Symptoms & Treatment


  • The incubation period (time from tick bite to onset of illness) ranges from about 1 to 14 days.
  • The most common symptoms of Colorado tick fever (CTF) are fever, chills, headache, body aches, and feeling tired. Some patients have sore throat, vomiting, abdominal pain, or skin rash.
  • 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.
  • 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.


  • There are no medications to treat CTF virus infection.
  • If you think you or a family member may have CTF, see your healthcare provider.
  • Persons with severe CTF illnesses may need to be hospitalized. Treatment may include intravenous fluids and medications to reduce pain and fever.
  • 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.