LLIN Evaluation in Uganda Project (LLINEUP): factors associated with ownership and use of long-lasting insecticidal nets in Uganda: a cross-sectional survey of 48 districts

LLIN Evaluation in Uganda Project (LLINEUP)-effects of a vector control trial on Plasmodium infection prevalence and genotypic markers of insecticide resistance in Anopheles vectors from 48 districts of Uganda

Pyrethroid bednets treated with the synergist piperonyl butoxide (PBO) offer the possibility of improved vector control in mosquito populations with metabolic resistance. In 2017-2019, we conducted a large-scale, cluster-randomised trial (LLINEUP) to evaluate long-lasting insecticidal nets (LLINs) treated with a pyrethroid insecticide plus PBO (PBO LLINs), as compared to conventional, pyrethroid-only LLINs across 104 health sub-districts (HSDs) in Uganda. In LLINEUP, and similar trials in Tanzania, PBO LLINs were found to provide greater protection against malaria than conventional LLINs, reducing parasitaemia and vector density. In the LLINEUP trial, we conducted cross-sectional household entomological surveys at baseline and then every 6 months for two years, which we use here to investigate longitudinal changes in mosquito infection rate and genetic markers of resistance. Overall, 5395 female Anopheles mosquitoes were collected from 5046 households. The proportion of mosquitoes infected (PCR-positive) with Plasmodium falciparum did not change significantly over time, while infection with non-falciparum malaria decreased in An. gambiae s.s., but not An. funestus. The frequency of genetic markers associated with pyrethroid resistance increased significantly over time, but the rate of change was not different between the two LLIN types. The knock-down resistance (kdr) mutation Vgsc-995S declined over time as Vgsc-995F, the alternative resistance mutation at this codon, increased. Vgsc-995F appears to be spreading into Uganda. Distribution of LLINs in Uganda was previously found to be associated with reductions in parasite prevalence and vector density, but here we show that the proportion of infective mosquitoes remained stable across both PBO and non-PBO LLINs, suggesting that the potential for transmission persisted. The increased frequency of markers of pyrethroid resistance indicates that LLIN distribution favoured the evolution of resistance within local vectors and highlights the potential benefits of resistance management strategies.Trial registration: This study is registered with ISRCTN, ISRCTN17516395. Registered 14 February 2017, http://www.isrctn.com/ISRCTN17516395 .

LLIN Evaluation in Uganda Project (LLINEUP): modelling the impact of COVID-19-related disruptions on delivery of long-lasting insecticidal nets on malaria indicators in Uganda

BACKGROUND

Disruptions in malaria control due to COVID-19 mitigation measures were predicted to increase malaria morbidity and mortality in Africa substantially. In Uganda, long-lasting insecticidal nets (LLINs) are distributed nationwide every 3-4 years, but the 2020-2021 campaign was altered because of COVID-19 restrictions so that the timing of delivery of new nets was different from the original plans made by the National Malaria Control Programme.

METHODS

A transmission dynamics modelling exercise was conducted to explore how the altered delivery of LLINs in 2020-2021 impacted malaria burden in Uganda. Data were available on the planned LLIN distribution schedule for 2020-2021, and the actual delivery. The transmission model was used to simulate 100 health sub-districts, and parameterized to match understanding of local mosquito bionomics, net use estimates, and seasonal patterns based on data collected in 2017-2019 during a cluster-randomized trial (LLINEUP). Two scenarios were compared; simulated LLIN distributions matching the actual delivery schedule, and a comparable scenario simulating LLIN distributions as originally planned. Model parameters were otherwise matched between simulations.

RESULTS

Approximately 70% of the study population received LLINs later than scheduled in 2020-2021, although some areas received LLINs earlier than planned. The model indicates that malaria incidence in 2020 was substantially higher in areas that received LLINs late. In some areas, early distribution of LLINs appeared less effective than the original distribution schedule, possibly due to attrition of LLINs prior to transmission peaks, and waning LLIN efficacy after distribution. On average, the model simulations predicted broadly similar overall mean malaria incidence in 2021 and 2022. After accounting for differences in cluster population size and LLIN distribution dates, no substantial increase in malaria burden was detected.

CONCLUSIONS

The model results suggest that the disruptions in the 2020-2021 LLIN distribution campaign in Uganda did not substantially increase malaria burden in the study areas.

Under utilization of long-lasting insecticidal nets (LLINs) is challenging malaria elimination program in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Malaria is one of the most common causes of morbidity and mortality in developing countries including Ethiopia. Mass distribution of insecticide-treated nets and indoor residual spray for high malaria risk groups are the major prevention measures in different countries. Achievement of the malaria elimination plan is highly determined by the level of effective utilization of intervention measures. However, there is scarce information showing the national level of insecticide-treated nets utilization.

OBJECTIVE

To estimate the pooled prevalence of insecticide-treated nets utilization in Ethiopia, 2023.

METHOD

A Systematic Review and Meta-analysis employed to assess the utilization of long-lasting insecticidal nets in Ethiopia. Published articles were searched from Google Scholar, PubMed, Web Sciences, CINAHIL, EMBASE, and Scopus. The collected articles were screened for data extraction and further analysis using preferred reporting items for systematic review and meta-analysis (PRISMA) flow chart. The quality of each study was assessed using the Jonna Briggs Institute (JBI) checklist. The data were extracted using Microsoft Excel and exported to STATA version 17.0 for analysis. The overall pooled prevalence of long-lasting insecticidal nets utilization was determined using a random effects model.

RESULT

Out of 1657 articles reviewed, only 21 of them were eligible for final analysis. All of the included studies were used to estimate the pooled prevalence of long-lasting insecticidal net utilization. The point prevalence of LLIN utilization ranged from 14.23 to 91.9%. The Meta-analysis estimated that the overall pooled prevalence of insecticidal nets utilization among all study participants in Ethiopia was 56.26% (95%CI: 44.04-68.48%). Subgroup analysis revealed that insecticidal nets utilization was relatively highest in the Amhara region [63.0, 95%CI (37.0-89.0%)] and during 2020-2023 [61, 95% CI (53.0-69.0%)].

CONCLUSION

Long-lasting insecticidal nets utilization in Ethiopia is lower than the national target plan. Hence, it needs extra follow-up and intervention to enhance its utilization.

Utilization of long-lasting insecticide-treated net and its associated factors among pregnant women in Dawo district, Southwest Shoa Zone, Oromia, Ethiopia, 2023

Introduction

The use of long-lasting insecticide-treated net (LLIN) is one of the most effective malaria prevention strategies, particularly among pregnant women. It has mosquito-killing repellent and physical barrier properties. Pregnant women, children under 5 years of age, and patients with HIV/AIDS, as well as non-immune migrants, mobile populations, and travelers, are the most vulnerable groups to malaria. Even when pregnant women are given priority, not all nets owned by households are used by pregnant women. Therefore, the risk of the occurrence of malaria during pregnancy is also high.

Objective

This study aimed to assess the utilization of long-lasting insecticide-treated net and its associated factors among pregnant women in Dawo district, Southwest Shoa Zone, Oromia, Ethiopia, 2023.

Methods

A community-based analytical cross-sectional study was carried out in Dawo district, Southwest Shoa Zone, Oromia, Ethiopia, from 21 to 30 April 2023. A total of 353 pregnant women were chosen through simple random sampling and interviewed face-to-face using a structured and pre-tested questionnaire. Before being exported to the Statistical Package for Social Science (SPSS) version 23, the data were coded and entered into EPIDATA version 4.6. The study examined the prevalence of long-lasting insecticide-treated net use among pregnant women in the Dawo district using descriptive statistics. Analytical statistics, such as bivariable and multivariable logistic regression analyses, were used to determine the relationship between independent and dependent variables. Statistical significance was determined using a P-value of <0.05 and adjusted odd ratios with 95% confidence intervals.

Results

Long-lasting insecticide-treated nets were utilized by 55.5% (95% CI: 50.4-60.7%) of all pregnant participants in the study, which was below the national target. Pregnant women who have antenatal care (ANC) contact for current pregnancy adjusted odds ratio (AOR = 4.66, 95% CI: 1.95, 11.10), community-based health insurance (CBHI) enrollment (AOR = 2.38, 95% confidence intervals, CI: 1.38, 4.11), children under 5 years of age (AOR = 2.68, 95% CI: 1.62, 4.43), understanding that malaria poses a risk to fetuses (AOR = 3.25, 95% CI: 1.26, 8.41), and LLINs access (AOR = 12.47, 95% CI: 3.98, 39.08), were factors that significantly associated with LLIN utilization.

Conclusion

In conclusion, the utilization of LLINs was relatively low. ANC contact for current pregnancy, CBHI enrollment, having children under the age of 5, having a high income, and understanding that malaria poses a risk to fetuses were factors significantly associated with LLIN utilization among pregnant women.

