Colorado tick fever is a rare viral infection from a tick bite. For most, the infection is mild. Rarely, it can affect the nervous system.
Colorado tick fever is caused by the Colorado tick fever virus. People can get the virus from the bite of an infected tick. From there, the virus gets into the blood.
The virus is not passed from person to person. In rare cases, it has been passed from a transfusion of infected blood.
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Colorado tick fever is found in the Rocky Mountains of North America. It is also found in the western U.S and parts of Canada. The risk of getting the virus is highest for those who live in or travel to these regions, especially:
Symptoms usually appear 3 to 5 days after a tick bite. They may last for 3 weeks.
Symptoms of Colorado tick fever may be:
The doctor will ask about your symptoms and health history. A physical exam will be done. Blood tests may be done to detect the virus and look for other problems.
There is no specific treatment for Colorado tick fever. Most people recover in 1 week. The goal is to ease symptoms. Options are:
Serious problems are very rare. They may include aseptic meningitis, encephalitis, and hemorrhagic fever. Severe symptoms or problems need hospital care.
To reduce the risk of Colorado tick fever:
Centers for Disease Control and Prevention
National Institute of Allergy and Infectious Diseases
Colorado tick fever. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/colorado-tick-fever. Accessed March 31, 2021.
Eickhoff C, Blaylock J. Tickborne diseases other than Lyme in the United States. Cleve Clin J Med. 2017;84(7):555-567.
Tick avoidance and removal. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/tick-avoidance-and-removal-14 . Accessed March 31, 2021.
Last reviewed December 2020 by
EBSCO Medical Review Board
David L. Horn, MD, FACP
Last Updated: 3/31/2021