Reported reasons for not using a mosquito net when one is available: a review of the published literature

Pooled prevalence of malaria and associated factors among vulnerable populations in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Malaria is a serious, fatal disease, and a high-risk determinant for human health globally. Children, pregnant women, and migrants are vulnerable groups for malaria infection in African regions. Recently, malaria is an endemic disease in Ethiopia.

OBJECTIVES

This study aimed to determine the pooled prevalence of malaria and its determinant factors among the most vulnerable populations in Ethiopia.

METHODS

Electronic databases, including PubMed, Google Scholar, Web of Science, Semantic Scholar, and Scopus were used for searching articles published since the 2020 Gregorian calendar and onwards. All peer-reviewed Ethiopian journals, health institutions, and Universities were considered for article searching. A PRISMA flow chart and Endnote software were used for article screening, and to remove duplications, respectively. The modified version of the Newcastle-Ottawa Scale was used for potential risk of bias assessments. The heterogeneity among the included studies was evaluated using the indicator of heterogeneity (I2). Egger's test and funnel plot were used to examine the possible publication bias. A random-effects analysis was used to assess the pooled prevalence of malaria, and its determinant factors with a 95% CI. The screening process, data extraction, and quality assessment were done independently, and any disagreements were resolved through discussions.

RESULTS

A total of twelve studies were included in this study. The pooled malaria prevalence was 11.10% (95% CI: 6.10, 16.11). Stagnant water (AOR: 4.19, 95% CI: 2.47, 7.11), no insecticide-treated net utilization (AOR: 3.15, 95% CI: 1.73, 5.73), and staying outdoors at night (AOR: 5.19, 95% CI: 2.08, 12.94) were the pooled estimated statistically risk factors for malaria prevalence. Whereas, insecticide-treated bed net utilization (AOR: 1.59, 95% CI: 0.23, 10.95) reduces the risk of malaria infection.

CONCLUSIONS

The pooled prevalence of malaria is high among vulnerable populations. Creating awareness regarding utilization of insecticide-treated bed nets, and draining stagnant water from the environment are possible interventions to reduce the prevalence of malaria.

Reasons for mosquito net non-use in malaria-endemic countries: A review of qualitative research published between 2011 and 2021

Mosquito nets, particularly insecticide-treated nets, are the most recommended method of malaria control in endemic countries. However, individuals do not always have access to insecticide-treated nets or use them as recommended. The current paper expands on a previous review published in 2011 which highlighted a need for more qualitative research on the reasons for mosquito net non-use. We present a systematic review of qualitative research published in the past decade to assess the growth and quality of qualitative papers about net non-use and examine and update the current understanding. A comprehensive literature search was carried out in MEDLINE, CINAHL, and Global Health, in addition to a citation search of the initial review. Relevant papers were screened and discussed. The critical appraisal assessment tool was used to ensure quality. Thematic synthesis was used to extract, synthesise, and analyse study findings. Compared with the initial review, the results showed a 10-fold increase in qualitative research on the reasons for mosquito net non-use between 2011 and 2021. In addition, the quality of the research has improved, with more than 90% of the papers receiving high scores, using the critical appraisal assessment tool. The reported reasons for non-use were categorised into four themes: human factors, net factors, housing structure, and net access. More than two thirds of the studies (25/39) were led by authors affiliated with institutions in malaria-endemic countries. Despite the distribution of free mosquito nets in malaria-endemic countries, earlier reported challenges remain pertinent. The most common reasons for net non-use across all regions of Malaria endemic countries pertained to human- and net-related factors. The research focus should shift towards intervention studies to address these issues.

Will a lack of fabric durability be their downfall? Impact of textile durability on the efficacy of three types of dual-active-ingredient long-lasting insecticidal nets: a secondary analysis on malaria prevalence and incidence from a cluster-randomized trial in north-west Tanzania

BACKGROUND

The Dual-Active Ingredient long-lasting insecticidal nets (Dual-AI LLIN) have been developed to counteract the reduced efficacy of pyrethroid (PY)-only nets due to widespread pyrethroid insecticide resistance in malaria vector mosquitoes. They constitute half of the nets distributed in sub-Saharan Africa between 2022 and 2024. However, their effectiveness once they develop holes is unclear, particularly in pyrethroid-resistant settings. This study evaluates the textile integrity of three dual- AI LLINs compared to standard PY LLN, over 3 years of use in a community in Tanzania and the associated impact on malaria prevalence and incidence.

METHODS

A secondary analysis of data from a randomized controlled trial (RCT) in North-western Tanzania was conducted to evaluate the effectiveness of α-cypermethrin only; pyriproxyfen and α-cypermethrin (PPF-PY); chlorfenapyr and α-cypermethrin (chlorfenapyr-PY); and the synergist piperonyl butoxide and permethrin (PBO-PY) LLINs on malaria infection prevalence and case incidence. The association between the net textile condition and 1/malaria prevalence over 3 years of use between 2019 and 2022, and 2/malaria case incidence in a cohort of children over 2 years of follow-up was assessed between 2019 and 2021.

RESULTS

There was no significant association between damaged (OR 0.98, 95% CI 0.71-1.37, p-value  = 0.655) and too-torn (OR 1.07, 95% CI 0.77-1.47, p-value = 0.694) compared to intact nets on malaria prevalence for all net types. However, there were reduced rates of malaria case incidence in children sleeping under a net in good condition compared to too-torn nets (incidence rate ratio (IRR) 0.76 [95% CI 0.63-0.92], p = 0.005). Malaria incidence was also consistently lower in too-torn PBO-PY LLIN (IRR = 0.37 [95% CI 0.19-0.72], p = 0.003) and chlorfenapyr-PY LLIN (IRR = 0.45 [95% CI 0.33-0.97], p = 0.053) compared to an intact PY-only LLIN during the first year of follow up. In year 2, the incidence was only significantly lower in intact chlorfenapyr-PY LLIN (IRR = 0.49 [95% CI 0.29-0.81], p = 0.006) compared to intact PY LLIN.

CONCLUSION

The study confirmed that sleeping under a chlorfenapyr-PY LLIN or PBO-PY LLIN offered superior protection to pyrethroid-only nets even when torn. Preventing the development of holes is essential as they impact the level of protection offered against malaria infection.

TRIAL REGISTRATION

ClinicalTrials.gov, number (NCT03554616).

The effect of physical barriers under a raised house on mosquito entry: an experimental study in rural Gambia

BACKGROUND

Anopheles gambiae, the major malaria mosquito in sub-Saharan Africa, feed largely indoors at night. Raising a house off the ground with no barriers underneath reduces mosquito-house entry. This experiment tested whether walling off the space under an elevated hut affects mosquito-hut entry.

METHODS

Four inhabited experimental huts, each of which could be moved up and down, were used in rural Gambia. Nightly collections of mosquitoes were made using light traps and temperature and carbon dioxide levels monitored indoors and outdoors using loggers. Each night, a reference hut was kept at ground level and three huts raised 2 m above the ground; with the space under the hut left open, walled with air-permeable walls or solid walls. Treatments were rotated every four nights using a randomized block design. The experiment was conducted for 32 nights. Primary measurements were mosquito numbers and indoor temperature in each hut.

RESULTS

A total of 1,259 female Anopheles gambiae sensu lato were collected in the hut at ground level, 655 in the hut with an open ground floor, 981 in the hut with air-permeable walls underneath and 873 in the hut with solid walls underneath. Multivariate analysis, adjusting for confounders, showed that a raised hut open underneath had 53% fewer mosquitoes (95% CI 47-58%), those with air-permeable walls underneath 24% fewer (95% CI 9-36%) and huts with solid walls underneath 31% fewer (95% CI 24-37%) compared with a hut on the ground. Similar results were found for Mansonia spp. and total number of female mosquitoes, but not for Culex mosquitoes where hut entry was unaffected by height or barriers. Indoor temperature and carbon dioxide levels were similar in all huts.

CONCLUSION

Raising a house 2 m from the ground reduces the entry of An. gambiae and Mansonia mosquitoes, but not Culex species. The protective effect of height is reduced if the space underneath the hut is walled off.

Acceptance of and Adherence to a Four-Dose RTS,S/AS01 Schedule: Findings from a Longitudinal Qualitative Evaluation Study for the Malaria Vaccine Implementation Programme

BACKGROUND

The WHO recommended the use of the RTS,S/AS01 malaria vaccine (RTS,S) based on a pilot evaluation in routine use in Ghana, Kenya, and Malawi. A longitudinal qualitative study was conducted to examine facilitators and barriers to uptake of a 4-dose RTS,S schedule.

METHODS

A cohort of 198 caregivers of RTS,S-eligible children from communities where RTS,S was provided through the pilot were interviewed three times over a ≈22-month, 4-dose schedule. The interviews examined caregiver perceptions and behaviors. Children's vaccination history was obtained to determine dose uptake.

RESULTS

162 caregivers remained at round 3 (R3); vaccination history was available for 152/162 children. Despite early rumors/fears, the uptake of initial doses was high, driven by vaccine trust. Fears dissipated by R2, replaced with an enthusiasm for RTS,S as caregivers perceived its safety and less frequent and severe malaria. By R3, 98/152 children had received four doses; 34 three doses; 9 one or two doses; and 11 zero doses. The health system and information barriers were important across all under-dose cases. Fears about AEFIs/safety were important in zero-, one-, and two-dose cases. Competing life/livelihood demands and complacency were found in three-dose cases. Regardless of the doses received, caregivers had positive attitudes towards RTS,S by R3.

CONCLUSIONS

Findings from our study will help countries newly introducing the vaccine to anticipate and preempt reasons for delayed acceptance and missed RTS,S doses.

Risk of imported malaria infections in Zanzibar: a cross-sectional study

BACKGROUND

Zanzibar has made substantial progress in malaria control with vector control, improved diagnosis, and artemisinin-based combination therapy. Parasite prevalence in the population has remained around 1% but imported infections from mainland Tanzania contribute to sustained local transmission. Understanding travel patterns between mainland Tanzania and Zanzibar, and the risk of malaria infection, may help to control malaria importation to Zanzibar.

