Genotype of Giardia intestinalis isolates from children and dogs and its relationship to host origin.

The presence of human Giardia in several animals suggests a zoonotic transmission. We studied G. Intestinalis isolates obtained from: children with diarrhea (n=6), asymptomatic children (n=7), axenic cultures (n=7) and dogs (n=11). The sequence corresponding to 16 S rRNA was amplified by PCR, sequenced and compared with genotypes A, B and Dog sequences reported in the Gene Bank database. Results show that 9/20 (45%) of children isolates belonged to genotype A and 11/20 (55%) showed some variable sites, allowing classification in three arbitrary clusters: A1, A2 and A3. In addition 7/11 (63%) of dog isolates were genotype A, including those dogs that lived in the same locality as the children lived, while 4/11 (37%) belonged to an arbitrary A4 cluster living in a different locality. In this study, genotype A was associated with samples from children and dogs, and, therefore, we could infer zoonotic transmission as a way of getting the disease.