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Bison Death Caused by Rabies

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Department: Health & Environment
Release Date: Jun 29, 2012

Contact Information:

Adrienne LeBailly, MD, Director, Larimer County Health and Environment, 498-6711, alebailly@larimer.org

A bison that died at a Colorado State University facility on the Foothills Campus has been confirmed to have been infected with rabies.

On Thursday, June 21, an adult female bison died suddenly in her outdoor holding pen.  Laboratory tests, conducted by the CSU Veterinary Diagnostic Laboratory, revealed the animal died from rabies.

According to Dr. Adrienne LeBailly, director of the Larimer County Department of Health and Environment, the death of this bison, as well as possibly the death of two other bison from the facility, demonstrates the potential for skunks with rabies to spread this fatal disease to other susceptible animals through bites. 

The first rabid skunk ever identified in the Fort Collins area was found near this facility on May 4. Rabies in skunks has become increasingly common in Colorado, as infected animals have moved in from the eastern plains where they first appeared in 2008.

 “Once skunk rabies is established in an area, it cannot be eradicated, and it can spread rabies to other mammals,” said LeBailly. “We may see cases in other species, such as foxes, coyotes, deer and livestock, making it important for owners to vaccinate their animals and keep their shots up to date.”  

“Rabies disease is always fatal in animals, and it increases the risk of exposure to their owners and handlers,” LeBailly said. “Prevention of rabies in an exposed person requires costly vaccination and preventive treatment before any symptoms appear; otherwise it is nearly always fatal.”

Although rabies from bat bites has been a potential threat for years, rabies transmitted by skunks or other wild animals that travel on the ground (so-called “terrestrial rabies”) has begun to appear in this area only in the last two months.

Dean Hendrickson, director of CSU’s Veterinary Teaching Hospital concurs with LeBailly.

“Terrestrial rabies is an emerging issue in Colorado -- an issue that many people may just be coming aware of.” Hendrickson said.   “Because of the newness of this situation, we understand that many are just now beginning to consider vaccinating their livestock, horses and other animals.”

CSU’s Veterinary Teaching Hospital is located several miles from the Foothills Campus where the bison were housed.

“All resident animals at Veterinary Teaching Hospital at Colorado State University are vaccinated, and we are urging the public to do the same in the best interests of public health and their animals.”

Public health and veterinary experts believe the infected bison likely came into contact with a rabies-infected skunk, or possibly a rabid fox or other wild animal. Larimer County is currently experiencing a high level of rabies cases in skunks this spring and summer, with 17 testing positive so far in the past two months. 

“Our first rabid skunk was found in an area close to where the bison are kept,” said LeBailly. “It’s possible that the ill bison was bitten by a rabid skunk before we were even aware that terrestrial rabies was present in the Fort Collins area.”  

Samples from two other recently deceased female bison from the same herd are currently being tested for rabies. Laboratory results are expected in the next few weeks.

All three ill bison were part of a breeding project at CSU. CSU is taking steps to vaccinate the remainder of the herd of bison.

For more information on rabies, http://larimer.org/health/ehs/rabies.htm