Mixed Giardia duodenalis assemblage infections in children and adults in South India.

The assemblages of Giardia duodenalis in 25 children with and 25 children without diarrhoea and 24 adults with gastrointestinal symptoms in South India were determined. Polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) targeting the glutamate dehydrogenase ( gdh ), β -giardin and triosephosphate isomerase ( tpi ) genes was used. The tpi PCR was the most sensitive and detected G. duodenalis in all 74 microscopy-positive samples, while gdh and β -giardin PCR were positive in 62·2% and 56·8% of the samples. Assemblage B was predominant in both children and adults (82·4%) followed by assemblage AII (9·4%); assemblage AI was not detected. Infections with both assemblages A and B (detected by tpi PCR–RFLP) were seen exclusively in children and the mixed assemblage BIII and BIV (detected by gdh PCR–RFLP) was more common in children than adults ( P =0·058).