Tick-Borne Encephalitis Virus and Louping-Ill Virus May Co-Circulate in Southern Norway

Abstract The European subtype of tick-borne encephalitis virus (TBEV-Eu) and louping-ill virus (LIV) are two closely related tick-borne flaviviruses. However, whereas the first is the cause of one of Europe's most important zoonoses, the latter most often only causes disease in sheep and grouse. TBEV-Eu is typically found in the forests of central and northeastern Europe, and LIV typically is found in sheep pastures in the British Isles. In the 1980s, however, LIV was isolated from sheep with encephalomyelitis in Norway. In the 1990s, the first cases of human TBEV were also detected in this country, but while Louping-ill in sheep is very rare, the number of human TBEV cases is increasing. No larger investigations of TBEV and/or LIV seroprevalence and distribution in Norway have been published. However, before such studies are initiated, it is pertinent to know if LIV and TBEV are potentially co-circulating. In the current study, we examined if antibodies against LIV and TBEV were found in wild cervids in ...