BackgroundControl of animal tuberculosis (TB) through vaccination has emerged as a long-term strategy to complement test and slaughter control strategy. A pilot trial under field conditions was conducted in a goat herd with high TB prevalence to assess the efficacy of the Mycobacterium bovis BCG vaccine.ResultsTwenty-three goat kids vaccinated with BCG and other 22 unvaccinated control kids were euthanized at 18 months post-vaccination. Gross pathological and histopathological examination of target tissues was performed for detection of tuberculous lesions and assessment of vaccine efficacy. Mycobacterial culture and DNA detection were used to confirm Mycobacterium caprae infection. Vaccination significantly reduced the number of animals with TB lesions compared to unvaccinated controls (35% and 77%, respectively; P < 0.01). This reduction was even higher if only extra-pulmonary infection was considered (17% and 68%, respectively; P < 0.001).ConclusionsThis trial demonstrates that BCG vaccination of goats can significantly reduce the TB lesion rates in high disease exposure conditions, indicating that vaccination could contribute to the control of TB in domestic goats.

Increasing number of caprine tuberculosis (TB) reports grant the consideration of this zoonosis as an emerging disease that can play a role in the epidemiology of bovine TB in endemic areas. An outbreak of TB was detected in a caprine/ovine dairy mixed herd. Tuberculin skin test positive goats and ewes were euthanized and subsequent postmortem investigations were performed. Mycobacterium caprae (spoligotype profile SB0157) was isolated from tuberculous lesions detected in both sheep and goats. Our findings evidenced the direct transmission of the infection between both species elucidating that not only goats but also sheep may act as domestic reservoirs of TB compromising the eradication of TB in cattle. The results have implications for animal TB epidemiology and public health risk management.

Vaccination of goats against tuberculosis (TB) has been promoted as an ancillary tool for controlling the disease in infected livestock herds. A three-year trial to assess the efficacy of BCG vaccine was carried out in five goat herds. At the beginning of the trial (month 0), all animals were tested for TB using thee different diagnostic tests. Animals negative to all tests were vaccinated with BCG and all replacement goat kids were also systematically vaccinated throughout the trial. All animals were tested by Interferon-gamma release assay (IGRA) using vaccine compatible reagents at months 6, 12, 24, and 36. The risk factors for TB infection were also evaluated. At the end of the study, four out of five farms showed variable reductions of the initial prevalence (93.5%, 28.5%, 23.2%, and 14.3% respectively), and an overall incidence reduction of 50% was observed in BCG vaccinated goats, although adult vaccinated goats showed higher incidences than vaccinated goat kids. The unvaccinated positive animals remaining in herds and adult BCG vaccinated goats significantly enhanced the risk of infection in vaccinated animals. A systematic vaccination of goats with BCG, together with the removal of positive unvaccinated animals, may contribute to reducing the TB prevalence in goat herds.

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