Supplement to Parasitology 1997Survival of parasites, microbes and tumours: strategies for evasion, manipulation and exploitation of the immune responseEDITED BY M. J. DOENHOFF and L. H. CHAPPELL

Mathematical models of parasite responses to host immune defences

R. ANTIA a1 and M. LIPSITCH a1
a1 Department of Biology, Emory University, Atlanta, GA 30322, USA


We examine the evolution of microparasites in response to the immune system of vertebrate hosts. We first describe a simple model for an acute infection. This model suggests that the within-host dynamics of the microparasite will be a ‘race’ between parasite multiplication and a clonally expanding response by the host immune system, resulting either in immune-mediated clearance or host death. In this very simple model, in which there is only a single parasite and host genotype, maximum transmission is obtained by parasites with intermediate rates of growth (and virulence). We examine how these predictions depend on key assumptions about the parasite and the host, and consider how this model may be expanded to incorporate the effect of additional complexities such as host–parasite co-evolution, host polymorphism, and multiple infections.

Key Words: parasite–host evolution.