Ottardi Martina, Lechner Isabel, Wang Jessica, Schmitt Sarah, Schneeberger Marianne, Schmid Robin Michael, Stephan Roger, Meylan Mireille
Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
SAFOSO AG, Liebefeld, Switzerland.
Front Vet Sci. 2024 Jun 28;11:1409694. doi: 10.3389/fvets.2024.1409694. eCollection 2024.
Bovine paratuberculosis (PTB) is a chronic enteric disease caused by subsp. (MAP). Control of PTB is important given its negative economic consequences and the potential zoonotic role of MAP in Crohn's disease in humans.
To determine the seroprevalence of MAP in Swiss dairy herds and to identify risk factors associated with seropositive herd status and high within-herd seroprevalence, 10,063 serum samples collected from cattle over 12 months of age in 171 Swiss dairy farms were analyzed using a commercial ELISA test. Eight herds were excluded due to non-interpretable ELISA results. Risk factors associated with seropositive herd status and high within-herd seroprevalence were investigated with regression models using results from a questionnaire on management practices possibly associated with the introduction or spread of MAP in the remaining 163 herds. Univariable logistic regression was performed, carrying forward for multivariable regression analysis when < 0.2.
The calculated between-herd true seroprevalence was 3.6% (95% CI, 0.96-8.4%). Due to the low within-herd seroprevalence, it was not possible to calculate the true seroprevalence at animal level; the apparent within-herd seroprevalence ranged from 2.3 to 5.5% with a median of 3.6% in nine positive farms. Herd size ( = 0.037) and the common grazing of lactating cows with cows from other herds ( = 0.014) were associated with seropositive herd status, while heifers sharing alpine pasture with dairy cattle from other herds were associated with a decreased probability of the herd to test seropositive ( = 0.042). Reliable identification of significant risk factors associated with MAP spread and high seroprevalence of PTB within seropositive herds was not possible due to low observed seroprevalence within herds and low sensitivity of the ELISA test.
These results highlight the limitation of serology for MAP diagnosis in small herds with low infection prevalence.
牛副结核病（PTB）是由副结核分枝杆菌亚种（MAP）引起的一种慢性肠道疾病。鉴于其负面经济后果以及MAP在人类克罗恩病中可能的人畜共患病作用，控制PTB很重要。
为了确定瑞士奶牛群中MAP的血清流行率，并识别与血清阳性牛群状态及牛群内高血清流行率相关的风险因素，使用商业酶联免疫吸附测定（ELISA）试验分析了从171个瑞士奶牛场12月龄以上牛采集的10,063份血清样本。由于ELISA结果无法解读，排除了8个牛群。使用关于可能与MAP引入或传播相关的管理实践的问卷结果，通过回归模型研究与血清阳性牛群状态及牛群内高血清流行率相关的风险因素。进行单变量逻辑回归分析，当P<0.2时，将其纳入多变量回归分析。
计算得出牛群间的真实血清流行率为3.6%（95%置信区间，0.96 - 8.4%）。由于牛群内血清流行率较低，无法计算个体水平的真实血清流行率；在9个阳性农场中，牛群内表观血清流行率范围为2.3%至5.5%，中位数为3.6%。牛群规模（P = 0.037）以及泌乳母牛与其他牛群的母牛共同放牧（P = 0.014）与血清阳性牛群状态相关，而与来自其他牛群奶牛共享高山牧场的小母牛与牛群检测血清阳性的概率降低相关（P = 0.042）。由于观察到的牛群内血清流行率较低以及ELISA试验的敏感性较低，无法可靠地识别与MAP传播及血清阳性牛群内PTB高血清流行率相关的显著风险因素。
这些结果凸显了血清学在感染患病率低的小牛群中诊断MAP的局限性。
