A resident in California's popular vacation destination, Lake Tahoe, has recently tested positive for the plague, an illness commonly known as the Black Death. This individual, whose identity remains undisclosed, is currently recovering at home under medical care, following what officials speculate was a bite from an infected flea during a camping trip. This marks the first confirmed case of plague in El Dorado County since 2020, which was also believed to have originated in the South Lake Tahoe area. Prior to that, California had not detected the disease since 2015.

Plague, an infectious disease caused by the bacterium Yersinia pestis, is naturally present in many parts of California, particularly in higher-elevation regions of El Dorado County. The bacterium is carried by fleas and primarily transmitted between animals, often rodents. While historic accounts recall the Black Death wiping out an estimated 25 to 50 million people in Europe—representing 30 to 50 percent of its population between 1347 and 1351—modern cases in the United States are rare, averaging fewer than ten annually, according to the CDC. These cases typically occur in specific regions like California, New Mexico, Arizona, Colorado, and Utah, where rodent populations are more susceptible to carrying Yersinia pestis.

Symptoms of the plague usually manifest within one to eight days of infection, including fever, chills, debilitating fatigue, and sometimes painful swollen lymph nodes, known as buboes, in the groin or armpits. The disease primarily presents in three forms: bubonic, septicemic, and pneumonic. The bubonic plague is the most common, characterized by the distinctive buboes. If left untreated, the infection can become critically dangerous, spreading to the bloodstream and lungs, causing deadly infections. Untreated bubonic plague has a mortality rate of 30 to 60 percent, but if it progresses to the lungs or bloodstream, it becomes nearly 100 percent fatal due to the bacteria releasing deadly toxins that destroy cells.

A recent illuminating video vividly illustrated the progression of an untreated plague infection in the body. It depicted how, after a flea bite, bacteria rapidly multiply and migrate to the lymph nodes, causing painful swelling. Subsequently, the bacteria can enter the bloodstream, leading to bleeding under the skin that causes it to darken and turn black in certain areas. This alarming visual serves as a stark reminder of the disease's destructive power without intervention.

Despite its historical severity, modern antibiotics and improved hygiene have drastically reduced plague-related deaths. However, the disease remains endemic in wildlife. Recent US incidents include a fatal case in Colorado last month and a death in Arizona, its first since 2007, attributed to pneumonic plague—the most dangerous form, which can spread through airborne droplets. New Mexico also reported a plague fatality last year, its first since 2020. In the Lake Tahoe Basin, 45 ground squirrels or chipmunks showed evidence of exposure to the plague bacterium between 2021 and 2025.

Health officials, including Kyle Fliflet, acting director of public health for El Dorado County, strongly urge individuals to take precautions when outdoors, especially while hiking, walking, or camping in areas populated by wild rodents. Recommendations include avoiding contact with rodents and their fleas, refraining from feeding or touching wild animals, not camping near animal burrows or dead rodents, wearing long pants tucked into boots, and using insect repellent containing DEET to minimize exposure to fleas and ticks.