Performance evaluation of five detection tests for avian influenza antigen with various avian samples

Abstract In this paper, we report on the evaluation of five influenza antigen detection tests by avian influenza H5N1 virus–positive swab samples to estimate their diagnostic sensitivity. The tests included two chromatographic immunoassays, an H5 avian influenza–specific antigen detection enzyme-linked immunosorbent assay (ELISA), an influenza A antigen detection ELISA, and an H5 rapid immunoblot assay. The results showed that the overall sensitivities of these tests ranged from 36.3% to 51.4% (95% confidence interval ranging from 31.0% to 57.0%), which were comparable to Directigen™ Flu A antigen detection tests but substantially lower than genome detection methods. Diagnostic sensitivity performance is a function of the concentration of antigens in samples and the analytical sensitivity of the individual test. The test sensitivities were significantly higher for sick and dead birds by cloacal, tracheal, or tissue swabs than for fecal swabs from apparently healthy birds, and these tests would not be suit...