Varying incidence of Blastocystis hominis in cultures from faeces of patients with diarrhoea and from healthy persons.

A study was performed on the frequency of Blastocystis hominis in the faeces from 100 patients suffering from diarrhoea and from 100 healthy persons. Surprisingly, an increased detection rate was observed in samples from healthy persons after anaerobic cultivation. This increased frequency is obviously not dependent on the kind of serum used as a culture supplement and raises the question whether the protozoa morphologically described as B. hominis represent a homogenous species. When rabbit and horse sera were used instead of human serum for cultivation, in both groups the share of positive cultures increased and more large forms of B. hominis cells were observed. Biological implications are being discussed.