To develop effective control measures against diseases, such as highly pathogenic avian influenza (HPAI), it is essential that the transmission routes be understood. While exposure has, thus far, been primarily attributed to direct contact with infected animals, there is a new study suggesting that windborne transmission of HPAI may be feasible.
The proposition is based on molecular surveillance which identified identical H5N1 strains among unrelated commercial farms about five miles (8 km) apart in the Czech Republic during the 2023-24 HPAI season. With the outbreaks occurring at different, unrelated poultry farms with very high levels of biosecurity, windborne transmission appeared to be very likely.
Although windborne transmission is a contentious concept with a rarity of documented cases, the researchers used genetic, epizootiological, meteorological, and geographical data to reconstruct a model of events “strongly suggesting wind was the mechanism of infection transmission between poultry in at least two independent cases.” But because airborne transmission has not been considered as a primary mode of infection, and increasing distance can progressively dilute contaminated air, wind has been largely overlooked as a factor in transmission and its influence may be underestimated. However, it is suggested that windborne spread can be significant over longer distances under suitable weather conditions.
While poultry (and cattle) farms do need to continue to focus on biosecurity, these findings show that it is worth implementing airborne control technologies as well. Similar to recommendations made during the COVID pandemic for buildings and structures, farms could consider the use of approaches such as filters, air-handling systems, ultraviolet UV and UV-C systems, microwaves, ionization-based systems, etc.
TAG has worked with a number of clients on both biosecurity and airborne control measures for various diseases and outbreaks. Give us a call to further discuss your situation or general recommendations.
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Infectious Disease News:
- The USDA Center for Veterinary Biologics has granted a conditional license for an Avian Influenza Vaccine, H5N2 Subtype, Killed Virus, from Zoetis, for use in chickens. H5N2 can exist in both highly and low pathogenic avian influenza forms.
- USDA APHIS data indicates that as many as three-quarters of the dairy herds in CA are infected with H5N1.
- The Public Health Agency of Canada announced on Feb 19, 2025, that it has secured 500,000 initial doses of GSK’s human vaccine against avian influenza to protect people most at risk. This will be aimed at those who may be occupationally exposed to possibly infected animals. Guidance on use of this vaccine was also released.
- In a milestone reflecting Uganda’s prompt and comprehensive public health response, the last eight patients who recovered from Ebola were discharged from the hospital and no other positive cases have been reported in the outbreak which was declared last month.
- A meeting of the Advisory Committee on Immunization Practices (ACIP), which was scheduled for next week and had votes on several vaccines on the agenda, was postponed. Typically, the CDC accepts recommendations of this committee and bases vaccine schedules for children and adults on them.
- The ongoing measles outbreak in Texas that began in late January has increased to at least 124 cases. 16 patients have been hospitalized and there is 1 death reported. Only 5 of the case patients report being vaccinated. Cases are also reported in New Mexico, but it is not known if these cases are related to those in TX or not.
- Eighty-four members of Congress, led by Rep. Rosa DeLauro, have urged President Trump to lift restrictions on CDC and USDA communication, warning it hampers efforts to contain bird flu (H5N1). The virus has infected 70 people, caused one death, and spread to over 970 dairy herds, leading to the culling of 157 million poultry. Lawmakers call for restoring public health collaboration and expanding the National Milk Testing Strategy to improve detection.
