Detection and genotypic characterization of Giardia cysts in water samples.

Water samples were collected from a wastewater treatment plant and from two lakes in the vicinity of Rome (Italy) for detection and genotypic characterization of Giardia. All wastewater samples and all but two of the lake samples were scored by immunofluorescence as positive for Giardia. In addition, Giardia cysts were detected, by nested PCR, in all of the examined samples. Analysis of the SSU-rRNA gene sequences showed that all Giardia isolates belonged to Assemblage A. The presence of Assemblage A genotype in wastewater and surface bathing water represents an important public health concern. In fact, isolates showing this genotype are considered to be potential human pathogens and also have zoonotic implications.