METHODS

A rolling cross-sectional survey linked to routine reactive case detection of malaria was carried out in Zanzibar between May 2017 and October 2018. Households of patients diagnosed with malaria at health facilities were surveyed and household members were tested for malaria using rapid diagnostic tests and a sub-sample by quantitative PCR (qPCR). Interviews elicited a detailed travel history of all household members who had travelled within the past two months, including trips within and outside of Zanzibar. We estimated the association of malaria infection with travel destinations in pre-defined malaria endemicity categories, trip duration, and other co-variates using logistic regression.

RESULTS

Of 17,891 survey participants, 1177 (7%) reported a recent trip, of which 769 (65%) visited mainland Tanzania. Among travellers to mainland Tanzania with travel destination details and a qPCR result available, 241/378 (64%) reported traveling to districts with a 'high' malaria endemicity and for 12% the highest endemicity category was 'moderate'. Travelers to the mainland were more likely to be infected with malaria parasites (29%, 108/378) than those traveling within Zanzibar (8%, 16/206) or to other countries (6%, 2/17). Among travellers to mainland Tanzania, those visiting highly endemic districts had a higher odds of being qPCR-positive than those who travelled only to districts where malaria-endemicity was classified as low or very low (adjusted odd ratio = 7.0, 95% confidence interval: 1.9-25.5). Among travellers to the mainland, 110/378 (29%) never or only sometimes used a mosquito net during their travel.

CONCLUSIONS

Strategies to reduce malaria importation to Zanzibar may benefit from identifying population groups traveling to highly endemic areas in mainland Tanzania. Targeted interventions to prevent and clear infections in these groups may be more feasible than attempting to screen and treat all travellers upon arrival in Zanzibar.

Predictors of mosquito bed net use among children under-fives in Ghana: a multilevel analysis of the 2019 malaria indicator survey

BACKGROUND

Morbidities and mortalities due to malaria can be prevented by the use of insecticide-treated mosquito bed nets (ITN), which has been proven for malaria control and elimination. The purpose of this study was to assess the critical factors that predict the use of ITN among children under-fives in Ghana.

METHODS

The study utilized data from the 2019 Ghana Malaria Indicator Survey (GMIS). The outcome variable was mosquito bed net use among children under-fives. To determine critical factors that independently predict ITN use, multilevel multivariable logistic regression was employed using Stata version 16. Odds ratios and associated 95% confidence intervals and p-values were reported. A p < 0.05 was used to declare statistical significance.

RESULTS

The overall prevalence of ITN usage was 57.4%. Utilization of bed nets was 66.6% in the rural areas and 43.5% in the urban areas, was highest in the Upper West region (80.6%) even when stratified to rural (82.9%) and urban areas (70.3%) whilst Greater Accra region (30.5%, rural = 41.7%, urban = 28.9%) had the least. The community level multilevel analysis showed that bed net utilization was higher among children in rural areas [AOR = 1.99, 95% CI 1.32-3.01, p = 0.001] and in household with wooden wall materials [AOR = 3.29, 95% CI 1.15-9.40, p = 0.027]. Bed net utilization was however, less for households with 3 + children under-five [AOR = 0.29, 95% CI 0.19-0.46, p < 0.001), 4 years old (AOR = 0.66, 95% CI 00.48-00.92, p = 0.014], without universal access to bed net [AOR = 0.52, 95% CI 0.37-0.73, p < 0.001], those in the Greater Accra [AOR = 0.26, 95% CI 0.13-0.51, p < 0.001], Eastern [AOR = 0.47, 95% CI 0.23-0.95, p = 0.036], Northern [AOR = 0.42, 95% CI 0.20-0.88, p = 0.022], middle [AOR = 0.57, 95% CI 0.35-0.94, p = 0.026] and rich/richest [AOR = 0.51, 95% CI 0.29-0.92, p = 0.025] household wealth quintile. Substantial unobserved household and community level differences in bed net use were found.

CONCLUSION

This study demonstrates the need to intensify promotion of ITN use to those in urban areas, Greater Accra, Eastern and Northern regions, houses without wooden wall materials, middle and rich/richest households. Interventions should be targeted at older children and households with more under-five children and to ensure full access and use of ITNs among all children under-fives in each household as part of the overall goal of achieving the health-related SDGs.

Socio-demographic and economic inequity in the use of insecticide-treated bed nets during pregnancy: a survey-based case study of four sub-Saharan African countries with a high burden of malaria

Despite global investments in malaria eradication and mitigation efforts, including the dissemination of ITNs to vulnerable communities, the goal of widespread malaria control among pregnant women has yet to be realized in many African countries. One of the explanations forwarded for this is related to the adoption and regular use of ITNs by pregnant women. Based on the available DHS and MIS data from four malaria high burden African countries- according to WHO malaria report 2020- inequality was measured by applying both relative and absolute summary measures for the four dimensions of inequality: economic status, education, place of residence and region. By considering the number of subgroups in each variable, simple and complex summary measures were used.ITN utilization by pregnant women showed an increasing trend over time in all the four countries. There was also significant inequality (variability) in the ITN utilization among population groups. DRC, Mozambique and Uganda showed noticeable inequality that favors the richest population, whereas in Nigeria the inequality was observed among both the rich and the poor during different survey yearsIn conclusion, in all the four countries, there were significant regional variations or differences in ITN use among pregnant mothers across all dimensions of inequality in the survey years. Tailored cost-effective interventions could be considered to improve ITN utilization among pregnant women.

Effect of passive and active ventilation on malaria mosquito house entry and human comfort: an experimental study in rural Gambia

Rural houses in sub-Saharan Africa are typically hot and allow malaria mosquitoes inside. We assessed whether passive or active ventilation can reduce house entry of malaria mosquitoes and cool a bedroom at night in rural Gambia. Two identical experimental houses were used: one ventilated and one unventilated (control). We evaluated the impact of (i) passive ventilation (solar chimney) and (ii) active ventilation (ceiling fan) on the number of mosquitoes collected indoors and environmental parameters (temperature, humidity, CO₂, evaporation). Although the solar chimney did not reduce entry of Anopheles gambiae sensu lato, the ceiling fan reduced house entry by 91% compared with the control house. There were no differences in indoor nightly temperature, humidity or CO₂ between intervention and control houses in either experiment. The solar chimney did not improve human comfort assessed using psychrometric analysis. While the ceiling fan improved human comfort pre-midnight, in the morning it was too cool compared with the control house, although this could be remedied through provision of blankets. Further improvements to the design of the solar chimney are needed. High air velocity in the ceiling fan house probably reduced mosquito house entry by preventing mosquito flight. Improved ventilation in houses may reduce malaria transmission.

Utilization of Insecticide-Treated Nets in Households for Under-5 Children and Associated Factors in East Mesekan District, Gurage Zone, Southern Ethiopia

INTRODUCTION

Insecticide-treated nets (ITNs) are widely used tools that have been proven effective in preventing and controlling malaria. However, usage varies among households and can greatly affect the benefits of ITNs. Thus, this study aimed to assess the household utilization of insecticide-treated nets and its associated factors for under-5 children.

METHODS

A cross-sectional study was conducted in March-April 2020 in the East Mesekan district. A total of 591 households with under-5 children were chosen by using a systematic random sampling approach for the interviews. The data was collected using a pretested questionnaire. Epi-Data version 3.1 was used to enter data and SPSS version 21 for analysis. A P-value of .05 was considered statistically significant.

RESULTS

In this study, 58.2% (95% CI: [54.1%-62.2%]) of household participants used ITN for children under 5 years of age while sleeping the night before the survey. The study participants' overall knowledge and practice of malaria prevention were 27.1% and 23.9%, respectively. Having a family size of less than 5 (AOR = 0.60, 95% CI: [0.37-0.98]) and complaints of skin irritation (AOR = 0.43, 95% CI: [0.29-0.63]) significantly decreased ITN utilization. However, having 1 ITN (AOR = 2.15, 95% CI: [1.15-4.02]) or 2 ITNs (AOR = 2.58, 95% CI: [1.51-4.39]), as well as low (AOR = 2.07, 95% CI: [1.33-3.20]) and medium (AOR = 1.83, 95% CI: [1.11-3.02]) knowledge of ITN importance, increased ITN utilization significantly.

CONCLUSIONS

The households' use of ITNs for children under the age of 5 was inadequate. It was significantly associated with having a family size of less than 5, complaints of skin irritation, owning 1 or 2 ITNs, and having low and medium knowledge of its importance. It is recommended that continuous and progressive health awareness about the consistent use of ITN for malaria prevention in the study area be promoted.

Regional variations in child and mother's characteristics influencing the use of insecticide treated net in Nigeria

Nigeria accounts for a quarter of malaria cases worldwide, which can be prevented with the use of insecticide treated nets (ITN). While studies have documented mother-related characteristics influencing use of ITN, regional variations in the influence of those factors are not well known. This study investigated nine factors (age, place of residence, education, religion, wealth, number of children in the household, sex of child, age of child and previous experience of child mortality) as possible predictors of use of ITN for children and how the associations vary across northern and southern parts of the country. The study utilised the 2015 Nigeria Malaria Indicator Survey, which comprised 6524 mothers (4009 from the north and 2151 from the south) aged 15-49. Bivariate and multivariate logistic regression models were fitted. It was found that, less than half (47.9%) of the respondents reported no access to a mosquito net in the north compared to 70.8% in the south. More than half (51.4%) of the northern respondents used insecticide treated net (ITN) for the child compared to 27.1% of southern mothers. When the variables are fitted together in the same model, place of residence, mother's age, mother's education, wealth, religion, number of children in the household and previous experience of child mortality were associated with the use of ITN. Regional variations exist in the influence of mother's age, number of children in the household and previous experience of child mortality. It was submitted that mother's characteristics are more important than the child's factors in the use of ITN, and that, contrary to the theory of poor utilisation of health-related facilities in the north compared to the south, residents in the former have access to and use ITN more than their counterparts from the latter.

