四川省理塘县牦牛感染泰勒虫的分子流行病学调查及虫种鉴定

Molecular epidemiological investigation and species identification of Theileria infection in yaks in Litang County of Sichuan Province

为调查四川省理塘县牦牛泰勒虫的感染情况及流行规律,2019年5—11月和2020年4—10月自理塘县采集临床健康牦牛全血共345份,采用以18S rRNA为靶基因的巢式PCR方法进行泰勒虫检测,分析理塘县牦牛泰勒虫感染的季节规律、年龄段、体重变化、性别特点,对全部泰勒虫核酸检测阳性样本共计65份进行虫种鉴定。结果显示:345份牦牛样本中检测出泰勒虫核酸阳性样本65份,平均阳性率为18.84%;5、6月牦牛泰勒虫阳性率高于其他月份;2~5岁组牦牛泰勒虫阳性率最高,显著高于5岁以上组牦牛(P<0.05),与0~2岁组牦牛差异不显著(P>0.05);感染泰勒虫的牦牛体重普遍偏轻;公牦牛感染率略高,差异不明显;65份泰勒虫核酸检测阳性样本成功测序58份,鉴定出感染的虫种有中华泰勒虫57份、吕氏泰勒虫1份,其中中华泰勒虫占比98.28%,吕氏泰勒虫占比1.72%。提示:首次对理塘县牦牛感染泰勒虫的流行规律进行调查,理塘县牦牛泰勒虫感染率较高,不同季节、年龄段之间存在差异,优势虫种为中华泰勒虫,为理塘县牦牛梨形虫病的防控提供了重要参考。

This study was to investigate the infection and epidemic regularity of Theileria in yak in Litang County of Sichuan Province. From May to November in 2019 and April to October in 2020, 233 whole blood samples of clinically healthy yaks were collected on the farms in Litang County, every month. Then, the nested PCR with 18 S rRNA as the target gene was used to detect Theileria in the samples, to analyze the seasonal pattern, age groups, gender characteristics and weight change of Theileria infection in the animals. 65 positive PCR products were obtained to identify the parasite species. The 65 samples of the 345 yak blood samples were tested positive, at an average positive rate of 18.84%. The positive rate of Theileria infection in yak in May and June was higher than that in the other months. This positive rate was the highest in the 2-5 years old yaks, which was significantly higher than that in the yaks of above 5 year of age(P<0.05), but was not significantly different from that in the 0-2 year old yaks(P>0.05). The infected yaks were generally low in body weight. In terms of sex, the infection rate of male yaks was slightly higher,but with no significant difference. Of the 65 positive PCR products,58 copies were successfully sequenced,and the infected species were identified as Theileria sinensis (57) and Theileria luwenshuni (1),whose proportions being98. 28% and 1. 72%,respectively. It is the first time to have investigated the epidemic regularity of Theileria infection in yaks in Litang County,which showed a rather high infection rate,different infection rates between different seasons,ages,with Theileria sinensis being the dominant species. The present study provided important reference for prevention and control of piroplasmosis in yaks in Litang County.