Predominance of Giardia duodenalis All sub-assemblage in young children from Salvador, Bahia, Brazil

Objective. To characterize the Giardia duodenalis molecular isolates in children from Salvador, Bahia, Brazil. Methods. G. duodenalis positive fecal samples were obtained from 71 children from two daycare centers and from 39 users of a public clinical analysis laboratory. Samples were analyzed by PCR-RFLP of the glutamate dehydrogenase (gdh) and beta-giardin genes, and by sequencing of beta-giardin. Results. Of the 110 G. duodenalis samples, 80 (72.7%) amplified one or both target genes analyzed. Of these, 62 (77.5 %) were identified as assemblage A, and 18 (22.5%) as assemblage B. The sub-assemblage AII was identified in 58.8% (n = 47) of isolates, followed by sub-assemblage AI (18.8%, n = 15), BIV (11.2%, n = 9) and BIII (5.0%, n = 4). The AII sub-assemblage was the most frequent in children of both day care centers, whereas AI was found only in the group attended at the clinical laboratory. There was a predominance of sub-assemblage All in children under two years. Conclusions. The higher frequency of All sub-assemblage suggests that anthroponotic transmission is more common in Salvador, but that zoonotic transmission pathways are also present, and that a change in susceptibility to different molecular patterns of Giardia may occur during child growth.