Effect of malaria prevention education on bed net utilization, incidence of malaria and treatment seeking among school-aged children in Southern Ethiopia; cluster randomized controlled trial

BACKGROUND

School-aged children (SAC) have an increased risk to contract malaria and play a major role in its transmission dynamics. However, their malaria prevention experience is poor. Thus, the effect of malaria prevention education (MPE) on bed net utilization, treatment seeking from a health facility and cumulative incidence of malaria was evaluated in Southern Ethiopia.

METHODS

A two arm cluster randomized controlled trial was conducted by recruiting 2038 SAC from 32 schools. Structured questionnaire was used to collect data on socio-demographic, economic, bed net ownership, bed net utilization, whether the participated child suffered from malaria and has got treatment from a health facility. Generalized mixed effect logistic regression using school as random variable was used to assess the effect of the intervention on the outcome variables.

RESULTS

The ownership of bed net in households of the control and intervention schools was similar respectively with 84.6 and 88.6% (Crude Odds Ratio (COR): 1.5; 95%CI: 0.5-4.8). The percentage of SAC slept under the bed net the night before the survey was also similar (55.1% versus 54.0%); COR:1.04; 95%CI: 0.5-2.4). Bed net utilization was affected by household size to the bed net ratio ≤ 2 (Adjusted Odds Ratio (AOR) = 1.6; 95%CI:1.3-2.1), bed net utilization at baseline of the study (AOR = 2.3; 95%CI:1.5-3.6), and history of malaria attack in the last twelve months (AOR = 1.3; 95%CI:1.01-1.8). Reported cumulative incidence of malaria and treatment seeking from a health facility by SAC was similar between intervention and control arms: -2.1% (COR = 0.8; 95%CI: 0.5-1.5) and 9.6% (COR = 1.4; 95%CI: 0.4-4.3) respectively. The reported incidence of malaria was affected by altitude (AOR = 0.5; 95%CI: 0.3-0.8), low and medium wealth index (AOR = 0.7; 95%CI: 0.5-0.96 and AOR = 0.7; 95%CI: 0.5-0.98), adequate bed net number for household members (AOR = 0.7; 95%CI:0.5-0.9) and bed net utilization (AOR = 1.3; 95%CI:1.1-1.8).

CONCLUSIONS

MPE had no significant effect on the use of malaria prevention measures considered, treatment seeking from a health facility and reported cumulative incidence of malaria though bed net use was associated with malaria incidence. Before organizing any health education program, sustainable implementation efforts have to be warranted especially in SAC, a neglected but relevant vulnerable and reservoirs.

TRIAL REGISTRATION

Pan African Clinical Trials Registry PACTR202001837195738, registered 21/01/2020.

Residual Malaria Transmission: magnitude and drivers of persistent Plasmodium infections despite high coverage of control interventions in Burkina Faso, West Africa

This study collected baseline data on malaria vectors to characterize the drivers and the factors of persistent malaria transmission in two villages in the western part of Burkina Faso. Mosquitoes were collected in each village using the Human landing catch and pyrethrum spray catch and identified using the morphological keys. Molecular analyses were performed for the identification of An. gambiae complex species, the detection of Plasmodium infection and kdr-995F mutation. Anopheles mosquito larvae were also collected in the same villages, reared to adult's stage for the WHO tube and cone tests performing. The physical integrity of the LLINs already used by people in each village was assessed using the proportional hole index (pHI). An. gambiae s.l. was the main malaria vector accounting for 79.82% (5560/6965) of all collected mosquitoes. The biting pattern of An. gambiae s.l. was almost constant during the survey with an early aggressiveness before 8 p.m. and later biting activity after 6 a.m. The EIR varied from 0.13 to 2.55 infected bites per human per night (average: 1.03 infected bites per human per night). An. gambiae s.l. populations were full susceptible to Chlorpyrifos-methyl (0.4%) and Malathion (5%) with high kdr-995F mutation frequencies (>0.8). The physical integrity assessment showed high proportion of good nets in Santidougou compared to those collected in Kimidougou. This study highlighted a persistence of malaria transmission despite the intense use of vector control tools as LLINs and IRS by correlating mosquito biting time and human behavior. It provided a baseline guide for the monitoring of the residual malaria transmission in sub-Saharan Africa and encouraging the development of new alternative strategies to support the current malaria control tools.

Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): final results of a cluster-randomised trial embedded in a national distribution campaign

BACKGROUND

Long-lasting insecticidal nets (LLINs) are the foundation of malaria control but resistance of mosquito vectors to pyrethroids threatens their effectiveness. We embedded a cluster-randomised trial into Uganda's 2017-18 campaign to distribute LLINs. LLINs with piperonyl butoxide (PBO) reduced parasite prevalence more effectively than conventional LLINs (without PBO) for 18 months. Here, we report the final 25-month survey results.

METHODS

LLINEUP was a cluster-randomised trial conducted in 48 districts in eastern and western Uganda. 104 health subdistricts (clusters) without ongoing or planned indoor residual spraying with pirimiphos-methyl (Actellic, Basel, Switzerland) were eligible for inclusion in the trial. Clusters were randomly assigned to PBO LLINs (PermaNet 3.0 or Olyset Plus) and conventional LLINs (PermaNet 2.0 or Olyset Net) with proportionate randomisation using STATA version 14.2. LLINs were delivered from March 25, 2017, to March 18, 2018. Between April 23, 2019, and Sept 13, 2019, community surveys were conducted in 50 randomly selected households per cluster; ten households per cluster were randomly selected for entomology surveys. Mosquitoes were collected in the morning from indoor surfaces of households using Prokopack aspirators. Due to COVID-19 restrictions, only 90 of the 104 clusters were surveyed at 25 months. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population, determined using the results from the 6-month household survey on the type of LLINs received in each cluster. This trial is registered with ISRCTN, ISRCTN17516395, and is now completed.

FINDINGS

In the as-treated analysis, two clusters were excluded (no predominant LLIN received) and four were reassigned; 40 PBO LLIN clusters (30 PermaNet 3.0, ten Olyset Plus) and 48 non-PBO LLIN (36 PermaNet 2.0, 12 Olyset Net) were included. Parasite prevalence was 17·1% (506 of 2958 participants) in the PBO group and 19·8% (701 of 3534) in the non-PBO group (prevalence ratio adjusted for baseline 0·80 [95% CI 0·69-0·93], p=0·0048). Comparing within-treatment group parasite prevalence to baseline, parasite prevalence ratios were lower in the PBO groups at all timepoints, but the difference was greatest at 6 months (PBO LLINs parasite prevalence at baseline 28·8% [1001 of 3472, 95% CI 27·3-30·4] vs at 6 months 12·0% [361 of 3009, 10·9-13·2], prevalence ratio [PR] 0·43 [95% CI 0·36-0·52], p<0·0001; non-PBO LLINs parasite prevalence at baseline 25·4% [1015 of 4004, 24·0-26·7] vs 6 months 14·8% [526 of 3551, 13·7-16·0], PR 0·60 [0·54-0·68], p<0·0001) and 25 months (PBO LLINs parasite prevalence at 25 months 17·1% [506 of 2958, 15·8-18·5], PR 0·63 [95% CI 0·57-0·71], p<0·0001; non-PBO LLINs parasite prevalence at 25 months 19·8% [701 of 3534, 18·5-21·2], PR 0·79 [0·73-0·86], p<0·0001).

INTERPRETATION

In Uganda, PBO LLINs outperformed pyrethroid-only LLINs for 25 months. WHO concluded that PBO LLINs are more effective against malaria than non-PBO LLINs when resistance to pyrethroids is high and issued a conditional recommendation suggesting PBO LLINs should be deployed in areas of pyrethroid resistance.

FUNDING

The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.

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.

LLIN Evaluation in Uganda Project (LLINEUP2)-Factors associated with coverage and use of long‑lasting insecticidal nets following the 2020-21 national mass distribution campaign: a cross-sectional survey of 12 districts

BACKGROUND

In 2020-2021, long-lasting insecticidal nets (LLINs) were distributed nationwide in Uganda during the COVID-19 pandemic. A cross-sectional survey was conducted in 12 districts to evaluate the impact of the campaign 1-5 months after LLIN distribution.

METHODS

During April-May 2021, households were randomly selected from target areas (1-7 villages) surrounding 12 government-run health facilities established as Malaria Reference Centres; at least 50 households were enrolled per cluster. Outcomes included household ownership of LLINs distributed through the universal coverage campaign (UCC) (at least one UCC LLIN), adequate coverage of UCC LLINs (at least one UCC LLIN per 2 residents), and use of LLINs (resident slept under a LLIN the previous night). Multivariate logistic regression models were used to identify household- and individual-level factors associated with outcomes, controlling for clustering around health facilities.

