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

The Texas Parks & Wildlife Department issued a wildlife health alert as avian influenza, or bird flu, continues spreading among wild birds in parts of the Panhandle. —Faith Bugenhagen, Austin American Statesman, 27 Feb. 2026

Multiple elephant seal pups along the Northern California coast have tested positive for the deadly avian influenza, or bird flu, according to new research from the University of California. —Carlos E. Castañeda, CBS News, 25 Feb. 2026

On Friday, the Chiang Mai regional livestock office announced in a statement that autopsies of the animals found genetic material of canine distemper virus, or CDV, and traces of bacterial infection but no avian influenza type A virus, also known as bird flu. —Wasamon Audjarint, Los Angeles Times, 24 Feb. 2026

Public health officials have not recommended that people remove bird feeders because of the spread of avian influenza, or bird flu, but keep your eyes out for any future directives. —Lauren Landers, Better Homes & Gardens, 23 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