Reported reasons for non-use of insecticide-treated nets in large national household surveys, 2009-2021

BACKGROUND

Insecticide-treated nets (ITN) are the cornerstone of modern malaria vector control, with nearly 3 billion ITNs delivered to households in endemic areas since 2000. ITN access, i.e. availability within the household, based on the number of ITNs and number of household members, is a pre-requisite for ITN use. Factors determining ITN use are frequently examined in published literature, but to date, large household survey data on reasons given for non-use of nets have not been explored.

METHODS

A total of 156 DHS, MIS, and MICS surveys conducted between 2003 and 2021 were reviewed for questions on reasons why nets were not used the previous night, identifying twenty-seven surveys. The percent of nets that were reported used the previous night was calculated for the 156 surveys, and frequencies and proportions of reasons for non-use were calculated within the twenty-seven surveys. Results were stratified by household supply of ITNs in three categories (not enough", "enough", and "more than enough") and by residence (urban/rural).

RESULTS

The proportion of nets used the previous night averaged over 70% between 2003 and 2021, with no discernible change over this period. Reported reasons for why a net goes unused fell largely into three categories-nets that are extra/being saved for future use; the perception that there is little risk of malaria (particularly in dry season); and "other" responses. Net attributes such as colour, size, shape, and texture, and concerns related to chemicals were the least frequent reasons given. Reasons for non-use of nets varied by household net supply, and in some surveys by residence. In Senegal's continuous DHS, the proportion of nets used peaked during high transmission season, and the proportion of nets that went unused due to "no/few mosquitoes" peaked during the dry season.

CONCLUSIONS

Unused nets were primarily those being saved for later use, or were not used due to perceived low risk of malaria. Classifying reasons for non-use into broader categories facilitates the design of appropriate social and behaviour change interventions to address the major underlying reasons for non-use, where this is feasible.

Ideational factors and their association with insecticide treated net use in Magoe District, Mozambique

BACKGROUND

Insecticide treated bed nets (ITN) are considered a core malaria vector control tool by the WHO and are the main contributor to the large decline in malaria burden in sub-Saharan Africa over the past 20 years, but they are less effective if they are not broadly and regularly used. ITN use may depend on factors including temperature, relative humidity, mosquito density, seasonality, as well as ideational or psychosocial factors including perceptions of nets and perceptions of net use behaviours.

METHODS

A cross-sectional household survey was conducted as part of a planned randomized controlled trial in Magoe District, Mozambique. Interviewers captured data on general malaria and ITN perceptions including ideational factors related to perceived ITN response efficacy, self-efficacy to use an ITN, and community norms around ITN using a standardized questionnaire. Only households with sufficient ITNs present for all children to sleep under (at least one ITN for every two children under the age of five years) were eligible for inclusion in the study. Additional questions were added about seasonality and frequency of ITN use.

RESULTS

One-thousand six hundred sixteen mother-child dyads were interviewed. Responses indicated gaps in use of existing nets and net use was largely independent of ideational factors related to ITNs. Self-reported ITN use varied little by season nor meaningfully when different methods were used to solicit responses on net use behaviour. Mothers' perceived response efficacy of ITNS was negatively associated with net use (high perceived response efficacy reduced the log-odds of net use by 0.27 (95% CI - 0.04 to - 0.51), implying that stronger beliefs in the effectiveness of ITNs might result in reduced net use among their children.

CONCLUSIONS

In this context, ITN use among children was not clearly related to mothers' ideational factors measured in the study. Scales used in solicitation of ideation around ITN use and beliefs need careful design and testing across a broader range of populations in order to identify ideational factors related to ITN use among those with access.

Behavioural determinants of malaria risk, prevention, and care-seeking behaviours among forest-goers in Cambodia

BACKGROUND

Cambodia has made significant progress towards achieving malaria elimination by 2025. Cases continue to decrease and are primarily concentrated in forested areas. Forest-goers are most at risk of malaria due to their proximity to the forest, poor sleeping conditions, frequent mobility, and distance from health services. Consistent use of long-lasting insecticidal nets or hammock nets (LLINs/LLIHNs), early diagnosis and treatment of cases are central to reducing disease burden. The aim of this study was to understand forest-goers' knowledge, attitudes, and practices related to malaria prevention and care-seeking, and to identify key behavioural determinants of LLIN/LLIHN use and prompt care-seeking within 24 h of developing a fever.

METHODS

A mixed-methods study design consisting of a cross-sectional survey and qualitative in-depth interviews was implemented in two Cambodian provinces. Survey participants (N = 654) were recruited using respondent driven sampling. Interview participants (N = 28) were selected using purposive sampling. Findings from the survey were analysed using univariate and bivariate analysis and multivariate weighted logistic regression. Interviews were coded and analysed using thematic content analysis.

RESULTS

All study participants had heard of malaria and 98% knew that malaria was transmitted by mosquitoes. LLIN/LLIHN ownership was high (94%). Although 99% of participants perceived LLIN/LLIHN use as an important malaria prevention measure, only 76% reported using one during their last visit to the forest. Only 39% of survey participants who reported seeking care did so within the recommended 24 h from fever onset during their last febrile illness. Among all study participants, 43% did not seek any healthcare during their last febrile episode. In controlled regression models, perceived community social norms were significantly associated with LLIN/LLIHN use (OR: 2.7, 96% CI 1.99-2.64) and care-seeking within 24 h of fever onset (OR: 1.7, 95% CI 1.00-2.88). Social support from other forest-goers was also significantly associated with LLIN/LLIHN use (OR: 4.9, 95% CI 1.32-18.12).

CONCLUSIONS

Study findings are consistent with other studies on LLIN/LLIHN use and care-seeking behaviours. While rates of LLIN/LLIHN ownership were high among the study population, rates of use were not as high. More concerning were the delayed care-seeking behaviours. Social behaviour change activities should incorporate social norms and social support as mechanisms for behaviour change given the identified positive correlations with LLIN/LLIHN use and prompt care-seeking.

Factors influencing consistent use of bed nets for the control of malaria among children under 5 years in Soroti District, North Eastern Uganda

BACKGROUND

The use of insecticide-treated bed nets has been proven to be effective in reducing malaria transmission in highly endemic areas. Use of long-lasting insecticidal nets (LLINs) has been embraced by many malaria endemic countries. LLINs are up to 95% effective in inhibiting blood feeding, when used consistently even after 7 years. The challenge, however, is enhancing their consistent use, especially by the most vulnerable groups (children under 5 years and pregnant women). The study established factors associated with consistent use of bed nets for malaria control among children under 5 years in Soroti district.

METHODS

The study employed a cross-sectional design, with multi-stage sampling of households. A total of 400 households (HH) were sampled and the HH head in each household interviewed. Key informant interviews (KIIs) were conducted with 7 key informants who were knowledgeable on the subject matter. Data analysis was done using SPSS 17.0 at Univariate, Bivariate and Multivariable levels; after entry and cleaning. Key informants' data were summarized manually; verbatim quotes and text used to reinforce quantitative data in line with objectives.

RESULTS

Only 56.8% of the 690 children under 5 years used bed nets consistently. The factors affecting consistent bed net use were age of the child, their use of bed nets the previous night, occupation of caretaker, respondents' perceived susceptibility, perceived risk of getting malaria, size and shape of the bed nets. Rectangular nets were difficult to hang daily in huts according to most key informants.

CONCLUSION

Consistent bed net use among under fives is still below the RBM target of 85% by 2015 and can be enhanced by providing conical bed nets and setting aside a health education programme to emphasize the effectiveness of even one mosquito in spreading malaria at night to the entire household and ability of bed nets to stop transmission better than other methods.

Exploring Potential Determinants of Mosquito Net Ownership and Use in Somalia: A Cross-Sectional Study

In Somalia, malaria remains a major public health threat. Understanding what influences the ownership and use of mosquito nets is of vital importance to accelerate malaria prevention efforts in the country. To explore the potential determinants of mosquito net ownership and use, this study conducted a secondary data analysis of the Somalia Micronutrient Survey 2019. Survey participants were identified through the multi-stage stratified cluster sampling, and logistic regression was performed for bivariate and multivariate analysis. The results suggested that household head’s age, educational attainment, household size, employment status of household members, socioeconomic status, geographic regions and type of residence are significantly associated with mosquito net ownership (p < 0.05). The analysis also highlighted household head’s age as an influential factor to mosquito net use. By further exploring and understanding the psychosocial determinants of mosquito net ownership and use, malaria prevention interventions can be made more effective in Somalia.

Long-lasting insecticidal nets provide protection against malaria for only a single year in Burundi, an African highland setting with marked malaria seasonality

BACKGROUND

Long-lasting insecticidal nets (LLINs) are one of the key interventions in the global fight against malaria. Since 2014, mass distribution campaigns of LLINs aim for universal access by all citizens of Burundi. In this context, we assess the impact of LLINs mass distribution campaigns on malaria incidence, focusing on the endemic highland health districts. We also explored the possible correlation between observed trends in malaria incidence with any variations in climate conditions.

METHODS

Malaria cases for 2011-2019 were obtained from the National Health Information System. We developed a generalised additive model based on a time series of routinely collected data with malaria incidence as the response variable and timing of LLIN distribution as an explanatory variable to investigate the duration and magnitude of the LLIN effect on malaria incidence. We added a seasonal and continuous-time component as further explanatory variables, and health district as a random effect to account for random natural variation in malaria cases between districts.

RESULTS

Malaria transmission in Burundian highlands was clearly seasonal and increased non-linearly over the study period. Further, a fast and steep decline of malaria incidence was noted during the first year after mass LLIN distribution (p<0.0001). In years 2 and 3 after distribution, malaria cases started to rise again to levels higher than before the control intervention.

