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Rickettsia parkeri

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gulf-coast-tick Rickettsia parkeri is transmitted by the Gulf Coast tick (Amblyomma maculatum).  It has been identified in many of the southern states, including Florida. Cases have been reported throughout the range of the Gulf Coast tick, several cases have been reported in Northern Florida since 2007. Lone star ticks may also be a potential vector.

In the limited number of confirmed cases, symptoms appeared 2-10 days after a tick bite. Unlike Rocky Mountain spotted fever (RMSF), R. parkeri cases may have an inoculation eschar resembling a scabbed sore or pimple at the site of infection, which is often the first symptom.  Symptoms also included fever, fatigue, headache, muscle pain, and generalized rash. R. parkeri seems to be a less severe disease than RMSF, and may be misdiagnosed due to cross-reaction of the available diagnostic tests.


Paddock C. Rickettsia parkeri as a pardigm for multiple causes of tick-borne spotted fever in the Western Hemisphere. Annals of the New York Academy of Sciences. 2005; 1063: 315-326.

Sumner J, Durden L, Goddard J, Stromdahl E, Clark K, Reeves W, Paddock C. Gulf Coast Ticks and Rickettsia parkeri, United States. Emerging Infectious Diseases. 2007; 13(5) 751-753.