The first case of human plague in Oregon in 8 years likely came from a cat
Health officials announced this week that a resident of Deschutes County — a rural area of Oregon — has been diagnosed with plague, marking the first human case in the state in more than eight years. The person likely became infected through their pet cat, which showed symptoms, according to Deschutes County Health Services.
Humans are most often exposed to plague from the bites of fleas carrying Yersinia pestis, the bacteria that causes the disease. Household pets can also become infected if they catch plague-infected rodents or are similarly bitten by an infected flea.
Pets can then transmit the infection to humans via tissues or body fluids, such as respiratory droplets from coughing or sneezing. Alternatively, they may be carried by household fleas, which in turn bite humans.
Cats are particularly vulnerable to plague because their bodies have difficulty clearing the infection, and they are also more likely than some other pets to chase and catch rodents.
Plague is very rare in dogs. However, in 2014, Colorado reported four cases of plague among people who had close contact with an infected pitbull, including the dog’s owner and two veterinary clinic employees.
The cat in the latest case was “very sick” and had a draining abscess, indicating a “fairly significant” infection, said Dr. Richard Fawcett, Deschutes County health officer.
Fawcett said the owner’s infection likely began in the lymph node, which is known as bubonic plague. He added that by the time the owner entered the hospital, the infection had spread to his bloodstream. The patient “responded very well to antibiotic treatment,” Fawcett said.
But he noted that some doctors felt that the patient developed a cough while in the hospital. That could be an early sign of pneumonic plague — a version that passes between humans — but Fawcett said it’s not clear whether the disease has evolved that far.
Fawcett said doctors gave antibiotics to the patient’s close contacts out of an abundance of caution to prevent any potential infection from developing into symptoms.
“If we know the patient has the bacteria in the blood, we might decide to be on the safe side,” Fawcett said. He added, “I would be very surprised if we see any more cases.”
Before this week, the last case of human plague in Oregon was in 2015: a teenage girl supposedly became infected from a flea bite during a hunting trip, the state health department said at the time.
Where does plague occur in the United States?
On average, the United States sees about seven cases of human plague each year, most of them in the rural West. Cases are typically concentrated in northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon and western Nevada, according to the Centers for Disease Control and Prevention.
“The hotspot is actually the Four Corners region” near the borders of Utah, Arizona, Colorado and New Mexico, said David Wagner, director of the Center for Biodefense and Disease Ecology at the Pathogens and Microbiome Institute at Northern Arizona University.
“But we still don’t have a good handle on the persistence of plague in the environment in the western United States. It’s very mysterious. It’s kind of disappearing among these rodent populations, and we don’t know what’s going on,” Wagner said. there.”
Fawcett said he’s also unsure why cases have appeared sporadically in Central Oregon over the past 10 years or so.
“We don’t have a lot of problems with fleas in this part of the state,” he said, adding that rodents that carry plague don’t seem to be a particular problem either.
According to the Centers for Disease Control and Prevention, plague tends to occur in semi-arid forests and grasslands that are home to many rodent species. The person who recently became ill in Deschutes County lives in a rural, suburban neighborhood, and “there is open land not far” from the person’s home, Fawcett said.
Deschutes County Health Services advises pet owners to keep their animals on a leash when outdoors, give them flea control products and take them to a veterinarian if they become sick after touching rodents. The department also asks people to avoid contact with rodents and to refrain from feeding squirrels or chipmunks.
When is the plague fatal?
More than 80% of plague cases in the United States are bubonic, meaning the infection is limited to the lymph nodes. People with bubonic plague usually develop symptoms two to eight days after being bitten by an infected flea or coming into contact with an infected animal.
The most common sign of bubonic plague is swollen, painful lymph nodes. Other symptoms include sudden fever, nausea, weakness, chills or muscle pain. Doctors test for the infection with a blood or tissue sample, then treat it with antibiotics.
Wagner said the bubonic plague, which killed more than a third of Europe’s population in the 14th century, represented a much different threat than today.
“It’s the same thing that caused the Black Death, but that was in the pre-antibiotic era,” Wagner said. “Now it is treated very easily with simple antibiotics.”
However, if bubonic plague is not treated early, the bacteria may enter the bloodstream and cause sepsis — or septicemic plague. Typical signs of a bloodstream infection include severe weakness, abdominal pain, or bleeding from the nose, mouth, or under the skin. People’s skin may also turn black, especially on the nose, fingers, and toes.
Untreated bubonic infection or septicemia can lead to lung infection, or pneumonic plague, which is often fatal. People can also become infected with pneumonic plague directly by inhaling infectious droplets.
Fawcett said these different forms of plague can coexist at the same time, and it is not entirely clear when the disease transitions from one stage to another or becomes contagious between humans.
However, he is confident that the overall risk in Deschutes County is low. As long as the Department of Health is monitoring close contacts, he said, “I can’t imagine it won’t pose any significant risk to our community.”