Department of Mathematics and Statistics, University of Missouri-Kansas City, Kansas City, Missouri, United States of America.
Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States of America.
PLoS One. 2018 Oct 2;13(10):e0203190. doi: 10.1371/journal.pone.0203190. eCollection 2018.
Paratuberculosis, also known as Johne's disease (JD), is a chronic contagious disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP). The disease is incurable, fatal and causes economic losses estimated to exceed 200 million dollars to the U.S. dairy industry annually. Several preventive and control measures have been recommended; however, only a few of these measures have been validated empirically. Using a nested compartmental (NC) modeling approach, the main objective of this research was to identify the best combination of control and preventive measures that minimizes the prevalence and incidence of JD and the risk of MAP occurrence in a dairy herd. The NC model employs both MAP transmission estimates and data on pen movement of cattle on a dairy to quantify the effectiveness of control and preventive measures. To obtain reasonable ranges of parameter values for between-pen movements, the NC model was fitted to the movement data of four typical California dairy farms. Using the estimated ranges of the movement parameters and those of JD from previous research, the basic reproduction number was calculated to measure the risk of MAP occurrence in each pen environment as well as the entire dairy. Although the interventions evaluated by the NC model were shown to reduce the infection, no single measure alone was capable of eradicating the infection. The numerical simulations suggest that a combination of test and cull with more frequent manure removal is the most effective method in reducing incidence, prevalence and the risk of MAP occurrence. Other control measures such as limiting calf-adult cow contacts, raising calves in a disease-free herd or colostrum management were less effective.
副结核病，也称为约翰氏病（JD），是一种慢性传染性疾病，由鸟分枝杆菌副结核亚种（MAP）引起。该疾病无法治愈，具有致命性，每年给美国乳制品行业造成的经济损失估计超过 2 亿美元。已经推荐了几种预防和控制措施；然而，只有少数这些措施已经通过经验验证。本研究采用嵌套隔室（NC）建模方法，主要目的是确定控制和预防措施的最佳组合，以最大程度地降低 JD 的流行率和发病率以及奶牛场中 MAP 发生的风险。NC 模型利用 MAP 传播估计和牛在奶牛场中的围栏移动数据来量化控制和预防措施的有效性。为了获得围栏间移动的合理参数值范围，NC 模型拟合了四个典型的加利福尼亚州奶牛场的移动数据。使用估计的移动参数范围和之前研究中的 JD 范围，计算基本繁殖数，以衡量每个围栏环境以及整个奶牛场中 MAP 发生的风险。尽管 NC 模型评估的干预措施表明可以减少感染，但没有任何单一措施能够根除感染。数值模拟表明，测试和淘汰与更频繁的粪便清除相结合是减少发病率、患病率和 MAP 发生风险的最有效方法。其他控制措施，如限制犊牛与成年奶牛的接触、在无病牛群中饲养犊牛或管理初乳，效果较差。
