Abstract: Invited talk in the Symposium 'SEABIRD HEALTH' of the 2nd World Seabird Conference, Cape Town, South Africa, October 2015.
Infectious diseases have the potential to cause rapid declines and extinction in endangered vertebrate species. Animals in Antarctica and in the surrounding islands of the Southern Ocean have evolved in relative isolation and are likely to be particularly sensitive to the introduction of pathogens. In spite of this spatial isolation, increased exposition to humans and exotic species has generated opportunities for the introduction of pathogens to native and endemic species. A dramatic example is the recurrent chick mortality occurring in seabird populations of Amsterdam Island, where breeds the endangered and endemic Amsterdam albatross. On this island, the impact and extent of epizootics have increased during the last ten years and stress the urgent need for (1) the identification of the etiologic agents involved in these epizootics, and (2) the investigation of the epizootiology of these pathogens to better understand the ecology of the disease and accordingly define mitigation and prevention methods. Based on molecular analyses, we provide evidence for the presence of two potentially pathogenic bacteria species, Pasteurella multocida and Erysipelothrix rhusiopathiae, in the five seabird species breeding on Amsterdam. Demographic parameters and count surveys conducted on these species suggested that epizootics might affect only three of them, the sooty and yellow-nosed albatrosses and northern rockhopper penguins. P. multocida was isolated in pure culture on corpses of the two former species, which strongly suggests the role of this agent in the deaths reported. Genetic characterization of the isolates suggests that the bacteria could have been introduced to the island, where poultry have been locally reared until the last decade. Although there has not been evidence of epizootics in the Amsterdam albatross, recurrent chick mortalities on this species would have dramatic consequences. Strict biosecurity procedures have been designed and applied to limit the risk of dispersion of pathogens among the different populations, in particular during the course of bird monitoring by scientists.