Genetic Diversity of Blastocystis Isolated From Cattle in Khorramabad, Iran

Blastocystis is a zoonotic protozoan parasite living in the digestive system of some vertebrates. This parasite has some subtypes, pathogenicity status of which has still remained controversial. The aim of this study was to determine the subtype of Blastocystis in infected cattle. This descriptive cross-sectional study was performed on 196 isolates from cattle stool samples collected from slaughterhouse in Khorramabad city, Iran, in 2012. Genomic DNA was extracted and to determine the Blastocystis subtype, seven pairs of sequence-tagged sites (STS) primers were used. Of 196 specimens, 19 (9.6%) were infected with Blastocystis. Among the 19 positive samples, the most common subtype was ST5 (47.36 %), followed by ST3 (10.53%) and ST6 (10.53%). Two (10.53%) samples had mixed infections by ST3 and ST5. The four isolates not amplified by any STS primers were probably unknown genotypes. In the present study, the highest prevalence was for ST5, which is so important for epidemiology and risk of human infection. The report related to ST3 in cattle as a subtype of human showed mutual infection between human and cattle. Another important point in this study was the ST6 report. Finally, it seems that gathering epidemiological data is needed for a better understanding of the potential animal reservoirs for human infection.