The plague, a disease that devastated Europe in the 14th century, has reappeared in California. According to professor John Swartzberg of UC Berkeley’s School of Public Health, the plague is not as rare as people think, and it can still be deadly.
In 2020, a case of the plague was reported in El Dorado County, and in 2015, two cases were reported in Yosemite National Park. The disease is caused by the bacterium Yersinia pestis and primarily affects small animals or rodents in the United States.
There are three types of the plague: bubonic, septicemic, and pneumonic. Bubonic plague is characterized by swollen lymph nodes, while septicemic plague spreads throughout the body and can be fatal if left untreated. Pneumonic plague infects the lungs and can spread through respiratory droplets.
Most people who contract the plague do so while hiking or camping in areas where rodents are present. The principal source of plague in Los Angeles County today is wild rodents in rural areas. To protect themselves, people should avoid contact with these animals and their habitats.
The risk of contracting the plague is highest in areas such as the Angeles National Forest and San Gabriel Mountains. Public health officials warn that dogs and cats can also become infected if they get fleas from an infected rodent.
While medical advancements have made the plague treatable, it has not been eradicated. There are currently no FDA-approved vaccines for the disease. Experts say that eradicating the plague is unlikely in the near future due to its complex transmission dynamics and the presence of a vector like fleas.
If treated promptly with antibiotics, the risk of death from the plague is low. However, if left untreated, it can be fatal. The Centers for Disease Control and Prevention notes that only one human infectious disease has been eradicated: smallpox.
Source: https://www.latimes.com/california/story/2025-08-22/bubonic-plague-california-case-lake-tahoe-experts-explain