This is another spotted fever virus like Rocky Mountain spotted fever (RMSF). It is spread by Dermacentor occidentalis (Pacific coast tick) in California. The primary symptom is fever, but headache, muscle ache, and fatigue are also seen. Eschars, instead of a rash, are found where the tick bites, similar to Rickettsia parkeri. Antibody tests may cross react with Rickettsia rickettsia. The CDC recommends as a precaution that all patients should be treated as if they have RMSF.
Specific diagnosis can be made from a swab or biopsy of the eschar by PCR, immunohistochemistry stains of tissue, or cell culture.