Coltivirus

Coltivirus is a genus of non-enveloped, double-stranded RNA viruses in the family Reoviridae. Members are transmitted by ticks and can infect humans and animals. The best characterized member is Colorado tick fever virus (CTFV), the type species, which causes colorado tick fever in humans. Other coltiviruses have been identified in different geographic regions, including viruses associated with tick-borne illnesses in Europe.

Genomic and replication features: Coltiviruses possess segmented dsRNA genomes and replicate in the cytoplasm of infected cells. Transmission to humans occurs primarily through tick bites, often requiring the tick to remain attached for several hours.

Clinical features: In humans, coltivirus infection typically presents as an acute febrile illness with fever, headache, myalgia, and malaise. Colorado tick fever is classically biphasic, with a second fever spike after a brief afebrile interval, and may include photophobia, back or abdominal pain, and sometimes rash. Most infections are self-limited; severe disease is uncommon but can include meningitis or encephalitis in rare cases.

Diagnosis and treatment: Diagnosis is supported by serology (IgM and IgG antibodies) or nucleic acid testing; virus isolation can occur in specialized laboratories. There is no widely available specific antiviral therapy or approved vaccine for coltiviruses, and treatment is primarily supportive.

Epidemiology and prevention: Colorado tick fever is endemic to parts of western North America and Canada, with transmission linked to tick exposure in spring and summer. Prevention focuses on avoiding tick bites, performing thorough tick checks, and using protective clothing and repellents when in tick-infested areas.