Abstract: Toxoplasmosis is a disease caused by the protozoan Toxoplasma gondii, which is widely prevalent in animals and human throughout the world. It causes serious harm to human health and the development of animal husbandry. T. gondii isolates were considered a single species without geographical boundaries. However, high diversity has been revealed within and between T. gondii populations collected from around the world defined by the multi-locus enzyme electrophoresis（MLEE）, polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） or microsatellite analysis. Different strains of T. gondii may exhibit differences in virulence to mice. This paper summarizes the research progress on the genotypes from T. gondii isolates in different geographic regions around the world, and the relationship between genotype and virulence of T. gondii.

Key words: Toxoplasma gondii, Genotype, Population structure, Virulence