After a case of bubonic plague was confirmed in Oregon earlier this week, some people may wonder if there’s a danger of the disease spreading in the U.S.
The Oregon resident, who was the first to contract the infection since 2015, reportedly caught the infection from a pet cat, according to state health officials.
Experts shared with Fox News Digital what people should know about the infectious disease — including how to recognize symptoms, seek out treatment and prevent infection in the first place.
The bubonic plague is caused by Yersinia pestis, a bacterium that was likely first introduced in North America around 1900 from rats on ships coming from South Asia, according to Timothy Brewer, M.D., professor of medicine and epidemiology at UCLA.
"Since its introduction 120 years ago, it has become endemic in ground squirrels and rodents in the rural Southwestern U.S.," he told Fox News Digital.
Though the plague has most recently been found in Oregon, most cases occur around the "Four Corners" area of the Southwest — the southwestern corner of Colorado, southeastern corner of Utah, northeastern corner of Arizona and northwestern corner of New Mexico — primarily between late spring and early fall.
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Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security in Baltimore, Maryland, noted that the Oregon case was a rare occurrence, but that it is important to recognize that plague is endemic to the western part of the United States and that pets can be exposed via rodents or other animals.
"However, this is not something that the general public needs to worry very much about," he also told Fox News Digital.
Although the disease can affect people of all ages, half the cases involve patients between the ages of 12 and 45, according to the U.S. Centers for Disease Control and Prevention (CDC).
Globally, between 1,000 and 2,000 cases of plague are reported to the World Health Organization each year, although only an average of seven annual cases of are reported in the U.S.
Yersinia is usually transmitted by one of three ways, according to Brewer.
"Those include being bitten by an infected flea, handling an infected animal (such as skinning a ground squirrel), or by breathing in dust contaminated by dried rodent urine or feces with the bacteria," he said.
Erica Susky, a certified infection control practitioner based in Canada, said symptoms typically develop two to eight days after the initial exposure to the bacterium.
"It begins with fever, chills, a headache, weakness and the characteristic painful and swollen lymph nodes called buboes," she told Fox News Digital. "The buboes form at the site of the bite from the infected rodent or flea."
Anyone with these symptoms should seek immediate medical treatment if they have been exposed to an animal, generally a rodent or flea, Susky advised.
"Bubonic plague is a serious infectious illness alone, but can also develop quickly into more severe and deadly forms of plague," she warned.
"More serious forms include pneumonic and septicemic plague, which is where the bacteria invade the lungs and bloodstream," Susky said.
With pneumonic plague, the patient experiences a cough, shortness of breath and chest pain, and it can end in respiratory failure, shock and death.
Septicemic plague results in shock and often death.
The initial telltale symptom of the plague is an extremely swollen lymph node, according to Adalja.
"The danger is when the bacteria spreads from the involved lymph node systemically," he warned. "It is critical to seek medical attention to prevent the infection from spreading."
Plague can be life-threatening if left untreated, Brewer said; but if diagnosed in time, it can be treated effectively with antibiotics, typically gentamicin or fluoroquinolones.
In patients with pneumonic plague, the CDC recommends starting a course of antibiotics within 24 hours of the start of symptoms.
"The best way to avoid the disease is to avoid rodents in rural and semi-rural dry areas in the western U.S.," Brewer advised.
"Be careful about cleaning out rodent nests, airing out cabins that have been closed up for the season, or other activities where contaminated dust could be stirred up and inhaled."
For those who live in a plague-endemic area of the U.S., Adalja said they should be mindful that their dogs may encounter animals that could have plague, such as prairie dogs.
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"Keeping them leashed when they’re in areas where other animals might be present is something that individuals can do to prevent [transmission]," he said.
Brewer recommends keeping cats indoors to prevent them from picking up infected fleas, as well as using flea medications for cats and dogs.
"Plague is a dramatic but relatively rare disease," Brewer said.
"Using common sense about avoiding rodents and keeping rodents away from pets and habitats in the Southwest U.S. should be sufficient prevention for most people."
Susky agreed, adding, "Plague, though a serious infectious illness, is a smaller concern, as many people are much more likely to get infections from other bacteria and viruses."
"However, it is still important to be aware of areas where plague can occur in larger numbers, which would be in the Western U.S."
There is no vaccine currently available for bubonic plague.
