Toxocara and Toxascaris are parasitic nematodes that infect canids and felids although species of the genus Toxocara also infect humans. This work aimed to establish the phylogenetic and phylogeographic relationship between specimens of T. canis, T. cati, T. malaysiensis and Toxascaris leonina and to evaluate the degree of host specificity. In total, 437 samples (adults and pools of eggs) were collected from canids and felids from eight countries. Parasites were identified by morphology, PCR linked Restriction Fragment Length Polymorphism (PCR-RFLP) and partial sequencing of the mitochondrial gene cox1. Phylogenetic trees were constructed and genetic distance among isolates was estimated. Based on the molecular characterization all worms were identified in agreement with their respective hosts with the exception of three samples; two from cats and one from dogs identified as T. canis and T. cati, respectively. There was no clear geographical clustering of the samples despite this study including parasites from three continents. This is the first study, to our knowledge, to use molecular methods to identify T. canis in cats and T. cati in dogs with host specificity being the most common finding. Our developed PCR-RFLP method was found to be a facile and reliable method for identifying Toxocara species.

弓形虫和弓形虫是可感染犬科动物和猫科动物的寄生线虫，尽管弓形虫属也可感染人类。这项工作的目的是建立犬蛔虫，T. CATI，T和的马来西亚标本之间的系统发育和系统地理学关系Toxascaris并评估宿主的特异性程度。总共从八个国家的犬科动物和猫科动物中采集了437个样本（成虫和卵池）。通过形态学，PCR连接的限制性片段长度多态性（PCR-RFLP）和线粒体基因cox1的部分测序来鉴定寄生虫。建立了进化树，并估计了分离株之间的遗传距离。根据分子特征，除三个样品外，所有蠕虫均与它们各自的宿主一致被鉴定。两只来自猫，一只来自狗，分别被标识为犬毛犬和犬毛犬。尽管这项研究包括来自三大洲的寄生虫，但仍没有明确的地理区域聚类。就我们所知，这是首次使用分子方法鉴定T的研究。猫的犬科犬和犬的T. cati犬具有宿主特异性是最常见的发现。我们开发的PCR-RFLP方法被发现是鉴定弓形虫种类的简便可靠的方法。