Distribution, genetic diversity, and zoonotic significance of Blastocystis subtypes in pet dogs.

The common intestinal protist, Blastocystis sp., is a highly frequent parasitic agent in human and animal fecal samples, globally. The current study evaluated the prevalence of this parasite and involved subtypes (STs) in examined pet dogs in Shiraz, southwestern Iran. A number of 100 fresh fecal specimens were randomly collected from pet dogs referred to the veterinary clinics and pet shops in Shiraz during July 2021-January 2022. The genomic DNA was extracted from fecal samples and a conventional PCR was performed. Next, sequencing of the positive samples was done based on the small subunit ribosomal rRNA gene. The results showed that 5 % (5 out of 100) of the examined samples were positive for Blastocystis. As anticipated, three known Blastocystis subtypes with zoonotic concern, ST1 (60 %, n = 3), ST2 (20 %, n = 1) and ST3 (20 %, n = 1), were characterized. Based on phylogenetic analysis, these subtypes showed 100% identity with their reference counterparts. In conclusion, the zoonotic subtypes found in pet dogs in Shiraz can pose a drastic challenge to their pet owners and other domestic animals. Albeit the role of dogs as a potential natural reservoir of Blastocystis sp. stays unknown, it appears that these animals could represent possible reservoirs of zoonotic transmission of Blastocystis sp. Still, there is paucity of data on the epidemiology of Blastocystis and its subtypes in dogs in Iran.