TRACKING EMERGING PUBLIC HEALTH CHALLENGES – November 2, 2025 – Bird Flu
“Bird flu is back. After a quiet summer, the virus has hit dozens of poultry flocks, resulting in the deaths of nearly seven million farmed birds in the United States since the beginning of September. Among them: about 1.3 million turkeys, putting pressure on the nation’s turkey supply in the run-up to Thanksgiving.
Reports of infected wild birds have also surged this fall, and three states — Idaho, Nebraska and Texas — have identified outbreaks in dairy cows.
The virus often flares up in the fall as wild birds begin migrating south; this year, the uptick is occurring during a government shutdown, as federal agencies that are typically involved
“The new wave of detections makes clear that the past several months, during which the virus all but vanished from the nation’s poultry farms and egg prices fell from record highs, were a temporary respite. This fall’s surge began earlier than usual, and experts are bracing themselves for an acceleration in the months ahead.” (1)
A bird flu virus that has often been ignored because it mostly causes minor disease in birds has the potential to cause a human pandemic, says a team that has tracked how the H9N2 virus has become better adapted to infect people. The researchers say more surveillance of the virus is needed.
In the past few years, surveillance has been focused on the avian influenza virus H5N1, which has spread across most continents and can cause severe disease and death in people. Since 2020, H5N1 has killed about 21 people. In North America, the virus is also spreading among dairy cows.
Less attention is being paid to H9N2, says Kelvin To, a clinical microbiologist at the University of Hong Kong, despite the virus being the second most common strain of bird flu that infects people. H9N2 has caused 173 infections in people since 1998, mostly in China, says To, who presented his team’s research at the Pandemic Research Alliance International Symposium in Melbourne, Australia, on 27 October.
H9N2 might be more prevalent than we realize, says Michelle Wille, who studies bird flu at the Peter Doherty Institute for Infection and Immunity in Melbourne. Infections are probably being missed because they do not result in severe infection or hospitalization in people, or because people are more commonly tested for H5N1 instead, she adds.” (2)
Asymptomatic Human Infections With Avian Influenza A(H5N1) Virus Confirmed by Molecular and Serologic Testing, https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2840680
1.Bird Flu Is Back, By Emily Anthes and Apoorva Mandavilli, https://www.nytimes.com/2025/10/22/health/h5n1-bird-flu.html?smid=nytcore-ios-share&referringSource=articleShare
2.This ‘minor’ bird flu strain has potential to spark human pandemic, By Rachel Fieldhouse, https://www.nature.com/articles/d41586-025-03519-1
curated by Jonathan M. Metsch, Dr.P.H.
Clinical Professor of Environmental Medicine, Icahn School of Medicine at Mount Sinai