Frequency of Giardia duodenalis infection and its genetic variability in dogs in Cuiabá, Midwest Brazil

Giardia duodenalis, a unicellular, eukaryotic, and flagellated protozoan, presents two evolutionary forms in its life cycle, namely, trophozoites and cysts. It causes diarrhea in humans, dogs, cats, rodents, and ungulates. Despite being morphologically similar, the isolates of G. duodenalis are genetically diverse, affecting the stability and unanimity of taxonomic classification. Since different Giardia assemblages may occur within one isolate, multilocus genotyping is recommended for the genetic identification. To determine the frequency of G. duodenalis infections in domiciled dogs in Cuiabá Municipality (State of Mato Grosso, Midwestern Brazil) and characterize its genetic variability, fecal samples were collected from 147 dogs. Overall, 6.8% (10/147) of the samples presented cysts of G. duodenalis, which sequencing and genotypic characterization using tpi and gluD revealed assemblages C and A, genetic grouping of G. duodenalis. Only three samples amplified by tpi and one sample amplified by gluD. The risk factors age, gender, breed, diet and the presence of other dogs in the same house were not correlationated with giardiasis. The host-specific and zoonotic genotype warns of the risk of inter and intraspecies transmission and it provides, for the first time, information about genetic characterization of G. duodenalis isolates in dogs in Cuiabá, Midwest region of Brazil.