A survey of the prevalence and genotypes of Giardia duodenalis infecting household and sheltered dogs

Giardia duodenalis (syn. G. intestinalis, G. lamblia) is an intestinal protozoan parasite that infects humans and a wide range of mammals that includes dogs. Highly significant genetic heterogeneity has been found within this species, while only genotypes from assemblages A and B have zoonotic potential. Although Giardia infection in dogs has been reported worldwide, there is increasing molecular evidence that dogs may be infected with host-specific genotypes (C and D) as well as zoonotic ones (A and B). Therefore, dogs play a role as a potential source of Giardia infection impacting humans and other Canidae. Fecal samples from privately owned dogs and from dogs kept in two shelters in the west-central region of Poland were examined using a microscope and polymerase chain reaction. The total prevalence of Giardia in specimens was 1.9%. Deoxyribonucleic acid was extracted only from two out of the three Giardia-positive fecal samples. After amplification using the G7 and G759 β-giardin primers, 753 bp amplicons were obtained, and both amplification products were sequenced. Sequence and phylogenetic analyses showed that both G. duodenalis isolates were dog-specific genotypes (C and D).