Potential Zoonotic Transmission of between Children and Calves in Bangladesh.

is a zoonotic protozoan parasite that causes gastrointestinal illness in humans and livestock. We studied the genetic diversity of in children and calves from Bangladesh to determine its zoonotic potential. Fecal samples collected from children (299) and calves (699) were screened with nested PCR with primers targeting the gene for . Positive samples were further multilocus genotyped using the -giardin (), glutamate dehydrogenase (), and triose phosphate isomerase () genes. The overall infection rate of was 21.1% (63/299) in children and 5.7% (40/699) in calves. There were no significant differences in infection with among age groups, sex, and study areas in children and calves. Multilocus genotyping (MLG) of human identified zoonotic assemblages A (34.0%, 18/53) and B (50.9%, 27/53) and a so-called ruminant-specific assemblage E (11.3%, 6/53), as well as two mixed assemblages, B/D (1/53) and B/E (1/53). Assemblage E predominated in calves (82.3%, 28/34), followed by assemblages A (11.8%, 4/34) and B (5.9%, 2/34). Overall, zoonotic assemblages A, B, and E were found in 6.0% (18/299), 9.0% (27/299), and 2.0% (6/299) of the children's stool samples, respectively, and 0.6% (4/699), 0.3% (2/699), and 4.0% (28/699) of the calf fecal samples, respectively. Although there was a difference in the distribution of subassemblages in humans (mostly AII) and calves (mostly AI), the zoonotic assemblages A, B, and E present in both children and calves suggest the potential for zoonotic transmission of . This molecular study highlights the fact that infections were common in the study areas, with potential zoonotic transmission between children and calves, implying that cattle might play a role in zoonotic transmission.