Use of long-term vaccination with a killed vaccine to prevent fecal shedding of Mycobacterium avium subsp paratuberculosis in dairy herds

Abstract Objectives —To determine whether vaccination with a killed vaccine prevents fecal shedding of Mycobacterium avium subsp paratuberculosis , to compare effectiveness of a culture and cull program in vaccinated and nonvaccinated herds, and to compare paratuberculosis-related preventive management in vaccinated and nonvaccinated herds. Sample Population —58 commercial Dutch dairy herds. Design —Cross-sectional study (study A) in vaccinated (n = 25) and nonvaccinated (29) herds of dairy cows. Longitudinal study (study B) in vaccinated (n = 2) and nonvaccinated (2) herds of dairy cows. Procedure —In study A, fecal samples were obtained from adult cows in herds with and without a history of vaccination with a killed vaccine. Management measures were evaluated. In study B, fecal samples were obtained 4 times at 6-month intervals from cows older than 6 months. Cows that had positive test results were removed from the herd directly after the outcome of the culture. Results —In study A, differences were not detected among the 25 herds that were vaccinated; culture results were positive for M avium subsp paratuberculosis in 4.4% of herds. In 29 herds that had not been vaccinated, culture results were positive in 6.7%. In study B, the percentage of positive results on culture decreased from 10.9% and 5.7% to 3.5% and 0%, respectively in the 2 vaccinated herds. In the 2 nonvaccinated herds, percentages decreased from 6.1% and 16.5% to 0% and 2.3%, respectively. Management practices were different between herds that were vaccinated and herds that were not; owners of herds that were not vaccinated followed more preventive management procedures and practiced less feeding of raw milk to calves. Conclusions and Clinical Relevance —Vaccination of calves with a killed vaccine does not prevent transmission of M avium subsp paratuberculosis ; therefore, hygienic practices remain essential in herd management. ( Am J Vet Res 2001;62:270–274)