Fast-lived Vertebrate Hosts Exhibit Higher Potential for Mosquito-borne Parasite Transmission

Abstract

The emergence of mosquito-borne zoonoses has continually increased over the past decade, posing a significant global public health challenge. Ecological theory can point to the characteristics of populations that make them more likely to form reservoirs of disease. The pace of life hypothesis posits that species with more rapid reproduction and shorter lifespans are more likely to be disease reservoirs than their slower-living cousins. Mathematical modeling suggests theoretical conditions under which this hypothesis is correct for directly- and environmentally-transmitted pathogens but its applicability to mosquito-borne disease systems has yet to be examined. We parameterized a mechanistic model with host trait data to investigate the link between the position of a species on the fast-slow life history continuum and the potential for it to spread mosquitoborne diseases. We evaluated the resulting relationships for four medically important mosquito species across their thermal niches and for four pathogens characterized by infection duration and the level of susceptibility of the focal host to infection. Finally, because the fast-slow life history continuum differs across taxonomic ranks, we considered the theory in the context of two orders of vertebrate hosts, Rodentia and Primates. After parameterizing our model, we found that, near universally across all the axes of variation considered, fast-lived hosts have higher transmission potential than slow-lived hosts. There was one exception: slower-lived hosts have higher transmission potential for parasites that cause long-enduring infections to which these hosts are highly susceptible. Generally, however, these connections hinge on the often unknown links between immunological traits, population density, and pace of life. Our analyses highlight immunological traits as a key knowledge gap with strong influence over the potential for transmission. Further investigation of the pace of life hypothesis will require a better understanding of how, for mosquito-borne parasitic infections, susceptibility and infection duration vary across the members of a taxonomic order.