RESULTS

In total, 634 households, with 3342 residents and 1631 bed-nets, were included. Most households (93.4%) owned at least 1 UCC LLIN, but only 56.8% were adequately covered by UCC LLINs. In an adjusted analysis, the factor most strongly associated with adequate coverage by UCC LLINs was fewer household residents (1-4 vs 7-14; adjusted odds ratio [aOR] 12.96, 95% CI 4.76-35.26, p < 0.001; 5-6 vs 7-14 residents; aOR 2.99, 95% CI 1.21-7.42, p = 0.018). Of the 3166 residents of households that owned at least one UCC LLIN, only 1684 (53.2%) lived in adequately covered households; 89.9% of these used an LLIN the previous night, compared to 1034 (69.8%) of 1482 residents living in inadequately covered households. In an adjusted analysis, restricted to residents of inadequately covered households, LLIN use was higher in children under-five than those aged 5-15 years (aOR 3.04, 95% CI 2.08-4.46, p < 0.001), and higher in household heads than distantly-related residents (aOR 3.94, 95% CI 2.38-6.51, p < 0.001).

CONCLUSIONS

Uganda's 2021-21 campaign was successful, despite the COVID-19 pandemic. In future campaigns, strategies should be adopted to ensure high LLIN coverage, particularly for larger households. A better understanding of the drivers of LLIN use within households is needed to guide future interventions, educational messages, and behaviour change communication strategies; school-aged children and distantly-related residents appear vulnerable and could be targeted.

Bio-efficacy, physical integrity, use and attrition of long-lasting insecticidal nets under operational conditions for malaria prevention in Ghana

Background

Malaria remains a public health challenge in endemic countries of the world. The use of Long-lasting Insecticidal Nets (LLINs) is one of the major ways of malaria vector control. Recent evidence however suggests some LLINs are unable to maintain their effectiveness over their useful life span. This study assessed the bio-efficacy, physical integrity, use and attrition at 6 and 12-months post-distribution of LLINs (LifeNet).

Methods

Following a mass distribution of LLINs in the West Mamprusi District of the North-East region of Ghana in 2018, a total of 147 LLINs were sampled for physical integrity and attrition assessment using hole size and the number of holes as a measure of the proportionate hole index (pHI). Bioassays were conducted on sixty randomly selected LLINs using the WHO guidelines for bio-efficacy testing (cone tests), (20 each at baseline, midline and endline) over a one-year study period. Bed net ownership and use as well as malaria vector resistance status were also assessed.

Results

Findings indicate high bio-efficacy of approximately 100% average mortalities of mosquitoes at baseline, 6-months and 12-months post-distribution. A small proportion of LLINs (0.8% and 5.6% at the 6 and 12-months surveys respectively) were damaged beyond maintenance while 62.4% and 62.7% of LLINs were used the night before the survey for 6 and 12-months post-distribution respectively. Households with electricity were less likely to use LLINs compared to those without electricity (P-value = 0.016, OR = 0.39). There were 20 fewer LLINs recovered at the 12-months relative to the 6-months resulting in 14.3% attrition rate. Susceptibility testing showed high pyrethroid and organochlorine resistance (18%, 67.5% and 3.8%) to local malaria vectors respectively), whereas organophosphates and carbamates recorded vector susceptibility of 100% for pirimiphos-methyl and 98.7% for bendiocarb.

Conclusion

Biological efficacy, physical integrity and net attrition during the study period were in conformity with respect to the WHOPES one year net use. LLINs remained effective after one-year of usage. Net ownership was high in the study households. There should be continuous and regular distribution campaigns to maintain high coverage.

East Africa International Center of Excellence for Malaria Research: Impact on Malaria Policy in Uganda

Malaria is the leading cause of disease burden in sub-Saharan Africa. In 2010, the East Africa International Center of Excellence for Malaria Research, also known as the Program for Resistance, Immunology, Surveillance, and Modeling of Malaria (PRISM), was established to provide a comprehensive approach to malaria surveillance in Uganda. We instituted cohort studies and a robust malaria and entomological surveillance network at selected public health facilities that have provided a platform for monitoring trends in malaria morbidity and mortality, tracking the impact of malaria control interventions (indoor residual spraying of insecticide [IRS], use of long-lasting insecticidal nets [LLINs], and case management with artemisinin-based combination therapies [ACTs]), as well as monitoring of antimalarial drug and insecticide resistance. PRISM studies have informed Uganda's malaria treatment policies, guided selection of LLINs for national distribution campaigns, and revealed widespread pyrethroid resistance, which led to changes in insecticides delivered through IRS. Our continuous engagement and interaction with policy makers at the Ugandan Ministry of Health have enabled PRISM to share evidence, best practices, and lessons learned with key malaria stakeholders, participate in malaria control program reviews, and contribute to malaria policy and national guidelines. Here, we present an overview of interactions between PRISM team members and Ugandan policy makers to demonstrate how PRISM's research has influenced malaria policy and control in Uganda.

Factors associated with ownership and utilization of insecticide treated nets among children under five years in sub-Saharan Africa

Background

Insecticide-treated net (ITN) is a cost-effective means to control malaria and morbidity in under-five children. This study synthesizes the factors associated with using the ITN as a malaria prevention tool in sub-Saharan Africa.

Methods

There was an advanced search of four electronic databases, including PubMed Central, CINAHL, EMBASE, and Google Scholar, and identified articles between 2016 to April 2021. Following the title, abstract and full-text reading, 13 articles were deemed appropriate for this review. All the researchers developed, discussed, and accepted a matrix to extract relevant information from the studies. A convergent synthesis was adopted and allowed for integrating qualitative, quantitative, and mixed-method studies and transforming them into qualitative findings.

Results

Household and caregiver related factors that influenced utilization of the ITN were, Household heads having two or more sleeping places, a knowledge that ITN prevents malaria, the presence of hanging ITNs, high literacy, living female-headed households, birth spacing, unmarried mothers, and antenatal clinic attendance promoted utilization. Perceived malaria risk was a critical determinant of ITN ownership and utilization. Some factors that hindered the use of the ITN included hotness of the weather, absence of visible mosquitoes, cost, inadequate number, rooms designs, unaffordability, insufficient knowledge on causes of malaria, and poor attitude to use. Specific ITN factors that hindered use were color, chemicals use, odor, and shape.

Conclusion

It is important to use integrated multi-sectoral and culturally appropriate interventions to encourage households to prioritize and utilize the ITN in under-5 children.

Permethrin-treated baby wraps for the prevention of malaria: results of a randomized controlled pilot study in rural Uganda

Background

Progress against malaria has stalled and may even be slipping backwards in high-burden countries. This is due to a range of factors including insecticide resistance and mosquito feeding behaviours that limit contact with widely-employed interventions including long-lasting insecticidal nets and indoor-residual spraying. Thus, further innovations in malaria control are urgently needed.

Methods

The pilot was a randomized, placebo-controlled pilot study of permethrin-treated baby wraps—known locally as lesus—in children 6–18 months of age at a single site in rural western Uganda. Fifty mother–infant pairs were assigned to permethrin-treated or untreated lesus in a 1:1 allocation. Participants and clinical staff were blinded to group assignments through use of sham treatment and re-treatment of lesus. Participants attended scheduled clinic visits every 2 weeks for a total 12 weeks. The primary outcome of interest was the safety of the intervention, assessed as changes in the frequency of use, rates of discontinuation, and incidence of adverse events, such as skin rash. Secondary outcomes included acceptability and feasibility of the intervention as measured through participant satisfaction and completion of study activities, respectively.

Results

Overall, rates of retention and participation were relatively high with 86.0% (43 of 50) of participants completing all scheduled visits, including 18 (75.0%) and 25 (96.2%) in the intervention and control arms respectively. By the conclusion of the 12-week follow-up period, one adverse event (0.35 events per 100 person-weeks, one-sided 95% CI 0.0–1.65) was reported. Satisfaction with the lesu was high in both groups. In each study arm, there were five incident RDT positive results, but the only PCR-positive results were observed in the control group (n = 2).

Conclusions

Permethrin-treated baby wraps were well-tolerated and broadly acceptable. Adverse events were infrequent and mild. These findings support future trials seeking to determine the efficacy of treated wraps to prevent P. falciparum malaria infection in young children as a complementary tool to existing household-based interventions.

Trial registration: ClinicalTrials.gov Identifier: NCT04102592, Registered 25 September 2019. Available at: https://clinicaltrials.gov/ct2/show/NCT04102592

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04086-w.

The effect of long-lasting insecticidal nets (LLINs) physical integrity on utilization

BACKGROUND

In Ethiopia, despite improvements in coverage and access, utilization of long-lasting insecticidal nets (LLINs) remains a challenge. Different household-level factors have been identified as associated with LLIN use. However, the contribution of LLIN physical integrity to their utilization is not well investigated and documented. This study aimed to assess the association between the physical integrity of LLINs and their use.

METHODS

This study employed a nested case-control design using secondary data from the Ethiopian LLIN durability monitoring study conducted from May 2015 to June 2018. LLINs not used the night before the survey were identified as cases, while those used the previous night were categorized as controls. The physical integrity of LLINs was classified as no holes, good, acceptable, and torn using the proportionate hole index (pHI). A Generalized Estimating Equation (GEE) model was used to assess and quantify the association between LLIN physical integrity and use. The model specifications included binomial probabilistic distribution, logit link, exchangeable correlation matrix structure, and robust standard errors. The factors included in the model were selected first by fitting binary regression, and then by including all factors that showed statistical significance at P-value less than 0.25 and conceptually relevant variables into the multivariate regression model.

