Spotted fevers

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About spotted fevers
Symptoms and treatment
Prevention
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About spotted fevers

Spotted fever group Rickettsia are a group of bacteria that can cause disease in humans. This group includes Rocky Mountain spotted fever (RMSF) and Pacific Coast tick fever (PCTF). The bacteria that cause RMSF and PCTF are transmitted by the bite of an infected tick. Symptoms of these diseases usually include a fever and rash ("spots"). In California, only a few cases of RMSF are reported each year (CDPH).

In California, the American dog tick (Dermacentor similis), the Pacific Coast tick (Dermacentor occidentalis), and the brown dog tick (Rhipicephalus sanguineus) can transmit the bacteria that cause RMSF to people and dogs. PCTF is transmitted by the bite of an infected Pacific Coast tick (Dermacentor occidentalis).

The Vector Control Program routinely collects, identifies, and tests ticks for spotted fevers and other tick-borne pathogens. If tests come back positive, results are posted on our website.

Symptoms and treatment

The first sign of many spotted fevers is generally a dark scab at the site of the bite, known as an eschar. Eschars usually develop a few days to a week following the bite of an infected tick or mite.

Other signs and symptoms can include:

Fever
Headache
Rash
Muscle aches

Pacific Coast tick fever is less severe than RMSF; however, it can be difficult to distinguish between RMSF and other spotted fevers. See your doctor if you develop symptoms after having been bitten by a tick, or having spent time in areas where ticks may live. For RMSF, early treatment with antibiotics can be lifesaving.

Prevention

These tips will help protect you from spotted fevers:

Stay on paths and trails
- Ticks are found in grassy, brushy areas and on the plants that line trails
- Keep pets on leash and on trail while hiking
Dress for protection when outdoors
- Wear long-sleeved shirts and long pants
- Wear light-colored clothing that shows ticks crawling on you
Use Environmental Protection Agency (EPA)-registered insect repellent
- Look for repellent containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), or para-menthane-diol (PMD).
- Apply repellent to clothing and exposed skin; follow the directions carefully
Check yourself for ticks
- After you are in a tick-infested area, examine yourself and your companions for ticks and remove them right away
- Tick nymphs may be very small, about the size of a poppy seed