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Colorado Tick Fever

  • Cynthia M. Johnson, MA
Publication Type:


Colorado Tick Fever



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.

The virus is not passed from person to person. Rarely, it has been passed from a transfusion of infected blood.

Tick Bite.

Colorado tick fever is transmitted through the bite of an infected tick.

Bug biteshttp://services.epnet.com/getimage.aspx?imageiid=48864886si55551359_ma.jpgsi55551359_ma.jpgNULLjpgBug bitesNULL\\filer01a\Intellect\images\si55551359_ma.jpgNULL17NULL2004-04-142543904886_165024Copyright © Nucleus Medical Media, Inc.

Risk Factors

Colorado tick fever is found in the Rocky Mountains of North America. It is also found in the western United States and parts of Canada. The risk of getting the virus is highest for those who live in or travel to these regions, especially:

  • In mountain forest areas with heights of 4,000 to 10,000 feet
  • Between April and July


Symptoms usually appear 3 to 5 days after a tick bite. They may last for 3 weeks.

Symptoms of Colorado tick fever may be:

  • High fever and chills
  • Severe headache
  • Eye redness, sensitivity to light, or pain behind the eyes
  • Muscle pain
  • Feeling tired or weak
  • Nausea and vomiting
  • Diarrhea
  • Rash


The doctor will ask about symptoms and past health. You may be asked about exposure to places where ticks are present. A physical exam will be done. Blood tests may be done to look for signs of the virus.


There is no specific treatment for Colorado tick fever. Most people recover in about a week. The goal is to ease symptoms. This can be done with pain relievers and by drinking plenty of fluids.


Avoid tick-infested areas when possible. To lower the risk of Colorado tick fever:

  • Wear light-colored clothing. Tuck pants into socks. Put clothes in the dryer for 20 minutes after wearing to kill any ticks.
  • Use tick repellents.
  • Check for ticks often. Properly remove any ticks. Take a bath or shower after.
  • Wash tick bites with soap and water after removing a tick.




  • Colorado tick fever. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/colorado-tick-fever.
  • 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.


  • David L. Horn, MD, FACP
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.