Rocky Mountain Spotted Fever

Reviewed: July 2017

Rocky Mountain spotted fever (RMSF) is a disease caused by the bite of a tick infected with the bacterium Rickettsia rickettsii. In New York, the American dog tick (Dermacentar variablis) is the most common tick that spreads the disease. Fewer than 50 cases are reported annually in New York State. RMSF is a serious illness that can be fatal in the first 8 days of symptoms if not treated correctly, even in previously healthy people. The course of the disease varies greatly. Patients who are treated early may recover quickly on outpatient medication, while those who experience a more severe course may require intravenous antibiotics, prolonged hospitalization or intensive care.