Colorado tick fever is the most common tick-borne disease in Colorado although most cases probably go unrecognized. Colorado tick fever is an acute viral illness characterized by fever, headache, body aches, nausea, abdominal pain, and lethargy. Typically, the illness lasts four to five days, followed by an apparent recovery, then a relapse of symptoms for two or three more days. Complete recovery ay take two to three weeks. the disease is not life-threatening and infection results in life-long immunity. There is currently no preventative vaccine or effective treatment, except to let the disease run its course.
Colorado tick fever is caused by a virus maintained in the environment in a rodent-tick-rodent cycle. The virus is transmitted to humans by the bite of an infected Rocky Mountain wood tick. Ticks begin to emerge in late February and March and seek for an animal host to take a blood meal which is necessary for their growth and reproduction.
The virus is transmitted to humans while an infected tick is obtaining a blood meal. Studies have shown that a tick must usually be attached for several hours to transmit enough virus to cause illness. If infected, a person will become ill in four to five days.