Protective effect of Johne's disease attenuated vaccine in an intensive non-tuberculosis free dairy

ABSTRACT

This study was carried out to control Johne's disease [JD] without interfering with tuberculosis [TB] control programme. A dairy herd [n>1500 heads] was used over a period of 6 years, from 1994 to 1999 for this investigation. The herd had a history of heavy infection with Mycobacterium avium paratuberculosis [MAP] with culling rates of 1.5 and 5%, in 1991 and 1995, respectively. The mean annual losses due to the reduction in milk yield, pregnancy rate and carcass weight was about $32000. In addition, the farm has had positive tuberculin test. During this study, 2070 calves within 31 days of age, were inoculated once subcutaneously, with MERIAL JD attenuated vaccine, in the middle of brisket region. The vaccine protected the herd against JD effectively, so that from 1995 up to the end of 1999, the means of JD culling among 2-year-old vaccinated and unvaccinated cattle were 0.52 and 19.4%, respectively. This vaccination had no side-effects on TB control programme that was conducted by the comparative tuberculin test. In the site of inoculation, fibrocaseous inflammation, while increasing in size, was developed. during 2 years, on the majority of animals, this reaction disappeared; only in less than 1.5% of instances the lesion became tumoral. and permanent. These animals had no clinical abnormality. While inoculating the vaccine, the insertion of vaccine germ contaminated needles in fingers of vaccinators usually caused temporary, hard and painful inflammation. In one occasion, a progressive granuloma caused by vaccine germ was diagnosed histopathologically and treated with suitable antibiotics