Molecular prevalence and subtyping of Blastocystis sp. isolates in stray cats of İzmir, Turkey: First report of “ST4 allele 42” in cats

Blastocystis sp. is one of the most frequently detected intestinal parasites in humans and can inhabit a wide range of animals. Close contact with animals is one of the transmission factors of Blastocystis sp. infection in humans. In this study, we aimed to investigate the molecular prevalence and subtypes of Blastocystis sp. in stray cats living in İzmir, Turkey. The PCR targeting the barcode region in the SSU rRNA gene was performed with DNA samples isolated from feces (n:465) to investigate the presence of Blastocystis sp. PCR positive samples were sequenced for subtyping analysis. Among the samples analyzed, Blastocystis sp. DNA was detected in 17 (3.65%) of them and sequence data were obtained from only seven isolates. Phylogenetic analysis showed that seven Blastocystis sp. isolates clustered with the reference Blastocystis ST4 isolates. Similarity rates were between 83.22% and 99.25%. In addition, Blastocystis database results confirmed that all of these were "allele 42" corresponding to ST4. As a result, the present study shows for the first time the presence of "ST4 allele 42", the prevalent subtype in humans, in stray cats in İzmir, Turkey. This finding supports the notion that stray cats can be a source of Blastocystis sp. infection in humans.