Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Québec, J2S 2M2, Canada.
Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Québec, J2S 2M2, Canada.
Prev Vet Med. 2021 Jan;186:105231. doi: 10.1016/j.prevetmed.2020.105231. Epub 2020 Dec 10.
The bacterium Coxiella burnetii has been associated with reproduction disorders in dairy cattle. A cross-sectional study was conducted in Québec, Canada, to estimate the prevalence of C. burnetii in dairy cows from C. burnetii RT-PCR-positive and/or ELISA-positive herds. As a secondary objective, the associations between C. burnetii-positivity and three reproductive outcomes (purulent vaginal discharge, cytological endometritis, and success at first service) were assessed. A total of 202 post-parturient dairy cows from nine herds were sampled at 35 ± 7 days in milk. Vaginal mucus and composite milk were collected from each cow and screened for the presence of C. burnetii by real-time PCR (RT-PCR) and ELISA, respectively. Purulent vaginal discharge and cytological endometritis were evaluated using a Metricheck device and a modified cytobrush, respectively. The first insemination postpartum was done following an ovulation synchronization protocol around 70 days in milk, and success at first service was recorded. Multilevel logistic regressions adjusted for parity were used to model purulent vaginal discharge, cytological endometritis and success at first service according to C. burnetii cow status. All 202 RT-PCR-assayed vaginal samples were C. burnetii-negative. A positive result for anti-C. burnetii antibodies detection in composite milk was obtained in 25/202 samples and a doubtful result in 4/202 samples. After adjustment for sampling weights, the 202 ELISA-assayed composite milk samples gave an estimated overall prevalence of C. burnetii positive cows of 12.9 % (CI = 6.1-19.6 %) and of doubtful cows of 1.4 % (CI = 0.0-3.3 %). The proportion of ELISA-positive cows was lower in first parity (0%) compared to second (17.1 %) or third parity cows (20.0 %). The associations between ELISA positivity and reproductive outcomes were not statistically significant, perhaps due to the limited sample size, but could be used as pilot estimate for large-scale studies investigating the impact of C. burnetii infection on reproduction disorders in dairy cattle.
贝氏考克斯氏体已被证实与奶牛生殖障碍有关。本研究在加拿大魁北克省开展了一项横断面研究，以评估从贝氏考克斯氏体 RT-PCR 阳性和/或 ELISA 阳性牛群中分离的奶牛感染贝氏考克斯氏体的流行率。本研究的次要目标是评估贝氏考克斯氏体阳性与三种生殖结果（化脓性阴道分泌物、细胞学子宫内膜炎和首次配种成功率）之间的关系。共采集了 9 个牛场的 202 头产后奶牛，产犊后 35±7 天进行采样。从每头奶牛采集阴道黏液和混合奶样，分别通过实时 PCR（RT-PCR）和 ELISA 检测贝氏考克斯氏体的存在。使用 Metricheck 设备和改良的细胞刷评估化脓性阴道分泌物和细胞学子宫内膜炎。首次配种在产后 70 天左右进行同期排卵处理，并记录首次配种的成功率。采用多水平逻辑回归模型，根据牛只贝氏考克斯氏体状态，对化脓性阴道分泌物、细胞学子宫内膜炎和首次配种成功率进行调整。所有 202 个 RT-PCR 检测的阴道样本均为贝氏考克斯氏体阴性。202 个混合奶样中，25 个样本的抗贝氏考克斯氏体抗体检测呈阳性，4 个样本的检测结果可疑。调整采样权重后，202 个 ELISA 检测的混合奶样本估计总阳性牛的流行率为 12.9%（95%CI：6.1-19.6%），可疑牛的流行率为 1.4%（95%CI：0.0-3.3%）。首次配种的牛中 ELISA 阳性牛的比例（0%）低于第二胎（17.1%）或第三胎（20.0%）。ELISA 阳性与生殖结果之间的关联无统计学意义，这可能是由于样本量有限，但可以作为调查贝氏考克斯氏体感染对奶牛生殖障碍影响的大型研究的初步估计。