RESULTS

A total of 5277 observations fulfilled the inclusion criteria. Out of these 1767 observations were cases while the remaining 3510 were controls. LLINs that were in torn physical condition had higher odds (AOR [95% CI] = 1.76 [1.41, 2.19]) of not being used compared to LLINs with no holes. Other factors that showed significant association included the age of the LLIN, sleeping place type, washing status of LLINs, perceptions towards net care and repair, LLIN to people ratio, economic status, and study site.

CONCLUSION AND RECOMMENDATION

LLINs that have some level of physical damage have a relatively higher likelihood of not being used. Community members need to be educated about proper care and prevention of LLIN damage to delay the development of holes as long as possible and use available LLINs regularly.

Evaluation of Long-Lasting Insecticidal Net Distribution Through Schools in Southern Tanzania

Universal coverage with effective vector control remains the mainstay of malaria vector control in sub-Saharan Africa Tanzania has utilized a number of mechanisms for the maintenance of long-lasting insecticidal net (LLIN) coverage over time. Schools have been identified as one potential channel for continuous distribution of LLIN. This research aims to evaluate an annual school based LLIN distribution programme in Tanzania which began in 2013, called the School Net Programme (SNP). Following each of the first four rounds of SNP distribution, a household survey was conducted in intervention and comparison districts in Southern and Lake zones of Tanzania (N = 5083 households). Measures of ownership, access, and use were compared between intervention and comparison districts. Determinants of reach were assessed in intervention districts. Population access to an LLIN increased from 63.1% (95% CI: 58.8, 67.5) to 76.5% (95% CI: 72.9, 80.0) in the intervention districts between the first and last surveys. Access also rose in the comparison districts from 51.4% (95% CI: 46.9, 55.9) to 79.8% (95% CI: 77.3, 82.0) following a mass distribution and implementation of school-based distribution during the study period. LLIN use increased in intervention districts from 44.9% (95% CI: 40.5, 49.3) to 65.6% (95% CI: 59.4, 71.8) and from 57.2% (95% CI: 49.7, 64.7) to 77.4% (95% CI: 69.3, 85.5) specifically amongst primary school-aged children. Households reached by the SNP were wealthier households with children enrolled in school. The SNP in Tanzania was able to maintain population level LLIN ownership, use, and access in the absence of a mass distribution. The SNP successfully reached households which housed school-aged children. Alternative delivery strategies may need to be considered to reach households without children enrolled in school which experienced less benefit from the program.

Ownership and use of insecticide-treated nets under Ghana's National Malaria Control Program: What are the correlates?

OBJECTIVES

Ghana's National Malaria Control Program distributes free insecticide-treated nets (ITNs) as a malaria control measure. Some households with the ITN do not use it, however. This paper explores the socioeconomic and demographic determinants of ITN ownership and use among Ghanaian families.

METHODS

Data on 5741 households were obtained from the 2019 Ghana Malaria Indicator Survey. The survey is a nationally representative survey that obtains data on malaria-related issues. Negative binomial and Tobit regressions were applied to achieve the study's objectives.

RESULTS

Residence (rural-urban), wealth, and administrative region emerged as the most important predictors of ITN ownership and usage in Ghana. The results favoured rural and non-Greater Accra residents. However, wealth had a contrasting association with ITN ownership and use. Whereas affluent households owned more ITNs than the extremely poor, the latter used them more. Also, age and household size were significant for ITN ownership. Both variables had a nonlinear (inverted U-shaped) relationship with ITN ownership. In contrast, the proportion of household members under 5 and the bed net-to-household size ratio were positive and statistically significant determinants of ITN use.

CONCLUSION

The study highlights the need to effectively target the poor, especially in rural areas, for ITNs under the NMCP instead of universal distribution.

Coverage, determinants of use and repurposing of long-lasting insecticidal nets two years after a mass distribution in Lihir Islands, Papua New Guinea: a cross-sectional study

BACKGROUND

Universal coverage with long-lasting insecticidal nets (LLINs) is an essential component of malaria control programmes. Three-yearly mass distribution of LLINs in Papua New Guinea (PNG) has been successful in reducing infection transmission since 2009, but malaria prevalence ramped up from 2015 onwards. Although LLIN universal coverage is mostly achieved during these campaigns, it may not be related with net use over time. Uses given to LLINs and non-compliance of this strategy were evaluated.

METHODS

A knowledge, attitude and practice (KAP) cross-sectional study was conducted in Lihir Islands, PNG, 2-2.5 years after the last LLIN mass distribution campaign. Data on bed net ownership, use and maintenance behaviour was collected using a household questionnaire administered by trained community volunteers. Logistic regression models were used to identify factors associated with owning at least one LLIN and sleeping under a LLIN the previous night.

RESULTS

Among 2694 households surveyed, 27.4 % (95 % CI: 25.8-29.2) owned at least one LLIN and 8.7 % (95 % CI: 7.6-9.8) had an adequate LLIN coverage (at least one LLIN for every two people). Out of 13,595 individuals in the surveyed households, 13.6 % (95 % CI: 13.0--4.2) reported having slept under a LLIN the preceding night. Determinants for sleeping under LLIN included living in a household with adequate LLIN coverage [adjusted OR (aOR) = 5.82 (95 % CI: 3.23-10.49)], household heads knowledge about LLINs [aOR = 16.44 (95 % CI: 8.29-32.58)], and female gender [aOR = 1.92 (95 % CI: 1.53-2.40)] (all p-values < 0.001). LLIN use decreased with older age [aOR = 0.29 (95 % CI: 0.21-0.40) for ≥ 15 year-olds, aOR = 0.38 (95 % CI: 0.27-0.55) for 5-14 year-olds] compared to < 5 year-olds (p-value < 0.001). Knowledge on the use of LLIN was good in 37.0 % of the household heads. Repurposed nets were reported serving as fishing nets (30.4 %), fruits and seedlings protection (26.6 %), covering up food (19.0 %) and bed linen (11.5 %).

CONCLUSIONS

Two years after mass distribution, LLIN coverage and use in Lihir Islands is extremely low. Three yearly distribution campaigns may not suffice to maintain an acceptable LLIN coverage unless knowledge on maintenance and use is promoted trough educational campaigns.

Malaria prevalence and long-lasting insecticidal net use in rural western Uganda: results of a cross-sectional survey conducted in an area of highly variable malaria transmission intensity

Background

Long-lasting insecticidal nets (LLINs) remain a cornerstone of malaria control, but strategies to sustain universal coverage and high rates of use are not well-defined. A more complete understanding of context-specific factors, including transmission intensity and access to health facilities, may inform sub-district distribution approaches and tailored messaging campaigns.

Methods

A cross-sectional survey of 2190 households was conducted in a single sub-county of western Uganda that experiences highly variable malaria transmission intensity. The survey was carried out approximately 3 years after the most recent mass distribution campaign. At each household, study staff documented reported LLIN use and source among children 2 to 10 years of age and performed a malaria rapid diagnostic test. Elevation and distance to the nearest health facility was estimated for each household. Associations between parasite prevalence and LLIN use were estimated from log binomial regression models with elevation and distance to clinic being the primary variables of interest.

Results

Overall, 6.8% (148 of 2170) of children age 2–10 years of age had a positive RDT result, yielding a weighted estimate of 5.8% (95% confidence interval [CI] 5.4–6.2%). There was substantial variability in the positivity rates among villages, with the highest elevation villages having lower prevalence than lowest-elevation villages (p < .001). Only 64.7% (95% CI 64.0–65.5%) of children were reported to have slept under a LLIN the previous night. Compared to those living < 1 km from a health centre, households at ≥ 2 km were less likely to report the child sleeping under a LLIN (RR 0.86, 95% CI 0.83–0.89, p < .001). Households located farther from a health centre received a higher proportion of LLINs from government distributions compared to households living closer to health centres.

Conclusions

LLIN use and sourcing was correlated with household elevation and estimated distance to the nearest health facility. The findings suggest that current facility-based distribution strategies are limited in their reach. More frequent mass distribution campaigns and complementary approaches are likely required to maintain universal LLIN coverage and high rates of use among children in rural Uganda.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03835-7.

Genetic diversity and genetic relatedness in Plasmodium falciparum parasite population in individuals with uncomplicated malaria based on microsatellite typing in Eastern and Western regions of Uganda, 2019-2020

BACKGROUND

Genetic diversity and parasite relatedness are essential parameters for assessing impact of interventions and understanding transmission dynamics of malaria parasites, however data on its status in Plasmodium falciparum populations in Uganda is limited. Microsatellite markers and DNA sequencing were used to determine diversity and molecular characterization of P. falciparum parasite populations in Uganda.

METHODS

A total of 147 P. falciparum genomic DNA samples collected from cross-sectional surveys in symptomatic individuals of 2-10 years were characterized by genotyping of seven highly polymorphic neutral microsatellite markers (n = 85) and genetic sequencing of the Histidine Rich Protein 2 (pfhrp2) gene (n = 62). ArcGIS was used to map the geographical distribution of isolates while statistical testing was done using Student's t-test or Wilcoxon's rank-sum test and Fisher's exact test as appropriate at P ≤ 0.05.

