Genetic characterization of Giardia duodenalis in wild rats in China: Identification of a divergent lineage lineage within Assemblage B

Giardia duodenalisis a zoonotic intestinal protozoan parasite that causes gastrointestinal disease in both humans and a wide range of animals. This study investigated the prevalence and genetic diversity of G. duodenalisin wild rats in China to assess the potential role of these wild rats in zoonotic transmission. Fecal samples were collected from 228 wild rats in Chongqing Municipality and Guangdong Province. The parasite was detected and characterized by nested PCR amplification, sequencing, and phylogenetic analysis of the b-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes. A distinct genetic lineage of G. duodenalis Assemblage B was identified in wild rats, with an overall prevalence of 6.6%. Phylogenetic analysis revealed that these isolates formed a unique, strongly supported clade within Assemblage B, showing significant genetic divergence from previously documented subtypes. No other assemblages were detected in this study. These findings highlight the presence of a divergent lineage G. duodenalis lineage in wild rats and underscore the need for further research to determine the prevalence and molecular detection status and genetic diversity of this parasite in rodent populations across China.