Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.
Department of Pathobiology, Faculty of Veterinary Medicine, Bu-Ali Sina University, Hamedan, 6517658978, Iran.
Parasit Vectors. 2024 Nov 24;17(1):486. doi: 10.1186/s13071-024-06558-1.
In camels, thelaziosis is mainly caused by Thelazia leesei Railliet & Henry, 1910, a little-known eyeworm species. Given the paucity of scientific data, this study aimed to provide new insights into the morphology, molecular characterization, and phylogenetic relationship of T. leesei and its occurrence in camels from Iran, where animals suffer from the high burden of eyeworms.
From December 2020 to November 2022, slaughtered camels (n = 400) of different sex and age groups were examined in Sistan-va-Baluchestan province in Southeast Iran's local abattoirs. Adult eyeworms were fixed and stored for morphological identification by light and scanning electron microscopy (SEM). Polymerase chain reaction (PCR) products corresponding to the partial sequences of the mitochondrial cytochrome c oxidase subunit I (cox1) of eyeworms were Sanger sequenced and analyzed phylogenetically.
A total of 118 (29.5%) camels from all five counties examined were infected with eyeworms, with an abundance of 0.9 and a mean intensity of 3.2 (i.e., up to 18 worms from a single animal). The infection rate was higher in camels older than 4 years of age (P = 0.01901). Lachrymation was associated with infection in animals (P < 0.00001). The morphology of our specimens resembled that of T. leesei, with the exception of the position of the nerve ring and esophagus length. Genetic analysis showed that the cox1 partial sequences of our T. leesei specimens had genetic distances of 8.8% to 13.5% compared with other Thelazia species.
On the basis of the morphometrics and morphological characteristics, we identified our specimens as T. leesei. In the phylogenetic tree, T. leesei herein isolated formed a monophyletic group together with its congeners, and T. leesei formed a sister clade to T. lacrymalis. In addition, we demonstrated the epidemiology of the infestation of T. leesei in camels in the endemic areas of southeastern Iran. The data presented are crucial for better understanding the pathogenic role of T. leesei and developing effective treatment strategies. In particular, studies on the intermediate host(s) of T. leesei in these regions will support effective control strategies for this parasitosis.
在骆驼中，嗜眼线虫病主要由 Thelazia leesei Railliet & Henry，1910 引起，这是一种鲜为人知的眼虫物种。鉴于科学数据的缺乏，本研究旨在提供有关 T. leesei 的形态学、分子特征和系统发育关系的新见解，并探讨其在伊朗骆驼中的发生情况，这些动物遭受着高负担的眼虫病。
2020 年 12 月至 2022 年 11 月，在伊朗东南部锡斯坦-俾路支斯坦省的当地屠宰场检查了不同性别和年龄组的屠宰骆驼（n=400）。固定成年眼虫并通过光镜和扫描电子显微镜（SEM）进行形态学鉴定。聚合酶链反应（PCR）产物对应于眼虫线粒体细胞色素 c 氧化酶亚基 I（cox1）的部分序列，进行 Sanger 测序并进行系统发育分析。
共检查了来自五个县的 118 只（29.5%）骆驼感染了眼虫，丰度为 0.9，平均强度为 3.2（即每只动物多达 18 条蠕虫）。年龄大于 4 岁的骆驼感染率较高（P=0.01901）。流泪与动物感染有关（P<0.00001）。我们标本的形态与 T. leesei 相似，除了神经环的位置和食管长度。遗传分析显示，与其他 Thelazia 物种相比，我们的 T. leesei 标本的 cox1 部分序列具有 8.8%至 13.5%的遗传距离。
根据形态测量和形态特征，我们将标本鉴定为 T. leesei。在系统发育树中，本文分离的 T. leesei 与同属种形成单系群，T. leesei 与 T. lacrymalis 形成姐妹分支。此外，我们证明了嗜眼线虫感染在伊朗东南部流行地区骆驼中的流行情况。所提供的数据对于更好地了解 T. leesei 的致病作用和制定有效的治疗策略至关重要。特别是，对这些地区 T. leesei 中间宿主的研究将支持这种寄生虫病的有效控制策略。
