Acute Communicable Disease Control
Rocky Mountain Spotted Fever and Spotted Fever Group Rickettsia

Rocky Mountain Spotted Fever (RMSF) and Spotted Fever group (SFG) Rickettsia are diseases caused by Rickettsia bacteria that are transmitted to people through the bite of an infected tick. RMSF, caused by Rickettsia rickettsii is the most severe and most frequently reported rickettsial illness in the United States (U.S). Contrary to its name, RMSF is rare in the western U.S.; most cases occur in the Midwest and southeastern U.S. Only one or two cases of RMSF are reported each year in California. Initial signs and symptoms of the disease include sudden onset of fever, headache, and muscle pain, followed by development of rash. The disease can be difficult to diagnose in the early stages, and without prompt and appropriate treatment it can be fatal.

SFG Rickettsia can cause a fever, headache and a small open wound about inch in size that turns into a dark scab (called an eschar). A SFG Rickettsia called 364D has been recently identified from a small number of people in northern California and has been found in the Pacific Coast tick in eight counties, in both northern and southern California.

Additional Resources

Laboratory Testing