With highly pathogenic avian influenza (HPAI) continuing to be widespread in wild birds worldwide and causing outbreaks in poultry and dairy cows, the theory that the wind is carrying the virus from farm to farm is becoming more and more supported by global studies. While the virus is likely introduced by wild birds and can be spread by various means (such as close contact, particles spread on shoes or equipment, etc.), the studies are causing experts to take another look at HPAI transmission and methods of control.
Currently, USDA is heavily focused on the assumption that once spread by wild birds, it is tracked onto and between farms because of lax safety practices, such as shared people and equipment. As such, the agency recommends uniform biosecurity practices that include such practices as lines of separation, perimeter buffer areas, site-dedicated personnel and equipment, and pest control. While this can limit contact spread, it does not limit airborne spread.
Some of the global studies that support airborne spread include research in France that found dust laden with virus that came from infected farms and established the density of farms as a key risk of viral spread in France’s duck-farming regions, suggesting that contaminated dust and feathers could spread farm to farm. Additionally, a 2025 Czech Republic study that mapped the spread of the virus from a duck farm to two “high-biosecurity” chicken farms 5 miles away, with genomic and meteorological information showing that wind was the most probable mechanism of transmission.
Given the poultry industry diseases of the past, experts believe the answer to reducing airborne transmission is vaccination. While USDA has a proven poultry vaccine against HPAI, the poultry meat industry has fought back on vaccines, stating that it would impact international trade, with countries barring US poultry imports. Vaccination would also be costly, with one estimate approximating a cost of $33 million to vaccinate America’s turkey and egg industry birds.
COVID Risk Matrix:
Influenza:
Public Health News:
- Norovirus is spreading earlier again this season. Wastewater concentrations have increased nationwide by 69% since October according to data from WastewaterSCAN, an academic program through Stanford University in partnership with Emory University.
- A multi-country hepatitis A outbreak affecting Austria, Czechia, Hungary, and Slovakia has led to over 6,000 cases and 39 deaths from January to October 2025. Person-to-person transmission is driving the increase, mainly among those with limited access to hygiene facilities, such as homeless individuals and drug users.
- From Sept 6-Nov 14, 2025, Europe reported a rate of highly pathogenic avian influenza detections in wild birds, four times higher than the same period in 2024. The most affected countries were Germany, France, the Netherlands, the UK, and Spain, with significant mortality among ducks, swans, and cranes.
- In the ongoing Marburg virus outbreak in Ethiopia, 5 deaths have been reported among the 10 reported cases. 3 additional deaths are suspected to have been caused by the outbreak strain. No outbreak source has been identified, and health officials are working to contain its spread.
