Identification of Cryptosporidium viatorum XVa subtype family in two wild rat species in China.

Background: Cryptosporidium viatorum is a minor Cryptosporidium pathogen in humans. Currently, there is limited information regarding the prevalence and genotypes of C. viatorum in animals in China. Methods: In this study, 228 faecal samples were collected from two wild rat species (Leopoldamys edwardsi and Berylmys bowersi) in Chongqing Municipality and Guangdong Province, China. These specimens were analyzed for C. viatorum and then subtyped it using PCR and sequence analysis of the small subunit ribosomal RNA (SSU rRNA) and 60-kilodalton glycoprotein (gp60) genes, respectively. Results: A total of 25 (11.0%) faecal samples were tested positive for C. viatorum by SSU rRNA assay. Of these samples, 4 (3.6%) came from L. edwardsi and 21 (18.0%) from B. bowersi. Of the 25 C. viatorum-positive samples, 17 were successfully amplified at the gp60 gene locus, which represented four subtypes belonging to two subtype families, including XVa (XVaA6, XVaA3g, XVaA3h) and XVc (XVcA2G1). Phylogenetic analysis based on the gp60 amino acid sequences indicated that all of the C. viatorum isolates grouped together, supporting the conclusion that C. viatorum from the wild rats represent two subtype families. Conclusions: These results indicate an occurrence of C. viatorum XVa subtype family from rats which is genetically identical to those found in humans. Our findings suggest that wild rats may be a potential source of human cryptosporidiosis. [ABSTRACT FROM AUTHOR]