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Zoos try to ward off penguin-killing malaria
If left untreated, the disease would probably kill at least half the birds it infected. For penguins in captivity, the threat is so great that many zoos dose their birds in summer with pills for malaria.
The New York Times
Zoos all around the world love penguins. But as carefree as they might look, torpedoing through the water or rocketing into the air like a Poseidon missile, zoo penguins are stalked by an unrelenting killer: malaria.
“It’s probably the top cause of mortality for penguins exposed outdoors,” said Dr. Allison Wack, a veterinarian at the Maryland Zoo in Baltimore. If left untreated, the disease would probably kill at least half the birds it infected, though outbreaks vary widely in intensity.
The disease has not been an issue for the penguins at Woodland Park Zoo in Seattle, according to associate veterinarian Kelly Helmick.
The avian version is not a threat to humans because mosquitoes carrying malaria and the parasites are species-specific; mosquitoes that bite birds or reptiles tend not to bite mammals, said Dr. Paul Calle, chief veterinarian for the Wildlife Conservation Society, which runs New York City’s zoos. And avian malaria is caused by strains of the Plasmodium parasite that do not infect humans.
But for penguins in captivity, the threat is so great that many zoos dose their birds in summer with pills for malaria, said Dr. Richard Feachem, director of global health at the University of California, San Francisco.
Last year, six Humboldt penguins in the London Zoo died of malaria. Since first diagnosed there in a King penguin in 1926, there have been many outbreaks of avian malaria, including at zoos in Baltimore, South Korea, Vienna and Washington, D.C.
The last major American one was at the Blank Park Zoo in Des Moines, Iowa, during the hot, wet summer of 1986. From May to September of that year, 38 of the 46 Magellanic penguins the zoo had just imported from Chile succumbed.
While human malaria is a scourge of the tropics, killing an estimated 660,000 people a year, it has largely been chased out of the world’s temperate regions. But animal and bird variants of the disease are widespread.
Avian malaria is endemic everywhere except in the cold polar regions and on some Pacific islands where the right mosquitoes have never established themselves. (However, it is a new and growing threat in Hawaii, where it is devastating the honeycreeper population.)
Through long exposure, most bird species have built up a natural resistance. “But penguins have a problem,” said Christine Sheppard, a former chief of ornithology at the Bronx Zoo, “because they come from habitats without mosquitoes.”
Not all penguins hail from the frigid South Pole. Some nest on beaches where the daytime temperatures can reach 110 degrees. But all come from places so arid as to be considered deserts, so they do not face mosquitoes at home.
“We get maybe one mosquito a year at Punta Tombo,” said P. Dee Boersma, a University of Washington biologist who for 30 years has studied Magellanic penguins on a hot, dry stretch of Argentine coast.
She has found antibodies to malaria in some birds, she said, and assumes that they were bitten during their winter migration to coastal Brazil but survived.
Seattle Times reporter Colin Campbell contributed to this report.