Leptospirosis

There have been no human cases of Leptospirosis in this area or anywhere in Berkeley for at least a decade. Doctors statewide are -- and have been -- required to report all such cases to public health officials.

Leptospirosis, a bacterial disease, is present in rats in the area generally bounded by Codornices Creek, Gilman Street, San Pablo Avenue, and the railroad tracks. The most common way the bacteria is spread is through the urine of rats, which can be found mixed into standing water. 

The disease is transmitted to humans and animals when the contaminated water touches mucous membranes – such as eyes, nose, mouth, or cuts to the skin. Most people have no symptoms.

For the general public not living in encampments, there is a low risk of exposure to leptospirosis. The risk of infection is even lower. To further lower risk, people and pets should follow good hygiene practices and also avoid contact with water or mud that may be contaminated with the urine of infected rats.

For questions, see our Health Alert or contact leptoinformation@berkeleyca.gov; (510) 981-5460.

Good hygiene reduces risk of exposure

The general public has a low risk of exposure to leptospirosis and an even lower risk of infection. Since the disease spreads through the bodies and urine of infected rats, the risk is low for people with access to indoor shelter, running water, secure garbage, and safe food storage.

Those who spend time in the area bounded by Gilman Street, San Pablo Avenue, Codornices Creek and the railroad tracks can reduce their risk even more by taking preventative steps:

• Avoid contact with standing water in the area
• Do not drink, wade in, or touch the water in Codornices Creek
• Clean your wounds and cover them with waterproof bandages
• When gardening, wear gloves and protective foot coverings, such as rubber boots
• Wash all fruits and vegetables grown in the area thoroughly before consumption
• Do not touch sick or dead animals; call Animal Control at (510) 981-6600

 Pet owners who live in or walk their animals in this area can also take steps to reduce risk:

• Ensure dogs have the leptospirosis vaccine, already part of the core vaccines for dogs nationwide
• Keep pets on a short leash
• Bring water on walks, do not allow pets to drink from other sources

Pest management reduces spread

Protect your property from rats to reduce the spread of leptospirosis. Steps everyone can take to prevent rats include:

• Waste: Secure trash in bins, regularly dispose of waste
• Yard: Trim bushes and clean up fallen fruit
• Pets: Do not keep pet food or water outdoors
• Home: Keep food in sealed containers and seal entry points

If you have rats on your property in the area of Berkeley bounded by Codornices Creek, San Pablo Avenue, Gilman Street and the railroad tracks, Alameda County Vector Control can come to your property to do an inspection. Please contact online or by phone:

• Submit request online
• Call: (510) 567-6800

For rat concerns in other areas of Berkeley, please contact City of Berkeley Vector Control:

• Report online
• Call: (510) 981-5310
• Email: envhealth@berkeleyca.gov

About Leptospirosis

Leptospirosis is a bacterial disease that most commonly spreads through mud and water contaminated with the urine of infected rats. The bacteria is killed by exposure to ultraviolet rays in sunlight and by drying out.

Infection occurs through mucous membranes, such as the nose, mouth, eyes, or open wounds. Leptospirosis is not spread in the air or by coughing or sneezing.

Leptospirosis is usually asymptomatic but can present flu-like symptoms. In some cases, the disease can cause severe illness. 

There is antibiotic treatment for humans, dogs, and cats. An effective vaccine exists for dogs. 

For more information, please visit the official CDC Leptospirosis webpage and the CDPH Leptospirosis webpage.

Get medical care if you have symptoms

If you think you were exposed to leptospirosis and have flu-like symptoms – fever, chills, headache, red eyes, and muscle aches – contact your primary care provider for an urgent appointment.

Because leptospirosis is rarely seen by doctors in the United States, it is important to let your health care provider know that you may have been exposed.

Leptospirosis can cause a wide range of symptoms, including:

• Fever
• Headache
• Chills
• Body or muscle aches
• Vomiting or nausea
• Yellowed skin and eyes (jaundice)
• Red eyes
• Stomach pain
• Diarrhea
• Rash

Symptoms usually begin 2-30 days after exposure. If left untreated, the disease can cause serious illness. It's rare for people to spread leptospirosis to other people. 

Your health care provider can test and treat you for leptospirosis if you have symptoms and may have been exposed.

Contact a vet if your pet has symptoms

If you believe your pet was exposed to leptospirosis and has signs of illness—such as fever, jaundice, or changes in urination—contact your veterinarian immediately to discuss testing, or antibiotic treatment. The 2-dose vaccine for Leptospirosis is considered a core vaccine for all dogs nationwide.

Leptospirosis at the Harrison Street encampment

Leptospirosis was identified by veterinarians treating sickened dogs at encampments on or near Harrison Street as well as by Alameda County Vector Control, which tested rats in December 2025. 

At the request of the City of Berkeley, Vector Control trapped rats at the encampment in December 2025 due to the concern raised by the Leptospirosis infections in dogs at the encampment. Subsequent testing confirmed the presence of the bacteria in the rats tested.

There is an ongoing public health investigation into the status of Leptospirosis transmission at this encampment site and in the surrounding area. The City’s public health response is constrained by a federal court order that prohibits the City from fully closing the encampment. The City is seeking relief from the court’s order. 

The City of Berkeley’s actions in response to this public health concern have included: 

• Coordinating with Alameda County Vector Control to post notices around the area of the encampment, where the rats were trapped, to alert the neighborhood of the Leptospirosis risk. 
• Informing the people living in the encampment of the risk and screening for symptoms through outreach by Alameda County Health Care for the Homeless and Street Health teams. 
• Conducting Health Outreach events at the encampment to enhance communication, support, and response for the population. 
• Ongoing plans for continued rat testing and abatement efforts.
• Performing regular encampment clean-ups in the area to reduce the debris that can create conditions to harbor rats.

Learn more about leptospirosis at the Harrison Street encampment in the City of Berkeley’s Health Alert.

Harrison Park (Gabe Catalfo Fields)

The risk of infection is also low in the area of Harrison Park (Gabe Catalfo Fields). Health officials believe there is little risk of exposure by playing in the field. 

This belief of low risk for the general public is based on the observed conditions and known science about Leptospirosis:

• Alameda County Vector Control inspected Harrison Park (Gabe Catalfo Fields) in early December and saw no rats. Rats are not known to burrow in the playing fields. 
• Additionally, Leptospirosis bacteria is very sensitive to UV light, and these fields are exposed to the sun. 
• Exposure to the rat urine is in standing water. As conditions continue to dry, we anticipate that the already low risk will also continue to diminish. 

Field use should be avoided if there is standing water or creek flooding onto the fields. Importantly, people and pets should avoid wading in or touching water from Codornices Creek. If you retrieve any balls from the Creek, wash them thoroughly before using. 

Field users should practice good hand hygiene, including handwashing with soap and water as well as cleaning and dressing skin injuries before and after field use.