SEROSURVEY FOR ORTHOPOXVIRUSES IN RODENTS AND SHREWS FROM NORWAY

Two hundred and twenty one blood samples representing eight different rodent species and the common shrew (Sorex araneus), collect in Norway between 1993 and 1995, were examined for anti-orthopoxvirus antibodie s by a competition enzyme linked immunosorbent assay (ELISA) and, when possible, an indirect immunofluorescence assay. The serological resul ts indicated that the bank vole (Clethrionomys glareolus), woodmouse ( Apodemus sylvaticus) and Norway lemming (Lemmus lemmus) may be reservo ir species for orthopoxviruses in Norway, with antibody prevalences of 17 (12/69), 30 (24/81) and 56% (19/34), respectively. Orthopoxvirus i nfection in lemmings has not been reported previously. On some other s mall rodent species such as field voles (Microtus agrestis), common ra ts (Rattus norvegicus), and common shrews, seropositive individuals we re detected. However, the total number of tested animals was low, and the role of these species in the epidemiology of orthopoxvirus infecti ons remains unclear. Attempts to isolate orthopoxviruses from these sm all mammals failed, although orthopoxvirus specific DNA sequences were detected previously in the same animals by the polymerase chain react ion (PCR). The serological results were compared with and discussed in the context of the occurrence of orthopoxvirus-specific DNA sequences , and it is concluded that orthopoxviruses are widely distributed amon g wildlife in Norway.