top of page

Rickettsioses RMSF

(Rocky Mountain spotted fever)

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) 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.

The first sign of many spotted fevers (including Rickettsia parkeri rickettsiosis, Pacific Coast tick fever, or rickettsialpox) is generally a dark scab at the site of tick or mite bite, known as an eschar. Eschars usually develop a few days to a week following the bite of an infected tick or mite.

Several days after an eschar develops, patients can develop other signs and symptoms.

Signs and symptoms can include:




Muscle aches

R. parkeri rickettsiosis, Pacific Coast tick fever, and rickettsialpox are less severe than RMSF; however, it can be difficult to distinguish between RMSF and other spotted fevers, especially during early stages of these diseases. Ticks are typically found in grassy or wooded environments. See your health care provider if you become ill after having been bitten by a tick, or having spent time in areas where ticks may live. Rickettsialpox is spread by mites carried by the common house mouse. Be sure to mention any time spent in areas where mice may be found


bottom of page