Prevalence and molecular subtyping of Blastocystis from dairy cattle in Kanagawa, Japan

Blastocystis is an intestinal protist, commonly found in the human population and in a wide range of animals globally. Currently, isolates from mammalian and avian hosts are classified into 17 subtypes (STs) based on phylogeny of the small subunit rRNA gene (SSU rDNA), of which ten (ST1-9, 12) are reported in humans. ST10 is a major ST reported from livestock cattle. However, other STs including ST1, 3, 4, 5, and 6, which have the potential to be transmitted to humans, are also reported from cattle in several countries. Although a survey has been conducted previously in western Japan for livestock cattle, there is no information available regarding other parts of Japan. Therefore, this study surveyed the prevalence of Blastocystis and its STs in cattle from Kanagawa prefecture, eastern Japan. Fecal specimens, collected from 133 dairy cattle on four different farms, were subjected to a short-term xenic in vitro culture and Blastocystis were identified by microscopic examination. Seventy-two cattle were positive for Blastocystis (54.1%). Direct sequences for the partial SSU rDNA were obtained for 45 samples. Based on nucleotide sequence homology search and phylogenetic analysis, 44 isolates were identified as ST14 and one as ST10. Our study confirms the presence of these STs in dairy cattle in Japan for the first time. The STs identified here, ST10 and ST14, support previous findings that Bovidae may be the natural host for both STs.