Which tick-borne illness is associated with fever, photophobia, and a petechial rash after tick exposure in the western United States mountains?

Which tick-borne illness is associated with fever, photophobia, and a petechial rash after tick exposure in the western United States mountains?

• A. Lyme disease
• B. Ehrlichiosis
• C. Colorado Tick Fever
• D. Rocky Mountain Spotted Fever

Answer: (C)

Colorado tick fever is suggested by the combination of exposure in the western mountains and the symptoms of fever with headaches and photophobia. This illness is caused by a Coltivirus transmitted by the mountain wood tick (Dermacentor andersoni), a vector common to that mountainous region. A distinctive feature is the abrupt onset of fever with severe headache and photophobia, and many patients experience a biphasic course. A petechial rash can occur, which helps set it apart from other tick-borne diseases. Lyme disease typically starts with an expanding erythema migrans and migratory joint or neurologic symptoms rather than prominent photophobia. Ehrlichiosis usually lacks the hallmark photophobia and has a different geographic and clinical pattern. Rocky Mountain spotted fever can have a petechial rash, but it is not as closely tied to the western mountains or to photophobia as Colorado tick fever.

Colorado tick fever is suggested by the combination of exposure in the western mountains and the symptoms of fever with headaches and photophobia. This illness is caused by a Coltivirus transmitted by the mountain wood tick (Dermacentor andersoni), a vector common to that mountainous region. A distinctive feature is the abrupt onset of fever with severe headache and photophobia, and many patients experience a biphasic course. A petechial rash can occur, which helps set it apart from other tick-borne diseases.

Lyme disease typically starts with an expanding erythema migrans and migratory joint or neurologic symptoms rather than prominent photophobia. Ehrlichiosis usually lacks the hallmark photophobia and has a different geographic and clinical pattern. Rocky Mountain spotted fever can have a petechial rash, but it is not as closely tied to the western mountains or to photophobia as Colorado tick fever.