A simple camping stay can sometimes turn to unpleasant medical surprises. In California, a resident of South Lake Tahoe was tested positive for the plague after a supposed chip stuck, the health authorities of the County of El Dorado announced on Tuesday in a statement. The patient, followed by a doctor, is currently being treated at home. Dr. Gérald Kierzek, emergency doctor and medical director of True Medical, recalls what the plague is and how to protect it.
A human case of plague detected in California
The California Public Health Department (CDPH) regularly leads rodent surveillance in the region. Between 2021 and 2024, 41 animals carrying the bacteria Yersinia Pestis were identified in the county of El Dorado. Four new animal cases have been confirmed in the Tahoe basin since the beginning of 2025. The last human case dates back to 2020, already linked to an exhibition at South Lake Tahoe. In 2015, two visitors to the Yosemite National Park had also been contaminated after 9 years without any listed cases.
This new episode recalls that the plague is not a disease of the past. It remains present in certain rural areas of Africa, Asia, but also of North America, with an increased risk in the mountain regions where many wild rodents live. The county recalls that the bacteria still circulates in this region. “”The plague is naturally present in many areas of California, especially at altitude in the county of El Dorado“Said Kyle Fliflet, acting director of local public health. He calls residents like campers to caution during outdoor activities.
What are the symptoms of the plague?
Dr. Gérald Kierzek recalls that “The plague is a serious infectious disease caused by the bacteria Yersinia Pestis“. Three main forms exist, with symptoms that appear within 1 to 7 days after exposure:
- Bubonic plague: It is the most frequent. It manifests itself in a brutal fever, chills, headaches and great weakness. Its characteristic sign is the appearance of bobons, that is to say swollen and painful lymph nodes in the groin, armpits or necks;
- Septicemic plague: It occurs when the bacteria passes into the blood, often after an untreated bubonic plague. Symptoms include fever, abdominal pain, bleeding and skin necrosis at the extremities, which has earned the disease its nickname “black death”;
- Pulmonary plague: It is the most serious and contagious form. It affects the lungs and causes coughing, chest pain and breathing difficulties. Without rapid treatment, it is often deadly.
Three possible forms of transmission
For Dr. Kierzek, the infection is mainly spread by flea bite. “”Transmission to humans is mainly done in three ways: flea stings, direct contact with infected tissues, or inhalation of respiratory droplets“. He specifies that the chip plays a major role in contaminations:”An infected chip, having bitten a sick rodent like a rat or a squirrel, can then transmit the bacteria to the man“.
The doctor also recalls the danger of contact with dead or patient animals without protection, especially rabbits and hares. The respiratory path remains the most feared: “Inhale droplets from the cough of a human or an animal with pulmonary plague is the only mode of interhuman transmission“.
Dr. Kierzek’s advice to avoid bites
The best weapon remains prevention. “”Prevention is essential, especially in rural areas where the plague is known to circulate in rodents“, Explains the doctor. He insists on the need to avoid contact with wild rodents, whether alive or dead, and recommends never approaching a squirrel, rat, or sick prairie dog.
He also recommends the use of suitable repellents: “Use an insectifuge containing deet on the skin and clothing during hiking, camping or gardening“. Domestic animals must be protected with regular antiparasitic treatments, because”cats are particularly sensitive and can transmit the plague to man“Finally, the doctor advises to reduce the sources of shelter of rodents around the dwellings by eliminating the heaps of wood, stones or the waste where they like to hide.
In case of bite …
Dr. Gérald Kierzek recommends that he do not trivialize a suspicious bite in an area where the plague circulates. “”Carefully clean the bite area with water and soap, then apply an antiseptic“, He explains. In the days that follow, he advises to remain attentive to any unusual sign:”Monitor your health for a week and consult a doctor immediately if you suddenly develop fever, chills or swollen and painful nodes“.
If these symptoms appear, he insists on the urgency of care: “Antibiotic treatment is very effective if administered early. The delayed the treatment, the more dangerous the disease becomes“. In the case of respiratory symptoms, he recommends to isolate himself and warn medical staff before arrival to limit any risk of transmission.