Infectivity and pathogenicity of Yersinia enterocolitica serovar 0:8 to wild rodents in Japan

A long-term observation for ecology of pathogenic Yersinia in wild rodents living in Fukushima Prefecture, Japan

From 2012 to 2021, prevalence of pathogenic Yersinia in wild rodents captured in Fukushima Prefecture, Japan was investigated twice a year to clarify the ecology of this pathogen in wild rodent populations. Pathogenic Yersinia enterocolitica O8 was isolated from 13 (1.7%) of 755 wild rodents. The Y. enterocolitica O8 isolates harbored three virulent genes (ail, fyuA, and virF). This pathogen was isolated repeatedly from wild rodents in April 2015, 2016, and 2017, in June and November 2020, and in April 2021, which was 6 of 19 times of observations. All Y. enterocolitica O8 isolates showed the same PFGE patterns. These results indicated that the same clone of pathogenic Y. enterocolitica O8 has been maintained in wild rodent populations in Fukushima Prefecture. Therefore, wild rodent populations contribute substantially to the continuous transmission of Y. enterocolitica O8 and its persistence in the ecosystem. This is the first report on the isolation of pathogenic Y. enterocolitica O8 in wild rodents in Fukushima Prefecture, Japan.

Detection of pathogenic Yersinia enterocolitica in pet Djungarian hamsters in Japan

The prevalence of Yersinia enterocolitica (Y. enterocolitica) and Yersinia pseudotuberculosis was examined in 151 pet animals including 108 rodents, 39 rabbits and four sugar gliders from 13 pet stores in the Yamaguchi Prefecture, Japan. Y. enterocolitica serogroup O:3 biotype 3 negative for the Voges-Proskauer reaction (O:3/3 variant VP-) was isolated from five Djungarian hamsters (Phodopus sungorus) raised at the same pet store. These pathogenic Y. enterocolitica isolates carried the virulence genes, yadA, ail and virF, and were shown to be clonal by pulsed-field gel electrophoresis with NotI digestion. This is a first report of pathogenic Y. enterocolitica O:3/3 variant VP- in pet Djungarian hamsters in Japan.

Potential sources of sporadic human infection with Yersinia enterocolitica serovar O:8 in Aomori Prefecture, Japan

In November 1992 and June and August 1993 rectal contents from 204 small mammals living in the wild were collected and examined for the presence of Yersinia enterocolitica serovar O:8 to clarify the source of human infections caused by this microbe in the Tsugaru Region of Aomori Prefecture, Japan. Serovar O:8 was isolated from 10 (5.2%) of 193 wild rodents trapped in June 1993 (9 of 107) and August 1993 (1 of 23) but not from animals trapped in November 1992 (0 of 63). This serovar was not isolated from 11 moles. From May to September 1993, 12 human patients were found to have become ill and to be infected with Y. enterocolitica O:8. The patients lived in the same districts where the wild rodents harboring serovar O:8 were trapped. Two different patterns by restriction enzyme analysis of the virulence plasmid were observed. One pattern obtained by restriction enzyme analysis of the virulence plasmid was observed in 20 isolates from 11 human patients and 9 wild rodents, and the other was observed in 2 isolates from 1 human patient and 1 wild rodent. These findings indicate that wild rodents seem to play an important role as a source of human Y. enterocolitica O:8 infection.