séminaire du PEV - vendredi 24 janvier 2014

Parasite-parasite interactions and the effect of multiple infections on host’s and pathogen’s fitness

Godefroy Devevey, Institute of Evolutionary Biology, University of Edinburgh, UK

vendredi 24 janvier 2014 à 11 heures, amphi Monge


Host-parasite relationships are central in biology; they shape ecological interactions, evolutionary trajectories and affect many aspects of human development. Traditionally, the study of host-parasite interactions focused on one host and one parasite, omitting that most hosts are multiply infected. In this seminar, I want to stress the ubiquity of co-infection, and how the interactions between parasites modulate their own fitness and the effect they have on host life history traits.

From empirical examples in rodents, I will illustrate different outcome of co-infections. For example, in the blood several species of bacteria of the genus Bartonella showed patterns of competition within a host, even though infection by one species facilitates infestation by a new species. Similarly, in hosts sequentially infected by several strains of the bacteria Borrelia burgdorferi, causative agent of Lyme disease, we observed a strong inhibitory priority effect, which seems independent of the host’s adaptive immune response. Finally, there are interactions even among parasites as different as a round worm and a protist; focusing only on the macroparasite, for example by treating with an antihelmintic, can have deadly consequences. We will conclude by an attempt to predict when parasites interact.