Institute of Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Veterinary Centre for Resistance Research, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Vet Med Sci. 2023 Nov;9(6):2862-2870. doi: 10.1002/vms3.1276. Epub 2023 Sep 19.
Tropical theileriosis, Theileria annulata infection, is the most prevalent summer disease in Tunisia. It is transmitted by Hyalomma scupense, a two-host tick known to be endophilic.
The present study aimed to estimate the infection prevalence of cattle by T. annulata in two districts from central Tunisia.
Blood samples collected from 270 Holstein cattle from the Sidi Bouzid (140 samples) and Kasserine districts (130 samples) were analysed by Giemsa staining and T. annulata-specific PCR.
In both regions, PCR revealed a prevalence of 32.6%. This was significantly higher than the 6.3% prevalence obtained by Giemsa staining blood smears (p < 0.001). Giemsa staining also revealed a low parasitaemia of 0.05%. The PCR-based prevalence was not statistically different between the two districts (31.4 ± 0.04 and 33.8 ± 0.04% in Sidi Bouzid and Kasserine districts, respectively, p = 0.6). On the contrary, the results of blood smear examination (2.85 and 10% in Sidi Bouzid and Kasserine, respectively) differed significantly between the two sampling sites (p = 0.01). There was no evidence of a statistically significant difference between the overall molecular infection prevalence when the samples were segregated based on animals' age or gender (p = 0.1 and 0.2, respectively) and a similar trend was observed for Giemsa staining. Ten PCR amplicons of the Tams1 gene (721 bp) were subsequently sequenced from the two regions. The phylogenetic analyses showed 100% similarity between all sequences. The unique conserved Tams1 sequence was deposited in GenBank under the accession number OP428816 and used to infer its phylogenetic relationships with those available in the GenBank repository.
This is the first report of the presence of T. annulata in this region of central Tunisia which has no history of tropical theileriosis. Priority areas for future studies include understanding the origin of these T. annulata-positive animals in a region where the presence of a known natural vector tick, H. scupense, has not been reported. Given that the disease severely constrains cattle productivity, it would also be worthwhile to investigate if other potential vectors for T. annulata, such as Hyalomma dromedarii, are present in the arid regions.
热带泰勒虫病，即感染环形泰勒虫，是突尼斯夏季最常见的疾病。它由两宿主蜱虫（ known to be endophilic 的血蜱属）传播。
本研究旨在评估突尼斯中部两个地区的牛感染环形泰勒虫的流行率。
从西迪布济德（140 份样本）和卡塞林（130 份样本）的 270 头荷斯坦奶牛采集血液样本，通过吉姆萨染色和环形泰勒虫特异性 PCR 进行分析。
在这两个地区，PCR 显示的流行率为 32.6%。这显著高于吉姆萨染色血涂片检测到的 6.3%的流行率（p < 0.001）。吉姆萨染色还显示出低至 0.05%的寄生虫血症。PCR 检测的流行率在两个地区之间没有统计学差异（西迪布济德和卡塞林区分别为 31.4 ± 0.04%和 33.8 ± 0.04%，p = 0.6）。相反，血涂片检查的结果（西迪布济德和卡塞林区分别为 2.85%和 10%）在两个采样点之间存在显著差异（p = 0.01）。当根据动物年龄或性别对样本进行分类时，总体分子感染流行率没有统计学差异（p = 0.1 和 0.2），吉姆萨染色也呈现出类似的趋势。随后从这两个地区的 10 个 PCR 扩增子（721 bp）的 Tams1 基因进行测序。系统发育分析显示所有序列之间的相似度为 100%。独特的保守 Tams1 序列已在 GenBank 中以 OP428816 号登录号进行了存储，并用于推断其与 GenBank 存储库中可用序列的系统发育关系。
这是突尼斯中部地区首次报告存在环形泰勒虫，该地区无热带泰勒虫病的历史。未来研究的重点领域包括了解在已知天然传播媒介蜱（尚未报告存在）的区域中这些环形泰勒虫阳性动物的来源。鉴于该疾病严重限制了牛的生产力，也值得研究是否在干旱地区存在其他可能的环形泰勒虫传播媒介，如三趾钝缘蜱。
