Wildlife Staff Outside Denver Work To Stop The Spread Of Plague Among Prairie Dogs

An outbreak of plague has struck a prairie dog population outside of Denver. NPR's Ailsa Chang speaks with research wildlife biologist Dean Biggins about the risks to the region's ecology.

AILSA CHANG, HOST:

So there's a new outbreak of plague just outside Denver, not among humans but rather among prairie dogs. Some parks have been partially closed through Labor Day as staffers try to stop the spread.

Dean Biggins is a wildlife biologist with the U.S. Geological Survey, and he can explain more to us. Welcome.

DEAN BIGGINS: Thank you.

CHANG: So what made my mind kind of explode when I first heard about the story was I thought the plague ended centuries ago. Is this plague now the same as the Black Plague?

BIGGINS: It is the same disease. It's caused by the same bacterium that caused the Black Death in medieval Europe.

CHANG: And are these outbreaks common, like you've seen this before?

BIGGINS: This is fairly common in the western U.S. Since plague was introduced well over a hundred years ago - about 1900 in San Francisco - it's been spreading throughout wildlife populations. And pretty much the western half of the country has it, except in the most extreme environments, like desert. And it's been noticed a lot in colonial squirrel species, like ground squirrels and prairie dogs, where sometimes entire colonies will die out.

CHANG: So when prairie dogs are infected with the plague, how does that affect the overall food supply chain?

BIGGINS: It's an interesting question. In the case of the prairie dog system, it, of course, has a dire effect on the prairie dog population in general. And the most dependent species on those is the black-footed ferret, which is a highly endangered weasel-like animal that once was much more abundant on the plains but is now extremely rare.

CHANG: They eat prairie dogs usually, and so now their food supply is being threatened.

BIGGINS: They do, yes. They're entirely dependent on prairie dogs, mostly for food. But they also - ferrets use the prairie dog burrows as shelter, so they're highly linked to the prairie dog system. And the black-footed ferret is directed susceptible to plague itself. So it's not just a matter of losing its prey. It actually probably succumbs to the disease about as quickly as the prairie dogs do.

CHANG: So what's being done now to keep this from spreading further?

BIGGINS: The methods being used now are some that we've worked on for quite a few years. And now, two of them involve controlling the fleas that transmit plague, and we're doing that with a couple of different products, insecticides mainly. They're used as flea powder, deposited in burrow in one case. And in another case, we're feeding a fipronil product to prairie dogs in baits. And they ingest the baits, and the fipronil in their system kills fleas. That's a lot like products that you'll see used on pets.

CHANG: OK, so if this is about fleas - not to be selfish, but let's just say I'm planning a hiking trip around Denver - do I need to be worried about catching the Black Plague?

BIGGINS: If you're hiking around prairie dog colonies in particular, you should be very cautious about fleas. You definitely can contract plague from flea bites. They'll jump on you pretty readily. They don't bite humans as often as one might think, but if you do, you're at risk.

CHANG: So what precautions should I take? Does normal bug spray keep fleas away?

BIGGINS: Bug spray with DEET is a pretty good repellent, and that's what we actually use quite a bit of when we're working on plague in the field. One should also just be recognizing the symptoms of plague. And if you happen to have gotten a flea bite and you come down with flu-like symptoms within a three-day period or so, you should be cognizant that it might be plague and probably get over to a doctor and try to get on some antibiotics.

CHANG: Wow. All right. So, people, watch not only for ticks but fleas after those hikes.

Dean Biggins from the U.S. Geological Survey, thank you very much for helping us understand all of this.

BIGGINS: Well, thank you.

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