Abstract
BackgroundEnvironmental factors such as temperature, rainfall, and vegetation cover play a critical role in malaria transmission. However, quantifying the relationships between environmental factors and measures of disease burden relevant for public health can be complex as effects are often non-linear and subject to temporal lags between when changes in environmental factors lead to changes in malaria incidence. The study investigated the effect of environmental covariates on malaria incidence in high transmission settings of Uganda.MethodsThis study leveraged data from seven malaria reference centres (MRCs) located in high transmission settings of Uganda over a 24-month period. Estimates of monthly malaria incidence (MI) were derived from MRCs’ catchment areas. Environmental data including monthly temperature, rainfall, and normalized difference vegetation index (NDVI) were obtained from remote sensing sources. A distributed lag nonlinear model was used to investigate the effect of environmental covariates on malaria incidence.ResultsOverall, the median (range) monthly temperature was 30 °C (26–47), rainfall 133.0 mm (3.0–247), NDVI 0.66 (0.24–0.80) and MI was 790 per 1000 person-years (73–3973). Temperature of 35 °C was significantly associated with malaria incidence compared to the median observed temperature (30 °C) at month lag 2 (IRR: 2.00, 95% CI: 1.42–2.83) and the increased cumulative IRR of malaria at month lags 1–4, with the highest cumulative IRR of 8.16 (95% CI: 3.41–20.26) at lag-month 4. Rainfall of 200 mm significantly increased IRR of malaria compared to the median observed rainfall (133 mm) at lag-month 0 (IRR: 1.24, 95% CI: 1.01–1.52) and the increased cumulative IRR of malaria at month lags 1–4, with the highest cumulative IRR of 1.99(95% CI: 1.22–2.27) at lag-month 4. Average NVDI of 0.72 significantly increased the cumulative IRR of malaria compared to the median observed NDVI (0.66) at month lags 2–4, with the highest cumulative IRR of 1.57(95% CI: 1.09–2.25) at lag-month 4.ConclusionsIn high-malaria transmission settings, high values of environmental covariates were associated with increased cumulative IRR of malaria, with IRR peaks at variable lag times. The complex associations identified are valuable for designing strategies for early warning, prevention, and control of seasonal malaria surges and epidemics.
Highlights
Environmental factors such as temperature, rainfall, and vegetation cover play a critical role in malaria transmission
In high-malaria transmission settings, high values of environmental covariates were associated with increased cumulative incidence rate ratio (IRR) of malaria, with IRR peaks at variable lag times
Environmental covariates such as temperature, vegetation, and rainfall play a major role in malaria transmission [1,2,3], by changing the vector populations which often lead to changes in malaria burden and yet the quantitative relationships between changes in these covariates and malaria incidence are not well characterized in many settings especially in sub Saharan Africa
Summary
Environmental factors such as temperature, rainfall, and vegetation cover play a critical role in malaria transmission. The study investigated the effect of environmental covariates on malaria incidence in high transmission settings of Uganda. Environmental covariates such as temperature, vegetation, and rainfall play a major role in malaria transmission [1,2,3], by changing the vector populations which often lead to changes in malaria burden and yet the quantitative relationships between changes in these covariates and malaria incidence are not well characterized in many settings especially in sub Saharan Africa. Many studies have reported associations between changes in malaria burden and patterns of environmental factors [7,8,9,10,11,12,13]. A study from South Africa found that an increase in temperature significantly raised malaria infections [12], while another in Ethiopia showed a negative correlation [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
