The effect of heat on insecticide-treated net use across Africa: an analysis of 28 malaria-endemic countries from 2011-2022

A common barrier to insecticide-treated net (ITN) use, the backbone of malaria prevention, is heat discomfort. Using multilevel regression models, we quantified the association between temperature and ITN use reported in Demographic and Health and Malaria Indicator Surveys from 2011-2022 across 28 countries in sub-Saharan Africa. Marginal predicted probability of use was unimodal with nighttime temperature and decreased above a threshold daytime temperature. For women (n=731,947), temperatures above specified thresholds were associated with lower use, with adjusted odds ratios [aOR] 0.91 for daytime (95% confidence interval [CI] 0.88-0.94) and 0.87 for nighttime (95% CI 0.85-0.91). For children under 5 (n=524,926), corresponding aOR were 0.87 (95% CI 0.84-0.91) and 0.86 (95% CI 0.83-0.90). Considering a counterfactual in which temperatures never exceeded these thresholds, we estimated 25.8 million (95% CI 14.4-38.2 million) cases of malaria attributable to heat-associated non-use. These results demonstrate the importance of considering climate-behavior interactions for malaria control.