Effect of specific and non-specific prior sensitization on the outcome of amoebic infection.

Guinea-pigs were sensitized with monoaxenic amoebic antigen (Group I), bacterial associate antigen (Group II) and axenic amoebic antigen (Group III). All animals in Group I, 95% in Group II and 70% in group III, developed caecal lesions on intra-caecal inoculation of Entamoeba histolytica trophozoites; 92.8% of control (unsensitized) animals developed lesions in their caeca. Lesions were more severe in sensitized animals than in controls. Hepatic abscesses were found in 7.6% of group I, 11.1% of group II and 7.1% of group III. No animal from the untreated but infected group developed hepatic abscess. It thus appears that specific (amoebic) and non-specific (bacterial) prior sensitization may render the host more susceptible to hepatic amoebic infection.