Symptoms & Treatment


People who have CTF should not donate blood or bone marrow for 6 months after their illness. The virus may stay in red blood cells for several months and can be passed to others by blood transfusion or bone marrow transplant.

The time from tick bite to onset of illness (incubation period) for Colorado tick fever (CTF) ranges from about 1 to 14 days.

  • The most common symptoms are fever, chills, headache, body aches, and feeling tired.
    • About half of patients have a “biphasic” fever. This means they have several days of fever, feel better for several days, and then have a second short period of fever and illness.
    • Some patients have sore throat, vomiting, abdominal pain, or skin rash.
  • Most people who become ill have mild disease and recover completely. However, weakness and fatigue may last several weeks.
  • In rare cases, some patients may develop more severe illness that affects the central nervous system with symptoms that include stiff neck and confusion.
  • Life-threatening illnesses or deaths due to CTF virus are rare.


If you think you or a family member might have CTF, talk to your healthcare provider.

  • Healthcare providers diagnose CTF infection based on:
    • Signs and symptoms
    • History of living in or traveling to an area where CTF virus is known to circulate
    • History of possible exposure to the ticks that can carry CTF virus
    • Blood tests
  • Your healthcare provider can order tests to look for CTF virus infection and other infections that can cause similar symptoms.

To learn more about testing, visit our Healthcare Providers page.


  • There are no medications to prevent or treat CTF virus infection. Antibiotics do not treat viruses.
  • Rest, fluids, and over-the-counter pain medications may relieve some symptoms.
  • People with severe CTF illnesses may need to be hospitalized for intravenous fluids and medications to reduce pain and fever.

To learn more about treatment, visit our Healthcare Providers page.