Influenza A(H5N1) detection in two asymptomatic poultry farm workers in Spain, September to October 2022: suspected environmental contamination

Euro Surveill. 2023 Feb;28(8):2300107. doi: 10.2807/1560-7917.ES.2023.28.8.2300107.


In autumn 2022, the Spanish Influenza National Reference Laboratory (NRL) confirmed the detection of influenza A(H5N1) in samples from two asymptomatic workers linked to an outbreak in a poultry farm in Spain. Nasopharyngeal swabs were taken according to a national screening protocol for exposed workers. Absence of symptoms, low viral load and negative serology in both workers suggested environmental contamination. These findings motivated an update of the early detection strategy specifying timing and sampling conditions in asymptomatic exposed persons.

Keywords: HPAI A(H5N1); Spain; asymptomatic; highly pathogenic avian influenza; human; outbreak.

MeSH terms

  • Animals
  • Disease Outbreaks / veterinary
  • Farmers
  • Humans
  • Influenza A Virus, H5N1 Subtype*
  • Influenza in Birds* / diagnosis
  • Influenza in Birds* / epidemiology
  • Influenza, Human* / diagnosis
  • Influenza, Human* / epidemiology
  • Poultry
  • Poultry Diseases* / epidemiology
  • Spain / epidemiology