The Role of Human Movement and Spatial Heterogeneity in Malaria Transmission and Control

Mathematical models developed for studying malaria dynamics often focus on a single, homogeneous population. However, human movement connects environments with potentially different malaria transmission characteristics. To address the role of human movement and spatial heterogeneity in malaria transmission and malaria control, we consider a simple mathematical model for malaria that incorporates two regions, or patches, connected by human movement, with different degrees of malaria transmission in each patch. Using our two-patch model, we calculated and analyzed the basic reproduction number, R0, an epidemiologically important threshold quantity that indicates whether malaria will persist or go extinct in a population. Our results indicate that regions with low malaria transmission should have an interest in helping to control or eliminate malaria in regions with higher malaria endemicity if human movement connects them. Using R0, we determine, under different scenarios, which patch will be the better target for control measures, and within that patch, what type of control measure should be implemented. Whether mosquito biting rate or mosquito death rate is a better target for control depends on the average relative duration of the extrinsic incubation period and the mosquito lifespan. Although human movement between regions poses challenges to malaria control and elimination, if estimates of relevant parameters in the model are known, including migration rates, our results can help inform which region to target and what type of control measure to implement for the greatest success.