We are interested in the mechanisms affecting host-parasite interaction across scales, from within-host processes of infection to population-level mechanisms of transmission and persistence. We examine how hosts cope with co-infections, how concurrent parasite/pathogens interact through the host immune system, and how host immunity modulates parasite transmission and long-term persistence at the population level. Environmental factors influence the risk of infection, and we are also interested in exploring how climate changes and host spatial structure influence the dynamics of parasite free-living stages and transmission.