Antibody Response to Invasive Amebiasis in Durban, South Africa

Abstract

Serological response to amebic disease was investigated in Africans in Durban. Immunodiffusion (ID), indirect hemagglutination (IHA), and complement-fixation (C-F) tests were done to compare sensitivity of the tests and their value in differentiating between antibodies in an acute infection and those persisting after treatment. Sera were obtained from persons with amebic disease before and at varying times after treatment and from asymptomatic cyst passers and uninfected persons. In invasive amebiasis, the immunodiffusion and indirect hemagglutination tests were similar in their ability to detect antibodies yielding positive results in 95% and 94%, respectively, of the patients studied. The C-F test was the least sensitive of the three methods, with only 65% of patients with invasive amebiasis being positive. In the cyst-passer group, 55.5% and 39%, respectively, were positive by the IHA and ID tests. A high percentage of uninfected persons were positive by both tests; a possible explanation is the persistence of antibodies for more than 3 years after termination of an infection. All three techniques demonstrate the relative stability of antibody levels over a long period.