Evaluating the link between environmental temperature and transmission of malaria

Background/Question/Methods   Malaria transmission is strongly influenced by environmental temperature. However, the precise ways in which temperature affects the biology of the parasite and its mosquito vector remain poorly quantified. To date, most studies analyzing malaria-temperature relations, including investigations into impacts of climate change, draw insights from simplified lab studies and consider the effects of mean temperatures. Here we present novel empirical evidence to show that in addition to mean temperatures, daily fluctuations in temperature affect both the rate of parasite development and essential elements of mosquito biology that combine to determine transmission intensity.

Results/Conclusions   In general we find that temperature fluctuation around low mean temperatures acts to speed up rate processes while fluctuation around high mean temperatures acts to slow processes down, compared to rates at equivalent constant mean temperatures. At the extremes, fluctuation makes transmission possible at lower mean temperatures than currently predicted and can potentially block transmission at higher mean temperatures. These results challenge current assumptions concerning the possible impacts of climate change and strengthen arguments for greater ecological understanding of how infectious organisms respond to the natural environment.