Velusamy Rangasamy, Ponnudurai Gurusamy, Alagesan Alagarsamy, Rani Natarajan, Kolte Sunil W, Rubinibala Balan
Department of Veterinary Parasitology, Veterinary College and Research Institute (TANUVAS), Orathanadu, 614 625, Tamil Nadu, India.
Department of Veterinary Parasitology, Veterinary College and Research Institute (TANUVAS), Namakkal, 637 002, Tamil Nadu, India.
Parasitol Res. 2023 Dec;122(12):3077-3086. doi: 10.1007/s00436-023-07998-x. Epub 2023 Oct 13.
Tick-borne diseases are the most common in cattle in the tropical and subtropical regions of India and lead to substantial economic losses to small and marginal farmers. This study aimed to identify the diverse species of ticks infesting cattle in the central part of Tamil Nadu, India, and to assess the prevalence of Theileria annulata infection in various species of ticks through PCR. Out of 123 cross-bred and 105 native breed cattle examined for tick infestation, 40 (18%) and 29 (12.7%) cattle were infested with Ixodid ticks, respectively. The most prevalent tick species identified was Rhipicephalus microplus (n=589), followed by Hyalomma anatolicum (n=532), Hyalomma marginatum (n=145), Haemaphysalis intermedia (n=79), and Rhipicephalus haemophysaloides (n=1) found in the study area. The prevalence and intensity of the tick infestation were found to be higher in cross-bred (71.04%) than native breed cattle (28.96%), and there was no significant difference between the studied breeds (chi-square value =24; df =20; p value =0.24) was observed. However, a significant difference in the H. anatolicum tick infestation was observed between the Cauvery Delta (14.30%) and the North-Western (20%) zones of Tamil Nadu (p<0.05). DNA fragments of 193 bp derived from 18S rRNA gene sequences of T. annulata were amplified using species-specific primers. Of these, 16 out of 37 (43.2%) and 10 out of 39 (29%) pooled samples of H. anatolicum and 4 out of 18 (22.2%) and 1 out of 5 (20%) pooled samples of H. marginatum were found positive for T. annulata from the Cauvery Delta and North-Western zones, respectively. R. microplus, H. intermedia, and R. haemaphysaloides from these regions were negative. These findings confirm that H. anatolicum (52.17%) is the predominant vector for T.annulata rather than H. marginatum (18.84%), and the PCR is a useful method of determining the infection rates in ticks collected from animals carrying low levels of T. annulata piroplasms.
蜱传疾病在印度热带和亚热带地区的牛群中最为常见，给小农户和边际农户造成了巨大的经济损失。本研究旨在确定印度泰米尔纳德邦中部寄生在牛身上的蜱的不同种类，并通过聚合酶链反应（PCR）评估不同种类蜱中环形泰勒虫感染的流行情况。在检查蜱虫感染情况的123头杂交牛和105头本地牛中，分别有40头（18%）和29头（12.7%）感染了硬蜱。研究区域内鉴定出的最常见蜱种是微小扇头蜱（n = 589），其次是小亚璃眼蜱（n = 532）、边缘璃眼蜱（n = 145）、中间血蜱（n = 79）和血红扇头蜱（n = 1）。发现杂交牛（71.04%）的蜱虫感染率和感染强度高于本地牛（28.96%），且所研究的品种之间没有显著差异（卡方值 = 24；自由度 = 20；p值 = 0.24）。然而，在泰米尔纳德邦的科韦里三角洲地区（14.30%）和西北地区（20%）之间，观察到小亚璃眼蜱的感染存在显著差异（p < 0.05）。使用物种特异性引物扩增出了源自环形泰勒虫18S rRNA基因序列的193 bp DNA片段。其中，分别来自科韦里三角洲地区和西北地区的37份小亚璃眼蜱混合样本中有16份（43.2%）、39份中有10份（29%）呈环形泰勒虫阳性，18份边缘璃眼蜱混合样本中有4份（22.2%）、5份中有1份（20%）呈阳性。这些地区的微小扇头蜱、中间血蜱和血红扇头蜱均为阴性。这些发现证实，小亚璃眼蜱（52.17%）是环形泰勒虫的主要传播媒介，而非边缘璃眼蜱（18.84%），并且PCR是一种用于确定从携带低水平环形泰勒虫梨形虫的动物身上采集的蜱的感染率的有用方法。
