The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection

Praziquantel was given every eight weeks for two years to children aged und er six years of age, living in a Schistosoma haematobium endemic area. Infe ction with S. haematobium and haematuria were examined in urine and antibod y profiles (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) against S. haematobi um adult worm and egg antigens were determined from sera collected before e ach treatment. Chemotherapy reduced infection prevalence and mean intensity from 51.8% and 110 eggs per 10 ml urine, respectively, before starting re- treatment programme to very low levels thereafter. Praziquantel is not accu mulated after periodic administration in children. Immunoglobulin levels ch ange during the course of treatment with a shift towards 'protective' mecha nisms. The significant changes noted in some individuals were the drop in ' blocking' IgG2 and IgG4 whereas the 'protecting' IgA and IgG1 levels increa sed. The antibody profiles in the rest of the children remained generally u nchanged throughout the study and no haematuria was observed after the seco nd treatment. The removal of worms before production of large number of egg s, prevented the children from developing morbidity.