[Evaluation of ELISA-IgG test using a purified antigen in the diagnosis of human hydatidosis]

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of IgG antibodies to purified sheep hydatic cyst fluid antigen in 56 sera of confirmed cases of hydatidosis. The cut-off value was determined using serum samples from 80 healthy persons, employing two serum dilutions (1:100 and 1:500) with two and three standard deviations (SD). This assay was compared with the indirect hemagglutination test (IHAT). The sensitivity of ELISA-IgG was 94.3% for hepatic cysts and 92.9% for pulmonary cysts, whereas the values for IHAT were 77.1 and 64.3% respectively. According to Mac Nemar test, both method presented statistical significance (p < 0.05). In order to find out the specificity, additional 70 serum samples from individuals with other parasitoses, such as cysticercosis (30), trichinosis (26) and fascioliasis (14) were also tested. IHAT presented a specificity of 92.7% and for ELISA-IgG the specificity using a cut-off of mean + 3 SD was 99.3 and 100.0% with sera dilution of 1:100 and 1:500 respectively when a cut-off of mean + 2 SD was considered, we found a specificity of 91.3 and 97.3% for 1:100 and 1:500 dilutions. The use of ELISA-IgG and purified antigen in the diagnosis of human hydatidosis is discussed.