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

Two Indiana counties saw their first outbreaks of a relatively long-lasting strain of avian influenza, or bird flu, last week. —Karl Schneider, IndyStar, 18 Feb. 2026

According to the agriculture department, testing has confirmed the presence of highly pathogenic avian influenza in wild birds, as well as within backyard flocks and commercial flocks statewide. —Bryan Hendricks, Arkansas Online, 15 Feb. 2026

Though the threat of the highly pathogenic avian influenza (HPAI), or bird flu, is still high, the egg industry now has an oversupply, and wholesale egg prices in early January were at record lows, an egg farmer and others in the industry told USA TODAY. —Betty Lin-Fisher, USA Today, 13 Feb. 2026

Veterinarians and agriculture experts are warning Colorado flock owners to be cautious as high pathogen avian influenza is making a return to the region. —Dillon Thomas, CBS News, 4 Feb. 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