Mind the Gap: House Structure and the Risk of Malaria in Uganda

Abstract

BackgroundGood house construction may reduce the risk of malaria by limiting the entry of mosquito vectors. We assessed how house design may affect mosquito house entry and malaria risk in Uganda.Methods100 households were enrolled in each of three sub-counties: Walukuba, Jinja district; Kihihi, Kanungu district; and Nagongera, Tororo district. CDC light trap collections of mosquitoes were done monthly in all homes. All children aged six months to ten years (n = 878) were followed prospectively for a total of 24 months to measure parasite prevalence every three months and malaria incidence. Homes were classified as modern (cement, wood or metal walls; and tiled or metal roof; and closed eaves) or traditional (all other homes).ResultsA total of 113,618 female Anopheles were collected over 6,765 nights. 6,816 routine blood smears were taken of which 1,061 (15.6%) were malaria parasite positive. 2,582 episodes of uncomplicated malaria were diagnosed after 1,569 person years of follow-up, giving an overall incidence of 1.6 episodes per person year at risk. The human biting rate was lower in modern homes than in traditional homes (adjusted incidence rate ratio (IRR) 0.48, 95% confidence interval (CI) 0.37–0.64, p<0.001). The odds of malaria infection were lower in modern homes across all the sub-counties (adjusted odds ratio 0.44, 95%CI 0.30–0.65, p<0.001), while malaria incidence was lower in modern homes in Kihihi (adjusted IRR 0.61, 95%CI 0.40–0.91, p = 0.02) but not in Walukuba or Nagongera.ConclusionsHouse design is likely to explain some of the heterogeneity of malaria transmission in Uganda and represents a promising target for future interventions, even in highly endemic areas.

Measuring Socioeconomic Inequalities in Relation to Malaria Risk: A Comparison of Metrics in Rural Uganda

“…Household rankings from the two wealth indices were highly correlated, but controlling for other SEP indicators, only the wealth index that included house construction and food security variables was associated with HBR. House structure may explain part of the association between SEP and malaria in Nagongera since it is both a malaria risk factor 36 and associated with relative wealth, so it is plausible that its inclusion strengthens the association between the wealth index and malaria risk and that there is a trade-off between house type and SEP in the model. Previous wealth indices based on assets alone 39 and on assets and food security 36 in the same district were not significantly associated with parasite prevalence.…”

“…Wealth indices often include food security and house construction variables, 34 but these factors may be independently associated with malaria in the study area. 35,36 To evaluate whether including food security and house construction variables altered the association between the wealth index and malaria outcomes, Wealth Index II additionally included five variables: 10) main roof material, 11) main wall material, 12) main floor material, 13) frequency of meat consumption, and 14) number of meals per day. Households were ranked by wealth scores and grouped into tertiles.…”

Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases

“…There is increasing evidence to support a crucial role for housing improvement in malaria control [31–33, 60, 61]. It can be envisaged that ITWL could act as an effective and insecticidal method of house, and in particular, eave screening, if affixed to the base of the roof or ceiling and proven to have long-term durability.…”

Eave tubes for malaria control in Africa: a modelling assessment of potential impact on transmission

“…Other studies find better housing correlates with reductions in malaria, particularly if eaves are closed or screened to prevent Anopheles mosquitoes from entering [10–14]. …”