Fact and fiction: Do prairie dogs carry the plague?

Colorado is the home to three species of prairie dogs. They can be seen in parks, along trails, in fields and even in your own backyard. Many people will tell you that these cute critters carry the plague, but is it true?

As with any animal that shares living space with humans, interactions of various kinds, both positive and negative, can occur. It has become well-known among Coloradans that prairie dogs can be infected with Yersinia pestis, the bacterium that causes bubonic plague. 

Given the dark and dramatic history of this disease, one might expect public concern to be high. Rumors and falsehoods can easily spread in such an environment. So, what are the facts? What precautions should be taken? 

When discussing a particular pathogen, it is important to note that of the species that can catch the disease, only some of those species are “reservoirs”. 

A “reservoir” is a species that often carries a specific pathogen but shows little or no disease symptoms. Because a pathogen’s reservoir doesn’t get sick and die before it can spread the disease to other hosts, it serves as a reliable resource for that pathogen. 

When Yersinia pestis infects a prairie dog town, the animals quickly die off. Up to 90% of individual prairie dogs can die if a town is infected. Though the exact reservoir species of Yersinia pestis in Colorado is unknown, it is not prairie dogs.

Yersinia pestis is transmitted between hosts, human and nonhuman, primarily through the bites of infected fleas. Direct contact with sick or dead animals can also result in transmission. It is also possible to contract plague by inhaling the respiratory droplets of an infected animal or person, but this is extremely rare. 

Though there is some risk of transmission from wild rodents to humans and pets, there are reasonable precautions that we can all take to stay safe and enjoy wildlife. 

The Colorado Department of Public Health and Environment recommends not handling wildlife and reporting sick animals to Colorado Parks and Wildlife, orCPW. As previously mentioned, plague causes rapid die-offs if introduced to a prairie dog town, and members of the public should notify their local public health agency and the nearest CPW office if they notice a prairie dog town has “gone silent”. 

Three forms of plague can be caused by a Yersinia pestis infection in humans, each with its own set of symptoms. The bacterium most often infects wild rodents, rabbits, hares and wild and domestic cats. 

Cats show symptoms similar to those in humans when infected, along with loss of appetite. There have only been two confirmed cases of plague in dogs in Colorado.

Plague can be treated effectively with antibiotics if caught early, so seek medical attention promptly if symptoms appear in you or your pet. 

CPW implemented plague management efforts to protect prairie dogs, including the development of a vaccine and the deployment of anti-flea insecticide. 

When confronted with wildlife management issues, many feel that “letting nature take its course” is the best way. While some natural processes keep wildlife populations in check, such as predation and limited food resources, plague is not one of these. 

Plague is a new phenomenon in North America, first occurring in the early 1900s and only becoming common in Colorado in 1940s and 1950s. This recent introduction means that North American wildlife has not had time to evolve resistance to plague infection. In that sense, disease is a concern of both human and wildlife welfare.