Toxocariasis in Cats in Viet Nam Caused by Toxocara malaysiensis, A Novel Species, Identified by Sequence and Phylogenetic Analyses

Abstract

      Toxocariasis in cats and dogs is a disease caused by a species of the genus Toxocara, family Toxocaridae, class Nematoda, including Toxocara canis (T. canis), Toxocara cati (T. cati) and Toxocara malaysiensis (T. malaysiensis), which is potentially transmissible to humans. Cats might get infested with a different ascaridoid species, a novel species, namely T. malaysiensis, which was first time found in Malaysia and China, but there is no information about this novel species in other countries. In this study, we analyzed mitochondrial atp6 and nuclear ITS2 sequences to clarify taxonomic identification for 15 strains of Toxocara sp. collected from cats from Thuong Tin and Thanh Oai districts (Ha Noi, Viet Nam). Comparative analysis of atp6 nucleotide sequences showed that all 15 Vietnamese strains of Toxocara sp. from cats were identical with Toxocara malaysiensis species from 99.3 to 100%, but with T. Cati 89.6-90.1% , with T. canis 86.7-87.9%, and with T. vitulorum 80.5-88.4%. Genetic distances between Toxocara strains of Viet Nam and T. malaysiensis showed no difference, but it was highly distant from T. cati. Phylogenetic analysis based on genetic markers of atp6 and ITS2 confirmed that all 15 strains of Toxocara sp. from Ha Noi, Viet Nam on cats were placed within the T. malaysiensis group, while the strains of T. cati, T. canis, T. vitulorum and Toxascaris leonina (an outgroup) were separated completely, clustered within their respective groups. This study has provided some additional features on genetics and classification of T. malaysiensis and also was reported the first time regarding this novel species originated in Viet Nam for epidemiological surveillance in the community.