insecticidal nets (LLINs) are reduced with free distributions of nets. However, the relationship between social factors and retention of nets after a free distribution has been less studied, particularly using a longitudinal approach. Our research aimed to estimate the ownership and use of LLINs, and examine the determinants of LLIN retention, within an Indigenous Batwa population after a free LLIN distribution. Two LLINs were given free of charge to each Batwa household in Kanungu District, Uganda in November 2012. Surveyors collected data on LLIN ownership and use through six cross-sectional surveys pre- and post-distribution. Household retention, within household access, and individual use of LLINs were assessed over an 18-month period. Socioeconomic determinants of household retention of LLINs post-distribution were modelled longitudinally using logistic regression with random effects. Direct house-to-house distribution of free LLINs did not result in sustainable increases in the ownership and use of LLINs. Three months post-distribution, only 73% of households owned at least one LLIN and this period also saw the greatest reduction in ownership compared to other study periods. Eighteen-months post distribution, only a third of households still owned a LLIN. Self-reported age-specific use of LLINs was generally higher for children under five, declined for children aged 6–12, and was highest for older adults aged over 35. In the model, household wealth was a significant predictor of LLIN retention, controlling for time and other variables. This research highlights on-going socioeconomic inequities in access to malaria prevention measures among the Batwa in southwestern Uganda, even after free distribution of LLINs, and provides critical information to inform local malaria programs on possible intervention entry-points to increase access and use among this marginalized population.

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

Background

Universal long-lasting insecticidal net (LLIN) coverage (ULC) has reduced malaria morbidity and mortality across Africa. Although information is available on bed net use in specific groups, such as pregnant women and children under 5 years, there is paucity of data on their use among the general population. Bed net source, ownership and determinants of use among individuals from households in an eastern Rwanda community 8 months after a ULC were characterized.

Methods

Using household-based, interviewer-administered questionnaires and interviewer-direct observations, data on bed net source, ownership and key determinants of net use, including demographics, socio-economic status indicators, house structure characteristics, as well as of bed net quantity, type and integrity, were collected from 1400 randomly selected households. Univariate and mixed effects logistic regression modelling was done to assess for determinants of bed net use.

Results

A total of 1410 households and 6598 individuals were included in the study. Overall, the proportion of households with at least one net was 92 % while bed net usage was reported among 72 % of household members. Of the households surveyed, a total ownership of 2768 nets was reported, of which about 96 % were reportedly LLINs received from the ULC. By interviewer-physical observation, 88 % of the nets owned were of the LLIN type with the remaining 12 % did not carry any mark to enable type recognition. The odds of bed net use were significantly lower among males and individuals: from households of low socio-economic status, from households with <two bed nets, from households reporting use of ≥two sleeping spaces, and those reporting to have not slept on a bed.

Conclusion

In this study, despite high a bed net coverage, over 25 % of members reported not to have slept under a bed net the night before the survey. Males were particularly less likely to use bed nets even where nets were available. Household socio-economic status, number of bed nets and type and number of sleeping spaces were key determinants of bed net use. To maximize impact of ULC, strategies that target males as well as those that ensure ITN coverage for all, address barriers to feasible and convenient bed net use including covering over all sleeping space types, and provide net hanging supports, are needed.

Sleeping on the floor decreases insecticide treated bed net use and increases risk of malaria in children under 5 years of age in Mbita District, Kenya

Children who sleep on the floor are less likely to use long-lasting insecticidal nets (LLINs); however, the relationship between sleeping location and Plasmodium falciparum infection has not been investigated sufficiently. This study revealed whether sleeping location (bed vs floor) is associated with P. falciparum infection among children 7-59 months old. More than 60% of children slept on the floor. Younger children were significantly more likely to sleep in beds [odds ratio, OR 2.31 (95% confidence interval (CI) 2.02-2.67)]. Nearly 70% of children slept under LLINs the previous night. LLIN use among children who slept on the floor was significantly less than ones sleeping in beds [OR 0.49 (95% CI 0.35-0.68)]. The polymerase chain reaction (PCR) based P. falciparum infection rate and slide based infection rate were 65.2 and 29.7%, respectively. Both infections were significantly higher among children slept on the floor [OR1.51 (95% CI 1.08-2.10) for PCR base, OR 1.62 (95% CI 1.14-2.30) for slide base] while net availability was not significant. Sleeping location was also significant for slide based infection with fever (⩾ 37.5 °C) [2.03 (95% CI 1.14-3.84)] and high parasitemia cases (parasite ⩾ 2500 µL(-1)) [2.07 (95% CI 1.03-4.50)]. The results suggest that sleeping location has a direct bearing on the effectiveness of LLINs.

Assessing the infectious reservoir of falciparum malaria: past and future

Renewed interest in malaria eradication has placed greater emphasis on the development of tools to interrupt Plasmodium transmission, such as transmission-blocking vaccines. However, effective deployment of such tools is likely to depend on improving our understanding of which individuals transmit infections to mosquitoes. To date, only a handful of studies have directly determined the infectiousness of individuals in endemic populations. Here we review these studies and their relative merits. We also highlight factors influencing transmission potential that are not normally considered: the duration of human infectiousness, frequency of sampling by mosquitoes, and variation in vector competence among different mosquito populations. We argue that more comprehensive xenodiagnostic assessments of infectivity are necessary to accurately quantify the infectious reservoir and better target interventions.