印第安纳州商业奶牛场散装罐牛奶样本中伯氏考克斯氏体的估计群体流行率和序列类型
Estimated herd prevalence and sequence types of Coxiella burnetii in bulk tank milk samples from commercial dairies in Indiana.
作者信息
Bauer Amy E, Olivas Sonora, Cooper Maria, Hornstra Heidie, Keim Paul, Pearson Talima, Johnson April J
机构信息
Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA.
The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ, USA.
出版信息
BMC Vet Res. 2015 Aug 7;11:186. doi: 10.1186/s12917-015-0517-3.
BACKGROUND
Coxiella burnetii is the etiologic agent of Q fever, a zoonotic disease causing influenza-like illness, pregnancy loss, cardiovascular disease and chronic fatigue syndrome in people. C. burnetii is considered to be enzootic in ruminants, but clinical signs of infection do not always manifest. National studies have documented the presence of C. burnetii in dairy herds in Indiana. This represents an opportunity to better characterize the distribution and prevalence of C. burnetii infection at the state scale, allowing evaluation of the need for surveillance and response planning to occur at this level. A cross-sectional study was conducted to estimate the herd prevalence of C. burnetii in commercial cattle dairies in Indiana and characterize the strains of C. burnetii within these dairies.
RESULTS
Bulk tank milk samples were collected between June and August of 2011 by the Indiana State Board of Animal Health (ISBOAH). A total of 316 of these samples were tested for the IS1111 transposon of C. burnetii using quantitative real time polymerase chain reaction (PCR). Single nucleotide polymorphism (SNP) genotyping was used to identify the multispacer sequence genotypes (ST) present in samples where the IS1111 transposon was identified. The geographic distribution of dairies testing positive for C. burnetii DNA and the identified STs were also evaluated. The estimated overall herd prevalence for C. burnetii DNA was 61.1 % (95 % CI 55.6-66.3 %). The highest estimated regional prevalence was 70.2 % in the Central region of Indiana. An ST was identifiable in 74 of the positive 178 samples (41.6 %) and none of the 10 negative samples tested. Of these samples, 71 (95.9 %) were identified as ST20, 2 (2.7 %) as ST8 and a combination of ST20 and ST8 was identified in a single sample.
CONCLUSIONS
C. burnetii is present in dairy herds throughout Indiana. Indiana follows national trends with ST20 most commonly identified. The presence of multiple STs in a single bulk tank sample indicates that multiple strains of C. burnetii can circulate within a herd. This supports potential transmission of C. burnetii between goats and cattle, presenting the potential for a switch in the dominant genotype found in a given species.
背景
伯氏考克斯体是Q热的病原体，Q热是一种人畜共患病，可导致人类出现流感样疾病、流产、心血管疾病和慢性疲劳综合征。伯氏考克斯体被认为在反刍动物中呈地方流行性，但感染的临床症状并不总是显现出来。国内研究已记录了印第安纳州奶牛群中存在伯氏考克斯体。这为在州层面更好地描述伯氏考克斯体感染的分布和流行情况提供了契机，从而能够评估在此层面进行监测和应对规划的必要性。开展了一项横断面研究，以估计印第安纳州商业奶牛场中伯氏考克斯体的牛群流行率，并对这些奶牛场内的伯氏考克斯体菌株进行特征分析。
结果
2011年6月至8月期间，印第安纳州动物卫生委员会（ISBOAH）采集了大容量奶罐样本。使用定量实时聚合酶链反应（PCR）对其中316份样本检测伯氏考克斯体的IS1111转座子。对于检测到IS1111转座子的样本，采用单核苷酸多态性（SNP）基因分型来鉴定存在的多间隔序列基因型（ST）。还评估了检测伯氏考克斯体DNA呈阳性的奶牛场的地理分布以及鉴定出的ST。伯氏考克斯体DNA的估计总体牛群流行率为61.1%（95%可信区间55.6 - 66.3%）。印第安纳州中部地区估计的区域流行率最高，为70.2%。在178份阳性样本中的74份（41.6%）以及10份检测为阴性的样本中均未检测到可鉴定的ST。在这些样本中，71份（95.9%）被鉴定为ST20，2份（2.7%）为ST8，在单个样本中鉴定出ST20和ST8的组合。
结论
印第安纳州各地的奶牛群中均存在伯氏考克斯体。印第安纳州遵循全国趋势，最常鉴定出的是ST20。单个大容量奶罐样本中存在多种ST表明伯氏考克斯体的多种菌株可在牛群中传播。这支持了伯氏考克斯体在山羊和牛之间的潜在传播，表明在给定物种中发现的优势基因型可能会发生转变。
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