avian influenza

noun

variants or avian flu

: highly variable influenza A of birds caused by any of several subtypes of the causative orthomyxovirus (Alphainfluenzavirus influenzae) of which some strains have been or may be transmitted to other vertebrates including humans especially after undergoing mutation

Most cases of avian influenza infection in humans have resulted from contact with infected poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces contaminated with secretion/excretions from infected birds.

—The Tennessee Tribune

compare bird flu

Examples of avian influenza in a Sentence

Recent Examples on the Web

Learn ways to protect your flock this fall as migrating waterfowl raise the risk of deadly avian influenza entering your coop. —Ella Gonzales, Fort Worth Star-Telegram, 3 Nov. 2025

Egg prices, initially high in early 2025 due to avian influenza, have steadily declined. —Olivia Evans, Louisville Courier Journal, 29 Oct. 2025

Several commercial chicken operations have detected avian influenza over the past several years, in addition it being detected in several backyard flocks. —Laura Schulte, jsonline.com, 28 Oct. 2025

Second, avian influenza is widespread among wild birds, and many of those birds migrate south to warmer climates, carrying the virus with them. —Meghan Bartels, Scientific American, 24 Oct. 2025

Word History

First Known Use

1965, in the meaning defined above

Rhymes for avian influenza

• parainfluenza
• cadenza

Medical Definition

avian influenza

noun

variants or avian flu

: influenza of birds that is caused by any of several subtypes (such as H5N2 or H7N7) of an orthomyxovirus (Alphainfluenzavirus influenzae) of which some strains have been transmitted to other vertebrates including humans especially after undergoing mutation

More than 100 species of wild waterfowl have been identified as natural, usually asymptomatic hosts of a variety of avian influenza … subtypes.

—Discover

Bird flu, or H5N1 avian influenza, has been circulating across North America since 2022, infecting birds, livestock, wildlife, pets, and humans. Despite 70 documented human cases, there are no known instances of human-to-human transmission—but some scientists are starting to worry that it's only a matter of time.

—Catherine Caruso, Harvard Medical School

called also fowl pest, fowl plague

see bird flu