Plaza, P., Santangeli, A., Rosciano, N., Cancellario, T., Girardello, M., Wikelski, M., & Lambertucci, S. A. (2025). Wild Birds Affected by Highly Pathogenic Avian Influenza A (H5N1) Worldwide: Epidemiological Insights Into the Recent Panzootic. Global Change Biology, 31(10), e70523.
In a shell: This study mapped global H5N1 risk areas and found that from 2020 to 2025, the virus spread rapidly to nearly the entire world, mostly within predicted high-risk zones. It highlights that gregarious, non-migratory, carnivorous birds tolerant of human environments are most vulnerable—key information for guiding targeted surveillance and prevention efforts.
Abstract: In recent years, especially as a consequence of global
change, several emerging pathogens have caused alarming effects in wild
species. One of these pathogens, the Highly Pathogenic Avian Influenza A
(H5N1), is causing global mortalities in animals
with an increasing risk to humans. Wild birds play a key role in viral
transmission and spread. Using the distribution ranges of wild bird
species reported as infected, we mapped global risk areas for viral
spread and analyzed the spatio-temporal evolution
of H5N1 from January 2017 to March 2025.
We also examined the overlap
between the mapped risk areas and positive cases occurring in wild birds
and poultry over this period to evaluate whether these cases align with
the risk areas previously identified. Finally,
we evaluated whether ecological traits of wild birds, such as
gregariousness, tolerance of anthropic habitats, migratory behavior, and
trophic level, are associated with the viral infection. From 2017 to
September 2020, the H5N1 virus high-risk areas and cases
in wild birds and poultry were few and mainly limited to Asia and
Europe. From October 2020 to March 2025, the rise in H5N1 cases led to
rapid expansion of high-risk areas for virus circulation and spread to
almost the entire world. The increase in cases occurred
within predicted high-risk areas for both wild birds and poultry. The
wild bird species most at risk of contracting the viral infection were
those that are gregarious, tolerant of anthropic habitats, are
non-migratory, and occupy the upper trophic level. Our
findings provide insights that could enhance surveillance and
conservation efforts aimed at mitigating the adverse impacts of H5N1
virus. These efforts can be optimized by prioritizing high-risk regions
and species identified as particularly susceptible to
H5N1.
