A resident of the Lake Tahoe area has tested positive for plague, California health officials confirmed on Tuesday, marking the first known human infection in the region since 2020.
Authorities believe the person became infected after being bitten by a flea carrying the plague bacterium while camping in the South Lake Tahoe area, a region known for its outdoor recreation and wildlife.
According to a news release from El Dorado County, the patient is currently recovering at home and receiving care from medical professionals.
Health officials emphasized that the case, while concerning, is not an immediate threat to the broader community. Antibiotics are highly effective in treating the infection if caught early.
Kyle Fliflet, acting director of public health for El Dorado County, stressed the importance of awareness and prevention: “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, or camping in areas where wild rodents are present.”
Plague is caused by the bacterium Yersinia pestis. Historically, it is infamous for triggering catastrophic pandemics such as the Black Death in the 14th century, which killed millions across Europe. Today, however, the disease is extremely rare in the United States and is treatable with common antibiotics.
The bacteria are typically transmitted to humans through bites from infected fleas that live on rodents such as squirrels, chipmunks, or rats. Less commonly, people can contract the illness through direct contact with infected animals.
Symptoms generally appear within two weeks of exposure and include fever, chills, fatigue, and swollen lymph nodes. If untreated, plague can progress to more severe forms, such as septicemic or pneumonic plague, both of which can be fatal.
The U.S. Centers for Disease Control and Prevention (CDC) reports an average of seven human cases nationwide each year, with most occurring in rural areas of the western states, including California, New Mexico, Arizona, and Colorado.
The California Department of Public Health (CDPH) routinely monitors rodent populations in high-risk areas to track potential plague activity. So far in 2025, four rodents in the Tahoe Basin have tested positive for the bacteria, suggesting that plague is circulating in local wildlife. Prior to this new infection, the last confirmed human case in El Dorado County was reported five years ago.
Officials noted that plague activity in rodents does not necessarily mean human cases will occur. However, the presence of the disease in wildlife serves as a reminder that people spending time outdoors in the region should take precautions.
Health experts recommend several measures to reduce the risk of plague exposure: Keep campsites and residential areas clear of brush, wood piles, and debris that may attract rodents. Use insect repellents containing DEET when hiking, camping, or spending time outdoors in rodent-prone areas. Protect pets with veterinarian-approved flea control products. Avoid allowing pets to roam freely in regions where plague is known to circulate. Do not sleep with pets that may have been exposed to fleas in the wild.
Officials also advise residents to report unusual rodent die-offs, as sudden deaths among squirrels or chipmunks can sometimes indicate plague outbreaks in local populations.
While modern medicine has made plague far less dangerous than in the past, health officials caution that the disease should still be taken seriously. Early recognition and treatment are critical to preventing complications.
The case in South Lake Tahoe underscores the reality that plague, though rare, remains a natural part of the environment in California’s higher-elevation areas. For residents and visitors alike, the best defense is knowledge, preparation, and a commitment to simple preventive steps.
Officials continue to monitor the situation closely and urge the public not to panic but to remain cautious, particularly during peak outdoor recreation season in the Sierra Nevada.