Evaluation of eight serological tests in the diagnosis of human echinococcosis and follow-up.

Abstract

The ELISA with use of IgG, IgA, and IgE, latex agglutination, indirect hemagglutination (IHA), total IgE, the radioallergosorbent test (RAST), and immunoelectrophoresis (IEP) were carried out to determine the preoperative diagnosis of infection due to Echinococcus granulosus in 131 patients. Eighty-nine patients received follow-up care for 42 +/- 22 months (mean +/- SD); 72 were treated surgically and 17 with mebendazole only. We analyzed 5 +/- 2 serum samples per patient and analyzed each serum sample using the eight tests. IgG ELISA was the most sensitive (up to 94%) and specific (up to 99%) test for the majority of cyst locations in the patient. IEP was positive in only 73% of cases. The combination of IgG ELISA, IHA, and IgA ELISA allowed us to achieve a sensitivity of 81% in cases of pulmonary echinococcosis. IgE and IgA were both responsible for most nonspecific reactions, the former in patients with parasitic diseases other than echinococcosis and the latter in patients with cirrhosis of the liver and malignancies. IgG ELISA and IHA were the most adequate tests for postsurgical follow-up. In patients with favorable clinical outcome, the specific IgG level decreased early toward the end of the first year, although serological positivity could persist beyond 6 years. A rise of IgG level 2 or 3 years after treatment suggested persistent active infection. In patients with mebendazole-associated cure, only tests with total or specific IgE detection seemed to exhibit a strong association with decreasing levels or with negative results.