Multilocus genotyping of Giardia duodenalis in Brazilian children

Background: Giardia duodenalis is a parasite of several mammalian species, including humans, distributed worldwide. This research aimed to identify the molecular assemblages/sub-assemblages of G. duodenalis and to determine the intra-assemblage genetic variation of the different genes of assemblages A and B in preschool children in the cities of Araguari and UberlIndia, Minas Gerais, Brazil. Methods: The molecular characterization followed beta-giardin (bg), glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) protocols. Results: Of 226 stool samples, G. duodenalis cysts were found in 45 (19.9%). The tpi gene was amplified in 34 samples: 16 assemblage A, 14 B and four mixed samples A/B. The gdh gene was amplified in 32 samples, including 14 A, 16 B and two A/B. For the bg gene, 19 samples were sequenced: nine assemblage A, five B, three E, and two mixed, A/E and B/E. Animal-specific assemblage E were identified by bg, but were not confirmed for other genes. Twelve samples were characterized by full agreement of the three genes. Two new multilocus genotyping (MLGs) for assemblage A and two new MLGs for assemblage B were also described. Conclusions: These findings substantiate the importance of using more than one gene protocol since the sensitivity and genetic variability changes with the locus used.