Health officials announced this week that a resident of Oregon's rural Deschutes County has been diagnosed with plague, the first human case in the state in more than eight years. Deschutes County Health Services said the person likely contracted the virus from a pet cat that developed symptoms.
Humans are most commonly exposed to plague through the bites of fleas that carry the disease-causing Yersinia pestis bacteria. Domestic pets can also become infected if they hunt plague-infected rodents or are bitten by similarly infected fleas.
Pets can then transmit the infection to humans through tissue or body fluids, such as droplets from coughs or sneezes. Or they may bring the fleas home, which can then bite humans.
Cats are especially susceptible to plague because their bodies have a harder time eliminating infections and they are more likely to chase and catch rodents than other pets.
Plague is much rarer in dogs. However, in 2014, Colorado reported four cases of plague among people who had close contact with infected pit bull terriers, including the dog's owner and two veterinary hospital workers.
Deschutes County Health Officer Dr. Richard Fawcett said the cat involved in the recent incident was “very sick” and had an abscess, indicating a “pretty serious” infection.
Fawcett said the owner's infection likely started in the lymph nodes and is known as bubonic plague. By the time the owner was hospitalized, the infection had spread to the dog's bloodstream. Fawcett said the patient “responded very well to antibiotic treatment.”
However, he noted that some doctors felt that the patient started coughing while in the hospital. It could be an early sign of pneumonic plague, the version that is contagious among humans, but it's unclear whether the disease has progressed that far, Fawcett said.
Fawcett said doctors administered antibiotics to the patient's close contacts out of an abundance of caution to prevent any potential infection from developing into symptoms.
“If we see that the bacteria is present in the patient's blood, we may decide to be on the safe side,” Fawcett said. He added: “I would be very surprised if there were other incidents.”
Before this week, the last human case of plague in Oregon was in 2015, when a teenage girl probably contracted the disease from a flea bite while on a hunting trip, the state health department said at the time.
Where does the plague occur in the United States?
On average, there are about seven human epidemics each year in the United States, most of which occur 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 Northern Arizona University's Pathogen and Microbiome Institute.
But “we still don't really understand the persistence of plague in the western U.S. environment,” Wagner said, adding, “It's very puzzling. Plague disappears into rodent populations.” It's like, I have no idea what's going on.” It's over there. ”
Fawcett said he also doesn't know why there have been sporadic outbreaks in central Oregon over the past dozen years.
“We don't really have a lot of flea problems in this part of the state,” he said, adding that disease-carrying rodents also don't seem to be a particular problem.
According to the CDC, plague tends to occur in semiarid forests and grasslands, where many rodents live. Fawcett said the person who recently became ill in Deschutes County lives in a rural to near-suburban area and “has a vacant lot not too far” from his home.
Deschutes County Health Services advises pet owners to keep their animals on a leash when outdoors, give them flea killer, and take them to the veterinarian if they become sick after handling a rodent. There is. The department also urges people to avoid contact with rodents and avoid feeding squirrels and chipmunks.
When does the plague become deadly?
More than 80% of plague cases in the United States are bubonic plague, where infection is confined to the lymph nodes. A person with bubonic plague usually develops symptoms 2 to 8 days after being bitten by an infected flea or coming into contact with an infected animal.
The most common signs of bubonic plague are swollen and painful lymph nodes. Other symptoms include sudden onset of fever, nausea, weakness, chills, and muscle pain. Doctors use blood or tissue samples to test for infections and treat them with antibiotics.
The bubonic plague, which killed more than a third of Europe's population in the 14th century, was much different from the current threat, Wagner said.
“It's the same thing that caused the Black Death, but this was before antibiotics,” Wagner said. “Now it can be treated very easily with simple antibiotics.”
However, if bubonic plague is not treated early, the bacteria can enter the bloodstream and cause sepsis, or septicemic plague. Typical signs of a bloodstream infection include extreme weakness, abdominal pain, and bleeding from the nose, mouth, or under the skin. The skin, especially on the nose, fingers, and toes, may also darken.
Untreated glandular or septic infections can lead to lung infections or pneumonic plague, which is often fatal. People can also contract pneumonic plague directly by breathing in 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 when it is transmitted between humans. Stated.
That said, he believes the general risk in Deschutes County is low. He said as long as the health department monitors close contacts, “it's unlikely to be a significant risk to our community.”
