Colorado tick fever and other arthropod-borne reoviruses

Human pathogens are found in six genera of Reoviridae: Reovirus, Rotavirus, Orthoreovirus, and three arthropod-borne genera: Coltivirus (Colorado tick fever, Salmon River virus, and Eyach viruses); Orbivirus (Kemerovo, Changuinola, Orungo, and Lebombo); and Seadornavirus (Banna virus). Colorado tick fever is common in parts of north-western North America; acquired from tick (ixodid) bites, most often by hikers and campers, presenting 3–6 days later with sudden fever, rigors, generalized aches, myalgia, headache and backache, rashes (12%), and gastrointestinal symptoms (20%). Diagnosis is confirmed by detection of viral antigen in erythrocytes or serum, or by serodiagnosis. Management is symptomatic. Illness usually resolves in 10–14 days, but convalescence may be prolonged. Prevention is by avoiding, repelling, and rapidly removing ticks; no vaccines are available.