CONCLUSION

This study highlights that LLINs did reduce the incidence in the first year after a mass distribution campaign, but in the context of Burundi, LLINs lost their impact after only 1 year.

Malaria Knowledge-Base and Prevalence of Parasitaemia in Asymptomatic Adults in the Forest Zone of Ghana

PURPOSE

To determine the levels of knowledge, awareness and perception of malaria, and to determine the infection status among asymptomatic adults in selected districts.

METHODS

This descriptive, cross-sectional study recruited 849 participants from seven districts in the malaria meso-endemic forest zone of Ghana. Questionnaires were administered to elicit responses from asymptomatic adults on malaria awareness, knowledge and insecticide-treated net (ITN) usage. Capillary blood samples were taken from study subjects for malaria Rapid Diagnostic Test (RDT) and microscopy. Descriptive statistics was used to analyse quantitative and qualitative data.

RESULTS

Ninety-eight percent of participants were aware of malaria, 94.0% owned ITNs but only 35.5% consistently used them. Also, 56.7% correctly associated malaria with mosquitoes and 54.5% identified stagnant water as the breeding site. Twelve percent (12.2%) and 13.1% of the subjects tested positive for malaria via RDT and microscopy, respectively. Of the 111 confirmed malaria cases, 107 had Plasmodium falciparum infections, two had Plasmodium ovale infections and there were two Plasmodium falciparum-Plasmodium ovale mixed infections.

CONCLUSION

Awareness and knowledge of malaria was satisfactory but this did not translate into mosquito avoidance behaviour due to deep-seated perceptions and myths. With the prevalence of asymptomatic parasitaemia observed, this reservoir of infection could be dislodged with appropriate health education targeted at women in the rural communities.

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.

Factors associated with non-use of insecticide-treated bed nets among pregnant women in Zambia

Background

Despite the Zambian government’s efforts to ensure 80% use of insecticide-treated nets (ITNs) among pregnant women, ITN use remains critically low. Only 49% of pregnant women reported sleeping under an ITN in 2018 in the country. This study aims to determine the prevalence of, and the factors associated with the non-use of ITNs among pregnant women in Zambia.

Methods

This study was a secondary analysis of the data collected during the 2018 Zambian Demographic and Health Survey. One thousand one hundred and thirty-eight (1 138) pregnant women were included in the study. The prevalence of the non-use of ITNs was computed and univariable and multivariable logistic regression models were fitted to determine the factors associated with the non-use of ITNs in the study population.

Results

The study found that 578 (50.8%) pregnant women reported not using an ITN the night before the survey. The results of the multivariable logistic regression indicated that, primary level education (OR = 2.13, 95% CI 1.23–3.68), ITN per household member (OR = 0.01, 95% CI 0.00–0.02), parity (OR = 0.83, 95% CI 0.70–0.99), moderate malaria prevalence provinces (OR = 0.34, 95% CI 0.23–0.50), high malaria prevalence provinces (OR = 0.26, 95% CI 0.18–0.39) and currently in a union (OR = 0.52, 95% CI 0.30–0.88) were significantly associated with the non-use of ITNs.

Conclusion

This study showed a high prevalence of the non-use of ITNs among pregnant women in Zambia. Factors found to be associated with the non-use of ITNs in the study population are: ITN per household member, parity, education, marital status and malaria prevalence provinces. Addressing the identified factors will require intensification of ITN programming and other malaria preventive measures.

Understanding the current state-of-the-art of long-lasting insecticide nets and potential for sustainable alternatives

Long-lasting insecticide-treated nets (LLINs) are widely distributed to communities where malaria is a major cause of mortality, especially to those under the age of 5 years-old. To protect people from this illness, LLINs provide physical and chemical barriers by containing insecticides within the matrix of the polymer fibers or on the surface. Synthetic polymers including polyethylene and polyester are common material choices for these nets, and pyrethroids, along with other additives, are the insecticides of choice for this application. Many studies have shown the effectiveness of these nets on the impact of malaria is highly significant, but there is a demand for more durable nets that last longer than only a few years as the available products are rated for 2–3 years of use. Improvements in this area would increase cost effectiveness, because better durability would reduce the frequency of manufacturing and worldwide shipping. Additionally, due to the plastic fibers, the waste can build quickly, damaging the environment. To deal with the sustainability and durability issues, biodegradable and renewable materials should be chosen as an alternative.

•

LLINs are important for malaria control, but they require a sustainable and durable alternative to synthetic polymers.

•

LLINs are made by extrusion of pyrethroids and synthetic polymers or by coating.

•

The current LLINs include important active ingredients to improve insecticidal activity.

•

Bio-based polymers have the potential to be used to develop a superior LLIN to those available currently.

Assessing the impact of a novel house design on the incidence of malaria in children in rural Africa: study protocol for a household-cluster randomized controlled superiority trial

Background

Traditional rural housing in hot, humid regions of sub-Saharan Africa usually consists of single-level, poorly ventilated dwellings. Houses are mostly poorly screened against malaria mosquitoes and limited airflow discourages the use of bednets resulting in high indoor transmission. This study aims to determine whether living in a novel design house with elevated bedrooms and permeable screened walls reduces malaria, respiratory tract infections, and diarrhoea among children in rural Tanzania.

Methods/study design

This is a household-randomized, controlled study in 60 villages in Mtwara, Tanzania. A total of 550 households are randomly selected, 110 of which are allocated a novel design house and 440 households continue to reside in traditional houses. A dynamic cohort of about 1650 children under 13 years will be enrolled and followed for 3 years, approximately 330 living in novel design houses and 1320 in traditional rural houses. The primary endpoint is the incidence of malaria; secondary endpoints are incidences of acute respiratory tract infections and diarrhoea diseases detected by passive and active surveillance. Exposure to malaria vectors will be assessed using light traps in all study houses. Structural, economic, and social science studies will assess the durability, cost-effectiveness, and acceptability of the new houses compared with traditional housing. Environmental data will be collected indoors and outdoors in study homes to assess the differences between house typologies.

Discussion

This is the first randomized controlled trial to assess the protective efficacy of a new house design targeting malaria in sub-Saharan Africa. The findings of this study could influence the future construction of homes in hot and humid zones of Africa.

Trial registration

ClinicalTrials.govNCT04529434. Registered on August 27, 2020

A qualitative study of the acceptability of remote electronic bednet use monitoring in Uganda

BACKGROUND

Distribution of long-lasting insecticide treated nets (LLINs) is the most widely used intervention for the prevention of malaria but recall and social desirability biases may lead to challenges in accurately measuring use of bednets. SmartNet is a remote electronic monitor that provides objective measurements of bednet use over weeks at a time. Assessing local acceptability is important when implementing innovative global health technologies such as SmartNet. This study draws on established models such as the Technology Acceptance Model (TAM) and Theoretical Framework of Acceptability (TFA) to assess acceptability of SmartNet in Ugandan households.

METHODS

Semi-structured qualitative interviews were conducted at weeks one and six following installation of SmartNet in ten households in Western Uganda. Heads-of-households answered open-ended questions addressing the main acceptability domains of the TFA and TAM models (i.e. perceived ease of use, ethicality, etc.). Responses were digitally recorded, transcribed, coded and analyzed using a thematic analysis approach.

RESULTS

Seven out of ten households interviewed reported no difference in use between SmartNet and a standard LLIN. Households stated the large size, soft fabric, and the efficacy of SmartNet relative to a standard LLIN contributed to perceived usefulness and perceived ease of use. Opportunity costs of the novel monitoring system expressed by households included difficulty washing nets and dislike of blinking lights on the device. Barriers to SmartNet use focused on questions of the ethics of bednet use monitoring, discomfort with technical aspects of the device and a poor understanding of its function amongst others in the community. However, explaining SmartNet to other community members resolved these concerns and often resulted in interest and acceptance among peers.

CONCLUSION

Objective monitoring of bednet use with SmartNet appears acceptable to these households in Uganda. Use of SmartNet seems to be similar to behaviors around use of standard LLINs. Viewpoints on many aspects of SmartNet were generally favorable. Concerns around ethicality of bednet monitoring are present and indicate the need for continuing community education. The device will continue to be optimized to make it more acceptable to users and to accurately reflect standard LLIN use to improve our understanding of prevention behaviors in malaria endemic settings.

Has Zika Been Forgotten? Findings From Nationwide Survey on Knowledge, Attitudes, and Mosquito Preventive Practices in Malaysia

OBJECTIVE

The aim of this study is to assess knowledge and attitudes toward Zika virus disease (ZVD) as well as mosquito prevention practices in Malaysia at a nationwide level.

METHODS

Computer-assisted telephone interviews (CATI) were conducted between June 2019 and February 2020.

RESULTS

There are gaps in knowledge about the symptoms, mode of transmission, and risk of microcephaly. The mean for the Zika-related knowledge score was 5.9 (SD ± 4.4) out of a possible score of 14. The majority perceived little or no risk of getting ZVD (75.0%) and 75.5% were a little or not at all worried about ZVD. A high proportion reported the use of insect sprays or mosquito coils to prevent mosquito bites; however, a relatively lower proportion of people reported fixing mosquito netting on doors and windows, and using mosquito bed nets. The mean for the mosquito prevention practices score was 11.9 (SD ± 4.7) out of a possible score of 27. Important factors influencing mosquito prevention practices include household income, environment factors, risk perception, and Zika-related knowledge.

CONCLUSION

Zika prevention measures should be targeted in priority toward residents in lower socioeconomic neighborhoods. Campaigns should focus on messages highlighting the high risk of getting dengue.

Mixed effect analysis of factors influencing the use of insecticides treated bed nets among pregnant women in Ghana: evidence from the 2019 Malaria Indicator Survey

Background

Malaria during pregnancy is a major cause of maternal morbidity globally and leads to poor birth outcomes. The World Health Organization has recommended the use of insecticide treated bed nets (ITN) as one of the effective malaria preventive strategies among pregnant women in malaria endemic areas. This study, therefore, seeks to examine the individual and household factors associated with the use of ITNs among pregnant women in Ghana.

