In the western U.S., the causative agent R rickettsii is transmitted by the wood tick , and in the eastern U.S., by the dog tick. Other ticks transmit the infection in the southern U.S. and in Central and South America. The incidence of infection is 8 out of 100,000 people. Most cases occur in the spring and summer with about 1,000 cases reported per year. The incubation period of the illness is from 2 to 14 days after the tick bite .
Symptoms usually start suddenly with a persistent fever .
A rash will appear 2 to 5 days after the onset of the fever. The risk factors include recent hiking or exposure to ticks in an endemic area. The objective of treatment is careful removal of the tick from the skin and antibiotics to eliminate the infection. Chloramphenicol and tetracycline are frequently used. Complications are rare.