RESULTS

Overall, 75.5% (95% CI 61.1-85.8) and 24.5% (95% CI14.2-38.9) of parasites examined were of multiclonal (mixed genotype) and single clone infections, respectively. Multiclonal infections occurred more frequently in the Eastern region 73.7% (95% CI 48.8-89.1), P < 0.05. Overall, multiplicity of infection (MOI) was 1.9 (95% CI 1.7-2.1), P = 0.01 that was similar between age groups (1.8 vs 1.9), P = 0.60 and regions (1.9 vs 1.8), P = 0.43 for the < 5 and ≥ 5 years and Eastern and Western regions, respectively. Genomic sequencing of the pfhrp2 exon2 revealed a high level of genetic diversity reflected in 96.8% (60/62) unique sequence types. Repeat type AHHAAAHHATD and HRP2 sequence Type C were more frequent in RDT-/PCR + samples (1.9% vs 1.5%) and (13% vs 8%), P < 0.05 respectively. Genetic relatedness analysis revealed small clusters of gene deleted parasites in Uganda, but no clustering with Eritrean parasites.

CONCLUSION

High level of genetic diversity of P. falciparum parasites reflected in the frequency of multiclonal infections, multiplicity of infection and variability of the pfhrp2 gene observed in this study is consistent with the high malaria transmission intensity in these settings. Parasite genetic analysis suggested spontaneous emergence and clonal expansion of pfhrp2 deleted parasites that require close monitoring to inform national malaria diagnosis and case management policies.

The impact of stopping and starting indoor residual spraying on malaria burden in Uganda

The scale-up of malaria control efforts has led to marked reductions in malaria burden over the past twenty years, but progress has slowed. Implementation of indoor residual spraying (IRS) of insecticide, a proven vector control intervention, has been limited and difficult to sustain partly because questions remain on its added impact over widely accepted interventions such as bed nets. Using data from 14 enhanced surveillance health facilities in Uganda, a country with high bed net coverage yet high malaria burden, we estimate the impact of starting and stopping IRS on changes in malaria incidence. We show that stopping IRS was associated with a 5-fold increase in malaria incidence within 10 months, but reinstating IRS was associated with an over 5-fold decrease within 8 months. In areas where IRS was initiated and sustained, malaria incidence dropped by 85% after year 4. IRS could play a critical role in achieving global malaria targets, particularly in areas where progress has stalled.

The consequences of declining population access to insecticide-treated nets (ITNs) on net use patterns and physical degradation of nets after 22 months of ownership

Background

As insecticide-treated nets (ITNs) wear out and are disposed, some household members are prioritized to use remaining ITNs. This study assessed how nets are allocated within households to individuals of different age categories as ITNs are lost or damaged and as new ITNs are obtained. The study also explored how ITN allocation affects ITN durability.

Methods

A cross-sectional household survey and ITN durability study was conducted among 2,875 households across Tanzania to determine the proportion of nets that remain protective (serviceable) 22 months after net distribution aiming for universal coverage. Allocation of study nets within houses, and re-allocation of ITNs when new universal replacement campaign (URC) nets arrived in study households in Musoma District, was also assessed.

Results

Some 57.0% (95% CI 53.9–60.1%) of households had sufficient ITNs for every household member, while 84.4% (95% CI 82.4–86.4%) of the population had access to an ITN within their household (assuming 1 net covers every 2 members). In households with sufficient nets, 77.5% of members slept under ITNs. In households without sufficient nets, pregnant women (54.6%), children < 5 years (45.8%) and adults (42.1%) were prioritized, with fewer school-age children 5–14 years (35.9%), youths 15–24 years (28.1%) and seniors > 65 years (32.6%) sleeping under ITNs. Crowding (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 3 people sleeping under nets) was twice as common among people residing in houses without sufficient nets for all age groups, apart from children < 5. Nets were less likely to be serviceable if: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 3 people slept under them (OR 0.50 (95% CI 0.40–0.63)), or if nets were used by school-age children (OR 0.72 (95% CI 0.56–0.93)), or if the net product was Olyset®. One month after the URC, only 23.6% (95% CI 16.7–30.6%) of the population had access to a URC ITN in Musoma district. Householders in Musoma district continued the use of old ITNs even with the arrival of new URC nets.

Conclusion

Users determined the useful life of ITNs and prioritized pregnant women and children < 5 to serviceable ITNs. When household net access declines, users adjust by crowding under remaining nets, which further reduces ITN lifespan. School-age children that commonly harbour gametocytes that mediate malaria transmission are compelled to sleep under unserviceable nets, crowd under nets or remain uncovered. However, they were accommodated by the arrival of new nets. More frequent ITN delivery through the school net programme in combination with mass distribution campaigns is essential to maximize ITN effectiveness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03686-2.

Evaluation of malaria preventive measures among adult patients attending the Bamendjou and Foumbot district hospitals of the West Region of Cameroon

BACKGROUND

Although a significant decrease in entomological and epidemiological indicators was reported in Cameroon since the introduction of insecticide-treated bed nets, malaria prevalence remains high also in some parts of the West Region of Cameroon. This study was designed to evaluate malaria preventive measures among patients attending the Bamendjou and Foumbot District hospitals of the West Region of Cameroon.

METHODS

This was a cross-sectional study carried out within a period of 3 months, from January to March 2020. Data was obtained using a structured questionnaire and laboratory analysis. The CareStart™ Pf Malaria HRP2 qualitative rapid diagnostic test was used for malaria diagnosis. The questionnaire was designed to collect information on respondent's socio-demographic characteristics, and the use of malaria preventive measures. Data were analysed using descriptive statistics, regression analysis, and Chi-square (and Fisher's exact) test.

RESULTS

A total of 170 study participants were recruited in Foumbot and 197 in Bamendjou. Malaria was significantly (P < 0.0001) more prevalent in Foumbot (47.06%) than in Bamendjou (19.8%). In Foumbot, non-use of insect repellent spray (P = 0.0214), insect repellent body cream (P = 0.0009), mosquito spray (P = 0.0001) and not draining stagnant water (P = 0.0004) predisposed to higher risk of malaria. In Bamendjou, non-use of insect repellent spray (P = 0.0012), long-lasting insecticidal bed nets (P = 0.0001), window and door nets (P = 0.0286), predisposed to a higher risk of malaria.

CONCLUSIONS

Malaria prevalence was high among the study participants especially in Foumbot. An adequate follow-up to ensure effective execution of the recently launched third phase of LLINs distribution campaign in Cameroon is recommended. Additionally, integrated vector management is required to ensure effective control of malaria transmission in Foumbot and Bamendjou.

Limitations of rapid diagnostic tests in malaria surveys in areas with varied transmission intensity in Uganda 2017-2019: Implications for selection and use of HRP2 RDTs

BACKGROUND

Plasmodium falciparum histidine-rich protein 2 (HRP2)-based rapid diagnostic tests (RDTs) are exclusively recommended for malaria diagnosis in Uganda; however, their functionality can be affected by parasite-related factors that have not been investigated in field settings.

METHODS

Using a cross-sectional design, we analysed 219 RDT-/microscopy+ and 140 RDT+/microscopy+ dried blood spots obtained from symptomatic children aged 2-10 years from 48 districts in Uganda between 2017 and 2019. We aimed to investigate parasite-related factors contributing to false RDT results by molecular characterization of parasite isolates. ArcGIS software was used to map the geographical distribution of parasites. Statistical analysis was performed using chi-square or Fisher's exact tests, with P ≤ 0.05 indicating significance. Odds ratios (ORs) were used to assess associations, while logistic regression was performed to explore possible factors associated with false RDT results.

RESULTS

The presence of parasite DNA was confirmed in 92.5% (332/359) of the blood samples. The levels of agreement between the HRP2 RDT and PCR assay results in the (RDT+/microscopy+) and (RDT-/microscopy+) sample subsets were 97.8% (137/140) and 10.9% (24/219), respectively. Factors associated with false-negative RDT results in the (RDT-/microscopy+) samples were parasite density (<1,000/μl), pfhrp2/3 gene deletion and non-P. falciparum species (aOR 2.65, 95% CI: 1.62-4.38, P = 0.001; aOR 4.4, 95% CI 1.72-13.66, P = 0.004; and aOR 18.65, 95% CI: 5.3-38.7, P = 0.001, respectively). Overall, gene deletion and non-P. falciparum species contributed to 12.3% (24/195) and 19.0% (37/195) of false-negative RDT results, respectively. Of the false-negative RDTs results, 80.0% (156/195) were from subjects with low-density infections (< 25 parasites per 200 WBCs or <1,000/μl).

