Small forms of Blastocystis hominis

Abstract

Unusually small forms of Blastocystis hominis were found in the stools of Indonesian immigrants. The size of the parasites seen in faecal samples of the lndonesian isolates were 3-5 μm whereas larger vacuolar forms measuring 10-15 μm were seen in Malaysian and Bangladeshi isolates. These small forms showed a distinct growth profile with an optimum parasite yield as high as 11.7 x 105 when cultured in Jones' medium compared to yields of 3.9 x 105 and 0.5 x 105 for Malaysian and Bangladeshi isolates respectively. The unusually small forms of Blastocystis, unlike the other isolates, was found to grow in cultures at 37°C even after being kept at room temperature for as long as 9 days.