Genetic characteristics and geographic segregation of Giardia duodenalis in dairy cattle from Guangdong Province, southern China

Abstract Giardia duodenalis is a gastrointestinal parasitic protozoan with important veterinary and public health implications worldwide. In this study, a total of 1440 fecal specimens were collected from dairy calves in Guangdong Province, China. The overall prevalence of G. duodenalis was 2.2% (31/1440) by polymerase chain reaction (PCR). The prevalence was 8.4% and 1.1% in pre- and post-weaned calves, respectively. Both assemblages A (6.5%, 2/31) and E (93.5%, 29/31) were found based on sequence analysis of the SSU rRNA gene. All G. duodenalis -positive samples were assayed with PCR followed by sequencing the beta giardin ( bg ), glutamate dehydrogenase ( gdh ), and triosephosphate isomerase ( tpi ) genes, and 20, 23, and 18 sequences were obtained, respectively. Multilocus genotyping yielded 10 assemblage E multilocus genotypes (MLGs). All assemblage E MLGs were genetically distinct from those obtained in cattle from Henan, Xinjiang, Shanghai, and Shaanxi in China. This finding was also supported by F ST , N m , and median-joining network analysis. Results of this study indicated that G. duodenalis was found in low prevalence in dairy calves in Guangdong Province, southern China; nevertheless, the infected calves might represent a public health risk in this region. Additionally, the differences in assemblage E MLGs from the five analyzed regions revealed significant geographic segregation of G. duodenalis in China.