Evidence of long- range airborne transport of the avian influenza virus

Background HE-FARM is a European project aimed at enhancing biosecurity along the farm-to-fork chain. It focuses on detecting pathogenic aerosols by developing innovative air sampling techniques. One of the key pathogens of concern in this context is the highly pathogenic avian influenza virus, which can have extensive impacts on the poultry industry. Methods During the highly pathogenic avian influenza outbreak in Spain in autumn 2025, air sampling was carried out around a poultry farm confirmed to be infected, during depopulation operations. Samples were collected using a Counterfog BIAFTS air sampler positioned 150 meters from the farm. Results PCR analysis detected the influenza viral genome in three out of three samples and the H5 subtype in two out of three samples. Conclusions The presence of H5-influenza aerosols positive at this distance provides strong evidence that viral particles can be dispersed through the air beyond the immediate vicinity of infected farms. These results suggest that airborne transport may play a role in virus transmission between farms.