According to the molecular characterization of nucleotide sequences of Glutamate Dehydrogenase (GDH), Elongation factor 1α (ef-1), Triosephosphate isomerase (tpi) and small subunit rRNA (SSU-rRNA) gene suggest the presence of eight assemblages (A–H) of G. duodenalis among which assemblages A and B are associated with human and a wide range of hosts infection while assemblages C, D, E, F and G,H are animal host-specific (3, 13–15); assemblage C, D, E, and F have also been isolated from infected humans (16). This evidence concerns the gene TPI1 and infection.