Methods

Data for this study was obtained from the 2019 Ghana Malaria Indicator Survey (GMIS) conducted between September 25 and November 24, 2019. The weighted sample comprised 353 pregnant women aged 15–49 years. Data was analyzed with SPSS version 22 using both descriptive and multilevel logistics regression modelling. Statistically significant level was set at p < 0.05.

Results

The study found that 49.2% of pregnant women in Ghana use ITN to prevent malaria. Pregnant women aged 35–49 years (AOR = 3.403, CI: 1.191–9.725), those with no formal education (AOR = 5.585, CI = 1.315–23.716), and those who had secondary education (AOR = 3.509, CI = 1.076–11.440) had higher odds of using ITN. Similarly, higher odds of ITN usage was found among who belonged to the Akan ethnic group (AOR = 7.234, CI = 1.497–34.955), dwell in male-headed households (AOR = 2.232, CI = 1.105–4.508) and those whose household heads are aged 60–69 years (AOR = 4.303, CI = 1.160–15.966). However, pregnant women who resided in urban areas (AOR = 0.355, CI = 0.216–0.582), those whose household heads aged 40–49 years (AOR = 0.175, CI = 0.066–0.467) and those who belonged to richer (AOR =0.184, CI = 0.050–0.679) and richest (AOR = 0.107, CI = 0.021–0.552) households had lower odds of using ITN for malaria prevention.

Conclusions

Individual socio-demographic and household factors such as pregnant women’s age, educational level, place of residence, ethnicity, sex and age of household head, and household wealth quintile are associated with the use of ITN for malaria prevention among pregnant women. These factors ought to be considered in strengthening malaria prevention campaigns and develop new interventions to help increase ITN utilization among vulnerable population living in malaria- endemic areas.

"In starvation, a bone can also be meat": a mixed methods evaluation of factors associated with discarding of long-lasting insecticidal nets in Bagamoyo, Tanzania

BACKGROUND

Between 2000 and 2019, more than 1.8 billion long-lasting insecticidal nets (LLINs) were distributed in Africa. While the insecticidal durability of LLINs is around 3 years, nets are commonly discarded 2 years post distribution. This study investigated the factors associated with the decision of users to discard LLINs.

METHODS

A mixed-method sequential explanatory approach using a structured questionnaire followed by focus group discussions (FGDs) to collect information on experiences, views, reasons, how and when LLINs are discarded. Out of 6,526 households that responded to the questionnaire of LLINs durability trial, 160 households were randomly selected from the households in four villages in Bagamoyo Tanzania for FGDs but only 155 households participated in the FGDs. Five of the household representatives couldn't participate due to unexpected circumstances. A total of sixteen FGDs each comprising of 8-10 adults were conducted; older women (40-60 years), older men (40-60 years), younger women (18-39 years), younger men (18-39 years). During the FGDs, participants visually inspected seven samples of LLINs that were "too-torn" based on Proportionate Hole Index recommended by the World Health Organization (WHO) guidelines on LLIN testing, the nets were brought to the discussion and participants had to determine if such LLINs were to be kept or discarded. The study assessed responses from the same participants that attended FGD and also responded to the structured questionnaire, 117 participants fulfilled the criteria, thus data from only 117 participants are analysed in this study.

RESULTS

In FGDs, integrity of LLIN influenced the decision to discard or keep a net. Those of older age, women, and householders with lower income were more likely to classify a WHO "too-torn" net as "good". The common methods used to discard LLINs were burning and burying. The findings were seen in the quantitative analysis. For every additional hole, the odds of discarding a WHO "too-torn" LLIN increased [OR = 1.05 (95%CI (1.04-1.07)), p < 0.001]. Younger age group [OR = 4.97 (95%CI (3.25-7.32)), p < 0.001], male-headed households [OR = 6.85 (95%CI (4.44 -10.59)), p < 0.001], and wealthy households [OR = 3.88 (95%CI (2.33-6.46)), p < 0.001] were more likely to discard LLINs.

CONCLUSION

Integrity of LLIN was the main determinant for discarding or keeping LLINs and the decision to discard the net is associated with socioeconomic status of the household, and the age and gender of respondents. WHO "too torn" nets are encouraged to be used instead of none until replacement, and disposal of nets should be based on recommendation.

The durability, functionality and acceptability of novel screened doors and windows after 4 years of use in a Gambian village: a cross-sectional survey

BACKGROUND

The World Health Organization recommends house screening as a tool for malaria control, yet evidence of the long-term durability, functionality and acceptability of this intervention is lacking. In this study, the sustainability and use of novel types of screened doors and windows was examined 4 years after installation in a Gambian village.

METHODS

A survey of 31 houses, each with two screened doors and two screened windows, was conducted in the rainy season. There were four types of screened door and two types of screened window. Trained staff carried out the survey and interviews of room owners were conducted in the local language before translation into English.

RESULTS

Structurally, the manufactured doors and windows were highly durable and in excellent condition. Most doors shut smoothly 50/61 (82%), although only 25/61 (41%) shut fully automatically with the latch slotting into the hole on the frame and holding fast. Door locks were less robust, with only (24/61) 39% present and working. Blinds proved especially flimsy, with only 4/109 (4%) of door blinds and 10/56 (18%) of window blinds present and in working order. Householders hung curtains inside most doors 50/61 (82%) and in 26/61 (43%) of the windows. Front doors were commonly found propped open 21/31 (68%) and 23/27 (85%) of those with a front door curtain, put their curtains down at night. Doors and windows were well liked, 19/31 (61%) of respondents were happy with them because they kept mosquitoes out 14/31 (45%) and provided security 12/31 (39%). The main reason given for the use of curtains was to provide privacy 26/28 (93% of those with curtains), especially while the door was open or had 'see-through' panels.

CONCLUSIONS

Overall, the screened doors and windows were in full-working order and undamaged after 4 years of use. The doors and windows were well liked, especially for their ability to reduce the entry of mosquitoes and for the security they afforded. Improvements to the lock design are needed before scale-up. Most householders hung curtains behind their doors for privacy. Installation of screening in buildings should be accompanied with recommendations that at night, when doors and windows are closed, curtains be lifted or drawn to one side-to improve ventilation and keep the house cool.

The effect of light and ventilation on house entry by Anopheles arabiensis sampled using light traps in Tanzania: an experimental hut study

Background

In sub-Saharan Africa, house design and ventilation affects the number of malaria mosquito vectors entering houses. This study hypothesized that indoor light from a CDC-light trap, visible from outside a hut, would increase entry of Anopheles arabiensis, an important malaria vector, and examined whether ventilation modifies this effect.

Methods

Four inhabited experimental huts, each situated within a large chamber, were used to assess how light and ventilation affect the number of hut-entering mosquitoes in Tanzania. Each night, 300 female laboratory-reared An. arabiensis were released inside each chamber for 72 nights. Nightly mosquito collections were made using light traps placed indoors. Temperature and carbon dioxide concentrations were measured using data loggers. Treatments and sleepers were rotated between huts using a randomized block design.

Results

When indoor light was visible outside the huts, there was an 84% increase in the odds of collecting mosquitoes indoors (Odds ratio, OR = 1.84, 95% confidence intervals, 95% CI 1.74–1.95, p < 0.001) compared with when it was not. Although the odds of collecting mosquitoes in huts with closed eaves (OR = 0.54, 95% CI 0.41–0.72, p < 0.001) was less than those with open eaves, few mosquitoes entered either type of well-ventilated hut. The odds of collecting mosquitoes was 99% less in well-ventilated huts, compared with poorly-ventilated traditional huts (OR = 0.01, 95% CI 0.01–0.03, p < 0.001). In well-ventilated huts, indoor temperatures were 1.3 °C (95% CI 0.9–1.7, p < 0.001) cooler, with lower carbon dioxide (CO2) levels (mean difference = 97 ppm, 77.8–116.2, p < 0.001) than in poorly-ventilated huts.

Conclusion

Although light visible from outside a hut increased mosquito house entry, good natural ventilation reduces indoor carbon dioxide concentrations, a major mosquito attractant, thereby reducing mosquito-hut entry.

Malaria prevention interventions beyond long-lasting insecticidal nets and indoor residual spraying in low- and middle-income countries: a scoping review

Background

Significant progress in malaria prevention during the past two decades has prompted increasing global dialogue on malaria elimination. Recent reviews on malaria strategies have focused mainly on long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), with little emphasis on other prevention methods. This article is a scoping review of literature on malaria prevention methods beyond LLINs and IRS in low- and middle-income countries (LMICs).

Methods

This scoping review found articles published between from 1994 to 2020. Studies were obtained from a search of the PubMed, the Cochrane Library and Social Science abstracts. Grey literature and manual search of secondary references was also done. The search strategy included all study designs but limited only to English. Three independent reviewers performed the selection and characterization of articles, and the data collected were synthesized qualitatively.

Results

A total of 10,112 studies were identified among which 31 met the inclusion criteria. The results were grouped by the 3 emerging themes of: housing design; mosquito repellents; and integrated vector control. Housing design strategies included closing eves, screening of houses including windows, doors and ceilings, while mosquito repellents were mainly spatial repellents, use of repellent plants, and use of plant-based oils. Integrated vector control included larvae source management. Evidence consistently shows that improving housing design reduced mosquito entry and malaria prevalence. Spatial repellents also showed promising results in field experiments, while evidence on repellent plants is limited and still emerging. Recent literature shows that IVM has been largely ignored in recent years in many LMICs. Some malaria prevention methods such as spatial repellents and IVM are shown to have the potential to target both indoor and outdoor transmission of malaria, which are both important aspects to consider to achieve malaria elimination in LMICs.

Conclusion

The scoping review shows that other malaria prevention strategies beyond LLINs and IRS have increasingly become important in LMICs. These methods have a significant role in contributing to malaria elimination in endemic countries if they are adequately promoted alongside other conventional approaches.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04052-6.

