Department of Pathobiology, School of Veterinary Medicine, Shahid Bahonar University of Kerman, PO Box 76169 14111, Kerman, Iran.
Department of Pathobiology, School of Veterinary Medicine, Shahid Bahonar University of Kerman, PO Box 76169 14111, Kerman, Iran.
J Dairy Sci. 2019 Jun;102(6):4954-4959. doi: 10.3168/jds.2018-15233. Epub 2019 Apr 17.
Coxiella burnetii is a gram-negative and polymorphic rod bacterium that causes Q fever, a common zoonotic disease distributed worldwide. Widespread occurrences of the disease outbreaks indicate the importance of coordinated animal and human health efforts to control these outbreaks. Different tests are available to determine the C. burnetii infection status of a flock, but false negative responses may occur, as infectious animals can shed bacteria in milk intermittently, especially during an asymptomatic infection. In this study, a Bayesian latent class model was implemented to estimate the sensitivity (Se) and specificity (Sp) of a PCR method for the detection of C. burnetii in milk samples (PCR) and vaginal swabs (PCR) from Iranian sheep and goats. A nested PCR assay was conducted to detect infected animals among 170 milk samples and 170 vaginal swabs from goat flocks and 170 milk samples and 170 vaginal swabs from sheep flocks. We implemented a Bayesian latent class model to estimate the Se and Sp of a PCR method for the detection of C. burnetii in milk samples and vaginal swabs from sheep and goats. Estimations were based on the cross-classified results of PCR and PCR from the sheep and goat subpopulations. Positivity was 17.6 and 33.5%, respectively, for PCR and PCR samples among sheep. In goats, the apparent prevalence was 32.9 and 56.4% in PCR and PCR samples testing positive, respectively. This indicated the lower sensitivity of PCR. The Se of PCR was significantly higher than Se of PCR, which corresponded to a higher rate of vaginal-positive, milk-negative PCR samples. In contrast, Sp of PCR was lower than Sp of PCR, representing the higher false-positive rate of vaginal swabs. The PCR outperformed PCR in terms of identifying latently infected sheep and goats; however, neither method could identify all latently infected sheep and goats, thus the combination is recommended to maximize our ability to identify infected animals. The true prevalence of C. burnetii infection was higher in Iranian goats than sheep.
贝氏考克斯氏体是一种革兰氏阴性、多形性的杆状细菌，可引起 Q 热，这是一种广泛分布于全球的常见人畜共患病。该病的广泛发生表明，需要协调动物和人类健康工作来控制这些疫情。有多种方法可用于确定羊群的贝氏考克斯氏体感染状态，但可能会出现假阴性反应，因为感染动物的细菌在乳汁中会间歇性排出，特别是在无症状感染期间。在这项研究中，我们实施了贝叶斯潜在类别模型来估计检测伊朗绵羊和山羊乳汁（PCR）和阴道拭子（PCR）中贝氏考克斯氏体的 PCR 方法的敏感性（Se）和特异性（Sp）。我们对来自山羊群的 170 个乳汁样本和 170 个阴道拭子以及来自绵羊群的 170 个乳汁样本和 170 个阴道拭子进行了巢式 PCR 检测，以检测感染动物。我们实施了贝叶斯潜在类别模型来估计检测绵羊和山羊乳汁和阴道拭子中贝氏考克斯氏体的 PCR 方法的 Se 和 Sp。估计值是基于绵羊和山羊亚群的 PCR 和 PCR 的交叉分类结果。在绵羊中，PCR 和 PCR 样本的阳性率分别为 17.6%和 33.5%。在山羊中，PCR 和 PCR 样本的阳性率分别为 32.9%和 56.4%。这表明 PCR 的敏感性较低。PCR 的 Se 显著高于 PCR 的 Se，这对应于更高比例的阴道阳性、乳汁阴性的 PCR 样本。相反，PCR 的 Sp 低于 PCR 的 Sp，这代表了阴道拭子的更高假阳性率。PCR 在识别潜伏感染的绵羊和山羊方面优于 PCR，但这两种方法都无法识别所有潜伏感染的绵羊和山羊，因此建议联合使用这两种方法以最大限度地提高我们识别感染动物的能力。在伊朗山羊中，贝氏考克斯氏体感染的真实流行率高于绵羊。
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