infectious diseases
Rocky Mountain Spotted Fever (RMSF)
Key Points
Despite its name, Rocky Mountain spotted fever (RMSF) occurs in practically all of the United States and throughout Central and South America. Small-vessel vasculitis can cause serious illness affecting the central nervous system, lungs, heart, kidneys, liver, and spleen; untreated mortality is about 20%. Symptoms (severe headache, chills, prostration, muscle pain) begin abruptly, followed by fever and usually a rash. Neurologic symptoms (headache, restlessness, insomnia, delirium, coma) may develop, indicating encephalitis. Suspect RMSF in any seriously ill patient who lives in or near a wooded area anywhere in the Western Hemisphere and has unexplained fever, headache, and prostration, with or without a history of tick contact. Test during acute illness with PCR or immunohistology of a skin biopsy specimen, but because sensitivity is only about 70%, a negative result should not affect the decision to begin antibiotics. Treat withdoxycyclineand provide supportive care as needed for hypovolemia and/or organ involvement. 