Association of Live Vaccine with Swine Erysipelas Found in Meat Inspection

Abstract

From 2017 to 2020, a large number of cases of arthritic swine erysipelas were observed in pigs brought into a slaughterhouse from three farms in Hokkaido, Japan. In this study, we investigated whether 60 isolates of Erysipelothrix rhusiopathiae in each case were derived from wild strains or live vaccine. The results of PCR for serotyping, sequencing of spaA and PCR for determining the vaccine strain using single nucleotide mutation showed that 58 isolates had the same properties as the vaccine strain. In addition, whole genome analysis of 22 of the 58 isolates revealed that all of them were derived from the vaccine. In farms where swine erysipelas outbreaks occur despite vaccination, it is necessary to consider quarantine plans while assuming the possibility of vaccine-associated outbreaks.