Colorado tick fever

Alternative names:

American mountain fever; mountain fever; mountain tick fever

Definition:

An acute viral infection transmitted by the bite of the tick Dermacentor andersoni.

Causes, incidence, and risk factors:

The disease is limited to the western U.S. and is most prevalent during March to August, the tick season. The incubation period is 3 to 6 days. Symptoms of fever continue for 3 days, then abate and recur 1 to 3 days later for another few days. Risk factors are recent outdoor activity and recent tick bite. The incidence is 4 out of 100,000 people.