College of Agricultural and Life Sciences, Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI 53706, United States.
Prev Vet Med. 2013 Nov 1;112(3-4):276-84. doi: 10.1016/j.prevetmed.2013.07.016. Epub 2013 Aug 7.
Paratuberculosis (Johne's disease) is a contagious intestinal infection of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). In cattle, young calves are at the highest risk for acquiring the infection which occurs mainly through ingestion of MAP from contaminated milk, colostrum and feces or environmental contacts. Data consisted of birth dates and ELISA results of 8000 mature cows from 24 Jersey herds from throughout the US and 4 Wisconsin Holstein herds. Some herds also had complete fecal culture (FC) results. The first infection (case) definition (CD1) relied on only ELISA results. A second case definition (CD2) was used in which results of both ELISA and FC tests were considered: animals testing positive to either test were considered "test-positives" and cows testing negative to ELISA or to both ELISA and FC were regarded as "test-negatives". Objective one was to assess seasonality in birth of MAP-infected animals. The effects of age, breed, herd and season of birth (expressed as the sine and cosine functions of birth days within year) were examined using logistic regression. Age was significantly associated with the MAP infection status of dairy cows for both CDs (OR=1.11; 95% CI 1.09, 1.14; P<0.0001 for CD1; OR=1.16; 95% CI 1.08, 1.24; P<0.0001 for CD2). Season of birth had a significant effect on the risk of MAP infection based on CD1 (OR=0.79; 95% CI 0.71, 0.89; P<0.001 for cosine of birth days) with a peak in summer and a trough in winter based on the fitted model. Objective two was to assess whether test-positive animals were randomly distributed or were clustered by date of birth within herds. A temporal cluster analysis approach (scan statistic) implemented in SaTScan software was used for each case definition to detect clusters of birth cohorts using birthdates. Results identified significant clustering of MAP infection cases for CD1 in multiple herds (P<0.05). These results necessitate matching cases and controls of MAP infection on their birth dates to control for non-uniform exposure to MAP in paratuberculosis case-control genome wide association studies, candidate gene studies or in on-farm disease intervention trials.
副结核病（约翰氏病）是一种由分枝杆菌亚种副结核分枝杆菌（MAP）引起的传染性肠道感染，主要发生在反刍动物中。在牛中，幼牛感染该病的风险最高，主要通过摄入受污染的牛奶、初乳和粪便或环境接触感染 MAP。该数据来自美国 24 个泽西牛群和 4 个威斯康星荷斯坦牛群的 8000 头成年牛的出生日期和 ELISA 结果。一些牛群还有完整的粪便培养（FC）结果。第一个感染（病例）定义（CD1）仅依赖于 ELISA 结果。第二个病例定义（CD2）用于考虑 ELISA 和 FC 测试的结果：两种测试均呈阳性的动物被视为“测试阳性”，而 ELISA 或 ELISA 和 FC 均呈阴性的牛被视为“测试阴性”。目的一是评估 MAP 感染动物出生的季节性。使用逻辑回归分析了年龄、品种、牛群和出生季节（用年内出生天数的正弦和余弦函数表示）对 MAP 感染状态的影响。对于两个 CD（OR=1.11；95%CI 1.09,1.14；P<0.0001 用于 CD1；OR=1.16；95%CI 1.08,1.24；P<0.0001 用于 CD2），年龄与奶牛的 MAP 感染状态显著相关。出生季节对 MAP 感染风险有显著影响（OR=0.79；95%CI 0.71,0.89；P<0.001 用于出生天数的余弦），根据拟合模型，夏季高峰期和冬季低谷期。目的二是评估测试阳性动物是否随机分布或在牛群内按出生日期聚类。使用 SaTScan 软件中的时间聚类分析方法（扫描统计），为每个病例定义使用出生日期检测出生队列的聚类。结果表明，多个牛群的 CD1 中存在 MAP 感染病例的显著聚类（P<0.05）。这些结果需要根据出生日期匹配 MAP 感染病例和对照，以控制在副结核病病例对照全基因组关联研究、候选基因研究或农场疾病干预试验中对 MAP 的非均匀暴露。
