Fourth Person Infected by Emerging Tick-Bourne Disease

Another California resident tested positive for the bacteria Rickettsia lanei, as confirmed by The California Department of Public Health. This marks the fourth verified case of human infection since 2023.

Scientists first discovered the novel tick-borne bacteria in 2018 in Sonoma County, home to California's sprawling wine country. It wasn't until the first case in 2023, however, that researches found out that humans could also be infected.

Rickettsia lanei, named after UC Berkeley professor Robert Lane, can cause extreme symptoms like fever, skin lesions, coma, acute kidney injury, brain inflammation, and more. It has been characterized as very similar to Rocky Mountain spotted fever, an illness with a fatality rate of 5-10% that thousands of Americans contract each year.

Since Rickettsia lanei is a newly emerging pathogen, it's still unknown just how deadly this new variant of the spotted fever group actually is. Two of the initial, unidentified patients survived after falling into a coma and spending weeks in the hospital. Both cases occurred in Northern California and were part of a scientific study looking into the new disease.

The bacteria are carried by young, host-seeking rabbit ticks along the California coastal counties. Three of the four known cases have occurred in California, though information about the exact whereabouts is still not public knowledge. Men's Journal reached out to The California Department of Public Health, but did not receive any further information regarding the natural habitat of potentially infected rabbit ticks, also called Haemaphysalis leporispalustris.

Public health officials first confirmed the new case to SF Gate, but did not share any further details on the demographics of the patient or in what part of the state that they were initially infected.

Publicly available data shows that the counties where infected ticks have been found are mainly Northern California coastal counties like Sonoma and Contra Costa. These San Francisco adjacent counties are known for having large grassy areas where rabbit ticks thrive.

This story was originally published by Men's Journal on Jun 12, 2026, where it first appeared in the Health section. Add Men's Journal as a Preferred Source by clicking here.

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This story was originally published June 12, 2026 at 2:56 PM.