Insecticide-treated net (ITN) use, factors associated with non-use of ITNs, and occurrence of sand flies in three communities with reported cases of cutaneous leishmaniasis in Ghana

Background

The insecticide treated bed net (ITN) has been proven for malaria control. Evidence from systematic review also suggests benefits of ITN roll out in reducing the incidence of cutaneous leishmaniasis (CL) and other vector borne diseases.

Methods

Using a community-based cross-sectional study design, ITN use, factors associated with non-use of ITNs, and occurrence of sand flies were investigated in three communities with reported cases of CL in the Oti region of Ghana.

Results

A total of 587 households comprising 189 (32.2%), 200 (34.1%), and 198 (33.7%) households from Ashiabre, Keri, and Sibi Hilltop communities with de facto population of 3639 participated in this study. The proportion of households that owned at least one ITN was 97.1%. The number of households having at least one ITN for every two members was 386 (65.8%) and 3159 (86.8%) household population had access to ITN. The household population that slept in ITN the night before this survey was 2370 (65.1%). Lack of household access to ITN (AOR = 1.80; CI: 1.31, 2.47), having a family size of more than 10 members (AOR = 2.53; CI: 1.20, 4.24), having more than 10 rooms for sleeping in a household (AOR = 10.18; CI: 1.28, 81.00), having 2–4 screened windows (AOR = 1.49; CI: 1.00, 2.20), and having 8–10 screened windows (AOR = 3.57; CI: 1.25, 10.17) were significantly associated with increased odds of not sleeping in ITN the night before the survey. A total of 193 female sand flies were trapped from various locations within the study communities.

Conclusions

Factors associated with ITN non-use such as lack of household access to ITN should be incorporated into future efforts to improve ITN use. Species of sand flies and their potential vectorial role in the study communities should also be investigated.

Assessing health-seeking behaviour and malaria prevention practices among communities in four districts of the Volta Region of Ghana

Background

Malaria is a preventable disease that causes huge morbidity and mortality in malaria-endemic areas, especially among children and pregnant women. The malaria control programme focuses on the prevention of mosquito bites using insecticide-treated nets (ITNs) and mosquito aerosol sprays and coils, as well as prevention of severe disease among those infected through prompt and adequate treatment. The success of the malaria control programme in Ghana is dependent on the malaria prevention practices of people in the community. Therefore, this study evaluated the malaria prevention practices of participants in four districts of the Volta Region of Ghana.

Methods

This was a cross-sectional study conducted in Ketu South, Nkwanta South, Hohoe Municipality and Ho West districts of the Volta Region of Ghana. Questionnaire were administered to adults who consented to each household visited. Questions were asked on the socio-demographics and malaria prevention practices of the households. Data analysis was done using SPSS version 23 with frequency distribution done for all the variables. Pearson chi-square was used to determine the significant association between socio-demographics and malaria prevention practices, and Multivariate nominal logistic regression analysis was used to model the relationship between dichotomous dependent variables (ITN ownership and usage) and independent variables.

Results

Out of the 2493 participants; 2234 (89.6%) owned ITN and 1528 (68.4%) used ITN a night before this study, 768 (30.8%) used mosquito aerosol spray and 368 (15%) used mosquito coil. More females significantly owned ITN than males (1293, 92.4%, p ≤ 0.001). Participants from Ketu South had 1.5 times higher odds of owning an ITN compared to Ho West whose odds are not different from Nkwanta South or Hohoe (AOR, 1.56 [95% 1.09–2.22]; p = 0.01). In terms of ITN usage, participants in Nkwanta South were less likely to use ITN compared to the other districts; AOR, 0.434 [95% CI 0.31–0.62, p < 0.001]. Also, of the 668 participants that had a fever within the past 3 days, 268 (40.1%) visited a patent medicine store and 156 (23.4%) visited health facilities.

Conclusion

There is high ownership of ITNs, but relatively low utilization among the community members. Education on malaria prevention practices should be intensified and continuous among the population of the Volta Region to ensure the success of malaria control in the region.

Effects of indoor air movement and ambient temperature on mosquito (Anopheles gambiae) behaviour around bed nets: implications for malaria prevention initiatives

Background

Until recently, relatively little research has been done on how mosquitoes behave around the occupied bed net in the indoor environment. This has been partly remedied in the last few years through laboratory and field studies, most of these using video methods and mosquito flight tracking. Despite these recent advances, understanding of the mosquito-bed net environment system, and the principles that underlie mosquito behaviour within it, is limited. This project aimed to further understand this system by studying the effects of gently moving air (such as might be introduced through room design to make the indoor environment more comfortable and conducive to ITN use) and warmer vs. cooler ambient conditions on mosquito activity around ITNs and other bed nets.

Methods

The activity of colonized female Anopheles gambiae around an occupied untreated bed net set up in a mosquito-proof tent in a large laboratory space was recorded under different ambient conditions using a laser detection-video recording system. Conditions tested were ‘cool’ (23–25 °C) and ‘warm’ (27–30 °C) air temperatures and the presence or absence of a cross-flow produced by a small central processing unit (CPU) fan pointed at the side of the net so that it produced a ‘low-’ or ‘high-’ speed cross-draught (approx. 0.1 and 0.4 m/s, respectively). Near-net activity in recordings was measured using video image analysis.

Results

In cool, still air conditions, more than 80% of near-net activity by An. gambiae occurred on the net roof. Introduction of the low-speed or high-speed cross-draught resulted in an almost total drop off in roof activity within 1 to 2 min and, in the case of the high-speed cross-draught, a complementary increase in activity on the net side. In warm, still conditions, near-net activity appeared to be lower overall than in cool, still air conditions and to be relatively less focussed on the roof. Introduction of the high-speed cross-draught in warm conditions resulted in a decrease in roof activity and increase in side activity though neither effect was statistically significant.

Conclusions

Results are interpreted in terms of the flow of the stimulatory odour plume produced by the net occupant which, consistent with established principles of fluid dynamics, appears to rise quickly and remain more intact above the net occupant in cool, still air than in warm, still air. Cross-draught effects are ascribed to the changes they cause in the flow of the host odour plume as opposed to mosquito flight directly. The implications of these results for house designs that promote indoor air movement, on bed net design, and on other vector control measures are discussed. How mosquitoes approach a net is influenced both by indoor temperature and ventilation and their interaction. This system is in need of further study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03957-y.

Effect of roof colour on indoor temperature and human comfort levels, with implications for malaria control: a pilot study using experimental houses in rural Gambia

Background

In rural sub-Saharan Africa, thatch roofs are being replaced by metal roofs. Metal roofing, however, increases indoor temperatures above human comfort levels, and thus makes it more likely that residents will not use an insecticide-treated bed net (ITN) at night. Whether the colour of a metal roof affects indoor temperature and human comfort was assessed.

Methods

Two identical, experimental houses were constructed with metal roofs in rural Gambia. Roof types were: (1) original bare-metal, (2) painted with red oxide primer or (3) white gloss, to reflect solar radiation. Pairwise comparisons were run in six, five-night blocks during the malaria season 2018. Indoor climate was measured in each house and multivariate analysis used to compare indoor temperatures during the day and night.

Results

From 21.00 to 23.59 h, when most residents decide whether to use an ITN or not, the indoor temperature of a house with a bare metal roof was 31.5 °C (95% CI  31.2–31.8 °C), a red roof, 30.3 °C (95% CI 30.0–30.6) and a white roof, 29.8 °C (95% CI 29.4–30.1). During the same period, red-roofed houses were 1.23 °C cooler (95% CI 1.22–1.23) and white roofs 1.74 °C cooler (95% CI 1.70–1.79) than bare-metal roofed houses (p  < 0.001). Similar results were found from 00.00 to 06.00 h. Maximum daily temperatures were 0.93 °C lower in a white-roofed house (95% CI  0.10–0.30, p  < 0.001), but not a red roof (mean maximum temperature difference  = 0.44 °C warmer, 95% CI  0.43–0.45, p  = 0.081), compared with the bare-metal roofed houses. Human comfort analysis showed that from 21.00 to 23.59 h houses with white roofs (comfortable for 87% time) were more comfortable than bare-metal roofed houses (comfortable for 13% time; odds ratio  = 43.7, 95% CI 27.5–69.5, p  < 0.001). The cost of painting a metal roof white is approximately 31–68 USD.

Conclusions

Houses with a white roof were consistently cooler and more comfortable than those with a bare metal roof. Painting the roofs of houses white is a cheap way of making a dwelling more comfortable for the occupants and could potentially increase bed net use in hot humid countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03951-4.

Effects of Door-to-Door Hang-Up Visits on the Use of Long-Lasting Insecticide-Treated Mosquito Nets in the Democratic Republic of the Congo: A Cluster Randomized Controlled Trial

Malaria accounts for 14% of child deaths in the Democratic Republic of the Congo, and one of the key interventions used to prevent malaria is to distribute insecticide-treated bednets (ITNs), especially long-lasting insecticidal nets (LLINs). The global health community and the Roll Back Malaria initiative have been struggling to achieve universal health coverage using ITNs, and recent studies have reported mixed results about the effects of door-to-door visits and mass distribution campaigns. We aimed to compare LLIN use for those provided by door-to-door hang-up visits and by conventional fixed distribution from distribution centers accompanied by a mass distribution campaign. A cluster randomized control trial was conducted in rural areas of Maniema Province, Democratic Republic of the Congo (DR Congo). Cross-sectional surveys were conducted on 2120 and 2156 households, respectively, with at least one child aged less than five in 76 villages. We assessed the effectiveness of door-to-door hang-up visits on the use of LLINs by exploring the interaction between the “intervention group” and “time” using generalized estimating equation models. Increased LLINs use was observed in all age groups in both arms, but usage differences were not significantly different (relative risk (RR) of LLINs use among children < 5 in the intervention group versus the control group after adjusted for clustering: 1.06, 95% CI: 0.85–1.33). We conclude that the door-to-door hang-up visits are not sufficient to persuade individuals (pregnant woman, children < 5, or all study participants) to use LLINs, although it did appear to be effective for the youngest children in the household.

