Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, VIC, Australia.
Department of Parasitology, University of Veterinary and Animal Sciences, Lahore, Punjab, Pakistan.
Ticks Tick Borne Dis. 2020 Sep;11(5):101472. doi: 10.1016/j.ttbdis.2020.101472. Epub 2020 May 22.
Tick infestation is a leading cause of tick-worry and tick-borne diseases in livestock and associated economic losses in tropical and subtropical regions of the world. The cattle and buffalo populations in Pakistan are exposed to tick infestation throughout the year, but very little is known about the biology, diversity and distribution of tick species across different agro-ecological zones (AEZ) of the country. The present study aimed to investigate the prevalence (number of bovines infested with ticks out of the investigated population) and diversity of hard ticks infesting bovines in 30 villages located in five distinct AEZs (i.e. Arid, Indus delta, Northern irrigated plain, Sandy desert and Southern irrigated plain). We collected a total of 774 ticks (adult and nymphs) from cattle (n = 116) and water buffaloes (n = 88) on small-holder dairy farms (with <10 bovids per establishment) from September to November 2017. The overall tick prevalence was 46.1% (cattle: 47.9%; buffaloes: 44%), which varied significantly from 22.2% in the Indus delta to 70.5% in the Sandy desert. Tick prevalence was slightly higher in female (46.5%) than male animals (45%), and higher in calves (i.e. ≤ 1 year of age) (55%) than in young animals (i.e. up to 3 years of age) (39%) and adults (48%). Five tick species - Hyalomma anatolicum, Hyalomma hussaini, Hyalomma scupense, Rhipicephalus microplus and Rhipicephalus annulatus - were identified morphologically and then genetically. Genetic identification, achieved using the sequences of two mitochondrial (cytochrome c oxidase subunit 1 and 16S) and one nuclear ribosomal (second internal transcribed spacer) regions, was consistent with the morphological findings. Phylogenetic analyses of the DNA sequence data sets showed that the five species of tick identified here were closely related to the same species or closely related species from within and outside of Pakistan. Of five presently recognised taxa within the R. microplus complex, two were identified herein, including the R. microplus clade C and R. annulatus. This investigation provides the first genetic evidence of the occurrence of R. annulatus in Pakistan as well as Hy. hussaini and Hy. scupense in bovines specifically in the provinces of Sindh and Punjab, respectively. The present findings emphasise the importance of combining morphological and molecular approaches to study the diversity of ticks. Further longitudinal studies are required to establish seasonal variations in the prevalence and distribution of bovine ticks in different AEZs of Pakistan.
蜱虫侵扰是导致牲畜出现蜱虫担忧和蜱传疾病以及在世界热带和亚热带地区造成经济损失的主要原因。巴基斯坦的牛和水牛种群全年都面临蜱虫侵扰，但对该国不同农业生态区（AEZ）的蜱种的生物学、多样性和分布情况知之甚少。本研究旨在调查在五个不同 AEZ（即干旱区、印度河三角洲、北部灌溉平原、沙质荒漠和南部灌溉平原）的 30 个村庄中，侵袭牛的硬蜱的流行率（在所调查的牛群中感染蜱虫的牛的数量）和多样性。我们于 2017 年 9 月至 11 月从小型奶牛场（每个农场<10 头牛）采集了总共 774 只蜱虫（成虫和若虫），这些蜱虫来自牛（n=116 只）和水牛（n=88 只）。总体蜱虫流行率为 46.1%（牛：47.9%；水牛：44%），在印度河三角洲地区为 22.2%，在沙质荒漠地区为 70.5%，差异显著。雌性（46.5%）的蜱虫流行率略高于雄性（45%），小牛（即<1 岁）（55%）的流行率高于小牛（即<3 岁）（39%）和成年动物（48%）。通过形态学和随后的两种线粒体（细胞色素 c 氧化酶亚基 1 和 16S）和一种核核糖体（第二内部转录间隔区）区域的 DNA 序列鉴定了 5 种蜱虫 - 安纳托利亚钝缘蜱、Hyalomma hussaini、Hyalomma scupense、Rhipicephalus microplus 和 Rhipicephalus annulatus。使用两种线粒体（细胞色素 c 氧化酶亚基 1 和 16S）和一种核核糖体（第二内部转录间隔区）区域的 DNA 序列进行的遗传鉴定与形态学发现一致。DNA 序列数据集的系统发育分析表明，在这里鉴定的 5 种蜱虫与来自巴基斯坦境内和境外的同一物种或密切相关的物种密切相关。在所识别的 R. microplus 复合体的五个目前公认的分类群中，有两个在此处被识别，包括 R. microplus 分支 C 和 R. annulatus。本研究首次提供了在巴基斯坦发现 R. annulatus 以及在信德省和旁遮普省专门在牛身上发现 Hy. hussaini 和 Hy. scupense 的遗传证据。本研究结果强调了将形态学和分子方法相结合研究蜱虫多样性的重要性。需要进一步进行纵向研究，以确定巴基斯坦不同农业生态区中牛蜱的流行率和分布的季节性变化。
