Extremely rare tick-borne disease infects Northern California patient; what to know
An individual from Northern California was hospitalized this year with a newly recognized and extremely rare tick-borne illness, becoming only the fourth documented case of the infection in the world, the California Department of Public Health confirmed.
The patient became seriously ill in late April with an infection involving Rickettsia lanei — a bacterium of the spotted fever group Rickettsia that is transmitted to humans by ticks, mites and fleas.
Two other cases of Rickettsia lanei have been documented in California: the first in 2004, followed by a second in 2023, a California Department of Public Health spokesperson confirmed in an email Friday. The fourth case was reported in Oregon.
According to health department officials, a patient, whose county of residence was not disclosed for privacy’s sake, likely encountered an infected tick while traveling through a shaded area of Northern California. . Experiencing symptoms of a fever, fatigue, headache, rash and loss of consciousness, the person was hospitalized for over two weeks, when officials determined the patient was suffering from an infection borne by the Rickettsia lanei pathogen.
The patient has since been discharged and is recovering, the CDPH spokesperson added.
SFGate reported this latest human case of Rickettsia lanei on Jun. 12. Researchers first became aware of the pathogen in 2018, after it was detected in rabbit ticks in Sonoma County. It was only after a man presenting fever-like symptoms was tested in July 2023 that officials discovered the bacterium could infect humans.
“Rickettsia lanei likely circulates primarily in rabbits where it is maintained by the rabbit tick, which rarely bites people. Infections in rabbits and rabbit ticks appear to be uncommon,” a CDPH spokesperson wrote in the email to The Bee. “The Pacific Coast tick, which bites humans more frequently, may occasionally acquire the organism from an infected rabbit, which is the most likely route for the rare human infections that have been identified.”
Public health officials added the Ricketssia lanei bacterium to the list of newly recognized pathogens in 2024, after investigating the July 2023 case and a separate 2004 infection that were determined to have been caused by Rickettsia lanei. Both patients presented with symptoms similar to Rocky Mountain Spotted Fever, a life-threatening disease not normally contracted in California.
According to the study, the first patient was likely exposed to an infected tick when camping in San Mateo and Marin counties in June 2004. They were discharged after a 13-day hospital stay, during which they became comatose.
The second patient, reported in July 2023, likely came into contact with an infected tick while playing golf in Alameda and Contra Costa counties, officials concluded. After 22 days in the hospital, during which time they suffered septic shock with acute kidney injury, respiratory failure, cutaneous necrosis, gangrene and encephalitis, they were discharged.
Janet Foley, a professor of medicine and epidemiology at the UC Davis School of Veterinary Medicine, who spoke to SFGate when the case was first reported, warned that the tick-borne disease is highly serious given how similar symptoms are to Rocky Mountain Spotted Fever.
Ongoing tick surveillance efforts have identified a Pacific Coast tick infected with the bacterium and two infected rabbit ticks in Contra Costa and San Mateo counties, according to the CDPH.
What should I know about ticks?
“Ticks are small, wingless bugs that usually live in the woods or tall grass,” the Cleveland Clinic said. “They bite people and animals to feed off of their blood.”
Ticks can carry a variety of diseases, with Lyme disease, Rocky Mountain spotted fever and alpha-gal syndrome among the most common, the Centers for Disease Control and Prevention said.
The U.S. Forest Service cautions hikers to stay away from areas with high grass and leaf litter, and to hike in the middle of trails, to avoid ticks.
Here are some other tips from the Forest Service:
- Use insect repellent containing 20 percent or more DEET, picaridin, or IR3535.
- Treat clothes and other gear with products that contain permethrin to repel ticks.
- Bathe or shower after being outdoors to wash off or find ticks before they bite you.
- Check yourself for ticks using a hand-held or full-length mirror after returning from tick-infested areas.
- After returning home, put clothes in a dryer on high heat for 10 minutes to kill any ticks.
If you find a tick still attached to your skin, the CDC suggests you take these steps:
- Remove the tick as soon as possible. Don’t wait to go to a doctor.
- Grab the tick close to the head using tweezers or your fingers.
- Pull the tick away from your skin with steady, even pressure.
- Don’t twist or jerk the tick, which can cause the mouth to break off in your skin.
- Dispose of the live tick by putting it in a sealed container, wrapping it in tape, flushing it down the toilet or putting it in alcohol.
- Wash your hands and the bite area with soap and water.
- Check yourself for other ticks.
“Do not use petroleum jelly, heat, nail polish, or other substances to try and make the tick detach from the skin,” the CDC said. “This may agitate the tick and force infected fluid from the tick into the skin.”
