Unhealthy herds: Some epidemiological consequences of host heterogeneity in predator-host-parasite systems

Models in which all hosts respond in the same fashion to challenge by disease make a number of clear predictions regarding the ameliorating effect of predation on disease burden in prey populations. However, natural populations are typically exposed to a broad spectrum of stressors, some of which can induce changes in an individual's susceptibility to infection and transmission, as well as vulnerability to mortality once infected. When only a subset of the population is exposed to these other factors, host populations will express some heterogeneity in resistance to disease. Here I investigate the influence that such heterogeneity can have on the predicted beneficial epidemiological effect of predators on certain homogeneous prey populations. Results show that, under some conditions, predation can exacerbate disease burden in the heterogeneous prey population. I conclude that such a possibility might have implications for wild and domesticated animal management programs.