Models of the dynamics of parasite – host interactions often assume random encounters between infected and susceptible hosts. In wildlife populations that is rarely the case. Different animal “personalities” and social structures can have a major influence on interactions, on exposure and risk of infection, and on the spread of parasites and pathogens around populations.
Our research program has explored social networks within largely solitary Australian skink species and the role of those networks in determining the infection patterns of the lizards. We ask whether the edges that link network nodes act as pathways for parasite transmission. We have found evidence supporting this transmission pathway in that more highly connected individuals are more likely to be infected, from closer genetic relatedness among parasites infecting hosts that are more closely linked on the network, and from the experimental release of genetically unique parasite strains. We also find that different transmission pathways drive infection patterns in different parasite species, and in the same species in different years.
Our data come from a range of endemic parasites including bacteria, nematodes and ectoparasitic ticks, none of which has a major impact on individual host fitness at natural infection levels. We argue that understanding these transmission pathways will be vital background information for intervention management in the case where some new more virulent pathogen enters a population and threatens its persistence.