Epidemiological survey of hemoprotozoan parasites in cattle from low-country wet zone in Sri Lanka

The diseases caused by hemoprotozoan parasites in cattle often result in economic losses. In Sri Lanka, previous studies found that the up-country wet zone, which is located in central Sri Lanka, was characterized by a high rate of Theileria orientalis and a low rate of Theileria annulata compared with the dry zone. In this study, DNA samples were prepared from the blood of 121 cattle in Galle, a coastal district located in low-country wet zone in Sri Lanka, and were PCR-screened for Babesia bovis, Babesia bigemina, T. annulata, T. orientalis, and Trypanosoma theileri. All the parasite species, except B. bovis, were detected among the surveyed cattle. The animals had a high rate of T. orientalis (100%) and a low rate of T. annulata (1.6%), as in the up-country wet zone. Babesia bigemina and Tr. theileri were detected in 19.0% and 20.6% of the animals, respectively, and their infection rates were higher in the animals reared in extensive management systems (32.8% and 27.9%, respectively) than in those managed in intensive/semi-intensive systems (5.0% and 13.3%, respectively). Genotypic analyses found that the T. orientalis mpsp type 5 was predominant similar to up-country wet zone, and that Tr. theileri consisted of seven cad genotypes, including two new genotypes (IL and IM) and four previously detected genotypes (IA, IB, II, and IK). These findings suggest that the hemoprotozoan infection profiles are largely conserved within the wet zone, despite differences in the geography, cattle breeds, and management practices between the up-country and low country wet zones.

牛体内血原虫寄生虫引起的疾病常常导致经济损失。在斯里兰卡，先前的研究发现，与干旱地区相比，位于斯里兰卡中部的山地湿润区的特征是东方泰勒虫感染率高，环形泰勒虫感染率低。在这项研究中，从斯里兰卡低地湿润区的沿海地区加勒的121头牛的血液中制备了DNA样本，并对牛巴贝斯虫、双芽巴贝斯虫、环形泰勒虫、东方泰勒虫和泰勒锥虫进行了PCR筛查。在接受调查的牛中，除了牛巴贝斯虫外，所有的寄生虫种类都被检测到。这些动物的东方泰勒虫感染率高（100%），环形泰勒虫感染率低（1.6%），与山地湿润区的情况相同。双芽巴贝斯虫和泰勒锥虫分别在19.0%和20.6%的动物中被检测到，在粗放养殖系统中饲养的动物其感染率（分别为32.8%和27.9%）高于在集约/半集约养殖系统中饲养的动物（分别为5.0%和13.3%）。基因型分析发现，东方泰勒虫的mpsp 5型占主导地位，与山地湿润区相似，泰勒锥虫由7种cad基因型组成，包括2种新基因型（IL和IM）和4种先前检测到的基因型（IA、IB、II和IK）。这些发现表明，尽管山地湿润区和低地湿润区在地理、牛的品种和养殖方式上存在差异，但血原虫感染情况在湿润区内大体上是相似的。