Abstract

Serum samples collected from a total number of twenty parasitologically confirmed cases of human fasciolosis were used to evaluate the diagnostic sensitivity and specificity of snail derived antigens; non infected snail (SA), infected snail (ISA), redia (RA), cercaria (CA) and encysted metacercaria (EMCA) of F. gigantica using the enzyme linked immunosorbent assay (ELISA) and enzyme linked immunotransfer blot (EITB). ELISA results showed that the highest level of sensitivity (100%) was with the CA as compared with ISA, RA and EMCA which displayed lower sensitivity levels of 30, 60 and 90%, respectively. All fasciolosis patients were seronegative with SA. Sodium dodecyle sulfate polyacrylamide gel electrophoresis and EITB (with rabbit antiserum raised against F. gigantica somatic antigen) of the snail derived antigens were carried out to characterize their protein profiles and detect cross-reactive polypeptide bands between them. The immunoblot profile of SA displayed cross-reactive bands at 61 and 30 kDa with ISA, RA, CA and EMCA; CA at 61, 34 and 30 kDa with ISA; 96, 61, 34, 30 and 23 kDa with RA and 61, 34, 23 and 19 kDa with EMCA. Cross reactive antigens may be important as possible candidates for vaccine and diagnosis of fasciolosis. Immunoblot of sera from fasciolosis patients using fractionated cercarial antigen on nitrocellulose strips showed that all sera recognized common reactive band at 32.5 kDa molecular weight from cercarial antigen. We suggest that the 32.5 kDa component of Fasciola cercarial antigen may be the most sensitive and specific for the diagnosis of human fasciolosis.