CONCLUSION

This is the first evaluation and report of the contributions of pfhrp2/3 gene deletion, non-P. falciparum species, and low-density infections to false-negative RDT results under field conditions in Uganda. In view of these findings, the use of HRP2 RDTs should be reconsidered; possibly, switching to combination RDTs that target alternative antigens, particularly in affected areas, may be beneficial. Future evaluations should consider larger and more representative surveys covering other regions of Uganda.

Non-adherence to long-lasting insecticide treated bednet use following successful malaria control in Tororo, Uganda

Indoor residual spraying (IRS) and long-lasting insecticide-treated bednets (LLINs) are common tools for reducing malaria transmission. We studied a cohort in Uganda with universal access to LLINs after 5 years of sustained IRS to explore LLIN adherence when malaria transmission has been greatly reduced. Eighty households and 526 individuals in Nagongera, Uganda were followed from October 2017 -October 2019. Every two weeks, mosquitoes were collected from sleeping rooms and LLIN adherence the prior night assessed. Episodes of malaria were diagnosed using passive surveillance. Risk factors for LLIN non-adherence were evaluated using multi-level mixed logistic regression. An age-matched case-control design was used to measure the association between LLIN non-adherence and malaria. Across all time periods, and particularly in the last 6 months, non-adherence was higher among both children <5 years (OR 3.31, 95% CI: 2.30-4.75; p<0.001) and school-aged children 5-17 years (OR 6.88, 95% CI: 5.01-9.45; p<0.001) compared to adults. In the first 18 months, collection of fewer mosquitoes was associated with non-adherence (OR 3.25, 95% CI: 2.92-3.63; p<0.001), and, in the last 6 months, residents of poorer households were less adherent (OR 5.1, 95% CI: 1.17-22.2; p = 0.03). Any reported non-adherence over the prior two months was associated with a 15-fold increase in the odds of having malaria (OR 15.0, 95% CI: 1.95 to 114.9; p = 0.009). Knowledge about LLIN use was high, and the most frequently reported barriers to use included heat and low perceived risk of malaria. Children, particularly school-aged, participants exposed to fewer mosquitoes, and those from poorer households, were less likely to use LLINs. Non-adherence to LLINs was associated with an increased risk of malaria. Strategies, such as behavior change communications, should be prioritized to ensure consistent LLIN use even when malaria transmission has been greatly reduced.

Changing malaria fever test positivity among paediatric admissions to Tororo district hospital, Uganda 2012-2019

BACKGROUND

The World Health Organization (WHO) promotes long-lasting insecticidal nets (LLIN) and indoor residual house-spraying (IRS) for malaria control in endemic countries. However, long-term impact data of vector control interventions is rarely measured empirically.

METHODS

Surveillance data was collected from paediatric admissions at Tororo district hospital for the period January 2012 to December 2019, during which LLIN and IRS campaigns were implemented in the district. Malaria test positivity rate (TPR) among febrile admissions aged 1 month to 14 years was aggregated at baseline and three intervention periods (first LLIN campaign; Bendiocarb IRS; and Actellic IRS + second LLIN campaign) and compared using before-and-after analysis. Interrupted time-series analysis (ITSA) was used to determine the effect of IRS (Bendiocarb + Actellic) with the second LLIN campaign on monthly TPR compared to the combined baseline and first LLIN campaign periods controlling for age, rainfall, type of malaria test performed. The mean and median ages were examined between intervention intervals and as trend since January 2012.

RESULTS

Among 28,049 febrile admissions between January 2012 and December 2019, TPR decreased from 60% at baseline (January 2012-October 2013) to 31% during the final period of Actellic IRS and LLIN (June 2016-December 2019). Comparing intervention intervals to the baseline TPR (60.3%), TPR was higher during the first LLIN period (67.3%, difference 7.0%; 95% CI 5.2%, 8.8%, p < 0.001), and lower during the Bendiocarb IRS (43.5%, difference - 16.8%; 95% CI - 18.7%, - 14.9%) and Actellic IRS (31.3%, difference - 29.0%; 95% CI - 30.3%, - 27.6%, p < 0.001) periods. ITSA confirmed a significant decrease in the level and trend of TPR during the IRS (Bendicarb + Actellic) with the second LLIN period compared to the pre-IRS (baseline + first LLIN) period. The age of children with positive test results significantly increased with time from a mean of 24 months at baseline to 39 months during the final IRS and LLIN period.

CONCLUSION

IRS can have a dramatic impact on hospital paediatric admissions harbouring malaria infection. The sustained expansion of effective vector control leads to an increase in the age of malaria positive febrile paediatric admissions. However, despite large reductions, malaria test-positive admissions continued to be concentrated in children aged under five years. Despite high coverage of IRS and LLIN, these vector control measures failed to interrupt transmission in Tororo district. Using simple, cost-effective hospital surveillance, it is possible to monitor the public health impacts of IRS in combination with LLIN.

Association between recent overnight travel and use of long-lasting insecticidal nets in rural Uganda: a prospective cohort study in Tororo

Background

The burden of malaria in Uganda remains high, but has become increasingly heterogenous following intensified malaria control. Travel within Uganda is recognized as a risk factor for malaria, but behaviours associated with travel are not well-understood. To address this knowledge gap, malaria-relevant behaviours of cohort participants were assessed during travel and at home in Uganda.

Methods

Residents from 80 randomly selected households in Nagongera sub-county, Tororo district were enrolled into a cohort to study malaria in rural Uganda. All participants were given long-lasting insecticidal nets (LLINs) at enrolment and were evaluated every 4 weeks at the study clinic. Participants were asked if they had travelled overnight from their home, and if so, a questionnaire was administered to capture information on travel details and behaviours. Behaviour while travelling was assessed within 4 weeks following travel during the study clinic visit. Behaviour while at home was assessed using a similar questionnaire during two-weekly home visits. Behaviours while travelling vs at home were compared using log binomial regression models with generalized estimating equations adjusting for repeated measures in the same individual. Analysis of factors associated with LLIN adherence, such as destination and duration of travel, time to bed during travel, gender and age at time of travel, were assessed using log binomial regression models with generalized estimating equations adjusting for repeated measures in the same individual.

Results

Between October 2017 and October 2019, 527 participants were enrolled and assessed for travel. Of these, 123 (23.2%) reported taking 211 overnight trips; 149 (70.6%) trips were within Tororo. Participants were less likely to use LLINs when travelling than when at home (41.0% vs. 56.2%, relative risk [RR] 0.73, 95% CI 0.60–0.89, p = 0.002); this difference was noted for women (38.8% vs 59.2%, RR 0.66, 95% CI 0.52–0.83, p = 0.001) but not men (48.3% vs 46.6%, RR 0.96, 95% CI 0.67–1.40, p = 0.85). In an adjusted analysis, factors associated with LLIN use when travelling included destination (travelling to districts not receiving indoor residual spraying [IRS] 65.8% vs Tororo district 32.2%, RR 1.80, 95% CI 1.31–2.46, p < 0.001) and duration of travel (> 7 nights 60.3% vs one night 24.4%, RR 1.97, 95% CI 1.07–3.64, p = 0.03).

Conclusions

Travellers, particularly women, were less likely to use LLINs when travelling than when at home. LLIN adherence was higher among those who travelled to non-IRS districts and for more than 1 week, suggesting that perceived malaria risk influences LLIN use. Strategies are needed to raise awareness of the importance of using LLINs while travelling.

Long-lasting insecticide-treated bed net ownership, utilization and associated factors among school-age children in Dara Mallo and Uba Debretsehay districts, Southern Ethiopia

Background

Malaria is one of the major causes of morbidity and mortality among school-age children (SAC) in sub-Saharan Africa. SAC account for more than 60% of the reservoir of malaria transmission, but they are given less emphasis in prioritizing malaria prevention interventions. This study was aimed at assessing the ownership of long-lasting insecticide treated bed nets (LLINs), its utilization and factors associated with ownership of LLINs by households and LLINs utilization among SAC in malaria-prone areas of Dara Mallo and Uba Debretsehay districts in Southern Ethiopia, October to December 2019.

Methods

This study is part of a baseline assessment in a cluster-randomized controlled trial. The data was collected through interview and observation, following a structured questionnaire, of 2261 SAC households. Univariable and multivariable multilevel logistic regressions were used to assess the association between LLINs ownership and utilization and potential predictor variables. Odds ratio (OR) and corresponding 95% confidence interval (CI) were used to determine the strength and statistical significance of association.

Results

The ownership of at least one LLIN by households of SAC was about 19.3% (95% CI 17.7–21.0%) but only 10.3% % (95% CI 7.7–13.7%) of these households had adequate access of bed nets to the household members. Ownership of bed net was marginally affected by living in semi-urban area (adjusted OR = 2.6; 95% CI 1.0–6.9) and occupational status of the household head being a civil servant (adjusted OR = 2.7; 95% CI 0.9–7.9). About 7.8% (95% CI 6.7–10.0%) of all SAC participated in the study and 40.4% (95% CI 57.4–66.7%) of children in households owning at least one LLIN passed the previous night under LLIN. LLIN utilization by SAC conditional to presence of at least one net in the household was significantly correlated with education level of mother above grade 6 (adjusted OR = 3.4; 95% CI 1.3–9.3) and the household size to bed net ratio less than or equal to 2 (adjusted OR = 20.7; 95% CI 4.7–132.5).

