The antibody responses to adult-worm antigens of Schistosoma haematobium, among infected and resistant individuals from an endemic community in southern Ghana

Abstract

Antibody responses to antigens from adult Schistosoma haematobium were investigated in an endemic community in Ghana, using microplate-ELISA. The results of a survey of egg output in urine and of a questionnaire-based investigation of water-contact activities were used to select 'endemic normal' (EN) and patently infected (PI) individuals as subjects. The plasma levels of antibodies reacting with the adult-worm antigens were determined and compared and the correlations between these levels and the age, water-contact index and egg output of each subject were evaluated. Compared with the EN subjects, the PI generally had higher levels of anti-worm IgG and IgE but lower levels of anti-worm IgA. When the data for the EN and PI groups were combined, the levels of anti-worm IgG and IgE were found to be positively correlated with egg output and with each other. Whichever the antibody class considered, levels of anti-worm antibodies were never negatively correlated with egg output. These results indicate that anti-worm IgE and IgG could be used as markers to reflect current infection intensity, and that anti-worm antibodies may not act as protective antibodies in the natural course of urinary schistosomiasis.