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A man was diagnosed with bubonic plague at El Dorado County, California, after being stung by a flea while camping, US health officials reported on August 21, 2025.
Man in the US tests positive for black plague after flea chopped in camp. Photo: Reproduction
The infection, caused by the Yersinia Pestis bacteria, is rare but potentially fatal, and led authorities to intensify warnings for prevention in rural areas. The patient, whose identity was not revealed, is in home recovery under medical supervision. This is the first case registered in the region since 2020, according to the official statement of the county.
The disease, historically associated with devastating pandemics, is still present in wild rodents in the west of the US, which requires extra attention from camper and residents. The situation reinforces the importance of preventive measures against fleas and rodents.
The case rekindles concerns about the circulation of bacteria in natural areas. The Disease Control and Prevention Centers (CDC) records, on average, seven annual cases of human plague in the country. Transmission occurs mainly by contact with infected animals or flea bites.
- Prevention measures include the use of insect repellents.
- Cleaning areas with potential for rodent nests is recommended.
- Pets should receive flea treatment regularly.
- Avoid direct contact with wild rodents reduces risk of infection.
Origin and circulation of the bacteria
The plague, caused by Yersinia Pestis, is a zoonotic disease that circulates between rodents and fleas in natural environments, especially in rural areas of the west of the United States, such as California, New Mexico and Colorado.
El Dorado County, where the case was registered, is a mountainous region with a significant presence of wild rodents, which facilitates the maintenance of bacteria in the ecosystem. CDC data indicate that the bacteria is present in various parts of California, making constant surveillance essential.
Transmission to humans occurs mainly by infected fleas bites, which carry the bacteria after feeding on sick animals. In addition, direct contact with rodent body fluids or other infected animals can also propagate the disease. Although rare, the plague has lethal potential if not treated early.
The current case has no evidence of outbreak, but reinforces the need for monitoring. In 2020, another case in the same region mobilized authorities, which intensified awareness campaigns. The recovery of the current patient, using antibiotics, demonstrates the effectiveness of treatment when initiated rapidly.
Forms of disease and symptoms
The plague manifests itself in three main forms, each with different characteristics:
- Bubonic: The most common is characterized by painful swelling of lymph nodes, known as bubans.
- Pneumonic: It affects the lungs, being transmitted by respiratory droplets, which makes it more contagious.
- Septicêmica: Occurs when the bacteria spreads through the bloodstream and may cause septic shock.
Symptoms usually appear within two weeks after exposure. High fever, chills, extreme weakness and localized pain are initial signs. In pneumonic form, respiratory difficulties and chest pain are predominant, while septicemic can evolve into bankruptcy if not treated. Early diagnosis is crucial, and treatment with antibiotics such as doxycycline or ciprofloxacin has a high success rate.
El Dorado’s patient presented the bubonic, less severe form and is responding well to treatment. Pneumonic or septic cases are rarer, but require immediate intervention due to the risk of complications.
