||The objectives of program ECOPATH 1151 relate to the circulation of infectious agents in vertebrate populations of southern polar areas. Eco-epidemiological dynamics are studied by combining different approaches, from field observations and experiments to laboratory analyses and modeling. The questions have basic and applied implications, from the evolution of the immune system to the control of deleterious infectious diseases threatening wild populations. Within Amsterdam Island, where recurrent massive die-offs of nestlings of the yellow-nosed albatross have been recorded, a vaccine is tested and the role of the local breeding species in disease maintenance is explored. Scavenging and predatory subantarctic skuas prove highly exposed to the agent of avian cholera and their movements and interactions with rats are likely to contribute to disease spread. At larger scales, research is notably focused on dispersal of tick-borne disease agents. Consequences for setting up disease surveillance programs are also explored.