Avian influenza in poultry

Updated 19.05.2025

In November 2021, outbreaks of highly pathogenic avian influenza (HPAI) occurred for the first time in poultry in Norway. HPAI virus of the subtype H5N1 was detected in two commercial layer flocks in Klepp municipality in Rogaland County. Prior to this, virus of the same subtype was found in wild birds in the same geographical area.

Avian influenza (AI) is monitored in poultry and in wild birds.

The main goal of the surveillance programme for AI in poultry is to document that Norwegian poultry flocks are free of influenza A infections of the subtypes H5 and H7.

The surveillance programme for AI in wild birds serves as a potential early detection and monitoring system in relation to influenza A viruses of avian origin, with special emphasis on HPAI H5 and H7 subtype viruses in the wild bird reservoir.

Background

Avian influenza (AI) is cased by influenza A viruses, which are highly contagious, extremely variable viruses that are widespread in birds. Wild waterfowl such as ducks, geese, swans, waders and gulls are the natural reservoir for all low pathogenic influenza A virus subtypes. These virus carriers do not usually develop clinical disease, but shed large amounts of virus in their faeces.

In domestic poultry infection with influenza A viruses causes two main forms of disease, distinguished by high and low pathogenicity (ability to cause disease). Most of the low pathogenic AI (LPAI) viruses cause only mild disease in poultry, however LPAI strains of H5 or H7 subtype have the potential to mutate to highly pathogenic AI (HPAI) viruses following introduction to poultry populations. HPAI viruses induce a serious, highly contagious disease of poultry and other captive birds. The mortality in poultry flocks may in some cases be more than 90 %. All HPAI epidemics known so far have been of hemagglutinin subtype H5 or H7.

Even though avian influenza predominantly infects birds, some subtypes of avian influenza may occasionally infect humans after close contact with infected birds. In Asian countries, human infection with avian influenza subtypes H5N1 and H7N9 are associated with live poultry markets.

2023

Surveillance based on serological investigations to monitor avian influenza viruses (AIVs) in poultry in 2023 did not detect infection in poultry held for commercial purposes in Norway. In 2023, three outbreaks of highly pathogenic avian influenza (HPAI) occurred in domestic birds in Norway: one outbreak in a municipal park with captive birds and two outbreaks in backyard poultry flocks.

Download report

Avian influenza in poultry in Norway 2023 (pdf 760kb)

Previous reports

Avian influenza in poultry in Norway 2022 (pdf 740kb)
Avian influenza in poultry in Norway 2021 (pdf 743kb)
Avian influenza in poultry in Norway 2020 (pdf 731kb)
Avian influenza in poultry in Norway 2019 (pdf 793kb)
Avian influenza in poultry in Norway 2018 (pdf 871kb)
Avian influenza in poultry in Norway 2017 (pdf 845kb)
Avian influenza in poultry in Norway 2016 (pdf 842kb)
Avian influenza in poultry in Norway 2015 (pdf 1mb)
Avian influenza in poultry in Norway 2014 (pdf 518kb)
Avian influenza in poultry in Norway 2013 (pdf 666kb)
Avian influenza in poultry in Norway 2012 (pdf 1mb)
Avian influenza in poultry in Norway 2011 (pdf 653kb)
Avian influenza in poultry in Norway 2010 (pdf 564kb)
Avian influenza in poultry in Norway 2009 (pdf 529kb)
Avian influenza in poultry in Norway 2008 (pdf 455kb)