Genetic diversity of Toxoplasma gondii isolates from rodents in the world: A systematic review.

Toxoplasmosis is one of the most frequent food-borne infections in humans caused by an obligate intracellular protozoan parasite, Toxoplasma gondii (T. gondii). Rodents, as intermediate and reservoir hosts, play key role in the epidemiology of toxoplasmosis; because they are the main source of infection for the Felidae family members and establish the parasite life cycle. Hence, the infectious isolates of T. gondii in rodents may be the main genotypes infecting the environment, humans, and animals. Our review aimed to present the population structure of T. gondii in these mammals. To access the relevant studies, six English language databases were systematically searched from 1990 to 2019. Finally, 3,395 samples of rodents were analyzed for the genotyping data and 118 isolates were separated from the samples. The results of the present study showed that atypical genotypes were dominant with a frequency of 65.2% of the total isolates (77 out of 118). Clonal Types II, III, and I had less frequency, respectively. Type I clonal isolates were identified only from Asia. The examination of genotypes circulating in rodents around the world revealed that ToxoDB #1 or #3 (Type II) were the most common, followed by ToxoDB #9, and #2, respectively. Overall, our data showed low genetic diversity of T. gondii with circulating clonal strains in rodents compare to the isolates from Europe, North America, and Africa, while non-clonal parasites with high genetic diversity were dominant in South America and Asia.