Rare Case of the Human Plague Transferred From Cat to Owner

When you hear the phrase, "bubonic plague", you likely think of the deadly pandemics that wiped out millions of people in the Middle Ages, including The Black Death. Chances are you don't associate the plague with your best, furry friend, but one pet owner in Oregon maybe should have.

What is the Plague?

In 1900, the plague was brought to the U.S. by steamships infested with rats carrying the disease. According to the World Health Organization (WHO), the "plague is caused by the bacteria Yersinia pestis, a zoonotic bacteria usually found in small mammals and their fleas."

Humans are most commonly infected with this disease when bitten by fleas carrying Yersinia pestis, however, their pets can also become infected by fleas or when hunting infected rodents.

There are two types of plague, bubonic, which is the most common, and pneumonic. The bubonic plague can be diagnosed through painful and swollen lymph nodes, also known as buboes. Eventually if left untreated, the buboes can become open sores filled with pus. When this plague advances, it can spread to the lungs and become pneumonic.

This disease can be very serious and even fatal, with a 30-60% case-fatality ratio. However, the pneumonic type is always fatal if untreated.

Cat Owner Diagnosed with the Plague

According to Deschutes County Health Services, a cat owner in Deschutes County, Oregon was diagnosed with the plague. This diagnosis is Oregon's first in over eight years, which has seen 19 confirmed cases from 1970-2020, according to the Center for Disease Control. The most recent case was in 2015 where a teenage girl was reportedly gotten infected through a flea bite while on a hunting trip.

So, how did this pet cat transfer the plague to its owner?

Pets can transmit infections to humans through tissue or bodily fluids, including respiratory droplets from coughs or sneezes. They may also bring infected fleas into homes, which can then bite their humans.

Cats, in particular, are vulnerable to plague due to their bodies' difficulty in clearing the infection, coupled with their inclination to hunt rodents.

While plague is less common in dogs, there have been instances, such as in 2014 when Colorado reported four cases among individuals in close contact with an infected pit bull terrier, including the dog's owner and two veterinary clinic employees.

Dr. Richard Fawcett, a health officer for Deschutes County, described the cat involved in the recent case as "very sick," with a draining abscess indicating "a fairly substantial" infection.

According to Fawcett, the owner likely contracted bubonic plague initially, which manifests in lymph nodes. By the time the owner was hospitalized, the infection had progressed to the bloodstream. However, Fawcett stated that the patient responded well to antibiotic treatment.

Although some doctors suspected the patient developed a cough in the hospital, potentially indicating pneumonic plague, a version transmissible human-to-human, Fawcett clarified that it's uncertain if the disease had advanced to that stage.

As a precautionary measure, antibiotics were administered to the patient's close contacts to prevent potential infections from developing symptoms. Fawcett emphasized the cautious approach, stating that he would be "very surprised if we see any other cases."

Should You Be Worried?

No, health officials do not anticipate the disease spreading beyond Oregon or resulting in fatalities among humans.

Bubonic plague outbreaks were largely eradicated by the 1930s. Today, the CDC reports a few thousand cases worldwide annually, primarily in Madagascar, the Democratic Republic of Congo, and Peru. The fatality rate stands at approximately 11 percent, largely due to the efficacy of modern antibiotics against Yersinia pestis, coupled with improved hygiene and understanding of the disease.

According to the CDC, all forms of plague are treatable with common antibiotics, with early intervention significantly boosting survival rates. While Yersinia pestis can still emerge in various regions and pose a risk to individuals, the likelihood of a widespread pandemic akin to the Black Death is exceedingly low.