Colorado tick fever

Definition

An acute viral infection of humans caused by Colorado tick fever virus (CTFV), a coltivirus in the family Reoviridae, transmitted through the bite of infected Rocky Mountain wood ticks (Dermacentor andersoni). The disease presents with fever, headache, myalgia, and often biphasic temperature curves; it is endemic to the western United States and southern Canada at elevations above 4,000 feet. Unlike Rocky Mountain spotted fever, which is bacterial, CTF is viral and does not respond to antibiotics.

Etymology

Named for the U.S. state where the disease was first identified and its tick-borne transmission route.

Example

Field biologists collecting Dermacentor andersoni in the Rocky Mountains during spring and early summer face elevated risk of Colorado tick fever, as nymphal and adult ticks in this region carry CTFV at rates exceeding 5% in some populations.

Synonyms

• CTF
• mountain fever

Related Terms

• Rocky Mountain spotted fever
• Dermacentor andersoni
• coltivirus
• tick-borne disease
• Arbovirus

Usage Notes

Distinguished from Rocky Mountain spotted fever by viral versus bacterial etiology; the two diseases overlap geographically and share a common vector, requiring laboratory confirmation for accurate diagnosis. The term 'mountain fever' appears in historical pioneer accounts and may refer to CTF, though this cannot be confirmed retrospectively.