Srinivasan Sreenidhi, Conlan Andrew J K, Easterling Laurel A, Herrera Christian, Dandapat Premanshu, Veerasami Maroudam, Ameni Gobena, Jindal Naresh, Raj Gopal Dhinakar, Wood James, Juleff Nick, Bakker Douwe, Vordermeier Martin, Kapur Vivek
Department of Animal Science, The Pennsylvania State University, University Park, PA, United States.
The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, United States.
Front Vet Sci. 2021 Feb 18;8:637580. doi: 10.3389/fvets.2021.637580. eCollection 2021.
More than 50 million cattle are likely exposed to bovine tuberculosis (bTB) worldwide, highlighting an urgent need for bTB control strategies in low- and middle-income countries (LMICs) and other regions where the disease remains endemic and test-and-slaughter approaches are unfeasible. While Bacillus Calmette-Guérin (BCG) was first developed as a vaccine for use in cattle even before its widespread use in humans, its efficacy against bTB remains poorly understood. To address this important knowledge gap, we conducted a systematic review and meta-analysis to determine the direct efficacy of BCG against bTB challenge in cattle, and performed scenario analyses with transmission dynamic models incorporating direct and indirect vaccinal effects ("herd-immunity") to assess potential impact on herd level disease control. The analysis shows a relative risk of infection of 0.75 (95% CI: 0.68, 0.82) in 1,902 vaccinates as compared with 1,667 controls, corresponding to a direct vaccine efficacy of 25% (95% CI: 18, 32). Importantly, scenario analyses considering both direct and indirect effects suggest that disease prevalence could be driven down close to Officially TB-Free (OTF) status (<0.1%), if BCG were introduced in the next 10-year time period in low to moderate (<15%) prevalence settings, and that 50-95% of cumulative cases may be averted over the next 50 years even in high (20-40%) disease burden settings with immediate implementation of BCG vaccination. Taken together, the analyses suggest that BCG vaccination may help accelerate control of bTB in endemic settings, particularly with early implementation in the face of dairy intensification in regions that currently lack effective bTB control programs.
全球超过5000万头牛可能感染牛结核病（bTB），这凸显了在低收入和中等收入国家（LMICs）以及其他该疾病仍然流行且检测和扑杀方法不可行的地区，迫切需要制定牛结核病控制策略。虽然卡介苗（BCG）早在广泛用于人类之前就已被开发用作牛用疫苗，但其对牛结核病的疗效仍知之甚少。为了填补这一重要的知识空白，我们进行了一项系统综述和荟萃分析，以确定卡介苗对牛结核病攻击的直接疗效，并使用纳入直接和间接疫苗效果（“群体免疫”）的传播动力学模型进行情景分析，以评估对群体水平疾病控制的潜在影响。分析显示，与1667头对照牛相比，1902头接种疫苗的牛的感染相对风险为0.75（95%置信区间：0.68，0.82），对应直接疫苗效力为25%（95%置信区间：18，32）。重要的是，考虑直接和间接影响的情景分析表明，如果在未来10年内将卡介苗引入低至中度（<15%）流行率的环境中，疾病流行率可能会降至接近官方无结核病（OTF）状态（<0.1%），并且即使在疾病负担高（20 - 40%）的环境中立即实施卡介苗接种，在未来50年内也可能避免50 - 95%的累积病例。综合来看，分析表明卡介苗接种可能有助于加速在流行环境中控制牛结核病，特别是在目前缺乏有效牛结核病控制计划的地区，面对乳制品集约化时尽早实施。
