MORPHOMETRIC VARIABILITY OF SCHISTOSOMA-INTERCALATUM EGGS - A DIAGNOSTIC DILEMMA

Variability of Schistosoma intercalatum eggs in shape and size, and th eir similarity to those of S. haematobium presented a problem of speci es identification when egg morphology was the diagnostic criterion use d in a study of human schistosomiasis conducted on Sao Tome and Princi pe. More than 2500 egg measurements were obtained by light micoscopy t o gather data relating to size variability of S. intercalatum eggs, to evaluate whether factors such as age of host, sex of host and intensi ty of infection are correlated with variability, and the data were com pared with previously published measurements on different isolates and strains of S. intercalatum: the range in length (104-203 mu m) embrac es most of the measurements reported in other studies of S. intercalat um eggs. There was no correlation either between age and sex of the ho st, or intensity of infection with variability of egg size. Comparison between measurements of the eggs of S. haematobium, S. intercalatum a nd S. bovis eggs are presented.