Because survival is linked to early diagnosis, and rash may not be present in the early stages, it is important to consider RMSF before a rash is evident. The spinal fluid is usually normal, but an elevated spinal fluid protein and a few mononuclear cells may be present in comatose patients. The white cell count is normal or low, and thrombocytopenia and hyponatremia are common. Immunofluorescence staining of skin or rash biopsies can provide a rapid diagnosis. The indirect immunofluorescent antibody test is superior to the old Weil-Felix reactions, but serologies do not provide a rapid diagnosis.
Early therapy is crucial.
Do NOT attempt to prophylax for RMSF in asymptomatic patients with a history of a tick bite. Clinical Infectious Diseases.