As Polar Icebox Shrinks, Infectious Pathogens Move North

Jul 20, 2014
Originally published on July 20, 2014 10:08 am



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." And he joins me now from Montana Public Radio in Missoula. Welcome.

CHRISTOPHER SOLOMON: Good to be here, Arun.

RATH: So, 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: Yeah. So 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, for eons, had his relationship with this parasitical lung worm. 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 percent 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 percent 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.

RATH: Christopher Solomon's article "Sick In The Arctic" appears in the August issue of "Scientific American." Thanks for joining us.

SOLOMON: Oh, thanks so much for the time. Transcript provided by NPR, Copyright NPR.