The role of airborne particles in the epidemiology of clade 2.3.4.4b H5N1 high pathogenicity avian influenza virus in commercial poultry production units

Abstract

Since October 2021, Europe has experienced the largest avian influenza virus (AIV) epizootic, caused by clade 2.3.4.4b H5N1 high pathogenicity AIV (HPAIV), with over 320 poultry infected premises (IPs) and 2480 dead H5N1 positive wild birds detected in Great Britain alone. Many IPs have been detected as geographical clusters, raising questions around lateral spread between premises by airborne particles. Airborne transmission over short distances has been observed for some AIVs strains. However, the risk of airborne spread of this strain remains to be elucidated. We conducted extensive sampling from IPs where clade 2.3.4.4b H5N1 HPAIVs was confirmed during the 2022/23 epizootic, each representing a major poultry species (ducks, turkeys, and chickens). A range of environmental samples were collected inside and outside houses, including deposited dust, feathers, and other potential fomites. Viral RNA (vRNA) and infectious virus were detected in air samples collected from inside and outside, but in close proximity, of infected houses, with vRNA alone being detected greater distances (>10m) outside. Some dust samples collected outside of the affected houses contained infectious virus, while feathers from the affected houses, located up to 60m away, only contained vRNA. Together, these data suggest that airborne particles harbouring infectious HPAIV can be translocated short distances (<10m) through the air, while particles containing vRNA might travel further (<50m). Therefore, the potential for airborne transmission of clade 2.3.4.4b H5N1 HPAIV between premises is considered low. Other factors, including indirect contact with wild birds, and the efficiency of biosecurity represent greater importance in disease incursion.

Control technologies to prevent aerosol-based disease transmission in animal agriculture production settings: a review of established and emerging approaches

“…Influenza A virus, which is a threat to both animal and public health because of its ability to change, reassort and cause pandemics ( 22 ), has also been detected in air samples from rooms of experimentally infected pigs ( 23 ), in air samples inside animal buildings and in the exhaust air from infected farms and at 1 mile from infected farms ( 24 ), highlighting the potential for aerosol transmission in pigs and between farms. Furthermore, the airborne spread of the HPAI virus was also implicated in the spread of avian influenza under certain conditions ( 25 – 27 ).…”