Spatial patterns of persistence for environmentally transmitted parasites: Effects of regional climate and local landscape

Abstract

Both regional climatic conditions and local landscape characteristics can affect the ability of environmentally transmitted parasites to persist outside their host. In general, implications of shifting climate conditions on the persistence and spread of parasites have been examined in the absence of interactions with local landscape characteristics (e.g., forest fragmentation). Here, we test the utility of a model that includes regional climate and local landscape characteristics to model environmental persistence of parasites. We used a system with both a well-studied landscape and data-rich host-parasite relationship and investigated how regional and local conditions affected the transmission of a parasitic whipworm (Trichuris spp.) within a population of red colobus monkeys (Procolobus rufomitratus) in Kibale National Park, Uganda. We model persistence of a whipworm deposit in the environment as a function of both regional climate suitability and its sensitivity to the local conditions in which it was deposited. Our simulation suggests that changes to regional climate suitability impacts prevalence patterns in hosts to a larger extent than sensitivity to local landscape characteristics, with no evidence of an interaction effect. However, we find that in landscapes that offer fewer suitable sites for egg persistence (i.e., high sensitivity to local landscape characteristics), our model predicts greater variability in parasite prevalence among host groups, and a shift to source-sink parasite dynamics. Our results suggest that when modeling environmentally-transmitted parasites, explicitly considering spatial patterns of environmental persistence and host movement behaviour provides insight into transmission dynamics of specific landscape-host-parasite systems.