RESEARCH ARTICLE Identical Assemblage of Giardia duodenalis in Humans, Animals and Vegetables in an Urban Area in Southern Brazil Indicates a Relationship among Them

Background Giardia duodenalis infects humans and other mammals by ingestion of cysts in contaminat-ed water or food, or directly in environments with poor hygiene. Eight assemblages, desig-nated A–H, are described for this species. Methodology/Principal Findings We investigated by microscopy or by direct immunofluorescence technique the occurrence ofG. duodenalis in 380 humans, 34 animals, 44 samples of water and 11 of vegetables.G. duodenalis cysts present in samples were genotyped through PCR-RFLP of β giardin and glutamate dehydrogenase (gdh) genes and sequencing of gdh. The gdh gene was ampli-fied in 76.5 % (26/34) of the human faeces samples with positive microscopy and in 2.9 % (1/ 34) of negative samples. In 70.4 % (19/27) of the positive samples were found BIV assem-blage. In two samples from dogs with positive microscopy and one negative sample, as-semblages BIV, C, and D were found. Cysts ofGiardia were not detected in water samples, but three samples used for vegetable irrigation showed total coliforms above the allowe