Bird malaria moves north

Germs that cause a so-called tropical disease make themselves at home in frosty Alaska


 Black-capped chickadees, like the one shown here, stay in Fairbanks, Alaska, year-round. Scientists report that some of the birds have been found with avian malaria, suggesting that the germ that causes the disease has established itself in the far North.


Fairbanks is the second-largest city in Alaska, and according to a new study it’s also now home to malaria germs that infect birds. The finding that these germs — which thrive in warmer climates — have established themselves in North America’s cold, northern reaches could mean trouble for local birds.

Malaria microbes are parasites, or organisms that live on or in other organisms. The parasites make their home in mosquitoes, which can then transfer the germs from bird to bird, or from person to person. (Another reason to hate mosquitoes! Thwap!)

These avian malaria microbes — there are more than 80 different types — pose no risk to people. Likewise, none of the five germs that cause malaria in people infects birds.

Nonetheless, scientists are concerned. Because most North America birds are so frequently exposed to malaria, many have developed resistance to the germs. This means the birds no longer get very sick from the microbes. But in the upper reaches of Alaska, not too far from the Arctic Circle, the disease is new. So birds there may not have developed resistance, says study author Ravinder Sehgal.

Sehgal, of San Francisco State University, was part of the team of scientists that found birds were definitely catching malaria in Fairbanks. Some of the infected birds stay in Fairbanks year round, which means they must have been infected there, the disease ecologist told Science News. Disease ecologists study the germs that cause illness and how they interact with the world around them.

A germ that’s harmless in one part of the world may prove deadly in another, Robert Fleischer told Science News. Fleischer, who did not participate in this research, studies animal conservation at the Smithsonian Institution in Washington, D.C. He notes that a malaria parasite affecting birds arrived in Hawaii fairly recently, only in the past two centuries. This particular germ has caused little harm in other parts of the world. But in Hawaii, he says, the parasite severely sickens birds, even killing some. As a result, those vulnerable birds thrive only high up in the mountains, where the air is too cold for mosquitoes to survive.

Malaria-causing parasites and their mosquito hosts like warm temperatures. Since the average temperature is climbing, the reach of malaria may continue to expand within Alaska and beyond. At the current rate of warming, bird-carried malaria may reach beyond the Arctic Circle by 2080. And Sehgal says there could be problems for birds in the southern reaches of the globe, too. He worries that penguins there might prove vulnerable to the disease.

Power Words

avian Of or relating to birds.

malaria A disease caused by a parasite that invades the red blood cells. The parasite is transmitted by mosquitoes, largely in tropical and subtropical regions.

parasite An organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host’s expense.

ecology The branch of biology that deals with how organisms relate to one another and to their physical surroundings.

Stephen Ornes lives in Nashville, Tenn., and his family has two rabbits, six chickens and a cat. He has written for Science News Explores since 2008 on topics including lightning, feral pigs, big bubbles and space junk.

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