Frequently Asked Questions
- What is Colorado tick fever?
- How do people get infected with Colorado tick fever virus?
- Where and when have most cases of Colorado tick fever occurred?
- Who is at risk for infection with Colorado tick fever virus?
- How soon do people get sick after getting bitten by an infected tick?
Colorado tick fever (CTF) is a rare disease that is caused by the CTF virus. CTF virus is spread to people through bites of infected ticks. The most common symptoms of CTF are fever, chills, headache, body aches, and feeling tired.
CTF virus is transmitted by the bite of an infected Rocky Mountain wood tick (Dermacentor andersoni). The virus is not spread from person to person, except in rare instances by blood transfusion.
CTF occurs in people who live in or visit areas of the western United States and western Canada that are 4,000–10,000 feet above sea level. Most cases of CTF occur during spring or summer months when ticks are most active.
Anyone bitten by a tick in an area where the virus is circulating can get infected with CTF virus. People who work outdoors or participate in outdoor activities are most likely to be exposed to ticks.
The incubation period (time from tick bite to onset of illness) ranges from 1 to 14 days.
The most common symptoms are fever, chills, headache, body aches, and feeling tired. Some patients will have sore throat, vomiting, abdominal pain, skin rash, or stiff neck. About half of all people infected with CTF virus have several days of fever followed by several days of improvement, then a second short period of fever and illness.
Preliminary diagnosis is based on a patient’s symptoms and history of probable exposure to a tick in an area where CTF occurs. Laboratory tests typically detect CTF virus genetic material (RNA) or antibodies against the virus in blood.
There is no specific medication to treat CTF. Severe illnesses are treated by supportive care which may include medications to reduce pain and fever, hospitalization, and intravenous fluids.
There is no vaccine to prevent CTF. The best way to prevent CTF is to reduce your risk of tick bites.
- Use insect repellent
- Wear long sleeves and pants
- Avoid wooded and bushy areas with high grass
- Perform thorough tick checks after spending time outdoors
More information about reducing exposure to ticks is available on the CDC Ticks website.
If you are concerned that someone you know might have CTF, consult a healthcare provider.