[ A summary of the spread of disease in the Arctic in the August 2014 issue of Scientific American follows ]
Pathogens moving northward:
- Aleutian Islands, Alaska. A distemper virus that infects seals in the North Atlantic ocean now attacks sea otters in the North Pacific
- Saint Lawrence Island, Bering Sea. Avian cholera 200 kilometers off the alaskan mainland has killed hundreds of northern fulmars, murres, and crested auklets–seabirds unafflicted before.
- Sahtu, Northwest Territories. Ticks, never observed here efore, have been discovered on moose hides.
- Victoria Island, Arctic Archipelago. Lungworm has spread several hundred kilometers north across the musk oxen population
- Hay Island, Nova Scotia. Ringed seals have passed a parasite to gray seals that killed 400 pups in 2012.
- Sweden. Mosquitoes have spread the tularemia bacterium to people across the country. This can cause severe fever, inflammation and death. Sweden also has more hantavirus infections because of warming.
- Arkhangelsk Oblast, Russia. Tick-borne encephalitis cases in humans rose 50-fold from the decade 1980-1989 to the decade 2000-2009.
A warming climate helps parasites mature fast. Cold summers that used to keep parasites in check do so less often. A tipping point has happened, warmth lasts longer. Parasites like the lungworm now mature in one summer instead of two. This has caused musk ox populations to decline dramatically.
In Russia forests are advancing into tundra at a rate of about 1 km per year, and ticks along with them, affecting 4 million people.
Summary: For eons arctic cold kept a cap on disease, which wildlife has gotten used to. It’s thought that one reason birds migrate north is to avoid disease to devote their energy to raising young. Viruses, fungi and parasites are not just invading the north, but also tropical and temperate ecosystems as the climate heats up.
[ This is the transcript from NPR’s July 20th, As Polar Icebox Shrinks, Infectious Pathogens Move North. ]
Science writer Chris Solomon tells NPR’s Arun Rath that global warming has caused an influx of new diseases in animals that could eventually spread to humans.
ARUN RATH, HOST: Infectious diseases may be spreading more quickly, thanks to global warming. Viruses that were kept in check by the polar ice box are being released. And as some animals move north to keep cool, they’re bringing all sorts of parasites with them, from microbes to ticks. Christopher Solomon has written about this in the August issue of “Scientific American.” Christopher, you wrote about sea otters off the coast of Alaska’s Aleutian Islands that are now infected with a virus from halfway around the world. What happened?
SOLOMON: There is something called phocine distemper virus, and it’s a relative of canine distemper. Phocine distemper has killed 50,000 seals over the last 25 years in the North Atlantic. And as scientists were trying to figure out why sea otters splashing in the Aleutian Islands were not doing so well, they found evidence of phocine distemper in them, and it became a detective story. And they said, well, what’s it doing in the North Pacific? And their theory is that it has made its way through the fabled Northwest passage via a seal or its feces and met animals on the other side due to the dramatic level of sea ice reduction.
RATH: So in addition to opening up lanes for shipping, warming has opened up a highway for viruses?
SOLOMON: Yes. In essence, disease is finding new lanes of travel. Existing disease up there is becoming invigorated. And new disease is hitchhiking on all sorts of wildlife, whether it’s fish or wild boars or ticks that are moving north in search of new habitat that’s cooler.
RATH: Wow. And in terms of land animals, I know with your article there is a photo of a big herd of very serious looking musk oxen. And they’ve been affected as well?
SOLOMON: Yes, this is another interesting case. Musk oxen – people may be able to visualize from a Disney or Pixar movie – they’re those smelly, kind of shaggy, horned relics of the Ice Age. And they’ve had a relationship with this parasitical lung worm for eons. It gave them a bit of a smoker’s cough. But the lung worm was always kept in check because it never was able to thrive in the brutal Arctic environment too well. And now, with essentially longer, warmer summers, the lung worm can complete its life cycle in one summer instead of two. And it has proliferated and has expanded it’s range up to where 30% of the world population of musk oxen live. And this is not good for the declining number of musk oxen in the far north.
RATH: Now, diseases can sometimes jump from animals to humans. How much is there for people to worry about, beyond animal populations?
SOLOMON: Well, that’s the interesting point in all of this. Since 1940, 60% of the new infectious diseases we’ve discovered in humans have come from animals. We’ve knocked down the borders between the natural world and the man-made world. Or, in these cases, the borders are simply melting away.
As one parasitologist Michael Grigg at the National Institutes of Health told me – he said, if the animals get sick, we can get sick. So we really need to pay attention to what’s happening out there. I’m not saying that the Arctic is collapsing under the weight of contagion right now. But things are happening that the scientists are really only starting to grasp in the north. And we need to pay attention to these flares that are going up.