This viral disease occurs in the Rocky Mountain states and the Black Hills of South Dakota. Since it develops from the bite of a tick, it occurs during the season of greatest tick activity. T

he incubation period following the tick bite is from three to six days. Colorado tick fever begins abruptly with fever, headache, joint and muscle pains, but usually no rash. The patient improves briefly after two or three days, but then relapses for another few days. The disease is usually mild but may be severe in children.