Analysis of components of variation in schistosoma mansoni egg counting

Abstract

Analysis of variance was applied to data collected. from counting of S. mansoni eggs obtained from fecal specimens of seventeen patients. The technique used (Bell method)'was unable to show a statistically significant difference among individuals, although these patients had var;ying d.egrees of severity of S. mansoni infections. The highest variation was due to sample to sample variation. The smallest variation was due to interobserver variation. The variation among single counting was very high therefore influencing the results found in the other components. Regarding the conditions under which this experiment was carried out, one must be careful in considering classiflying individual patients, according to the severity of S, mansoni infections, based on a single egg counting.