Development of an ELISA procedure to detect swine carriers of pathogenic Yersinia enterocolitica

An enzyme immunoassay (ELISA) was developed to detect antibodies in pigs against the lipopolysaccharidic antigen of the three serotypes of Yersinia enterocolitica mostly associated with human infections. Recent epidemiological evidence has demonstrated that pigs and pork are important sources of yersiniosis in humans. The purpose of this study was to clarify the use of an ELISA to detect swine carriers of this enteroinvasive bacteria by examining seroconversion and tissue distribution of Y. enterocolitica following experimental infection and then screening pigs at a slaughterhouse by bacterial culture and ELISA. It was observed that seroconversion occurred in animals experimentally inoculated with Y. enterocolitica but not with other enterobacteria. It was also found that 27% of swine at a slaughterhouse carried the bacterium in their tonsils and/or intestinal tract, whereas 66% showed serological evidence of previous infection. About 6% of swine at slaughter were culture-positive, but seronegative. Although, similar numbers of swine showed serological evidence of previous infection by each of the three Y. enterocolitica serotypes tested, virtually all culture isolates belonged to serotype O:3. This ELISA appears as a valuable control tool that can be used, in conjunction with culture, to identify pigs or herds infected by strains of Y. enterocolitica associated with human infections.