The distribution of Schistosoma japonicum eggs in faeces and the effect of stirring faecal specimens

Abstract

Experiments were performed to determine whether Schistosoma japonicum eggs are randomly dispersed in faeces and the effect of stirring faecal specimens prior to sampling. For each of 13 patients infected with S. japonicum, eggs were counted in 150 subsamples from a single stool specimen, using the Kato-Katz smear technique. Eggs were non-randomly distributed in all 13 stools, and showed an aggregated distribution. In most patients there were significant differences in the distribution of eggs between the centre and the surface of the stool. Stirring of the stool prior to sampling decreased the variability of counts.