Rare Tick-Borne Illness Reported in California
This spring, a resident of California was hospitalized with a tick-borne illness that’s incredibly rare—only four human cases have been recorded globally, as stated by the California Department of Public Health.
In April, the individual was diagnosed with an infection caused by Rickettsia lanei, a recently identified bacterium in the spotted fever Rickettsia group. The health department believes the infection was likely acquired in Northern California.
The patient has been released from the hospital and is on the road to recovery, although details about the patient’s identity, county of residence, symptoms, duration of hospitalization, or exact location of exposure have not been shared.
This incident marks the fourth known case of human infection from Rickettsia lanei and the third within California. Previous cases recorded in 2004 and 2023 were identified as severe illnesses resembling Rocky Mountain spotted fever and were linked to the same pathogen.
Symptoms associated with similar illnesses often include fever, headaches, muscle aches, and rashes. However, early symptoms can resemble those of other infections and might not clearly indicate a tick-borne illness, according to the health department.
Rickettsia lanei was first discovered in rabbit ticks in Sonoma County back in 2018. The risk of transmission to humans was unclear, as rabbit ticks typically do not bite people. Recent studies, though, suggest that the Pacific Coast tick may be a likely source of human infections.
A 2024 report in the CDC journal Emerging Infectious Diseases discussed two men from Northern California, who developed serious spotted fever-like illnesses nearly two decades apart. One had played golf in Alameda and Contra Costa counties before falling ill, while the other had visited various outdoor areas in San Mateo and Marin counties.
Both individuals were hospitalized, with one spending 22 days in the hospital, including 11 in intensive care, and the other for 13 days. Fortunately, both men recovered.
While Rocky Mountain spotted fever is uncommon in California, it can be life-threatening. The public health department notes that the state usually records only a handful of confirmed cases of Rocky Mountain spotted fever and Pacific Coast tick fever each year.
The CDC emphasizes that Rocky Mountain spotted fever can be fatal if not treated promptly with doxycycline, the recommended antibiotic for suspected tick-borne rickettsial diseases.
Health officials urge anyone experiencing fever, rash, severe headaches, or flu-like symptoms after potential tick exposure to seek medical attention quickly, making sure to mention any tick bites or recent time spent in grassy, brushy, or wooded areas.
If you find an attached tick, it’s advisable to remove it with fine-tipped tweezers. Grasp the tick close to the skin and pull upward with steady pressure. Monitor for symptoms and consult a healthcare provider if you become unwell.
