may refer to:

;Biology and disease * Avian influenza, influenza endemic to birds. * Influenzavirus A, the causative agent for bird flu; the genus of the Orthomyxoviridae family. of viruses to which all viruses responsible for Avian influenza belongs to, but also includes viruses that are endemic to humans and other animals. * H5N1, a subtype of Influenza A virus endemic to birds, currently perceived as a significant emerging pandemic threat. ;Music * Bird Flu (song), a single by British musician M.I.A.

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