Because the beaver isn't just an animal; it's an ecosystem!

Tag: Do beavers cause giardiasis


Now if you all had a question about beavers you’d ask me, right? And you know even if I didn’t know the answer you’d trust me not to make it up or pretend that I knew but take the trouble to find the right person who did. You know I’d never ask someone who knew nothing about the subject matter just because he’d say what I expected to hear because that would be foolish. Nature specializes, and if you want to know about jaguars you go to the jaguar expert, right?

Captur1eWe’re not quite as confident about the beaver education of “Ask a naturalist.com” run by Tom and Kate Pelletier.  They maintain a fairly glossy website where they answer questions from readers in mostly accurate ways. Tom is a writer and Naturalist and Kate is the editor of the site and Operations Assistant for the Nature Conservancy. I believe at one time they lived in Massachusetts not very far away from Mike Callahan, but I’m thinking their beaver knowledge is not exactly top notch, based on the answer to this recent question:

Can I swim with beavers?

BeaverCommon knowledge associates giardiasis and beavers so closely that people often call the disease “beaver fever.” However, it’s not clear that beavers very often contaminate people with Giardia. In fact, it seems that Giardia species tend to specialize. So the Giardia that most commonly infects beaver is different from the one that infects people. However, most Giardia have some ability to infect organisms other than their primary host, and you can find human-type Giardia in beavers. But the evidence suggests that when it is found in swimming waters and in beavers, the most common source of the human-type Giardia is not the beavers but people. Typically, it’s from untreated sewage that gets into the water or from fecal matter washing off people when they are in the water. For that reason, health officials recommend that people with diarrhea stay out of swimming waters.

When I asked Lihua Xiao, who is Chief of the Molecular Epidemiology Laboratory/WBDP of the Division of Foodborne, Waterborne, and Environmental Diseases for the United States Centers for Disease Control, for his opinion about swimming with beavers, he said flatly “I would not swim in a pond where beavers are active.”

First of all, just because it rhymes doesn’t mean its true.  Yes beavers can cause Giardiasis just like any other mammal, and most mammals, as it happens, aren’t too particular about not pooping in the water. But they don’t carry it MORE. To be fair, he does go on to describe a study which showed that muskrats carried the disease far more commonly than beavers.  BUT he accompanied it with a photo of a nutria which he only just recently changed when it was pointed out to him in by a reader in May two years after this article appeared. Which begs the question, naturalist?

If you do decide to swim in your beaver pond, you should, as much as possible, avoid swallowing the water, and you should never drink untreated surface waters. The recommendation is to boil or use filters that specifically say they will remove Giardia. The cysts of Giardia and Cryptosporidium are somewhat resistant to chlorine, so don’t count on that. Boiling and filtration will also kill or remove most other waterborne diseases and parasites at the same time, including any worm-like parasite.

facepalm

Do you think Tom has read any of the humorous articles from beaver researchers in other countries that point out that it’s only ENGLISH speaking nations that associate beavers with beaver fever because of it’s only in our language that they rhyme? Do you think he knows that the biggest risk of swimming is for dogs when folks let them swim too close to their families in June and July when they are protecting kits? Do you think he’s ever seen this photo of beaver expert Sharon Brown doing this?

I’m going out on a limb and saying the answer to these questions is NO. He does end the article with a reference to a Washington state website on living with beavers, but that is small compensation after talking to the foremost researcher on infectious diseases who, last I checked, knew bunk about beavers.

Might I suggest that the NEXT time someone asks you a question about beavers you talk to a beaver expert? Oh and here’s a helpful way to tell muskrats and nutria apart.

nutriamuskrat

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