A form of malaria that infects birds has been found in parts of Alaska, and scientists say the discovery is another indication of climate change in the north.
The spread could prove devastating to arctic bird species that have never encountered the disease and thus have no resistance to it, said San Francisco State University Associate Professor of Biology Ravinder Sehgal, one of the study’s co-authors. The study was published Wednesday, Sept. 19, 2012 in the journal PloS One.
The avian malaria parasite is related to the human form and so the bird study could help scientists track how climate change is affecting human malaria.
Researchers examined blood samples from both resident and migratory birds collected at four sites from 61°N to 67°N, with Anchorage as a southern point, Denali and Fairbanks as middle points. Coldfoot was the northern point, roughly 960 kilometres north of Anchorage. They found infected birds in Anchorage and Fairbanks as far north as 64°N, but not in Coldfoot
In migratory birds, samples were taken from both adults and hatchlings to see if the infection had occurred locally or during migration.
The study notes that the infected birds at 64°N were above the Arctic Circle commonly known to people across the region as “north of 60”)
Using satellite imagery and other data, researchers were able to predict how environments will change due to global warming — and where malaria parasites will be able to survive in the future. They found that by 2080, the disease will have spread north to Coldfoot and beyond.
“Right now, there’s no avian malaria above latitude 64 degrees, but in the future, with global warming, that will certainly change,” Sehgal said. The northerly spread is alarming, he added, because there are species in the North American arctic that have never been exposed to the disease and may be highly susceptible to it.
“For example, penguins in zoos die when they get malaria, because far southern birds have not been exposed to malaria and thus have not developed any resistance to it,” he said. “There are birds in the north, such as snowy owls or gyrfalcons, that could experience the same thing.”
Researchers are still unsure how the disease is being spread in Alaska and are currently collecting additional data to determine which mosquito species are transmitting the Plasmodium parasites that cause malaria.
The data may also indicate if and how malaria in humans will spread northward.
Modern medicine makes it difficult to track the natural spread of the disease, Sehgal said, but monitoring birds may provide clues as to how global climate change may effect the spread of human malaria.
The study is the fact that the malaria parasites were able to complete their transmission cycle in the North American Arctic” provides “empirical evidence that local hosts in the north of Alaska may be exposed to new parasites with impending global warming,” especially if there is increased variation of both day/night and season temperature changes. Rainfall is also a factor.
Both Anchorage and Fairbanks are likely to have suitable conditions for the avian malaria parasite “completion, other areas with high annual precipitation but mild precipitation and temperature seasonality would be predicted to also be suitable” for the parasite.
One form of the avian malaria parasite has been previously in four bird species: the Common Rosefinch (Carpodacus erythrinus) in South Korea, the Greater Scaup (Aythya marila), the Pacific Golden Plover (Pluvialis fulva) and the Common Yellowthroat (Geothlypis trichas) in the United States, and in six migratory species, meaning that form can tolerate cold temperatures.
The book Birds of British Columbia says the Greater Scaup is a common migrant on the BC coast and may winter in BC, and an abundant migrant in the BC interior in both spring and fall, and often winters in the Okanagan. The Pacific Golden Plover is rare in BC, because its migration route takes it toward the east coast. It is usually spotted in the Peace River region but has been seen occasionally near Massett and Boundary Bay. The Common Yellowthroat can be found through the BC mainland in the summer but is rare on Vancouver Island and Haida Gwaii.
A study in New Brunswick has shown that one form of mosquito that tolerates cold infects birds in that province. Although that mosquito is “rare” in Alaska, a close relative is common in the state and although the scientists were unable to find the source of the infection, that Alaskan mosquito could be a prime suspect.
