Autumn migration: H5N1 outbreaks intensify globally

As autumn migration unfolds across the globe, the spread of Highly Pathogenic Avian Influenza (HPAI) H5N1 has reached alarming levels, raising significant concerns for animal and public health.

David Corredor

As autumn migration unfolds across the globe, the spread of Highly Pathogenic Avian Influenza (HPAI) H5N1 has reached alarming levels, raising significant concerns for animal and public health. The seasonal movement of wild birds, particularly waterfowl, has long been associated with the transmission of avian influenza viruses. In 2025, this phenomenon is contributing to a surge in H5N1 outbreaks, affecting poultry, wild birds, mammals, and even humans.

According to the CDC and WHO, H5N1 is now widespread among wild birds and has spilled over into domestic poultry and dairy cattle in multiple countries, including the United States, Canada, and several nations in Latin America. The virus has infected over 170 million birds globally since 2022, with more than 4,700 outbreaks reported in the Americas alone.

• Autumn migration acts as a biological highway for the virus.
• Migratory birds, many of which are asymptomatic carriers, shed the virus through feces and respiratory secretions, contaminating water sources and agricultural environments.
• This has led to increased transmission to domestic animals and heightened risks for farm workers and wildlife.

The virus’s ability to infect a wide range of species—including seals, cats, dogs, and dairy cows—has surprised scientists and prompted calls for a “One Health” approach to surveillance and response. In the U.S., 70 human cases have been confirmed since 2024, with one fatality reported in Louisiana. Most infections occurred in individuals with direct exposure to infected animals, and no sustained human-to-human transmission has been observed.

• Despite the current low public health risk, experts warn that the virus is just one mutation away from becoming more transmissible among humans.
• This potential shift underscores the urgency of global cooperation in monitoring and controlling the spread.
• The FAO and WOAH have launched a ten-year strategy to combat HPAI, emphasizing biosecurity, rapid response, and data sharing.

As migratory birds continue their seasonal journey, the world faces a critical juncture. Strengthening surveillance, protecting farm workers, and investing in vaccine development are essential steps to mitigate the growing threat posed by H5N1. The convergence of wildlife, agriculture, and human health during migration seasons demands vigilant, coordinated action to prevent a potential pandemic.