Wyoming woman catches rare pneumonic plague from cats

A cat lying on the ground outside.
(Image credit: Shutterstock)

A woman in Wyoming has been diagnosed with pneumonic plague, a rare disease she likely caught from her pet cats, according to news reports.

On Sept. 15, health officials announced that they had detected a "rare but serious" case of plague in a person living in northern Fremont County, Wyoming, which is south of Yellowstone National Park, according to a statement from the Wyoming Department of Health. The person appears to have contracted the disease through "contact with sick pet cats," the statement said.

Related: 11 ways your beloved pet can make you sick

Plague, which is caused by the bacterium Yersinia pestis, is perhaps best known for causing the Black Death in Europe in the 1300s. The infection still occurs worldwide today, but it is quite rare. In the United States, about seven cases of plague occur each year, on average, according to the Centers for Disease Control and Prevention (CDC). The disease is limited to the western U.S. and is most commonly reported in New Mexico, Arizona and Colorado. The woman's case marks the seventh human case of plague in Wyoming since 1978 and the first reported case in the state since 2008, the statement said.

Humans can catch the plague through flea bites or contact with infected animals or their tissues or body fluids. More than 80% of human plague cases in the U.S. result from so-called bubonic plague, a form of the disease that is typically spread through flea bites and causes swollen lymph nodes called "buboes," according to the CDC. 

The woman's case is particularly unusual because she was infected with pneumonic plague, the rarest and most serious form of the disease. It's also the only form of the disease that can spread from person to person, the CDC says. 

People can catch pneumonic plague when they inhale infectious droplets, spread by another person or animal with pneumonic plague. People can also develop pneumonic plague from other forms of plague, including bubonic plague, if they are not treated promptly.

Cats are "highly susceptible" to plague and are a known source of infections in people, according to the CDC. Cats with pneumonic plague "can pose a significant plague risk to owners, veterinarians and others who handle or come into close contact with these animals due to possible aerosolization of bacteria," the agency said on its website.

Plague can be treated with antibiotics, but early treatment is important to avoid serious complications, including death. Before the advent of antibiotics, the death rate from plague in the U.S. was about 66%, but today the rate is around 11%, according to the CDC. 

The Wyoming Department of Health did not release further details about the patient or her current condition. A health official told Gizmodo that the woman is currently experiencing serious symptoms.

Officials are notifying people who had exposure to the patient so that they can receive "post-exposure" antibiotics to help prevent illness, the statement said.

Originally published on Live Science.  

Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.