Cysticercosis, a disease caused by the larval form of Taenia solium, is diagnosed by detection of specific antibodies or by imaging techniques. Our preferred immunologic assay for cysticercosis is the enzyme-linked immunoelectrodifusion transfer blot, or immunoblot, using the lentil lectin bound antigens from larval cysts. Antibody reactivity with any one of seven glycoproteins is diagnostic for cysticercosis. To develop a simple antibody detection assay for field use, we have synthesized an 8-kD diagnostic antigen, sTs18var1 (a secreted protein with a mature size of 67 amino acids), and expressed a 50-kD membrane protein antigen, rGp50. We used these two diagnostic proteins in a quantitative Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) to measure the antibody responses in Peruvian pigs with cysticercosis. Three study designs were used. First, we followed the kinetics of antibody responses against these two diagnostic proteins in pigs with cysticercosis that were treated with oxfendazole. Second, we measured antibody response in naive experimentally infected pigs. Third, we followed the maternal antibodies against rGp50 and sTs18var1 in piglets born from sows with cysticercosis. These studies showed that antibody responses against the two diagnostic proteins in the FAST-ELISA are quantitatively correlated with infection by viable cysts, with anti-sTs18var1 activity being most responsive to the status of infection.