A highly contagious poultry virus has infected penguins in Antarctica. It is the first known transmission of a "foreign" disease to wildlife on the icy continent. Although none of the birds appears to be sick, researchers say the outbreak, reported in today's issue of Nature, highlights the risk of tourists and researchers spreading disease.
Some types of penguins are ideal for detecting foreign pathogens, says Heather Gardner, a veterinary biologist with the Australia Antarctic Division. Many of the flightless birds do not leave eastern Antarctica, and they encounter few migratory birds. So Gardner's team checked the health of Emperor and Adélie penguins in colonies near Auster Rookery and Mawson, two eastern locales frequently visited by tourists and researchers.
The scientists detected antibodies to infectious bursal disease virus (IBDV), a pathogen that weakens the immune system of young chickens and sometimes kills them. About 65% of 52 emperor penguin chicks were infected. Adult Adélie penguins seemed more resistant; less than 3% of 133 carried the virus. (Adélie penguins in a remote and rarely visited colony at Edmonson Point carried no antibodies to the virus.) But because none of the birds fell ill during the 6-month study, the researchers don't know the effect of IBDV on the penguins' health.
The birds were probably exposed to the virus through contaminated chicken or egg scraps improperly disposed of, says Gardner. When eaten by scavenger birds, the virus could then be spread some 40 kilometers to penguins through droppings, says Gardner. Although protocols for handling poultry and other potentially harmful imports were introduced in Antarctica during the 1980s, Gardner maintains that the emergence of IBDV proves those regulations are too lax.
Researchers are urging a search for other viruses. "We need a more systematic study," says Bernie Tershy, a seabird biologist at the University of California, Santa Cruz. Gardner hopes that visitors to Antarctica will thoroughly disinfect their belongings, as researchers already do, to guard against other routes of infection. Tourists, says Gardner, are "not necessarily aware that viruses and bacteria can be tramped in on boots and brought in accidentally."