West Nile virus

noun

variants or less commonly West Nile

1

: a flavivirus (species West Nile virus of the genus Flavivirus) that causes an illness marked by fever, headache, muscle ache, skin rash, and sometimes encephalitis or meningitis and that is spread especially from birds to humans by mosquitoes

2

or West Nile fever : the illness caused by West Nile virus

Examples of West Nile virus in a Sentence

Recent Examples on the Web

Common causes of viral meningitis include enteroviruses, herpes viruses, the West Nile virus, mumps and influenza viruses. —Daryl Austin, USA TODAY, 31 Jan. 2025

Preventing the virus There is currently no vaccine for West Nile virus. —Melissa Rudy, Fox News, 9 Oct. 2024

In 2018, a study out of UW-Madison that analyzed bat poop found that little brown bats in Wisconsin were eating 17 different types of mosquitoes, including nine that carry West Nile virus. —Madeline Heim, Journal Sentinel, 31 Oct. 2024

And the truth is, wearing repellent can save your life, protecting you against West Nile virus and Lyme disease, just to name a few of the pathogens mosquitos and ticks can pass on. —Kristin Canning, WIRED, 14 Oct. 2024

Word History

Etymology

from West Nile province of Uganda, where the virus was isolated in 1937

First Known Use

1940, in the meaning defined at sense 1

Rhymes for West Nile virus

• adenovirus
• baculovirus
• coronavirus
• enterovirus
• poliovirus
• antivirus
• herpesvirus
• parvovirus
• reovirus
• retrovirus
• rhinovirus
• rotavirus

Medical Definition

West Nile virus

noun

variants also West Nile

1

: a single-stranded RNA virus of the genus Flavivirus (species West Nile virus) that causes an illness marked by fever, headache, muscle ache, skin rash, and sometimes encephalitis or meningitis, and that is spread especially from birds to humans by mosquitoes chiefly of the genus Culex

Note: West Nile virus is closely related to the viruses causing Japanese B encephalitis and Saint Louis encephalitis.

West Nile virus causes unusually severe infections in crows and blue jays, according to one CDC-led study that measured the number of virus particles in the birds' blood …

—Stephen S. Hall, Smithsonian

Of 5780 cases of arboviral disease reported in 2012, West Nile virus infection accounted of 5674, or 98% of the total, researchers reported in the Morbidity and Mortality Weekly Report.

—Rebecca Voelker, The Journal of the American Medical Association

2

or West Nile fever : the illness caused by West Nile virus

West Nile virus is such a disease. Last week, President Clinton declared an emergency in areas of New Jersey affected by the virus …

—James Ridgeway, The Village Voice

… residents are being urged to stay indoors while trucks spray insecticides through the streets to ward off outbreaks of West Nile fever, a mosquito-spread disease that last summer sickened dozens and killed seven.

—Joannie Schrof Fischer et al., U.S. News & World Report

see west nile encephalitis