THE COEXISTENCE OF COMPETING PARASITES .1. THE ROLE OF CROSS-SPECIES INFECTION

Extends previous models of multiparasite systems and relates these models to general concepts of predator-prey and competitive interactions. In particular, the authors explore 3 different roles that parasites may play: 1) a predator or true parasite of healthy hosts, 2) an intraguild predator of a competing parasite, and 3) a competitor with a 2nd parasite species or strain. Analyses uncover a varied and diverse array of outcomes, in terms of both species composition and ensuing population dynamics. The 2 parasites are most likely to persist when there are trade-offs in exploitative (eg transmission) and interference (eg cross-transmission) competition. Regulation of the host population occurs when both parasites act as true parasites (ie infected hosts may recover and/or give birth to healthy hosts), whereas when one parasite acts as a predator (or pathogen) persistent oscillations may ensue. -from Authors