Zoonotic genotypes of Blastocystis hominis detected in cattle and pigs by PCR with diagnostic primers and restriction fragment length polymorphism analysis of the small subunit ribosomal RNA gene

Twenty two Blastocystis isolates from cattle and pigs were genotyped by PCR using diagnostic primers, and the homology among isolates was then confirmed by restriction fragment length polymorphism (RFLP) analysis of the small subunit ribosomal RNA gene. Two distinct genotypes, subtypes 1 and 3, were detected in one and two of the ten isolates from cattle, and three and one of the 12 isolates from pigs, respectively. The RFLP profiles of all isolates designated as subtype 1 and subtype 3 were identical to those of known ribodemes 1 and 2, respectively. We found that 31.8% (7/22) of isolates examined were zoonotic genotypes of Blastocystis hominis. However, 68.2% (15/22) of isolates were not amplified with any of the diagnostic primers, and the profiles of these isolates were different from any ribodemes of B. hominis reported previously. This study shows that Blastocystis organisms in cattle and pigs are a potential source of human infection.