Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile.
Servicio Agrícola y Ganadero, Santiago, Chile.
Transbound Emerg Dis. 2022 May;69(3):1419-1425. doi: 10.1111/tbed.14108. Epub 2021 May 22.
Bovine tuberculosis (TB) is a chronic disease caused mainly by Mycobacterium bovis, a zoonotic pathogen that has a worldwide distribution causing serious economic losses for milk and meat producers. In Chile, the disease in dairy cattle has a heterogeneous distribution, where the Metropolitan Region concentrates the highest animal prevalence and the main challenge for the national control and eradication programme. In this epidemiological context, vaccination with the M. bovis Bacillus Calmette-Guerin (BCG) vaccine might be a useful strategy for disease prevention and control. The objective of this study was to assess the efficacy and impacts on productivity and fertility of vaccination with the BCG Russia strain in 11 month-old heifers from a dairy farm, under a natural transmission condition. Sixty-two animals were vaccinated via the subcutaneous route with the equivalent of one human dose of BCG, and 60 control animals received saline. Subsequently, blood sampling was performed at 3, 6, 9, 12, 15 and 18 months post-inoculation, and infection status was determined using the IFNγ release assay (IGRA) with the DIVA (differentiate infected from vaccinated animals) antigens ESAT-6, CFP-10 and Rv3615c. Efficacy was calculated as the percentage of reduction in the incidence of infection attributable to vaccination, which showed a statistically significant level of overall protection of 66.5%. No adverse effects on fertility and production were recorded. In contrast, we observed beneficial effects of vaccination on several milk production parameters, with the milk yield in the first 100 days after calving in the BCG group significantly higher compared to unvaccinated heifers (p < .05). These results suggest that BCG vaccination of heifers in a natural transmission setting might result in both sanitary and productive benefits, supporting its implementation as a new strategy for TB prevention in a high prevalence area of Chile.
牛结核病（TB）是一种由牛分枝杆菌引起的慢性疾病，是一种具有全球分布的人畜共患病原体，给牛奶和肉类生产者造成了严重的经济损失。在智利，奶牛中的这种疾病分布不均，首都大区集中了最高的动物流行率，这是国家控制和根除计划的主要挑战。在这种流行病学背景下，使用牛分枝杆菌卡介苗（BCG）疫苗进行免疫接种可能是预防和控制疾病的一种有用策略。本研究的目的是评估在自然传播条件下，对 11 月龄奶牛进行 BCG 俄罗斯株疫苗接种的效果和对生产力和繁殖力的影响。62 只动物通过皮下途径接种了相当于人类一剂 BCG 的剂量，60 只对照动物接受了生理盐水。随后，在接种后 3、6、9、12、15 和 18 个月进行了血液采样，并使用 ESAT-6、CFP-10 和 Rv3615c 的 IFNγ释放试验（IGRA）来确定感染状态。通过疫苗接种降低的感染发生率计算效力，总体保护率为 66.5%，具有统计学显著水平。没有记录到对繁殖力和生产的不良影响。相反，我们观察到疫苗接种对一些产奶参数有有益的影响，接种组在产后 100 天内的产奶量明显高于未接种组（p<.05）。这些结果表明，在自然传播环境下对奶牛进行 BCG 免疫接种可能既具有卫生效益，又具有生产效益，支持在智利高流行地区实施作为预防结核病的新策略。
