title: Multiyear Serological Surveillance of Notifiable Influenza A Viruses in Belgian Poultry: A Retrospective Analysis.
abstract: Surveillance of notifiable avian influenza (NAI) virus is mandatory in European member states, and each year a serological survey is performed to detect H5 and H7 circulation in poultry holdings. In Belgium, this serological monitoring is a combination of a stratified and a risk-based approach and is applied to commercial holdings with more than 200 birds. Moreover, a competitive nucleoprotein (NP) ELISA has been used as first screening method since 2010. A retrospective analysis of the serological monitoring performed from 2007 through 2013 showed sporadic circulation of notifiable low-pathogenicity avian influenza (LPAI) viruses in Belgian holdings with a fluctuating apparent flock seroprevalence according to years and species. Overall, the highest apparent flock seroprevalence was detected for the H5 subtype in domestic Anatidae, with 20%-50% for breeding geese and 4%-9% for fattening ducks. Positive serology against non-H5/H7 viruses was also observed in the same species with the use of the IDScreen influenza A antibody competition ELISA kit (ID-vet NP ELISA), and confirmed by isolation of H2, H3, H6, and H9 LPAI viruses. Among Galliformes, the apparent flock seroprevalence was lower, ranging between 0.3% and 1.3%. Circulation of notifiable LPAI viruses was only observed in laying hens with a similar seroprevalence for H5 and H7. Based on ID-vet NP ELISA results, no circulation of LPAI viruses, regardless the subtype, was observed in breeding chickens and fattening turkeys. Retrospectively, the use of an ELISA as first-line test not only reduced the number of hemagglutination inhibition tests to be performed, but also gave a broader evaluation of the prevalence of LPAI viruses in general, and might help to identify the most at-risk farms.
authors.affiliation: A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Marché
authors.affiliation: B Crisis Prevention and Management Unit, Federal Agency for the Safety of the Food Chain, Boulevard du Jardin Botanique 55, B-1000 Brussels, Belgium.
authors.forename: Philippe
authors.initials: P
authors.lastname: Houdart
authors.affiliation: A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: van den Berg
authors.affiliation: A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Lambrecht
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001530:Belgium / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D009980:Influenza A virus / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000821:virology; D011200:Poultry; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology; D015995:Prevalence; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies
chemical_list: D000914:Antibodies, Viral
keywords: H5; H7; NP ELISA; hemagglutination inhibition; notifiable avian influenza; poultry; serological survey; seroprevalence