Colorado Tick Fever

Colorado tick fever (CTF) is a viral disease transmitted to humans by the bite of an infected Rocky Mountain wood tick (Dermacentor andersoni). The virus that causes CTF is a type of coltivirus, which is a member of the Reoviridae family.

Cause and Transmission

CTF is primarily transmitted through the bite of an infected tick. The ticks become infected with the virus by feeding on small mammals, such as rodents and squirrels, that are infected with the virus. Humans can become infected when an infected tick feeds on their blood.

Symptoms

The symptoms of CTF typically begin within 3 to 6 days after the bite of an infected tick. The most common symptoms include:

  • Fever
  • Headache
  • Muscle and joint pain
  • Malaise (feeling unwell)
  • Nausea and vomiting

Diagnosis

CTF is typically diagnosed based on a combination of clinical symptoms, laboratory tests, and epidemiological information. Laboratory tests may include:

  • Serologic tests to detect the presence of antibodies against the CTF virus
  • Viral isolation from blood or tissue samples
  • Reverse transcription polymerase chain reaction (RT-PCR) to detect viral RNA

Treatment and Prevention

There is no specific treatment for CTF, and most cases are self-limiting, meaning they resolve on their own without treatment. However, supportive care may be provided to alleviate symptoms, such as:

  • Rest and hydration
  • Pain relief medication
  • Antipyretics to reduce fever

To prevent CTF, it is recommended to take measures to avoid tick bites, such as:

  • Wearing protective clothing and insect repellent when outdoors in areas where ticks are common
  • Conducting regular tick checks on the body
  • Removing attached ticks promptly and correctly

Epidemiology

CTF is primarily found in the western United States, particularly in the Rocky Mountain region. The disease is most commonly reported in Colorado, Utah, Wyoming, Montana, and Idaho. The majority of cases occur during the spring and summer months when ticks are most active.

Complications

In rare cases, CTF can cause more severe complications, such as:

  • Meningitis (inflammation of the membranes surrounding the brain and spinal cord)
  • Encephalitis (inflammation of the brain)
  • Hemorrhagic fever

These complications are more likely to occur in people with weakened immune systems or underlying medical conditions.

Article last updated on: 15th June 2025.
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