Turcotte Marie-Ève, Buczinski Sébastien, Leboeuf Anne, Harel Josée, Bélanger Denise, Tremblay Donald, Gagnon Carl A, Arsenault Julie
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.
Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Québec, J2S 2M2, Canada.
Prev Vet Med. 2021 Apr 25;191:105365. doi: 10.1016/j.prevetmed.2021.105365.
The bacterium Coxiella burnetii (C. burnetii) can infect a wide range of animals, most notably ruminants where it causes mainly asymptomatic infections and, when clinical, it is associated with reproductive disorders such as abortion. It is also the etiological agent of Q fever in humans, a zoonosis of increasingly important public health concern. A cross-sectional study was performed to estimate the apparent prevalence and spatial distribution of C. burnetii positivity in dairy cattle and small ruminant herds of two regions of Québec, Canada, and identify potential risk factors associated with positivity at animal and herd levels. In dairy cattle herds, individual fecal samples and repeated bulk tank milk samples (BTM) were collected. In small ruminant herds, serum and feces were sampled in individual animals. ELISA analyses were performed on serum and BTM samples. Real-time quantitative PCR (qPCR) was done on fecal and BTM samples. An animal was considered C. burnetii-positive when at least one sample was revealed positive by ELISA and/or qPCR, while a herd was considered C. burnetii-positive when at least one animal inside that herd was revealed positive. None of the 155 cows had a qPCR-positive fecal sample, whereas 37.2 % (95 % CI = 25.3-49.1) of the 341 sheep and 49.2 % (95 % CI = 25.6-72.7) of the 75 goats were C. burnetii-positive. The apparent prevalence of C. burnetii-positive herds was 47.3 % (95 % CI = 35.6-59.3) in dairy cattle herds (n = 74), 69.6 % (95 % CI = 47.1-86.8) in sheep flocks (n = 23) and 66.7 % (95 % CI = 22.3-95.7) in goat herds (n = 6). No spatial cluster of positive herds was detected. At the individual level, the only significant association with positivity in multivariable regressions was higher parity number in small ruminants. At the herd level, the use of calving group pen, the distance to the closest positive bovine herd, and small ruminant herd density in a 5 km radius were associated with dairy cattle herd positivity, whereas small ruminant herds with more than 100 animals and with a dog on the farm had greater odds of C. burnetii positivity. Our study shows that the infection is frequent on dairy cattle and small ruminant herds from the two studied regions and that some farm and animal characteristics might influence the transmission dynamics of the C. burnetii infection.
伯纳特柯克斯体（C. burnetii）可感染多种动物，最显著的是反刍动物，它在反刍动物中主要引起无症状感染，而当出现临床症状时，则与流产等生殖系统紊乱有关。它也是人类Q热的病原体，这是一种对公共卫生影响日益重要的人畜共患病。本研究开展了一项横断面研究，以评估加拿大魁北克两个地区奶牛和小反刍动物群体中伯纳特柯克斯体阳性的表观患病率和空间分布，并确定在动物和群体层面与阳性相关的潜在风险因素。在奶牛群中，采集了个体粪便样本和重复的奶罐乳样（BTM）。在小反刍动物群体中，采集了个体动物的血清和粪便样本。对血清和BTM样本进行了ELISA分析。对粪便和BTM样本进行了实时定量PCR（qPCR）检测。当至少一个样本通过ELISA和/或qPCR检测呈阳性时，该动物被视为伯纳特柯克斯体阳性；当群体中至少有一只动物检测呈阳性时，该群体被视为伯纳特柯克斯体阳性。155头奶牛中，没有一头的粪便样本qPCR呈阳性，而341只绵羊中有37.2%（95%CI = 25.3 - 49.1）、75只山羊中有49.2%（95%CI = 25.6 - 72.7）的样本伯纳特柯克斯体呈阳性。在奶牛群（n = 74）中，伯纳特柯克斯体阳性群体的表观患病率为47.3%（95%CI = 35.6 - 59.3），在羊群（n = 23）中为69.6%（95%CI = 47.1 - 86.8），在山羊群（n = 6）中为66.7%（95%CI = 22.3 - 95.7）。未检测到阳性群体的空间聚集情况。在个体层面，多变量回归中与阳性唯一显著相关的因素是小反刍动物的胎次较高。在群体层面，产犊组围栏的使用、到最近阳性牛群的距离以及半径5公里内的小反刍动物群体密度与奶牛群阳性有关，而动物数量超过100且农场有狗的小反刍动物群体伯纳特柯克斯体阳性的几率更大。我们的研究表明，在这两个研究地区的奶牛和小反刍动物群体中，该感染很常见，并且一些农场和动物特征可能会影响伯纳特柯克斯体感染的传播动态。