Conclusion

Ownership of bed net was lower than universal coverage of at least one bed net for two individuals. It is important to monitor replacement needs and educate mothers with low education level with their SAC on the benefit of consistent utilization of bed nets.

Molecular surveillance reveals the presence of pfhrp2 and pfhrp3 gene deletions in Plasmodium falciparum parasite populations in Uganda, 2017-2019

Background

Histidine-rich protein-2 (HRP2)-based rapid diagnostic tests (RDTs) are the only RDTs recommended for malaria diagnosis in Uganda. However, the emergence of Plasmodium falciparum histidine rich protein 2 and 3 (pfhrp2 and pfhrp3) gene deletions threatens their usefulness as malaria diagnostic and surveillance tools. The pfhrp2 and pfhrp3 gene deletions surveillance was conducted in P. falciparum parasite populations in Uganda.

Methods

Three-hundred (n = 300) P. falciparum isolates collected from cross-sectional malaria surveys in symptomatic individuals in 48 districts of eastern and western Uganda were analysed for the presence of pfhrp2 and pfhrp3 genes. Presence of parasite DNA was confirmed by PCR amplification of the 18s rRNA gene, msp1 and msp2 single copy genes. Presence or absence of deletions was confirmed by amplification of exon1 and exon2 of pfhrp2 and pfhrp3 using gene specific PCR.

Results

Overall, pfhrp2 and pfhrp3 gene deletions were detected in 29/300 (9.7%, 95% CI 6.6–13.6%) parasite isolates. The pfhrp2 gene was deleted in 10/300 (3.3%, 95% CI 1.6–6.0%) isolates, pfhrp3 in 9/300 (3.0%, 95% CI 1.4–5.6%) while both pfhrp2 and pfhrp3 were deleted in 10/300 (3.3%, 95% CI 1.6–6.0%) parasite isolates. Proportion of pfhrp2/3 deletions was higher in the eastern 14.7% (95% CI 9.7–20.0%) compared to the western region 3.1% (95% CI 0.8–7.7%), p = 0.001. Geographical location was associated with gene deletions aOR 6.25 (2.02–23.55), p = 0.003.

Conclusions

This is the first large-scale survey reporting the presence of pfhrp2/3 gene deletions in P. falciparum isolates in Uganda. Roll out of RDTs for malaria diagnosis should take into consideration the existence of pfhrp2/3 gene deletions particularly in areas where they were detected. Periodic pfhrp2/3 surveys are recommended to inform future decisions for deployment of alternative RDTs.

Case Report: The Role of Spatial Repellant Devices to Prevent Malaria in Low-Income Countries

Malaria is the leading cause of morbidity and mortality in Uganda. The role of spatial repellent devices in preventing malaria is controversial. The goal of this study was to evaluate the populations' acceptability of a newly designed insecticide diffuser. We distributed to three families living in southern Uganda a device commercially available, the VAPE^® portable set. This spatial repellent device offers several advantages compared with other traditional products. It is powered by lithium batteries that guarantee 20 days of uninterrupted delivery of insecticide; it contains two insecticides: empenthrin and transfluthrin; and it is simple to use, one switch to turn it "on" and/or "off." It is odorless, and it can be placed anywhere in the living/sleeping area. People can also carry it outside the house. We planned to evaluate people's compliance with its usage, its reliability, and its overall costs. We conducted a 5-month survey. We distributed the devices to three households, one device per bedroom. Ten males and 11 females, with a mean age of 26 ± 16 (range 10-51) years, lived in these houses. The compliance with the use of the device and its acceptability were high. No side effects were reported. No individual contracted malaria during the 5-month period. The major obstacle we found was the timely delivery of the devices to the evaluation area and initial compliance with the instructions on how to use the device. Larger randomized studies are needed to clarify whether there is a role for this type of spatial repellent devices in the global efforts to prevent malaria.

Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): a pragmatic, cluster-randomised trial embedded in a national LLIN distribution campaign

BACKGROUND

Long-lasting insecticidal nets (LLINs) are the primary malaria prevention tool, but their effectiveness is threatened by pyrethroid resistance. We embedded a pragmatic cluster-randomised trial into Uganda's national LLIN campaign to compare conventional LLINs with those containing piperonyl butoxide (PBO), a synergist that can partially restore pyrethroid susceptibility in mosquito vectors.

METHODS

104 health sub-districts, from 48 districts in Uganda, were randomly assigned to LLINs with PBO (PermaNet 3.0 and Olyset Plus) and conventional LLINs (PermaNet 2.0 and Olyset Net) by proportionate randomisation using an iterative process. At baseline 6, 12, and 18 months after LLIN distribution, cross-sectional surveys were done in 50 randomly selected households per cluster (5200 per survey); a subset of ten households per cluster (1040 per survey) were randomly selected for entomological surveys. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population at 6, 12, and 18 months. This trial is registered with ISRCTN, ISRCTN17516395.

FINDINGS

LLINs were delivered to households from March 25, 2017, to March 18, 2018, 32 clusters were randomly assigned to PermaNet 3.0, 20 to Olyset Plus, 37 to PermaNet 2.0, and 15 to Olyset Net. In the as-treated analysis, three clusters were excluded because no dominant LLIN was received, and four clusters were reassigned, resulting in 49 PBO LLIN clusters (31 received PermaNet 3.0 and 18 received Olyset Plus) and 52 non-PBO LLIN clusters (39 received PermaNet 2.0 and 13 received Olyset Net). At 6 months, parasite prevalence was 11% (386/3614) in the PBO group compared with 15% (556/3844) in the non-PBO group (prevalence ratio [PR] adjusted for baseline values 0·74, 95% CI 0·62-0·87; p=0·0003). Parasite prevalence was similar at month 12 (11% vs 13%; PR 0·73, 95% CI 0·63-0·85; p=0·0001) and month 18 (12% vs 14%; PR 0·84, 95% CI 0·72-0·98; p=0·029).

INTERPRETATION

In Uganda, where pyrethroid resistance is high, PBO LLINs reduced parasite prevalence more effectively than did conventional LLINs for up to 18 months. This study provides evidence needed to support WHO's final recommendation on use of PBO LLINs.

FUNDING

The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.

Review of malaria situation in Cameroon: technical viewpoint on challenges and prospects for disease elimination

Malaria still has a devastating impact on public health and welfare in Cameroon. Despite the increasing number of studies conducted on disease prevalence, transmission patterns or treatment, there are to date, not enough studies summarising findings from previous works in order to identify gaps in knowledge and areas of interest where further evidence is needed to drive malaria elimination efforts. The present study seeks to address these gaps by providing a review of studies conducted so far on malaria in Cameroon since the 1940s to date. Over 250 scientific publications were consulted for this purpose. Although there has been increased scale-up of vector control interventions which significantly reduced the morbidity and mortality to malaria across the country from a prevalence of 41% of the population reporting at least one malaria case episode in 2000 to a prevalence of 24% in 2017, the situation is not yet under control. There is a high variability in disease endemicity between epidemiological settings with prevalence of Plasmodium parasitaemia varying from 7 to 85% in children aged 6 months to 15 years after long-lasting insecticidal nets (LLINs) scale-up. Four species of Plasmodium have been recorded across the country: Plasmodium falciparum, P. malariae, P. ovale and P. vivax. Several primate-infecting Plasmodium spp. are also circulating in Cameroon. A decline of artemisinin-based combinations therapeutic efficacy from 97% in 2006 to 90% in 2016 have been reported. Several mutations in the P. falciparum chloroquine resistance (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr1) genes conferring resistance to either 4-amino-quinoleine, mefloquine, halofanthrine and quinine have been documented. Mutations in the Pfdhfr and Pfdhps genes involved in sulfadoxine-pyrimethamine are also on the rise. No mutation associated with artemisinin resistance has been recorded. Sixteen anopheline species contribute to malaria parasite transmission with six recognized as major vectors: An. gambiae, An. coluzzii, An. arabiensis, An. funestus, An. nili and An. moucheti. Studies conducted so far, indicated rapid expansion of DDT, pyrethroid and carbamate resistance in An. gambiae, An. coluzzii, An. arabiensis and An. funestus threatening the performance of LLINs. This review highlights the complex situation of malaria in Cameroon and the need to urgently implement and reinforce integrated control strategies in different epidemiological settings, as part of the substantial efforts to consolidate gains and advance towards malaria elimination in the country.

Role of individual perceptions in the consistent use of malaria preventive measures: mixed methods evidence from rural Rwanda

Background

Malaria preventive measures, including long-lasting insecticide-treated bet nets (LLINs), indoor residual spraying (IRS), and controlling mosquito breeding sites, are key measures to achieve malaria elimination. Still, compliance with these recommended measures remains a major challenge. By applying a novel and comprehensive model for determinants of malaria prevention behaviour, this study tests how individual perceptions influence the intentions to use malaria preventive measures and explores strategies that stimulate their consistent use.

