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 H5N 1 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 suitable for surveillance testing of clinically healthy birds. Furthermore, the sensitivity for testing tracheal and cloacal swabs from waterfowl and wild birds was not as good as for chickens. This was most likely to be associated with variation in virus titers between specimens from different bird species. However, the tests showed good sensitivities for testing brain swabs from clinically affected waterfowl species. The results indicate that these antigen detection tests could be used for preliminary investigations of H5N 1 outbreaks as a low-cost, simple flock test in sick and dead birds for the rapid detection of H5N1 infection. However, the relatively low sensitivity of the tests as individual bird tests means that they should be used on optimal clinical specimens from diseased birds, testing birds on a flock basis, or testing samples as close to the onset of disease as possible before viral titers diminish. They should be followed up by confirmatory tests, such as reverse transcription polymerase chain reaction or viral culture, wherever possible but could assist in facilitating rapid investigations and control interventions.

Evaluation of two commercial lateral flow devices (LFDs) used for flockside testing of H5N1 highly-pathogenic avian influenza infections in backyard gallinaceous poultry in Egypt

“…Several commercial lateral flow device (LFD) tests are available for rapid flockside testing of AI. LFD evaluations have been described using field specimens collected during H5N1 HPAI outbreaks (Chua et al, 2007; Loth et al, 2008) and from experimentally-infected birds (Marché and van den Berg, 2010). In Egypt, H5N1 HPAI first occurred in 2006 (Aly et al, 2008) and is now considered endemic (Cattoli et al, 2009).…”

Analysis of H5N1 avian influenza infections from wild bird surveillance in Hong Kong from January 2006 to October 2007

“…Although the sensitivity of the rapid antigen tests for influenza A NP antigen on C&T swabs from the dead wild birds were lower than by virus isolation and RRT-PCR tests the sensitivity for the Directigen test (83.3% with 95% CI = 62.2–100%) was higher than the range of the sensitivities for 5 rapid antigen detection tests (including the Rockeby test) for H5N1 avian influenza on swabs from dead waterfowl and wild birds in Hong Kong collected in 2002, which ranged from 29.3% (95% CI = 19.0–36.6%) to 50.7% (95%CI = 39.4–62.0%) (Chua et al, 2007). The sensitivity of the Rockeby test in the current study (58.3% with 95% CI = 30.4–86.2%) was at least as sensitive as it had been in the previous study (30.7% with 95% CI = 20.3–41.1%).…”

Quantifying the effect of swab pool size on the detection of influenza A viruses in broiler chickens and its implications for surveillance

“…For FluDETECT in particular, examples of the reported detection levels include: 55.1% infections in cloacal and combined tracheal and cloacal swabs and 76.9% in tissues from infected chickens [13]; 100% and 33.3% for doses of 10 6 and 10 5 EID 50 /ml in a serial dilution study [14] and, 71% (95% CI: 58–82%) in chicken samples from an outbreak [12]. These results, compared to those from this study, generally indicate that LFI kits perform better in detecting HPAIV infections.…”

“…Since LFI target the type A influenza virus nucleoprotein, they are suitable for any type A influenza virus [9, 13, 14]. Here, using H5N2 and H7N2 low pathogenicity influenza A viruses as models, we evaluated the impact pooling one positive swab with 4 or 5 versus 10 negative swabs on the ability of LFI kits to detect IAV in pools and also to compare individual tests’ analytical sensitivities on single swabs.…”