Plague

The California Department of Public Health (CDPH) provides information on plague, a disease caused by Yersinia pestis, which is found in wild rodents like squirrels and chipmunks in California's mountainous and foothill regions. To prevent infection, people should avoid wild rodents, their burrows, and fleas, and be cautious in rural, wild areas. Symptoms of plague include high fever, chills, weakness, nausea, and swollen lymph nodes. If symptoms appear after outdoor exposure, seek immediate medical attention and inform your healthcare provider of your potential exposure to rodents and fleas.  

What is Plague?

  • Plague is a rare but serious bacterial disease caused by Yersinia pestis. 
  • It's primarily spread through the bite of fleas from infected wild rodents, such as ground squirrels and chipmunks. 
  • People can also be infected by direct contact with infected animals, their body fluids, or by touching flea-infested areas. 

Where is Plague Found in California? 

  • Plague is endemic in the foothill and mountainous areas of California.
  • It is not typically found in urban areas or the Central Valley.
  • An endemic map on the CDPH website provides details on areas where plague is known to occur.

Symptoms and Treatment 

  • Symptoms 

appear within about two weeks of exposure and include high fever, chills, weakness, nausea, and swollen lymph nodes.

  • Treatment 

is available and highly effective with antibiotics if the disease is diagnosed and treated promptly in its early stages.

Prevention

  • Avoid: wild rodents and their burrows. 
  • Use: insect repellent (containing DEET) on skin and clothing, especially in rural areas. 
  • Keep: pets on a leash, away from rodent burrows, and apply flea control products. 
  • Do not: feed wild rodents in camping or picnic areas. 
  • Store: food and garbage in rodent-proof containers. 
  • Report: any sightings of sick or dead wild rodents to authorities, as these are warning signs of active plague in the area. 
  • Look for: and heed warning signs posted in campgrounds and trailheads. 

Important Considerations

Pets  

like cats are susceptible to plague and can potentially transmit the disease to humans. 

Human-to-human  

transmission is extremely rare in California and only possible if a patient with plague has a lung infection and is coughing.