The zymodemes of Entamoeba histolytica in New Delhi, India.

The prevalence of various pathogenic and non-pathogenic zymodemes of Entamoeba histolytica in New Delhi, India was studied by characterising its isoenzyme patterns. Non-pathogenic zymodeme I was found to be most common and was detected in 39 of 49 infections. The other non-pathogenic zymodemes detected were XVII and XVIII in two cases each. The pathogenic zymodemes detected were II (four cases), II alpha- (alpha) (one case) and XIV (one case). Approximately 72% of those harbouring non-pathogenic zymodemes and 33% of those harbouring pathogenic zymodemes were asymptomatic. All the symptomatic individuals harbouring non-pathogenic zymodemes were seronegative for amoebiasis. However, subjects harbouring pathogenic zymodeme but asymptomatic were seropositive for amoebiasis at a titre of greater than 1:80, indicating a past infection or subclinical tissue invasion by the parasite. The new zymodeme isolated from a case of acute dysentery was designated II alpha- on the basis of the banding pattern of the enzyme glucose phosphate isomerase.