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Rocky Mountain spotted fever (RMSF) is a bacterial disease spread through the bite of an infected tick. Most people who get sick with RMSF will have a fever, headache, and rash. RMSF can be deadly if not treated early with the right antibiotic.

Rocky Mountain spotted fever is one of several diseases caused by the spotted fever group rickettsia, which are a type of bacteria. Other causes of spotted fever group rickettsioses (spotted fevers) in the United States include:

  • Rickettsia parkeri rickettsiosis, caused by R. parkeri
  • Pacific Coast tick fever, caused by Rickettsia philipii
  • Rickettsialpox, caused by Rickettsia akari

These diseases have similar signs and symptoms, including fever, headache, and rash, but are often less severe than RMSF.