Fifth Case of Plague Confirmed in Wyoming Mountain Lions

May 21, 2008
Mountain Lion

Mountain lion hunters, domestic cat owners and others who may come in contact with mountain lions in Wyoming and other western states are urged to protect themselves and their animals against plague.

"Plague was confirmed in a mountain lion found dead in mid-April by a landowner in rural Johnson County," said Todd Cornish, an associate professor in the University of Wyoming College of Agriculture's Department of Veterinary Sciences.

Cornish said this is the fifth case of plague confirmed in mountain lions in Wyoming in the past three years. The other four cases were in Teton County and the Greater Yellowstone Area of northwestern Wyoming.

"Plague is an important consideration when mountain lions are found sick or dead in Wyoming and elsewhere in the western United States," Cornish said.

Those who find sick or dead mountain lions or similar species, including bobcats, should avoid contact with the animals and are asked to contact the Wyoming Game and Fish Department (WGFD), Cornish said. Contact information for regional offices can be found on the WGFD Web site at

"Appropriate personal safety precautions should be taken by wildlife professionals working in the field and diagnosticians working in laboratories when handling these animals or their tissues," he added. Information on how people can protect themselves is available on the Wyoming State Veterinary Laboratory (WSVL) Web site at Click on the following links: 2008, 2006 and 2005.

"Plague is a serious zoonotic disease capable of causing significant illness and even death in humans, as exemplified by a recent fatal case of plague in a wildlife biologist working at Grand Canyon National Park (in Arizona)," Cornish said. A zoonotic disease is one that can be transmitted from animals to humans.

The National Park Service biologist, Eric York, 37, performed a necropsy of a mountain lion carcass last October, and approximately five days later he developed a high temperature, mild nausea, muscle aches, chills, a cough and streaks of blood in his saliva, according to an article in the April edition of the Newsletter of the Wildlife Disease Association (WDA). York died several days later, and specimens from the biologist and the mountain lion both tested positive for the bacterium that causes plague, Yersinia pestis, according to the WDA article.

Wildlife biologists, wildlife veterinarians, public health officials, hunters skinning an animal with plague and the owners of domestic cats stricken with the disease are among those susceptible to plague. Cats can contract plague by eating an infected rodent or by being bitten by fleas from an infected host.

Cornish said, "What's becoming more of a common recommendation is to avoid allowing your cats to hunt wildlife. Concerned cat owners should also consider visiting with their veterinarian about a flea-control program."

There have been one fatal and four non-fatal cases of humans contracting plague in Wyoming since 1978, said Karl Musgrave, state public health veterinarian with the Wyoming Department of Health. There were two cases in Washakie County and one each in Goshen, Laramie and Sheridan counties.

The 1992 Sheridan County case resulted in the death of a man after he contracted the disease when skinning an infected bobcat. The Goshen County case involved a resident of Colorado.

WGFD assistant veterinarian Cynthia Tate said, "Finding plague in animals such as mountain lions and bobcats -- and occasionally domestic cats -- is not surprising because they eat rodents, and rodents are the typical carriers."

Tate added, "Those who hunt or trap predators should protect themselves while skinning animals or handling traps by wearing long rubber or latex gloves. They should avoid contact with an animal that appears sick (rough hair coat and/or drainage out of the eyes) and immediately contact the WGFD."

Tate cautions that animals having plague may not appear sick because the disease can kill rapidly. The incubation period of plague is between two and six days after exposure, she noted. If hunters or others develop flu-like symptoms within that period, they should call their doctor.

Ken Mills, a professor in the UW Department of Veterinary Sciences, said, "Plague could be a risk to mountain lion hunters, but I see it as more of a risk to the owners of domestic cats allowed to go outside and hunt rodents."

There have been at least seven unrelated cases of plague in domestic cats in Wyoming since 2005, Mills said. They included four in Laramie County and one each in Albany, Natrona and Teton counties.

"If your cat develops a fever and has swollen lymph nodes, it is definitely time to call a veterinarian," he said.

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