Serpulina hyodysenteriae challenge of fattening pigs vaccinated with anadjuvanted bivalent bacterin against swine dysentery.

An experimental fattening period was performed with 36 pigs in order to evaluate the safety and efficacy of a bivalent adjuvanted Serpulina hyodysenteriae bacterin. The pigs originated from three different farms and were split into six groups. Eighteen pigs were vaccinated twice, two weeks apart and the rest served as controls. One unvaccinated pig in each group was inoculated intragastrically with 4 x 10(8) active S. hyodysenteriae spirochaetes, B 78 strain. Weight evolution, clinical symptoms, shedding of S. hyodysenteriae and serum antibody titres were monitored for 12 weeks in all pigs. The severity of clinical symptoms and shedding of spirochaetes in faeces were significantly reduced in vaccinated pigs as compared to controls. Statistically significant differences in weight gain between vaccinates and controls were detected coinciding with the maximum shedding of S. hyodysenteriae in faeces. All vaccinated pigs seroconverted, as measured by indirect ELISA, and had a good anamnestic response after the second vaccine dose. The bacterin proved to be useful for both the reduction of clinical symptoms and the number of infected animals in a fattening unit. Adverse post-vaccinal reactions were not observed in any pig.