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Pinedale Online > News > December 2009 > Did imported wolves bring new parasite?
Did imported wolves bring new parasite?
by Cat Urbigkit, Pinedale Online!
December 7, 2009

The U.S. Fish and Wildlife Service notes that a new research paper reports that the parasite, the tapeworm Echinococcus granulosus, has now been detected in Montana and Idaho for the first time. It is apparently widespread through the wolf population, and has now spread to elk, deer, and at least one mountain goat. The researchers ponder whether this tapeworm arrived in the region through the importation of wolves from Canada, or whether it was already here, but undetected.

The paper was published in the Journal of Wildlife Diseases. Here's the abstract and publication information:

Echinococcus granulosus in Gray Wolves and Ungulates in Idaho andMontana, USA. William J. Foreyt,1,4 Mark L. Drew,2 Mark Atkinson,3 and Deborah McCauley3 1Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040, USA; 2Wildlife Health Laboratory, Idaho Department of Fish and Game, Caldwell, Idaho 83607, USA; 3Montana Department of Fish, Wildlife and Parks, 1400 S. 19th Avenue, Bozeman, Montana 59718, USA; 4 Corresponding author (email:

ABSTRACT: "We evaluated the small intestines of 123 gray wolves (Canis lupus) that were collected from Idaho, USA (n563), and Montana, USA (n560), between 2006 and 2008 for the tapeworm Echinococcus granulosus. The tapeworm was detected in 39 of 63 wolves (62%) in Idaho, USA, and 38 of 60 wolves (63%) in Montana, USA. The detection of thousands of tapeworms per wolf was a common finding. In Idaho, USA, hydatid cysts, the intermediate form of E. granulosus, were detected in elk (Cervus elaphus), mule deer (Odocoileus hemionus), and a mountain goat (Oreamnos americanus). In Montana, USA, hydatid cysts were detected in elk. To our knowledge, this is the first report of adult E. granulosus in Idaho, USA, or Montana, USA. It is unknown whether the parasite was introduced into Idaho, USA, and southwestern Montana, USA, with the importation of wolves from Alberta, Canada, or British Columbia, Canada, into Yellowstone National Park, Wyoming, USA, and central Idaho, USA, in 1995 and 1996, or whether the parasite has always been present in other carnivore hosts, and wolves became a new definitive host. Based on our results, the parasite is now well established in wolves in these states and is documented in elk, mule deer, and a mountain goat as intermediate hosts."

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