Detection, transmission and spread of airborne avian influenza and Newcastle disease viruses: experimental and field investigations.

Both avian influenza (AI) and Newcastle disease (ND) viruses cause highly contagious respiratory diseases in chicken. These viruses are transmitted through the oro-faecal route, with airborne transmission via virus-laden droplets or dust. In this study, the Coriolis^® µ air sampler was evaluated for its suitability to assess the air detection and dispersion of highly pathogenic avian influenza virus (HPAIV) or live Newcastle disease virus (NDV) vaccines between chickens in both experimental and field settings. Experimental assays demonstrated HPAIV and NDV detection in air samples, indicating aerial persistence beyond the end of viral shedding measured in tracheal and cloacal swabs. Viral particles were detected in field air samples taken inside and outside HPAIV H5N1 outbreak farms, with outside aerial dispersion reaching up to 40 m from the exhaust fans. In accordance with these findings, viral particles were detected in air samples both indoors and outdoors from three live NDV-vaccinated farms; however, their aerial dispersion extended only up to 5 m from the exhaust fans. As observed in the NDV controlled assays, high levels of viral concentrations persisted in the air samples, whereas the viral concentrations in the individual swabs collected from the chickens were lower in the live NDV-vaccinated farms. For both the HPAIV and NDV field data, chicken density seemed to impact the viral air concentrations within and outside the studied farms. Coriolis^® µ proved effective as a non-invasive method for diagnosing AIV and NDV in both experimental and field studies, highlighting the value of air samples for monitoring poultry disease outbreaks.