Study of Entamoeba histolytica isolates from Calcutta with special reference to their zymodeme, animal pathogenicity and erythrophagocytosis.

Entamoeba histolytica isolates, obtained mainly from asymptomatic human cyst passers, were tested for their in vitro erythrophagocytic activity and lesion-forming ability in hamster liver. Simultaneous zymodeme typing of the isolates showed that, along with the pathogenic zymodemes, a number of isolates having nonpathogenic zymodemes also produced liver lesions in hamsters and engulfed higher numbers of RBCs. The observed positive correlation between the rate of erythrophagocytosis of an E. histolytica trophozoite and its degree of lesion-producing capacity in hamster liver suggest that the erythrophagocytosis assay in conjunction with the hamster liver inoculation test, can be useful in the identification of virulent E. histolytica isolates.