Either tetracycline or erythromycin for 5-10 days is effective. Rare treatment failures have occurred using doxycycline. Severely ill patients may require intravenous antibiotic treatment and hospitalization. CTF has also been transmitted by blood transfusions. Between 200-300 cases are reported annually in the U.S., but the actual incidence of the disease is likely to be much higher.
Most cases occur in mountainous regions of the western states.
Once infected, a person develops long-lasting immunity. A rare disease caused by another tick-borne virus, Powassan encephalitis, causes similar symptoms but more often leaves survivors with neurologic impairments. Three to 6 days after infection, symptoms begin abruptly with fever, chills, severe headache, photophobia, abdominal pain, nausea, and muscle aches. Symptoms last for up to 7-10 days and may recur several days later. The second bout of illness typically lasts only 2-4 days.