[Etiology of Karelia fever--a new arbovirus infection].

In August-September 1981, in some areas of Karelia (on the border of northern and middle taiga) there occurred diseases with signs of fever, rash, and arthralgia developing in some patients into a chronic condition. Examinations of paired sera from patients with the acute disease and from convalescents using a set of Toga- and Bunya-viruses showed the etiology of the disease to be associated with a virus from the Togaviridae family, genus Alphavirus, of the antigenic Sindbis complex.