Protocol for a case-control study on risk factors for introduction of highly pathogenic avian influenza into holdings with poultry and other captive birds in Denmark

This document presents the protocol for a case-control study on risk factors for introduction of highly pathogenic avian influenza into holdings with poultry and other captive birds in Denmark. The objective is to assess potential risk factors for introduction of HPAI into poultry and other captive bird holdings in Denmark. More specifically, the objective is to compare the odds of introduction of HPAI related to a range of potential risk factors, such as biosecurity measures, in poultry and other captive bird holdings with and without a history of HPAI detection in the epidemiological seasons 2020/2021, 2021/2022 and 2022/2023. An additional objective is to identify reasons for non-participation in the source population.