Rickettsia species 364D 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 a headache, muscle aches, and fatigue are also seen. Instead of a rash, eschars are found where the tick bites, similar to Rickettsia parkeri. Antibody tests may cross-react with Rickettsia rickettsii. The CDC recommends that all patients be treated as if they have RMSF as a precaution.
Specific diagnosis can be made from a swab or biopsy of the eschar by PCR, immunohistochemistry tissue stains, or cell culture.
