Incidence of Blastocystis hominis in patients with diarrhoea.

We studied the occurrence of the parasite Blastocystis hominis in 1066 stool specimens from patients with diarrhoea, and investigated the relationship between the presence of B. hominis in the faeces and the age of patients. The parasite was recovered from 3.7% samples, but as the sole species of micro-organism in the stool it was recovered from 1% samples. There was no statistically significant difference in the number of B. hominis-positive stools between the younger and the older patients (P < 0.25), yet in the latter, B. hominis was more frequently identified as the only species of micro-organism as compared with the younger group (P < 0.005). The presence of B. hominis in faecal samples of patients with diarrhoea harbouring no other intestinal pathogens suggests an aetiology that should receive more attention in Slovenia.