Data from: Temperature and population density determine reservoir regions of spatial persistence in highland malaria

A better understanding of malaria persistence in highly seasonal environments such as highlands and desert fringes requires identifying the factors behind the spatial and temporal reservoir of the pathogen in the low season. In these ‘unstable’ malaria regions, such reservoirs play a critical role during the low transmission season by allowing persistence between seasonal outbreaks. In the highlands of East Africa, the most populated epidemic regions in Africa, temperature is expected to be intimately connected to spatial persistence because of pronounced altitudinal gradients. It is not clear, however, that variation in altitude is in itself sufficient to explain persistence of the disease during the low season, and that other environmental and demographic factors, in particular population density are not also major factors. We address this question here with an extensive spatio-temporal data set of confirmed monthly Plasmodium falciparum cases from 1995 to 2005 that finely resolves space in an Ethiopian highland. With a Bayesian approach for parameter estimation and a generalized linear mixed model that includes a spatially-structured random effect, we demonstrate that population density is important to disease persistence during the low transmission season. As malaria risk usually decreases in more urban environments with increased human densities, this counter-intuitive finding identifies novel control targets during the low transmission season in African highlands. It also underscores limitations of current coupled vector-host models for the population dynamics of the disease, which do not typically incorporate an explicit effect of density.