Evaluation of the effects of a killed whole-cell vaccine against Mycobacterium avium subsp paratuberculosis in 3 herds of dairy cattle with natural exposure to the organism

• Autores: Barbara Knust, Elisabeth Patton, João Ribeiro-Lima, Jeff J Bohn, Scott J. Wells
• Localización: JAVMA: Journal of the American Veterinary Medical Association, ISSN-e 0003-1488, Vol. 242, Nº. 5, 2013, págs. 663-669
• Idioma: inglés
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• Resumen

  • Objective—To evaluate effects of vaccination with a killed whole-cell vaccine against Mycobacterium avium subsp paratuberculosis (MAP) on fecal shedding of the organism, development of clinical paratuberculosis (Johne's disease [JD]), milk production, measures of reproduction, and within-herd longevity of dairy cattle naturally exposed to MAP.

    Design—Controlled clinical trial.

    Animals—200 vaccinated and 195 unvaccinated (control) dairy cows from 3 herds in Wisconsin.

    Procedures—Every other heifer calf born in each herd received the MAP vaccine; 162 vaccinates and 145 controls that had ≥ 1 lactation were included in analyses. Bacteriologic culture of fecal samples for MAP was performed annually for 7 years; results were confirmed via histologic methods and PCR assay. Production records and culture results were evaluated to determine effects of vaccination on variables of interest in study cows. Annual whole-herd prevalence of MAP shedding in feces was also determined.

    Results—Vaccinates had a significantly lower hazard of testing positive for MAP via culture of fecal samples than did controls over time (hazard ratio, 0.57; 95% confidence interval, 0.34 to 0.97). Fewer vaccinates developed clinical JD than did controls (n = 6 and 12, respectively), but these differences were nonsignificant. Overall within-herd longevity, total milk production, and calving-to-conception intervals were similar between vaccinates and controls. In all herds, prevalence of MAP shedding in feces decreased over time.

    Conclusions and Clinical Relevance—Vaccination with a killed whole-cell MAP vaccine appeared to be an effective tool as part of a program to control the spread of JD in dairy cattle.