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Disease overviewWestern North America

What is Colorado tick fever?

Colorado tick fever is a viral illness transmitted mainly by Rocky Mountain wood ticks in western North America, often causing fever, chills, headache, muscle aches and fatigue.

Reviewed by VuxLore® Knowledge Team For Everyone

Short answer

Colorado tick fever is a viral illness transmitted mainly by Rocky Mountain wood ticks in western North America, often causing fever, chills, headache, muscle aches and fatigue.

At a glance

Fever can be biphasic, improving and then returning, while exposure location and altitude help clinicians assess risk.

Key takeaways

• Record mountain travel and dates.

• A second fever phase can occur.

• Diagnosis needs appropriate laboratory testing.

A regional viral infection

Exposure is associated with areas where Dermacentor andersoni occurs. Symptoms overlap with other infections and a rash is not required.

Medical assessment is important

Contact a clinician for fever after relevant tick exposure, especially for severe or persistent illness. Blood donation restrictions may apply after infection; follow local services.

Sources and further reading

US Centers for Disease Control and Prevention: Clinical Features and Diagnosis of Colorado Tick Fever

US Centers for Disease Control and Prevention: Tickborne Diseases of the United States