coltiviruses

Coltiviruses are a genus of double-stranded RNA viruses in the family Reoviridae. They are nonenveloped, icosahedral virions with a segmented genome of twelve dsRNA segments. The best known member is Colorado tick fever virus (CTFV), which causes Colorado tick fever in humans; other members, such as Eyach virus, have been identified in Europe. Coltiviruses are transmitted by ticks and are associated with temperate regions of the Northern Hemisphere.

Transmission occurs primarily through bites of infected Dermacentor ticks. Reservoirs include small mammals; humans are incidental hosts. Infections occur mainly during spring and summer when ticks are active.

Clinical presentation typically begins with a sudden onset of fever, severe headache, myalgia, and photophobia, about 2–5 days after exposure. The illness is often biphasic, with a second fever spike after several days. Most cases are self-limited, but some patients develop leukopenia, thrombocytopenia, and, rarely, meningitis or encephalitis.

Diagnosis relies on serology (IgM or IgG) and nucleic acid testing (RT-PCR) during acute illness; virus isolation is possible in specialized labs. There is no specific antiviral therapy; care is supportive, addressing fever, pain, hydration, and any neurologic symptoms.

Prevention focuses on tick avoidance: protective clothing, repellents, prompt tick removal, and environmental tick control in endemic areas. There is no licensed human vaccine for coltiviruses.