New research has shed light on how wind might have carried the H5N1 virus between farms, challenging previous assumptions about its transmission mechanisms and potentially reshaping outbreak prevention strategies.
A study published to the bioRxiv preprint server presents genetic evidence suggesting that windborne transmission of highly pathogenic avian influenza (HPAI) H5N1 is feasible. While windborne transmission has been a theoretical possibility, documented cases have been rare, with previous air-sampling studies typically detecting the virus within about 150 meters from infected farms.
This study offers compelling evidence supporting long-distance transmission but emphasizes that it remains unverified without peer review. The research focuses on an outbreak at a duck farm and subsequent infections in nearby chicken farms, exploring how meteorological conditions influenced viral spread.
Tunnel ventilation systems were found to play a significant role in the spread of HPAI H5N1 by facilitating the movement of airborne particles. Fine aerosolized viral particles rather than dust generated during depopulation events are highlighted as key carriers. The study also underscores that these fine particles can remain suspended for extended periods, especially under specific weather conditions like those observed during the outbreak.
Key findings include:
- The HPAI H5N1 outbreak began at a duck farm on February 4, with mallards near a nearby lake as the likely origin.
- A transmission window from noon on February 4 to midnight on February 5 was identified, coinciding with winds from the southwest or west at speeds up to 10 m/s.
- Proximity of affected birds to air inlets and genetic identity of viral strains further supported windborne transmission as the most plausible mechanism.
The study challenges traditional assumptions about airborne transmission risks, particularly emphasizing that finer aerosolized particles rather than dust might be more significant carriers. This suggests that efforts to mitigate HPAI outbreaks should consider both meteorological conditions and ventilation systems in poultry farms with high-density populations.
Overall, while these findings provide valuable insights into the potential role of windborne transmission in HPAI spread, they are preliminary and not yet peer-reviewed. As such, they should be considered as a basis for further investigation rather than definitive conclusions guide clinical practices or health behaviors.
