A resident of South Lake Tahoe, California, has tested positive for the plague, local health authorities announced this week. Officials believe the individual was likely bitten by an infected flea while camping in the area, a popular mountain recreation spot.
El Dorado County’s acting director of public health, Kyle Fliflet, stated: “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.” The patient is recovering at home under medical care.
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. Dogs and cats can also carry infected fleas into the home. Officials advised avoiding contact with wild rodents and preventing pets from approaching rodent burrows.
While human cases are extremely rare, they can be serious. Symptoms appear within two weeks of exposure and include fever, nausea, weakness and swollen lymph nodes. If detected early, plague can be effectively treated with antibiotics. The California Department of Public Health routinely monitors rodent populations; surveillance in El Dorado county from 2021 to 2024 identified 41 rodents with plague exposure. So far in 2025, four rodents have tested positive.
This is not the region’s first human case. The last confirmed case in El Dorado county was in 2020, also linked to South Lake Tahoe. Two cases were reported in 2015 after exposure in Yosemite National Park, and in 2021 the US Forest Service closed several sites at Lake Tahoe after discovering plague in chipmunks. Last year, Colorado also confirmed a human case. The Centers for Disease Control and Prevention estimates an average of seven human plague cases per year in the US, mostly in the western states.
