Subtype identification of human Blastocystis spp. isolated from Lao People's Democratic Republic.

Blastocystis sp. is the most common protist found in the intestinal tract of humans and animals. Blastocystis subtypes (STs) are classified based on the molecular phylogeny of the small subunit rRNA gene (SSU rDNA). At least 17 Blastocystis STs have been reported and, of these, STs 1-9 have been found in humans. This study revealed the presence of human Blastocystis STs in Lao People's Democratic Republic (Lao PDR). Fecal samples were collected from apparently healthy people from the central province of Khammouane and the southern province of Champasak. Fresh fecal samples, found to be positive for Blastocystis using microscopy, were individually cultured in Jones' medium and each sample was used for the amplification and sequencing of a fragment of SSU rDNA. BLAST searches and phylogenetic analysis confirmed the distribution of four Blastocystis STs: ST1 (64%), ST2 (8%), ST3 (24%) and ST7 (4%). This is the first report to provide molecular data revealing the prevalence of Blastocystis STs in apparently healthy people from Lao PDR.