Methods

The study was carried out in the sectors of Ruhuha and Busoro, Rwanda during October and November 2017, and these were conducted into two phases. Phase one involved a questionnaire survey (N = 742), whereas Phase two employed a qualitative approach that included nine focus group discussions, seven key informant interviews, and three in-depth interviews.

Results

The findings of the quantitative study showed that participants very often use LLINs (66.6%), accept IRS (73.9%), and drain stagnant water in case of presence (62%). The intentions to use malaria preventive measures were consistently driven by perceived severity, perceived self-efficacy, perceived response efficacy, and subjective norms, and hindered by perceived barriers. The intentions were also positively associated with the actual use of LLINs, acceptance of IRS, and drainage of stagnant water. There is no evidence that either not having enough LLINs (ownership of at least one bed net in the household, here referred to as availability) or having sufficient LLINs (having one LLIN per two people in the household, here referred to as accessibility) moderated the relationship between behavioural intentions and actual use of LLINs. The qualitative study indicated that participants believed malaria risk to be high and perceived a high mosquito density. They also believed that repetitive malaria episodes are caused by the perceived low effectiveness of anti-malaria medications. Lack of LLINs increased the perceived added value of LLINs, and together with the increased malaria burden increased the perceived response efficacy. Participants highlighted the need to continuously mobilize and engage community members especially those who do not use LLINs when having one, and those who do not accept the spraying activities.

Conclusion

Malaria prevention interventions should target individual perceptions to enhance consistent use of malaria preventive measures. Three strategies to improve consistent use and acceptance of these measures are highlighted: (1) ensure access to LLINs and regular spraying activities, (2) community mobilization and (3) citizen engagement in malaria prevention activities.

LLIN Evaluation in Uganda Project (LLINEUP): factors associated with childhood parasitaemia and anaemia 3 years after a national long-lasting insecticidal net distribution campaign: a cross-sectional survey

Background

Recent reductions in malaria burden have been attributed largely to long-lasting insecticidal nets (LLINs). In March–June 2017, approximately 3 years after a national LLIN distribution campaign, a cross-sectional community survey was conducted to investigate factors associated with malaria parasitaemia and anaemia, in advance of Uganda’s 2017–2018 LLIN campaign.

Methods

Households from 104 clusters in 48 districts were randomly selected using two-staged cluster sampling; 50 households were enrolled per cluster. Eligible children aged 2–10 years had blood obtained for a thick blood smear and those aged 2–4 years had haemoglobin measured. Associations between outcomes and variables of interest were assessed using log-binomial regression with generalized estimating equations to adjust for household clustering.

Results

In total, 5196 households, 8834 children with blood smear results, and 3753 with haemoglobin results were included. Only 16% of children lived in households with adequate LLIN coverage. Overall, parasite prevalence was 26.0%, ranging from 8.0% in the South West to 53.1% in East Central. Limiting data to children 2–4 years of age, parasite prevalence was 21.4%, up from 16.9% in 2014–2015 following the national LLIN campaign. In a multivariate analysis, factors associated with parasitaemia included region (East-Central vs South-Western; adjusted prevalence ratio [aPR] 6.45, 95% CI 5.55–7.50; p < 0.001), older age (8–10 vs 2–3 years; aPR 1.57, 95% CI 1.43–1.72; p < 0.001), living in a poorer household (poorest vs least poor tercile; aPR 2.32, 95% CI 2.05–2.63; p < 0.001), one constructed of traditional materials (aPR 1.13, 95% CI 1.03–1.24; p = 0.008), or without adequate LLIN coverage (aPR 1.30, 95% CI 1.14–1.48; p < 0.001). Overall, the prevalence of anaemia (haemoglobin < 10 g/dL) was 15.1% and varied geographically. In a multivariate analysis, factors associated with anaemia included region, younger age, living in a traditional house, and parasitaemia, which was the strongest predictor (aPR 2.50, 95% CI 2.12–2.95; p < 0.001).

Conclusions

Three years after a national LLIN campaign, LLIN coverage was low and parasite prevalence had increased. Parasite prevalence varied widely across Uganda; older children, those living in poorer households, and those with inadequate LLIN coverage, were at highest risk of parasitaemia. LLINs may need to be distributed more frequently through mass campaigns or continuously through sustainable mechanisms. Targeting interventions to geographic areas and populations at highest risk should also be considered.

Malaria prevention in the city of Yaoundé: knowledge and practices of urban dwellers

Background

Malaria prevention in Cameroon mainly relies on the use of ITNs. Although several free distribution campaigns of treated nets have been conducted across the country, bed net usage remains very low. A household survey was conducted to assess knowledge of the population and practices affecting treated net usage in the city of Yaoundé.

Methods

A community-based descriptive cross-sectional survey was conducted in January 2017 in 32 districts of the city of Yaoundé. Parents (household head, spouse or an elder representative) who consented to the study, were interviewed using a structured pre-tested questionnaire. Interviews were conducted in French or English. A questionnaire consisting of 22 questions was administered to know (i) people’s knowledge and attitude on preventive measures; and, (ii) attitudes concerning the treatment of malaria and estimated amount spent for malaria prevention and treatment.

Results

A total of 1643 household heads were interviewed. Over 94% of people interviewed associated malaria transmission to mosquito bites. The main methods used against mosquito bites were: treated bed nets (94%; n = 1526) and insecticide spray or coils (32.2%; n = 523). The majority of people interviewed reported using bed nets mainly to prevent from mosquito bites (84.4%, n = 1257), rather than for malaria prevention (47.3%). Knowledge and attitude analysis revealed that people with university or secondary level of education have better knowledge of malaria, prevention and treatment measures compared to those with the primary level (OR = 7.03; P < 0.001). Also, wealthy households were more aware of good practices concerning malaria prevention and treatment compared to poor ones. In the majority of districts of Yaoundé, over 50% of people interviewed per district, had good knowledge of malaria and prevention measures but less than 50% applied good practices concerning malaria treatment and prevention. The amount spent annually by a household for vector control was CFAF 11,589 ± 1133 (US$21.87 ± 2.14) and CFAF 66,403 ± 4012 (US$125.29 ± 7.57) for malaria treatment.

Conclusion

The study indicated that, despite good knowledge of malaria and prevention measures, few people apply good practices. More sensitization needs to be done to improve adherence to good practices concerning malaria prevention and treatment.

Electronic supplementary material

The online version of this article (10.1186/s12936-019-2799-6) contains supplementary material, which is available to authorized users.

LLIN Evaluation in Uganda Project (LLINEUP): a cross-sectional survey of species diversity and insecticide resistance in 48 districts of Uganda

BACKGROUND

Long-lasting insecticidal nets (LLINs) are the principal tool for malaria control in Africa and are presently treated with a single class of insecticide; however, increasing levels of insecticide resistance threaten their success. In response to this threat nets have been developed that incorporate the synergist, piperonyl butoxide (PBO), which inhibits the activity of cytochrome P450s which is one main mechanisms of insecticide resistance, allowing resistance to pyrethroids to be reversed. However, data on the value and cost effectiveness of these nets is lacking. A large-scale cluster randomised trial of conventional LLINs and PBO-LLINs was conducted in Uganda in 104 health sub-districts (HSDs) in 2017-2019. Prior to the mass distribution of LLINs, a baseline entomological survey was carried out, the results of which are reported herein. Ten households from each HSD were randomly selected for entomological surveillance at baseline which included household mosquito collections.

RESULTS

Prior to LLIN distribution entomological collections were carried out in 1029 houses across the 104 HSDs. Anopheles gambiae (s.l.) was the principal vector in all but 9 of the 71 HSDs that yielded vector species. Molecular analysis found An. gambiae (s.s.) to be the predominant vector collected. Plasmodium falciparum was detected in 5.5% of An. gambiae (s.s.) and in 4.0% of An. funestus (s.s.) examined. Infection rates of other plasmodium species (P. vivax, P. ovale and P. malariae) were lower with infection rates of 1.2% and 1.7% for An. gambiae (s.s.) and An. funestus (s.s.), respectively. The knockdown resistance (kdr) mutation Vgsc-L1014S was found at very high frequency in An. gambiae (s.s.) with the Vgsc-L1014F mutation at low frequency and the wild-type allele virtually absent. In An. arabiensis the wild-type allele was predominant. The resistance-associated alleles, Cyp4j5-L43F and Coeae1d were found at moderate frequencies which varied across the study site. Vgsc-N1575Y mutation was not found in any samples examined.

CONCLUSIONS

No significant differences between planned intervention arms was observed in vector densities, sporozoite infection rate or insecticide resistance marker frequency across the study site prior to the distribution of LLINs. Very high levels of kdr resistance were observed in all areas; however, the resistance-associated markers Cyp4j5-L43F and Coeae1d were found at varying frequencies across the study site which may have implications for the effectiveness of standard LLINs. Trial registration This study is registered with ISRCTN, ISRCTN17516395. Registered 14 February 2017, http://www.isrctn.com/ISRCTN17516395.