A recent study published in GeoHealth has revealed that a greater variety of wild birds are playing a crucial role in the spread of avian influenza (H5N1) globally.
From pelicans to peregrine falcons, these species have spread the virus from Asia to Europe, Africa, and the Americas over the past two decades. This challenges the belief that the transmission of H5N1 was limited to certain birds.
A new pattern of avian influenza spread
Historically, avian influenza was associated with birds such as ducks, geese, and swans, considered victims of contact with infected poultry. However, the study demonstrates that more diverse wild species, such as cormorants, buzzards, vultures, and hawks, act as transmission vectors. This could explain why the strategy of selective culling of domestic birds has not been successful in stopping the current outbreak.
The findings reveal that the most active outbreaks of avian influenza are found in Europe and the Americas, unlike the 1990s when they were predominant in southeast Asia.
Pandemic risk and use of geospatial analysis
Epidemiologist Raina MacIntyre from the University of New South Wales warned that H5N1 has the potential to become a human pandemic. To better understand this threat, researchers combined geographic information systems (GIS) with epidemiology, mapping the virus from its initial outbreak in Hong Kong in 1997 to its current expansion.
Through machine learning, the team tracked how the virus has spread through avian superhighways, migratory routes connecting different regions and allowing contact between wild and poultry birds, facilitating the evolution of H5N1.
Outbreaks and global expansion
Since its first significant outbreak in 1997, when it infected 18 people in Hong Kong, H5N1 has shown alarming expansion:
- In 2005, it caused a massive die-off of wild birds in China’s largest lake.
- Between 2010 and 2015, the virus infiltrated 55 countries, demonstrating the impact of bird migrations on its transmission.
- Since 2020, the outbreak has not subsided, despite strategies of selective culling of domestic birds.
The need for new strategies
The study indicates that traditional approaches to monitoring and responding to avian influenza must be updated, as the new species identified as vectors of the virus have changed the disease landscape.
According to MacIntyre, it is essential to expand surveillance beyond ducks, geese, and swans and consider additional migratory routes to anticipate future outbreaks.
Implications for global health
With H5N1 spreading through new species and routes, experts warn that the containment model based on culling poultry is no longer sufficient.
The combination of geospatial analysis, epidemiological tracking, and bird migration studies could provide better tools to mitigate risks and prevent a possible human pandemic.
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