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

According to the Centers for Disease Control and Prevention, one of the main drivers of elevated and unpredictable egg prices has been the ongoing outbreak of highly pathogenic avian influenza. —Marley Malenfant, Austin American Statesman, 20 Jan. 2026

Kansas has not recorded any human cases of avian influenza. —Moná Thomas, PEOPLE, 15 Jan. 2026

Since 2022, an outbreak of H5N1 avian influenza has resulted in the loss of nearly 185 million birds raised for food. —Ellen P. Carlin, STAT, 14 Jan. 2026

The laboratory confirmed a positive result for highly pathogenic avian influenza Monday evening. —Christopher Harris, CBS News, 14 Jan. 2026

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