A Study of The Genetic Variability of Blastocystis hominis Isolates in Hamadan, West of Iran

Blastocystis is a common protozoan parasite in mammals, birds, amphibians, reptiles, fish, arthropods, and annelids. This parasite has some subtypes, which pathogenicity status of them still remained controversial. Some of Blastocystis subtypes are potentially pathogenic to human. This study has identified the Blastocystis hominis subtypes and their prevalence rates in Hamadan. During two months of summer 2011, a total number of 250 human fecal samples referred for parasitology examination to Beasat Hospital and a few clinical laboratories of Hamadan city were collected. The samples were examined by direct method and formalin-ether. 41 samples exhibited positive results for B. hominis thereby were cultured in Locke-egg medium. After the growth and in order to genotype identification, B. hominis isolates were amplified by PCR, using seven pairs of sequencestagged site primers. In this study, three subtypes of B. hominis consisted of one [SB83], two [SB340] and three [SB227] were identified. The most dominant genotype was SB83 with 56.1 % frequency. The prevalence rate of genotype SB227 and SB340 were 22 % and 7.3 %, respectively. Coexistence of genotypes SB83 and SB227 was detected in 14.6 % of positive cases. This is the first study in Hamadan on genotyping of B. hominis, which may trigger other epidemiologic and zoonotic studies on different subtypes and hence control clinical manifestations of infection.