Examination of tick-borne encephalitis virus natural reservoirs in active and latent tick-borne encephalitis foci in Slovenia

Tick-borne encephalitis is the most important human central nervous system virus infection in Europe. The virus is maintained in nature by a cycle involving reservoirs (small mammals, deer) and vector (ticks). Tick-borne encephalitis occurs in endemic areas, which vary in activity. The purpose of the study was to determine the species and frequency of tick-borne encephalitis infection among small mammals caught in Gorjanci and Tenetise endemic areas. The enzyme immunoassay was used for demonstration of specific viral anti­bodies, and the polymerase chain reaction for direct detection of viral genome. Seroprevalence was 8,3%, while viral genome was detected in 45,9% of the tested animals. Our study con­firmed that the demonstration of viral antibod­ies alone cannot provide an accurate information of the incidence of tick-borne encephalitis infec­tion in small mammals. The yellow-necked mouse was found to be a primary reservoir of tick-borne encephalitis virus in Slovenia. No difference in infection rate was found between studied natural foci. Polymerase chain reaction, which was for the first time employed for the detection of tick-borne encephalitis in natural reservoirs, represents a convenient tool for determining tick-borne encephalitis natural foci.