Molecular identification of Giardia duodenalis isolates from humans, dogs, cats and cattle from the state of São Paulo, Brazil, by sequence analysis of fragments of glutamate dehydrogenase (gdh) coding gene.

The nucleotide sequence of glutamate dehydrogenase (gdh) coding genes were obtained from cysts of Giardia duodenalis isolated from feces of naturally infected cats (n=19), dogs (n=27), humans (n=37) and cattle (n=5). The samples were from several municipalities within the state of São Paulo, Brazil and were collected from January 2004 to August 2006. Sequences analysis of the 37 specimens recovered from humans revealed 29 G. duodenalis assemblage AII and 8 G. duodenalis assemblage B. Among samples from cats, 11 were classified into assemblage F and 8 into assemblage AI. Only the host-adapted assemblages C and D were detected in samples from dogs (7 and 20, respectively). Among the samples from cattle, the genotype livestock was found in four samples and the assemblage AI was detected in one sample. The molecular identification of assemblages of G. duodenalis isolates from different hosts reveals that genetic diversity of this protozoon in Brazil is similar to that of Giardias from other parts of the world.