Improved immunodiagnosis of human cysticercosis with scolex protein antigens.

Crude antigenic extract (CAE) and a scolex protein antigen (SPA) of Taenia solium cysticerci were used in indirect haemagglutination (IH) and enzyme-linked immunosorbent assay (ELISA) to detect serum antibodies in cysticercosis patients. Complement fixation (CF) was used for comparison with antigens obtained as an alcoholic extract of CAE (ACAE) and SPA (ASPA). For each test, a dilution was chosen which showed no cross-reactivity with sera from patients with other parasitic diseases such as taeniasis, schistosomiasis, ancylostomiasis, ascaridiasis, strongyloidiasis, Chagas' disease and syphilis. For the CF, 1:4 was the discriminative dilution determined; for IH, 1:16 and for ELISA, 1:256. The CF could detect serum antibodies to cysticerci in 45% of patients when ACAE antigen was used and 73% using ASPA. In the IH, serum antibody was detected in 73% of patients when CAE was used and 86% using SPA. In ELISA 63% of patients were positive when CAE was used and 91% using SPA. The use of SPA improved the serological distinction between infected and uninfected patients in all tests and the ELISA showed a significantly higher capacity to detect infected patients.