Health officials are investigating a flea-borne typhus outbreak in Santa Monica, marking the second outbreak Los Angeles County has faced this year as cases of the bacterial infection continue to climb across the region.
The Los Angeles County Department of Public Health is investigating five outbreak-associated cases in the City of Santa Monica. Officials said all cases were hospitalized and recovered. In response to this outbreak, Public Health continues to monitor the area for additional outbreak-associated cases. Field staff have conducted an environmental assessment in the affected area to identify transmission risk factors, and they are collaborating with the City of Santa Monica on control efforts.
Public Health said it has conducted outreach to nearby residences, schools, animal control agencies and veterinary practices. Public Health has also disseminated a health advisory via the Los Angeles Health Alert Network (LAHAN) to healthcare providers to increase awareness of risk and prompt early testing and treatment of patients.
Public Health has instructed the Santa Monica Animal Shelter to implement additional intake procedures to prevent the disease from spreading further. Workers at the shelter will now test fleas specifically from cats brought in from an area of the city near 25th and Kansas, Virginia or Stewart streets.
The Santa Monica outbreak follows an earlier outbreak Public Health investigated in Central Los Angeles this year. County health officials are urging residents to take precautions to protect themselves and their pets as they expect additional cases and clusters to emerge in the coming months.
"This ongoing increase in flea-borne typhus highlights the importance of taking preventive steps to reduce the risk of infection," said Dr. Muntu Davis, Los Angeles County Health Officer.
Los Angeles County has seen a dramatic rise in flea-borne typhus cases since 2010. Last year marked a record high with 187 documented cases. So far in 2025, 106 cases have already been reported — higher than the same period last year. The infections typically peak during late summer and fall months.
Flea-borne typhus, also known as murine typhus, is an acute febrile illness caused by Rickettsia typhi bacteria spread by infected fleas. People become infected when flea feces are rubbed into cuts or scrapes on the skin or into the eyes. The disease is not transmitted from person to person.
In Los Angeles County, infected fleas are most commonly found on rats, free-roaming cats and opossums. Pets such as dogs and cats that go outdoors can bring fleas into homes. Infected animals typically show no signs of illness.
Human symptoms begin within two weeks of contact with an infected flea and may include fever, headache, muscle pain, nausea, vomiting and a rash that spares the palms and soles. While the illness can be mild and self-limiting, it can also present as severe disease requiring hospitalization.
In rare cases, complications may include swelling at the lining of the brain or in heart valves. Though fatalities are uncommon, the first flea-borne typhus deaths in LA County since 1993 were reported in 2022.
"Flea-borne typhus is serious, but preventable," Davis said. "We urge people to take precautions by using flea control on their pets, avoiding contact with stray animals, and preventing wildlife from living in or next to their home or property. If you develop symptoms, such as fever, chills, or a rash, seek medical attention right away."
There are no vaccines to prevent flea-borne typhus, but the disease can be treated with antibiotics. Doxycycline is the treatment of choice.
Health officials recommend several prevention measures: Use EPA-registered insect repellent labeled for protection against fleas when outdoors. Routinely use flea control products on pets and keep them indoors as much as possible.
Residents should avoid attracting wild or stray animals by not leaving pet food or water outside and avoiding feeding or touching stray or wild animals. Properties should be kept free of debris and overgrown plants, with trash stored in containers with tightly fitting lids.
Officials also recommend sealing crawl spaces and any openings where animals could enter, hide or find food and water. Residents should report stray animals or signs of rodents or opossums near their property to local animal control officials.
Healthcare providers should consider flea-borne typhus in patients with non-specific febrile illness accompanied by headache, muscle pain, rash and laboratory abnormalities. Treatment decisions should be based on clinical presentation and exposure history rather than waiting for diagnostic test results.