Sheep have been implicated as sources of Giardia that infect humans.But few studies have been conducted in China.In total,faecal samples of 716 native sheep from 9 intensively reared sheep farms in different cities in Henan were examined for the presence of Giardia by microscopy.47 positive G.duodenalis cysts(6.7%)were detected on 5 farms.The prevalence of Giardia is higher in lambs aged less than 6 months(12.9%)than adults older than 6 months(2.1%).The difference was statistically significant(P < 0.01).To assess the potential public health significance of these infections,molecular analyses were conducted on positive Giardia isolates with PCR targeted at β-giardin,glutamatedehy drogenase and triose phosphate isomerase genes.Assemblage E was predominantly detected in all animals,while assemblage A was found in only five samples.The presence of mixed G.duodenalis genotypes was detected in three samples.Two new sequences of tpi and one of gdh for G.duodenalis were found in this study.One novel MLG AⅠ and six assemblage E MLGs have been detected in the present study when MLG model was applied.The results of the present study indicate that Giardia is a common parasite on intensively reared sheep farms in Henan province,central China,and that sheep here might have some public health significance.