Infectious Diseases 2025

Highly pathogenic avian influenza A/H5N1 clade 2.3.4.4b has expanded rapidly across multiple continents, causing extensive mortality in birds and marine mammals and an unprecedented scope of mammalian spillover. Despite widespread infection in terrestrial and marine mammals, bats had not previously been implicated as hosts for H5 viruses.
A new study reports the first evidence of H5 influenza A virus (IAV) infections in wild vampire bats (Desmodus rotundus) along Peru’s coastal regions. The researchers demonstrated that vampire bats experience repeated exposure to H5 IAVs, particularly those affecting marine wildlife during the 2.3.4.4b epizootic. The data indicate that these bats likely acquire infection through contact with virus-infected marine animals, feeding on prey such as seabirds and marine mammals, especially in coastal foraging zones where interactions with marine sources are frequent. The study further shows that vampire bat cells are permissive to infection and that H5 viruses can replicate within bat tissues.
Bats have long been recognized as reservoirs for genetically and biologically unusual influenza A viruses. Initial work in Central America identified the highly divergent H17N10 and H18N11 subtypes in New World bats, demonstrating that bat-associated influenza A lineages constitute a distinct evolutionary branch with atypical genome constellations and receptor usage that differ fundamentally from classical avian and mammalian strains (1,2).
The new findings provide the first evidence that vampire bats are exposed to, and susceptible to infection with, H5 influenza viruses, suggesting a potential role as spillover hosts at the marine–terrestrial interface.

1. Tong S, Li Y, Rivailler P, et al. A distinct lineage of influenza A virus from bats. Proceedings of the National Academy of Sciences. 2012;109(11):4269–4274.
2. Tong S, Zhu X, Li Y, et al. New World bats harbor diverse influenza A viruses. PLoS Pathogens. 2013;9(10):e1003657.