Frequently Asked Questions

What is Colorado tick fever?

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.

How do people get infected with Colorado tick fever virus?

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.

Where and when have most cases of Colorado tick fever occurred?

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.

Who is at risk for infection with Colorado tick fever virus?

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.

How soon do people get sick after getting bitten by an infected tick?

The incubation period (time from tick bite to onset of illness) ranges from 1 to 14 days.

What are the symptoms of Colorado tick fever?

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.

How is Colorado tick fever diagnosed?

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.

What is the treatment for Colorado tick fever?

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.

How can I reduce the chance of getting infected with Colorado tick fever virus?

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.

What should I do if I think a family member might have Colorado tick fever?

If you are concerned that someone you know might have CTF, consult a healthcare provider.