Rat-Borne Disease Outbreak Prompts Health Alert at Homeless Encampment

Health officials in Berkeley, California have issued a public health alert after detecting a dangerous bacterial infection in a local homeless encampment. The disease, leptospirosis, has been confirmed in multiple rats and dogs at encampments along Harrison Street near Eighth Street in West Berkeley.

Leptospirosis is a zoonotic infection caused by Leptospira bacteria that can be transmitted from animals to humans. According to the City of Berkeley Public Health, rats and their urine are the primary vectors of the disease, though it can also spread through contaminated soil or water that has been exposed to infected animal urine.

“People or animals who touch or drink contaminated water or mud are potentially exposed to the bacteria,” the health alert stated. “The disease is transmitted to humans and animals when the contaminated water touches mucous membranes, such as eyes, nose, mouth or skin cuts.”

Public health experts note that the risk of infection increases significantly after heavy rainfall, flooding, or hurricanes, as these weather events create more opportunities for contact with infected water or soil. Unlike respiratory infections, leptospirosis is not airborne and cannot spread through coughing or sneezing.

The Centers for Disease Control and Prevention (CDC) reports that leptospirosis typically causes flu-like symptoms, including fever, chills, headache, body aches, vomiting, and nausea. Some infected individuals may also develop more visible symptoms such as yellowed eyes or skin (jaundice), rash, stomach pain, or diarrhea.

If left untreated with antibiotics, the disease can progress to serious conditions including kidney damage, liver failure, meningitis, and respiratory problems. In rare cases, leptospirosis can prove fatal to both humans and animals.

The incubation period for leptospirosis ranges from two to 30 days after exposure to the bacteria. While most people begin to feel better within days or weeks, complete recovery without medical treatment can take several months.

In response to the outbreak, Berkeley officials have designated public health risk zones in the affected area. The highest risk area inside the encampment has been labeled as the “Red Zone,” while surrounding areas with elevated but lower risk have been designated as the “Yellow Zone.”

“The presence of rats that are transmitting leptospirosis has made the area unsafe for human encampment conditions in the vicinity of Harrison Street encampments in the area generally bounded by San Pablo Avenue, Gilman Street, Codornices Creek and the railroad tracks,” the alert explained.

City health officials are strongly recommending that encampment residents evacuate the defined “Red Zone” immediately and relocate at least one-third of a mile away from the area due to the public health risk posed by the rat infestation.

The outbreak highlights the ongoing public health challenges faced by homeless populations in urban areas. Homeless encampments often lack proper sanitation infrastructure, making residents particularly vulnerable to diseases spread through contaminated environments.

Those living in or near the affected area are advised to take precautionary measures, including avoiding contact with standing water and mud, wearing protective clothing when in potentially contaminated areas, and monitoring themselves and their pets for any signs of illness.

Health officials emphasize that prompt medical attention is crucial for anyone who believes they have been exposed to the bacteria or who is experiencing symptoms consistent with leptospirosis. With appropriate antibiotic treatment, most patients recover completely, but early intervention is key to preventing severe complications.

Local health departments are coordinating efforts to address the rat infestation and mitigate the spread of the disease, while also working to provide safer housing alternatives for affected residents.