Colorado tick fever is a viral disease transmitted to humans by the wood tick, Dermacentor andersoni, from small mammals.
It occurs in the Rocky Mountain area and in eastern California and Oregon. The
symptoms, which
usually appear within a week of a tick bite, include high fever, nausea, malaise, loss of appetite, and muscle and joint aches. Symptoms last about two days, disappear, and recur, usually more severely. Fatalities are rare.