Hot weather and heat extremes: health risks

Hot ambient conditions and associated heat stress can increase mortality and morbidity, as well as increase adverse pregnancy outcomes and negatively affect mental health. High heat stress can also reduce physical work capacity and motor-cognitive performances, with consequences for productivity, and increase the risk of occupational health problems. Almost half of the global population and more than 1 billion workers are exposed to high heat episodes and about a third of all exposed workers have negative health effects. However, excess deaths and many heat-related health risks are preventable, with appropriate heat action plans involving behavioural strategies and biophysical solutions. Extreme heat events are becoming permanent features of summer seasons worldwide, causing many excess deaths. Heat-related morbidity and mortality are projected to increase further as climate change progresses, with greater risk associated with higher degrees of global warming. Particularly in tropical regions, increased warming might mean that physiological limits related to heat tolerance (survival) will be reached regularly and more often in coming decades. Climate change is interacting with other trends, such as population growth and ageing, urbanisation, and socioeconomic development, that can either exacerbate or ameliorate heat-related hazards. Urban temperatures are further enhanced by anthropogenic heat from vehicular transport and heat waste from buildings. Although there is some evidence of adaptation to increasing temperatures in high-income countries, projections of a hotter future suggest that without investment in research and risk management actions, heat-related morbidity and mortality are likely to increase.

Investigating differences in village-level heterogeneity of malaria infection and household risk factors in Papua New Guinea

Malaria risk is highly heterogeneous. Understanding village and household-level spatial heterogeneity of malaria risk can support a transition to spatially targeted interventions for malaria elimination. This analysis uses data from cross-sectional prevalence surveys conducted in 2014 and 2016 in two villages (Megiar and Mirap) in Papua New Guinea. Generalised additive modelling was used to characterise spatial heterogeneity of malaria risk and investigate the contribution of individual, household and environmental-level risk factors. Following a period of declining malaria prevalence, the prevalence of P. falciparum increased from 11.4 to 19.1% in Megiar and 12.3 to 28.3% in Mirap between 2014 and 2016, with focal hotspots observed in these villages in 2014 and expanding in 2016. Prevalence of P. vivax was similar in both years (20.6% and 18.3% in Megiar, 22.1% and 23.4% in Mirap) and spatial risk heterogeneity was less apparent compared to P. falciparum. Within-village hotspots varied by Plasmodium species across time and between villages. In Megiar, the adjusted odds ratio (AOR) of infection could be partially explained by household factors that increase risk of vector exposure, such as collecting outdoor surface water as a main source of water. In Mirap, increased AOR overlapped with proximity to densely vegetated areas of the village. The identification of household and environmental factors associated with increased spatial risk may serve as useful indicators of transmission hotspots and inform the development of tailored approaches for malaria control.

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.

Human-Mosquito Contact: A Missing Link in Our Understanding of Mosquito-Borne Disease Transmission Dynamics

Despite the critical role that contact between hosts and vectors, through vector bites, plays in driving vector-borne disease (VBD) transmission, transmission risk is primarily studied through the lens of vector density and overlooks host-vector contact dynamics. This review article synthesizes current knowledge of host-vector contact with an emphasis on mosquito bites. It provides a framework including biological and mathematical definitions of host-mosquito contact rate, blood-feeding rate, and per capita biting rates. We describe how contact rates vary and how this variation is influenced by mosquito and vertebrate factors. Our framework challenges a classic assumption that mosquitoes bite at a fixed rate determined by the duration of their gonotrophic cycle. We explore alternative ecological assumptions based on the functional response, blood index, forage ratio, and ideal free distribution within a mechanistic host-vector contact model. We highlight that host-vector contact is a critical parameter that integrates many factors driving disease transmission. A renewed focus on contact dynamics between hosts and vectors will contribute new insights into the mechanisms behind VBD spread and emergence that are sorely lacking. Given the framework for including contact rates as an explicit component of mathematical models of VBD, as well as different methods to study contact rates empirically to move the field forward, researchers should explicitly test contact rate models with empirical studies. Such integrative studies promise to enhance understanding of extrinsic and intrinsic factors affecting host-vector contact rates and thus are critical to understand both the mechanisms driving VBD emergence and guiding their prevention and control.

Threats to the effectiveness of insecticide-treated bednets for malaria control: thinking beyond insecticide resistance

From 2004 to 2019, insecticide-treated bednets (ITNs) have been the most effective tool for reducing malaria morbidity and mortality in sub-Saharan Africa. Recently, however, the decline in malaria cases and deaths has stalled. Some suggest that this inertia is due to increasing resistance in malaria vectors to the pyrethroid insecticides used for treating ITNs. However, there is presently little evidence to reach this conclusion and we therefore recommend that a broader perspective to evaluate ITN effectiveness in terms of access to nets, use of nets, bioefficacy, and durability should be taken. We argue that a single focus on insecticide resistance misses the bigger picture. To improve the effects of ITNs, net coverage should increase by increasing funding for programmes, adopting improved strategies for increasing ITN uptake, and enhancing the longevity of the active ingredients and the physical integrity of nets, while simultaneously accelerating the development and evaluation of novel vector control tools.

The relationship between house height and mosquito house entry: an experimental study in rural Gambia

Most malaria infections in sub-Saharan Africa are acquired indoors, thus finding effective ways of preventing mosquito house entry should reduce transmission. Since most malaria mosquitoes fly less than 1 m from the ground, we tested whether raising buildings off the ground would prevent the entry of Anopheles gambiae, the principal African malaria vector, in rural Gambia. Nightly collections of mosquitoes were made using light traps from four inhabited experimental huts, each of which could be moved up or down. Mosquito house entry declined with increasing height, with a hut at 3 m reducing An. gambiae house entry by 84% when compared with huts on the ground. A propensity for malaria vectors to fly close to the ground and reduced levels of carbon dioxide, a major mosquito attractant, in elevated huts, may explain our findings. Raised buildings may help reduce malaria transmission in Africa.

The issue is not 'compliance': exploring exposure to malaria vector bites through social dynamics in Burkina Faso

Credited with averting almost 68% of new cases between 2000 and 2015, insecticide-treated bednets (ITNs) are one of the most efficacious malaria-prevention tools. Their effectiveness, however, depends on if and how they are used, making 'compliance' (and the social factors affecting it) a key area of interest for research on malaria transmission. This article situates the notion of compliance with 'bednet use' within everyday practices in an area of south-west Burkina Faso with high malaria transmission. By drawing on ethnographic fieldwork conducted between 2017 and 2018, it critically describes the precarious micro-environments that foreground bednet use-from gender and age to the means of (re)production of social and labour conditions-and assesses the bednets' effectiveness and community uptake. Bednet use stems from concrete, ordinary dynamics that interweave only apparently at the margins of the time individuals most need to be protected by a net. This work conceptualises 'compliance' beyond binary indicators of intervention uptake and locates 'use' as the result of contingent assemblages.

Epidemiological and entomological studies of malaria transmission in Tibati, Adamawa region of Cameroon 6 years following the introduction of long-lasting insecticide nets

BACKGROUND

Malaria remains a serious public health problem in Cameroon. Implementation of control interventions requires prior knowledge of the local epidemiological situation. Here we report the results of epidemiological and entomological surveys carried out in Tibati, Adamawa Region, Cameroon, an area where malaria transmission is seasonal, 6 years after the introduction of long-lasting insecticidal bed nets.

METHODS

Cross-sectional studies were carried out in July 2015 and 2017 in Tibati. Thick blood smears and dried blood spots were collected from asymptomatic and symptomatic individuals in the community and at health centers, respectively, and used for the molecular diagnosis of Plasmodium species. Adult mosquitoes were collected by indoor residual spraying and identified morphologically and molecularly. The infection status of Plasmodium spp. was determined by quantitative PCR, and positivity of PCR-positive samples was confirmed by Sanger sequencing.

RESULTS

Overall malaria prevalence in our study population was 55.0% (752/1367) and Plasmodium falciparum was the most prevalent parasite species (94.3%), followed by P. malariae (17.7%) and P. ovale (0.8%); 92 (12.7%) infections were mixed infections. Infection parameters varied according to clinical status (symptomatic/asymptomatic) and age of the sampled population and the collection sites. Infection prevalence was higher in asymptomatic carriers (60.8%), but asexual and sexual parasite densities were lower. Prevalence and intensity of infection decreased with age in both the symptomatic and asymptomatic groups. Heterogeneity in infections was observed at the neighborhood level, revealing hotspots of transmission. Among the 592 Anopheles mosquitoes collected, 212 (35.8%) were An. gambiae, 172 (29.1%) were An. coluzzii and 208 (35.1%) were An. funestus (s.s.). A total of 26 (4.39%) mosquito specimens were infected by Plasmodium sp. and the three Anopheles mosquitoes transmitted Plasmodium at equal efficiency. Surprisingly, we found an An. coluzzii specimen infected by Plasmodium vivax, which confirms circulation of this species in Cameroon. The positivity of all 26 PCR-positive Plasmodium-infected mosquitoes was successively confirmed by sequencing analysis.

CONCLUSION

Our study presents the baseline malaria parasite burden in Tibati, Adamawa Region, Cameroon. Our results highlight the high malaria endemicity in the area, and hotspots of disease transmission are identified. Parasitological indices suggest low bednet usage and that implementation of control interventions in the area is needed to reduce malaria burden. We also report for the first time a mosquito vector with naturally acquired P. vivax infection in Cameroon.

