High pathogenicity avian influenza (HPAI) is a fatal avian disease, which is associated with high mortality and massive economic losses worldwide. Yet despite apparently identical initial conditions, some poultry farms are repeatedly affected, while others have never experienced an outbreak. This review summarizes the most important risk factors that are non-modifiable through routine biosecurity practices for the occurrence of HPAI in poultry flocks identified since 2018. These comprise numerous different individual aspects, which were summarized in nine superordinate categories: host characteristics, factors related to the barn, farms in vicinity, anthropogenic factors, vegetation, weather, wild birds, water bodies and others. Raising awareness of these factors and promoting the implementation of suitable mitigation measures can play a key role in reducing avian influenza (AI) outbreaks in poultry.
Held et al. (2026) studied this question.