Rickettsia parkeri causes a mild form of Rocky Mountain spotted fever (RMSF). It was first confirmed in 2004 and is transmitted by the Amblyomma maculatum tick. This tick normally infects cattle on the Gulf Coast of Texas. R. parkeri has been reported in the East and Southern coastal regions of the United States.
An eschar (dry, dead tissue within a wound) or vesicular rash develops 2–10 days after the tick bite. Symptoms include myalgia, mild headache, and arthralgia. Mild elevation of liver enzymes, mild thrombocytopenia, and mild leukopenia are reported. Antibodies may cross-react with those of RMSF.
