The California Department of Public Health confirmed to SFGate.com that a patient tested positive for Rickettsia lanei, a Gram-negative, obligate intracellular bacterium associated with spotted fever diseases. Among the symptoms are fever, a body temperature usually ranging from 102° F to 104° F, headache, muscle pain, and a spotted rash on the limbs. In more severe cases, vasculitis, blood clots and gangrene can develop as the bacteria damage the lining of small blood vessels.
This particular case is only the third of its kind in the state and the fourth worldwide since scientists in Sonoma County identified the germ as being carried by the tick species Haemaphysalis leporispalustris, which is distributed throughout the western hemisphere from Alaska to Argentina.
In 2026, scientists at the CDPH also positively identified the Pacific Coast tick, classified as Dermacentor occidentalis and found from Washington State to Baja California Norte, as a carrier for Rickettsia lanei. One of the ticks that tested positive for the bacteria was found in Contra Costa County.
Although there have been few specific cases of Rickettsia lanei, the Centers for Disease Control reports that annually, several thousand people are infected with spotted fever in the United States. The most dangerous form of this disease, Rocky Mountain spotted fever, or RMSF, has had its fatality rate reach as high as 10% in the United States.
To avoid tick bites, stay close to the center of the trail when hiking and steer clear of tall grasses and dense vegetation. Ticks thrive in those types of environments, as they provide sufficient shade and moisture for the ticks to settle. Ticks will also climb to the top of tall grass and stick out their legs in the hopes of hitching a ride on a warm-blooded host.
Hiking trail on Mount Davidson. Photo by James Conrad
Wear light colored clothing so that the ticks are more visible, as they can be as small as a poppy seed. Tuck your shirt into your waistband and your pant leg into your socks. If you are unable to cover up your skin, use an insect repellent containing an active ingredient such as diethyltoluamide, also known as deet. As deet can disintegrate synthetic textiles such as spandex or polyester, permethrin is a viable alternative, provided it is used moderately, as topical application may cause mild skin irritation. There also are clothes available that are preemptively infused with this chemical.
If you are bringing your dog hiking or camping, consult your veterinarian for a medication purpose-designed to repel fleas and ticks.
When you arrive home from your adventure in the great outdoors, remove your clothes as soon as possible, then wash and dry them. Run your hands on your entire body and through your hair. Make sure to double check areas on your body that would provide a cozy, secluded area for a tick, such as your navel, armpits, groin, between the toes and behind the ears.
To check your dog for ticks, run your fingers through its fur, keeping a lookout for small bumps. Make sure to inspect the dog's face, in and around the ears and under their back legs. Be extra thorough if your dog has a thick undercoat.
If you've been bitten, slowly and safely remove the tick with tweezers, getting as close to the skin as possible and pulling up with a steady pressure. Dispose of the tick by flushing it down the toilet or submerging it in rubbing alcohol. Wash your hands and the bite area thoroughly with soap and water. If needed, apply an antiseptic unguent.
Keep track of the time and the place you were bitten. Monitor any symptoms for the next 30 days and consult a physician if warranted. If signs of disease are apparent, such as headache, muscle pain, fever or rash, you will need to get a prescription for doxycycline, an antibiotic used to treat spotted fevers and Lyme disease.
Also be mindful that as a result of climate change bringing about warmer summers and milder winters, ticks are staying active for longer periods throughout the year.
