Colorado tick fever (CTF) is an acute arboviral infection caused by a Coltivirus transmitted by an infected tick and characterized by a biphasic fever with headache, myalgias, arthralgias, and fatigue that can last 3 weeks or more. In some cases, macular, maculopapular, or petechial rash and/or stiff neck, nausea, vomiting, abdominal pain, diarrhea, and sore throat may also occur.