EID: Cats, Rats and the Prevalence of Microparasites in an Urban Landscape

Johns Hopkins University, Baltimore MD

Investigators

Abstract

In nature, host-parasite dynamics take place not as the interaction between just the host and parasite but they occur within a web of interacting species, including predators. Current theory predicts that predators impact the dynamics of host-parasite systems --improving the health of the host population. This suggests that predator control reduces the health of prey (host) populations, and attempts to control feral animals, such as cats and dogs that prey on rodents, should lead to increased levels of parasites in the rodents. The result can be subsequent increases in human disease risk. However, this project developed preliminary analyses to show that this is not the case, under certain well-defined conditions. The project will extend these theoretical analyses and field studies will be performed to test the predictions of the models. The field system uses house cats as predators of juvenile rats and examines patterns of viral infection in Norway rats. These studies are conducted in urban residential neighborhoods where Norway rats are common. Key parameters of infection status, movement, reproduction, survival and growth of Norway rats will be examined and the response of cats to the abundance of rats will be monitored. The model will be evaluated by predicting rates of infection at additional locations and these sites will be sampled to compare the predictions with the observed patterns of infection.