Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 6, 2009
Publication Date: June 1, 2009
Citation: Spackman, E., Pantin Jackwood, M.J., Swayne, D.E., Suarez, D.L. 2009. An evaluation of avian influenza diagnostic methods with domestic duck specimens. Avian Diseases. 53(2):276-280. Interpretive Summary: Screening of domestic poultry for avian influenza virus has increased considerably in recent years. The currently available tests were all designed and validated for chicken and turkey-origin specimens. Therefore it is necessary to determine if these tests can be used successfully with samples from domestic ducks. Here we evaluate the most widely used diagnostic tests for avian influenza virus in chickens and turkeys, for use with samples from ducks. We find that some virus detection tests perform similarly with duck specimens, but some are not sensitive enough for routine use in with duck specimens. We also evaluated antibody detections methods, and found that the most common test used for detection of avian influenza antibodies in chickens and turkeys will not work acceptably well with duck serum. Therefore a new alternative test which was also evaluated is recommended.
Technical Abstract: Monitoring of poultry, including domestic ducks, for avian influenza virus (AI) virus has increased considerably in recent years. However, the current methods validated for the diagnosis and detection of AI virus infection in chickens and turkeys have not been evaluated for performance with samples collected from domestic ducks. In order to ensure that methods for the detection of AI virus or AI virus antibody will perform acceptably well with specimens from domestic ducks, samples collected from ducks experimentally infected with a US-origin low pathogenicity AI virus isolate were evaluated. The ducks were infected with A/Avian/NY/31588-3/00 (H5N2) by the intranasal route, and oropharyngeal (OP) and cloacal swabs were collected at 1, 2, 3, 4, 5, 7, 10, 14 and 21 days post inoculation (PI) for virus detection by virus isolation and real-time RT-PCR. In addition, two commercial antigen immunoassays were used to test swab material collected 2-7 days PI. Virus isolation and real-time RT-PCR performed similarly, however the antigen immunoassays only detected virus during the peak of shed, 2-4 days PI, and both kits detected virus in fewer than half of the samples that were positive by virus isolation. Cloacal swabs yielded more positives than OP swabs with all virus detection tests. Serum was collected from the ducks at 7, 14 and 21 days PI and was tested for AI virus antibody by agar gel immunodiffusion (AGID) assay, a commercial blocking ELISA and hemagglutination inhibition (HI) assay for antibody detection. Results for the ELISA and HI were almost identical with serum collected at 7 and 14 days PI, however by 21 days PI 100% of the samples were positive by HI and only 65% were positive by ELISA. At all time points AGID detected antibody in substantially fewer samples than either ELISA or HI.