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a female Amblyomma triste from a dorsal view, as it is climbing a blade of grass

Spotted fever group rickettsioses (spotted fevers) are a group of diseases caused by closely related bacteria. These bacteria are spread to people through the bite of infected mites and ticks. The most serious and commonly reported spotted fever group rickettsiosis in the United States is Rocky Mountain spotted fever (RMSF).

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 species 364D
  • Rickettsialpox, caused by Rickettsia akari

Spotted fevers can range from mild to life-threatening. Most people who get sick with a spotted fever other than RMSF will have an eschar (dark scab at the site of tick or mite bite), fever, headache, and rash. Doxycycline is the treatment of choice for all spotted fever infections.

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