HUMAN RESISTANCE TO REINFECTION WITH SCHISTOSOMES 2- Specific IgA titres before & 3 months after praziquantel treatment Ali, E.A. and *Shaheen,H.I. Parasitology Department, Banna faculty of Medicine, Zagazig University. *NAMRU-3- Cairo • Abstract Specific IgA assays by ELISA technique for schistosomal cases of school age children (12 - 14 years), were performed before and 3 months after praziquantel treatment sera of the resistant cases (non -reinfected after chemotherapeutic cure) show a significant higher titres of anti-soluble egg antigen (anti-SEA ) and anti - soluble worm antigen preparation (anti-SWAP) IgA antibodies than that of reinfected schistosomal cases before and 3 months after treatment. Praziquantel therapy insignificantly ( P> 0.05 ) increases anti - SEA and anti -SWAP IgA antibodies in the sera of schistosomal cases, 3 months after treatment . Anti-SEA IgA & IgE anti-SWAP IgA & IgE are correlated positively with each other among schistosomal cases either resistant or reinfected while anti - SEA and anti-SWAP IgA antibody levels of schistosomal cases with eosinophilia are significantly higher than that with normal eosinophilic counts. Anti-SEA IgA antibody titres of schistosomal cases are correlated negatively, before treatment, with intensity of infection but anti-SWAP IgA titres are not, which may indicate that anti-SEA IgA antibodies inhibit schistosomes for egg laying and subsequently pathological complications due to granuloma formation .