Housing gaps, mosquitoes and public viewpoints: a mixed methods assessment of relationships between house characteristics, malaria vector biting risk and community perspectives in rural Tanzania

Abstract

Background: House improvement and environmental management can significantly improve malaria transmission control in endemic communities. This study assessed the influence of physical characteristics of houses and surrounding environments on mosquito biting risk in rural Tanzanian villages, and examined knowledge and perceptions of residents on relationships between these factors and malaria transmission. The study further assessed whether people worried about these risks and how they coped.

Methods: Entomological surveys of indoor mosquito densities were conducted across four villages in Ulanga district, south-eastern Tanzania. The survey involved 48 sentinel houses sampled monthly and other sets of 48 houses randomly recruited each month for one-off sampling over 12 months. Physical characteristics of the houses and surrounding environments were recorded. Questionnaire surveys were administered to 200 household heads to assess their knowledge and concerns regarding the observed housing and environmental features, and whether they considered these features when constructing houses. Focus group discussions, were conducted to clarify emergent themes on people's perceptions on relationships between housing or environmental factors and malaria transmission.

Results: The entomological surveys showed statistically higher indoor densities of the malaria vectors (Anopheles arabiensis and Anopheles funestus) in houses with mud walls compared to plastered or brick walls, open eaves compared to closed eaves and unscreened windows compared to screened windows. Most respondents reported that their houses allowed mosquito entry, at least partially. Participants were aware that house structure and environmental characteristics influenced indoor mosquito densities and consequently malaria transmission. They were concerned about living in poorly-constructed houses with gaps on eaves, walls, windows and doors but were constrained by low income.

Conclusion: In rural south-eastern Tanzania, significant proportions of people still live in houses with open eaves, unscreened windows and gaps on doors. Though they are fully aware of associated mosquito biting and pathogen transmission risks, they are constrained by low-income levels. The study proposes that community-based house improvement initiatives combined with targeted subsidies could lower the financial barriers, improve access to essential construction materials or designs, and significantly accelerate malaria transmission control in these communities.

Keywords: Community knowledge; Environmental features; Housing characteristics; Malaria transmission; Mosquitoes; Tanzania.

Fig. 1

Map of the study villages. The study was conducted in households across four villages in Ulanga district, south of the Kilombero river in south-eastern Tanzania

Fig. 2

Pictorial representation of typical local house types in the study area. Top left: a house with grass thatch roofing with mud walls. Top right: a house with corrugated iron roof and brick walls not plastered on the outside, and sometime also not plastered on the inside. Bottom left: grass thatch roof with brick walls not plastered on the outside, and sometime also not plastered on the inside. Bottom right: a house with iron sheet roofing and plastered brick walls. A variety of window and door designs and covers are also illustrated

Fig. 3

Mixed methods study design

Fig. 4

Monthly trends of mean number of mosquitoes of different species collected per house per night. The Y-error bars represent 95% CI. All the species generally followed same trend peaking between April and June, except Mansonia spp., whose densities peaked between January and March