Center for Comparative Epidemiology, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
Prev Vet Med. 2011 Jan 1;98(1):10-8. doi: 10.1016/j.prevetmed.2010.10.001. Epub 2010 Oct 28.
To evaluate the effectiveness of management practices implemented to control the spread of Johne's disease (JD), we conducted a 5-year observational study (January 2003 to December 2007) on seven Michigan, USA dairy herds containing cows infected with Mycobacterium avium subsp. paratuberculosis (MAP; the causative agent of the disease). The JD incidence and prevalence was monitored in each herd annually by serum ELISA and/or fecal culture of all adult cows. A JDCP was designed specifically for each herd based on the results of an initial risk-assessment. The risk-assessment was repeated annually and the control program updated as needed. Herd risk-assessment scores were used to measure compliance with the control program and create JD-risk profiles for individual cows raised on the farms. The association between specific risk-assessment scores and the JD-test status of individual cows was evaluated using logistic regression. We accounted for clustering of cows within herds using generalized estimating equations (GEE). Multivariable models were built with purposeful selection of risk factors assessed on univariable analyses. The dataset analyzed consisted of 3707 cows raised on the respective farms, of which 616 were classified as infected with MAP based on testing positive on fecal culture or serum ELISA. Of the cows that were not exposed to the control program, 20% were classified as infected, while only 7% of cows that were exposed to the control program were infected. The final multivariable model consisted of two factors: exposure to adult cows other than dam at birth (OR=1.09, 95% CI: 1.06, 1.13), and feeding colostrum from one cow to multiple calves (OR=1.10, 95% CI: 1.09, 1.12). Based on this study, implementing practices that minimize the exposure of newborn calves to MAP being shed by infected adult cows should take priority.
为了评估为控制约翰氏病（JD）传播而实施的管理措施的有效性，我们对美国密歇根州的七个奶牛场进行了为期五年的观察研究（2003 年 1 月至 2007 年 12 月），这些奶牛场的奶牛均感染了分支杆菌 avium subsp。paratuberculosis（MAP；该病的病原体）。每年通过对所有成年奶牛进行血清 ELISA 和/或粪便培养，监测每个牛群的 JD 发病率和患病率。根据初始风险评估的结果，为每个牛群专门设计了 JDCP。每年重复进行风险评估，并根据需要更新控制计划。使用 herd risk-assessment 分数来衡量对控制计划的遵守情况，并为农场饲养的个体奶牛创建 JD 风险概况。使用逻辑回归评估特定风险评估分数与个体奶牛 JD 测试状态之间的关系。使用广义估计方程（GEE）来评估牛群内牛的聚类。使用单变量分析评估的有目的选择的风险因素构建多变量模型。分析的数据集包括在各自农场饲养的 3707 头奶牛，其中 616 头根据粪便培养或血清 ELISA 检测呈阳性被归类为感染 MAP。在未接触控制计划的奶牛中，有 20%被归类为感染，而接触控制计划的奶牛中只有 7%被归类为感染。最终的多变量模型由两个因素组成：出生时接触除母牛以外的成年母牛（OR=1.09，95%CI：1.06，1.13），以及用一头母牛的初乳喂养多只小牛（OR=1.10，95%CI：1.09，1.12）。基于这项研究，应优先采取措施，最大限度地减少新生小牛接触受感染成年奶牛传播的 MAP。
