Prevalence and genotyping of Toxoplasma gondii in naturally-infected synanthropic rats (Rattus norvegicus) and mice (Mus musculus) in eastern China

Background: Synanthropic rats and mice share the same environment with humans and play an important role in epidemiology of toxoplasmosis; however, there is limited information about prevalence and genetic characterization of Toxoplasma gondii in synanthropic rats and mice in China. Findings: In the present study, the prevalence and genetic characterization of T. gondii naturally infected synanthropic rodents (Rattus norvegicus and Mus musculus) were investigated in the urban area of Xuzhou city, Eastern China between June 2013 and August 2014. DNA from the brain of each animal was prepared and screened by specific PCR assay targeting 35-fold repeated B1 gene (B1-PCR). PCR positive DNA samples were further genotyped by multi-locus PCR-RFLP. Overall, out of 123 synanthropic rodents, 29 samples were positive by B1 gene-targeted PCR (23.6%). Of these, 7 out of 31 (22.3%) M. musculus were positive, whereas the positive rate of R. norvegicus was 23.9% (22/92). Multi-locus PCR-RFLP analysis reveals that seven PCR-positive samples were completely genotyped and they were identified as type China 1 (ToxoDB# 9). Conclusion: To our knowledge, this is the first report of molecular detection and genetic characterization of T. gondii infection in synanthropic rodents in Eastern China. The results of the present study showed a high infection pressure of T. gondii exists in the environment and synanthropic rodents infected by T. gondii may be an important source of infection for cats and other animals.