Prevalence of Blastocystis hominis infection in asymptomatic individuals from Bangkok, Thailand.

Fresh stool examination was performed from 2,230 participants who enrolled in annual check-up programs of the Faculty of Medical Technology, Mahidol University in 1999-2000 and 2004. In this study, Blastocystis hominis infection was diagnosed by culturing in Jones' media. A total of 21% of fecal specimens (in 1999-2000) and 13.7% (in 2004) were positive for B. hominis. The vacuolated form was the predominant form found in culture solution after 48 hours of incubation. The distribution of infection was highest between the ages of 21-30 years (p<0.05). There was no significant difference in infection between male and female groups. Other parasites, eg Giardia lamblia, Entamoeba histolytica, Entamoeba coli, Endolimax nana, Trichomonas hominis, Strongyloides stercoralis, Opisthorchis viverrini and Taenia species, were also found by fresh stool examination.