A man in California has tested positive for the plague, according to local authorities.
Health officials in El Dorado county released a statement on Tuesday revealing that they were notified of the situation by the California department of public health (CDPH).
The patient, who is a resident of South Lake Tahoe in California, is now recovering at home and is under the care of a medical professional, per the statement.
Health officials believe the individual "may have been bitten by an infected flea while camping in the South Lake Tahoe area”, which a popular area for visitors in the California mountains. An investigation into exactly how the plague was contracted is underway.
Kyle Fliflet, El Dorado county’s acting director of public health, said per the Guardian: "Plague is naturally present in many parts of California, including higher-elevation areas of El Dorado county.
"It’s important that individuals take precautions for themselves and their pets when outdoors, especially while walking, hiking and/or camping in areas where wild rodents are present."
According to the release, the plague is caused by the bacterium Yersinia pestis, and is most often transmitted by fleas “that have acquired the bacteria from infected squirrels, chipmunks and other wild rodents”.
Officials also stated that dogs and cats are able to carry infected fleas into the home and advised the public to avoid contact with wild rodents, as to prevent pets from going near rodent burrows.
While human cases of the plague are "extremely rare" according to the statement, they can make a person seriously ill.
Symptoms usually appear within two weeks of exposure and include swollen lymph nodes, fever, nausea, and weakness.
If detected early, the plague can usually be effectively treated using antibiotics.
CDPH confirmed that the rodent population across California is regularly monitored for plague activity and stated that surveillance in El Dorado county from 2021 through 2024 identified a total of 41 rodents that showed evidence of exposure to the plague bacterium.
In 2025 thus far, four rodents have tested positive for the plague bacterium, with officials confirming that they were all within the Tahoe Basin.
The last confirmed human case of the plague in the region was in 2020 when a patient in El Dorado county tested positive, and was also believed to be linked to the South Lake Tahoe area.
According to the release, prior to that, two cases were reported in 2015 after exposure in Yosemite national park.
All of the individuals who contracted the plague were treated and made a full recovery.
The US Forest Service announced in 2021 that several popular sites in Lake Tahoe would be closed for several days after plague was discovered among the chipmunk population.
It stated at the time that “vector control” workers would complete “eradication treatments” in the area.
A human case of the plague was also confirmed in Colorado last year.
According to The Centers for Disease Control and Prevention, it is estimated that there is an average of seven human plague cases a year in the US, with most of the human cases occurring in the west.