Yersinia enterocolitica in small rodents from Norway, Sweden and Finland.

The purpose of the present investigation was to study the occurrence of Yersinia enterocolitica (Y.e.) among small rodents and shrews (Soricidae) from Norway, Sweden and Finland. During a period of one year beginning in the autumn of 1973, animals from seven localities were examined. Twenty-four strains of Y.e. were isolated from 551 small rodents. Isolations were made from six of the seven localities and from six of the nine small rodent species examined. Pooled faeces samples from 397 animals yielded 12 strains. Faeces from 154 small rodents were separately investigated: Twelve (8 per cent) of these animals harboured Y.e. No isolations were made from 52 shrews. Most of the strains showed antigenic relationship to O-serotypes previously reported from untreated drinking water in Norway. Two strains were antigenically related to O-serotype 3 but differed biochemically from the strains found in man and swine. The results indicate that Y.e. has a widespread distribution among small rodents in Norway, Sweden and Finland.