Impact of increased ventilation on indoor temperature and malaria mosquito density: an experimental study in The Gambia

In sub-Saharan Africa, cooler houses would increase the coverage of insecticide-treated bednets, the primary malaria control tool. We examined whether improved ventilation, using windows screened with netting, cools houses at night and reduces malaria mosquito house entry in The Gambia. Identical houses were constructed, with badly fitting doors the only mosquito entry points. Two men slept in each house and mosquitoes captured using light traps. First, temperature and mosquito density were compared in four houses with 0, 1, 2 and 3 screened windows. Second, carbon dioxide (CO2), a major mosquito attractant, was measured in houses with (i) no windows, (ii) screened windows and (iii) screened windows and screened doors. Computational fluid dynamic modelling captured the spatial movement of CO2. Increasing ventilation made houses cooler, more comfortable and reduced malaria mosquito house entry; with three windows reducing mosquito densities by 95% (95%CI = 90-98%). Screened windows and doors reduced the indoor temperature by 0.6°C (95%CI = 0.5-0.7°C), indoor CO2 concentrations by 31% between 21.00 and 00.00 h and malaria mosquito entry by 76% (95%CI = 69-82%). Modelling shows screening reduces CO2 plumes from houses. Under our experimental conditions, cross-ventilation not only reduced indoor temperature, but reduced the density of house-entering malaria mosquitoes, by weakening CO2 plumes emanating from houses.

Residual Malaria Transmission in Select Countries of Asia-Pacific Region: Old Wine in a New Barrel

Background

Despite substantial reductions in malaria burden and improvement in case management, malaria remains a major public health challenge in the Asia-Pacific region. Residual malaria transmission (RMT) is the fraction of total transmission that persists after achievement of full operational coverage with effective insecticide-treated bed nets (ITNs)/long-lasting insecticidal nets (LLINs) and/or indoor residual spray interventions. There is a critical need to standardize and share best practices for entomological, anthropological, and product development investigative protocols to meet the challenges of RMT and elimination goals.

Methods

A systematic review was conducted to describe when and where RMT is occurring, while specifically targeting ownership and usage of ITN/LLINs, indoor residual spray application, insecticide susceptibility of vectors, and human and vector biting behavior, with a focus on nighttime activities.

Results

Sixty-six publications from 1995 to present met the inclusion criteria for closer review. Associations between local vector control coverage and use with behaviors of human and mosquito vectors varied by locality and circumstance. Consequently, the magnitude of RMT is insufficiently studied and analyzed with sparse estimates of individual exposure in communities, insufficient or incomplete observations of ITN/LLIN use, and the local human population movement into and from high-risk areas.

Conclusions

This review identified significant gaps or deficiencies that require urgent attention, namely, developing standardized procedures and methods to estimate risk exposure beyond the peridomestic setting, analytical approaches to measure key human-vector interactions, and seasonal location-specific agricultural or forest use calendars, and establishing the collection of longitudinal human and vector data close in time and location.

Factors associated with use of insecticide-treated net for malaria prevention in Manica District, Mozambique: a community-based cross-sectional survey

BACKGROUND

Insecticide-treated net (ITN) use is crucial for preventing malaria infection. Despite significant improvements in ITN access and use over the past two decades, many malaria-endemic countries in sub-Saharan Africa have not yet reached global targets for universal coverage of ITNs. To reduce the gaps in ITN use, it is important to understand the factors associated with ITN use. The goal of this analysis was to determine the factors associated with ITN use in Manica District, Mozambique.

METHODS

A cross-sectional community-based survey was conducted from October to November 2019. Households were randomly selected, and all members of selected households were eligible to participate. Data on socio-demographic characteristics, housing construction and the ownership, use and characteristics of ITNs were collected using structured questionnaires. Factors independently associated with ITN use were identified using generalized estimating equations multivariate logistic regression.

RESULTS

Of the 302 households surveyed, 209 (69.2%) owned at least one ITN and 176 (58.3%) had one ITN for every two household members. The multivariate analysis indicated that the odds of ITN use was significantly lower among individuals in households with 3 or more members. However, the odds of ITN use was significantly higher among older age groups, poorer households, and as the number of ITNs in a household increased.

CONCLUSIONS

The findings of this analysis highlight the need for behaviour change communication strategies targeting young people and ITN distribution campaigns targeting larger households to increase ITN ownership, thereby improving ITN use in Manica District.

Human Behavior, Livelihood, and Malaria Transmission in Two Sites of Papua New Guinea

Background

Malaria transmission is currently resurging in Papua New Guinea (PNG). In addition to intervention coverage, social and cultural factors influence changes in epidemiology of malaria in PNG. This study aimed to better understand the role of human behavior in relation to current malaria control efforts.

Methods

A mixed-method design was used in 2 sites in PNG. In-depth interviews, focus group discussions, cross-sectional malaria indicator survey, and population census were implemented.

Results

We identified 7 population groups based on demographics and behavioral patterns with potential relevance to Anopheles exposure. People spend a substantial amount of time outdoors or in semiopen structures. Between 4 pm and 8 am, all types of activities across all groups in both study sites may be exposing individuals to mosquito bites; sleeping under a long-lasting insecticidal net was the exception. The later in the night, the more outdoor presence was concentrated in adult men.

Conclusions

Our findings highlight the potential of outdoor exposure to hamper malaria control as people spend a remarkable amount of time outdoors without protection from mosquitoes. To prevent ongoing transmission, targeting of groups, places, and activities with complementary interventions should consider setting-specific human behaviors in addition to epidemiological and entomological data.

Family, social and cultural determinants of long-lasting insecticidal net (LLIN) use in Madagascar: secondary analysis of three qualitative studies focused on children aged 5-15 years

Background

Although it is accepted that long-lasting insecticidal net (LLIN) use is an effective means to prevent malaria, children aged 5 to 15 years do not appear to be sufficiently protected in Madagascar; the malaria prevalence is highest in this age group. The purpose of this research is to summarize recent qualitative studies describing LLIN use among the Malagasy people with a focus on children aged 5–15 years.

Methods

Qualitative data from three studies on malaria conducted between 2012 and 2016 in 10 districts of Madagascar were analysed. These studies cover all malaria epidemiological profiles and 10 of the 18 existing ethnic groups in Madagascar. A thematic analysis was conducted on the collected data from semi-structured interviews, direct observation data, and informal interviews.

Results

A total of 192 semi-structured interviews were conducted. LLINs are generally perceived positively because they protect the health and well-being of users. However, regional representations of mosquito nets may contribute to LLIN lower use by children over 5 years of age including the association between married status and LLIN use, which leads to the refusal of unmarried young men to sleep under LLINs; the custom of covering the dead with a mosquito net, which leads to fear of LLIN use; and taboos governing sleeping spaces for siblings of opposite sexes, which leads to LLIN shortages in households. Children under 5 years of age are known to be the most vulnerable age group for acquiring malaria and, therefore, are prioritized for LLIN use when there are limited supplies in households. In contrast, children over 5 years of age, who are perceived to be at less risk for malaria, often sleep without LLINs.

Conclusions

Perceptions, social practices and regional beliefs regarding LLINs and vulnerability to malaria contribute to the nonuse of LLINs among children over 5 years of age in Madagascar. Modifying LLIN policies to account for these factors may increase LLIN use in this age group and reduce disease burden.

Dynamics of the Composition of Plasmodium Species Contained within Asymptomatic Malaria Infections in the Central Region of Ghana

BACKGROUND

Monitoring changes in the composition of the Plasmodium species circulating within the population over a period can inform appropriate treatment recommendations. This study monitored variations in the prevalence of four common human Plasmodium species carried by children with asymptomatic malaria infections over a two-year period.

METHODS

Two cross-sectional studies were conducted in November 2017 and December 2019. A total of 210 children aged between 4 and 13 years were recruited in 2017, and 164 similarly aged children were recruited in 2019. Approximately 150 μl of finger-pricked blood was used to prepare thick and thin blood smears as well as spot Whatman® #3 filter paper. Genomic DNA was extracted from the dried blood spots and used in PCR to amplify the 18S rRNA gene from four different human Plasmodium parasites.

RESULTS

Parasite prevalence by microscopy and the prevalence of P. falciparum detected by PCR was relatively similar at the two time points (Pearson chi-square = 0.405, p=0.525, and Pearson chi-square = 0.452, p=0.501, respectively). However, the prevalence of PCR detectable P. malariae increased by 8.5-fold, whilst P. ovale increased from 0 to 9% in the children sampled in 2019 relative to the children sampled in 2017. The only parasite species identified by microscopy in this study was P. falciparum, and no P. vivax was identified by either microscopy or PCR in the study population during the study period.

CONCLUSION

There is the need to implement molecular diagnostic tools for malaria parasite surveillance in Ghana. This will enable the identification and treatment of all circulating malaria parasites including P. malariae and P. ovale, whose population is expanding in parts of Ghana including Simiw.

Ownership and Utilisation of Long-Lasting Insecticidal Nets in Tiko Health District, Southwest Region, Cameroon: A Cross-Sectional Study

INTRODUCTION

Malaria is and remains a serious health concern in Africa. In Cameroon, where malaria is endemic and a major public health problem, the major control measure put in place is the use of long-lasting insecticidal nets (LLINs). In the Tiko Health District (THD), the challenges have been to assess and to evaluate the ownership and utilisation of LLINs. This study sought to assess the ownership and utilisation rates of LLINs in the THD. Methodology. A cross-sectional survey involving 418 households was conducted in four health areas in the THD. A structured questionnaire was used to collect data on LLIN ownership and utilisation as well as sociodemographic characteristics.

RESULTS

The ownership of at least one LLIN per household, coverage, and accessibility were, respectively, 89%, 56.2%, and 66.3%, while installing LLINs on all beds in the household, sleeping under LLINs the previous night (SULPN), and universal utilisation were 72%, 24.9%, and 14.1%, respectively. Factors significantly associated with the ownership of at least one LLIN per household were respondent's age and gender. Heat (21.1%) and forgetfulness (6.5%) were the main reasons postulated for irregular utilisation of LLINs.

CONCLUSION

The ownership LLINs failed to guarantee utilisation and definitely effective control of malaria in the THD, as expected. Continuous and appropriate use of LLINs is indispensable, in addition to periodic sanitation, booster campaigns of LLIN distribution, and evaluation research for effective prevention and control of malaria.