Statistics & Maps
Colorado tick fever (CTF) occurs in people who live in or visit areas where there are infected Dermacentor andersoni ticks. These ticks are found in the western United States or western Canada at elevations of 4,000‒10,000 feet above sea level. In the United States, a total of 83 CTF cases were reported to CDC from 2002 through 2012. CTF is not a nationally notifiable disease; however, several states require that CTF cases be reported to the state health department. As of January 2015, CTF was specifically reportable in six states: Arizona, Colorado, Montana, Oregon, Utah, and Wyoming. All state health departments are encouraged to report CTF cases to CDC on a voluntary basis.
Approximate geographic distribution of Dermacentor andersoni ticks and counties of residence for confirmed and probable Colorado tick fever (CTF) virus disease cases, United States, 2002–2012
* All cases were acquired in states where local transmission of CTF virus has been reported previously. Two additional cases were reported from Colorado with unknown county of residence.
**Derived from James AM, Freier JE, Keirans JE, Durden LA, et al. Distribution, seasonality, and hosts of the Rocky Mountain wood tick in the United States. J Med Entomol 2006; 43:17–24.