Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

See What's Trending Now See More Trending Words

West Nile virus

noun
variants: or less commonly West Nile
Updated on: 11 Sep 2017

Definition of West Nile virus

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

Read the Latest from M-W

alt-59c2960017c94
The Ambiguity of Pushing 'Up' and 'Back'
image536372841
Every Letter Is Silent, Sometimes
alt-59c2cb9e9ef54
Trending: Ivanka: "An 'Otherwise' Incredible Day"
video-title-words-of-the-year-1066
Words of the Year: 1066

Origin and Etymology of west nile virus

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

Medical Dictionary

West Nile virus

noun
variants: also West Nile

medical Definition of West Nile virus

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,  July 2003
  • 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,  21 Aug. 2013
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,  14 Nov. 2000
  • … 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,  7 Aug. 2000
— see west nile encephalitis

Learn More about west nile virus

  1. See words that rhyme with West Nile virus Britannica.com: Encyclopedia article about West Nile virus

Seen and Heard

What made you want to look up West Nile virus? Please tell us where you read or heard it (including the quote, if possible).

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

shofar

play

a ram's-horn trumpet used in Judaism

Get Word of the Day daily email!

TRENDING NOW

  1. otherwise "in other respects"

  2. federalism Graham says bill gives power to states

  3. bodega "Don’t mess with the beloved bodega."

  4. carceral Of, relating to, or suggesting a jail or prison

  5. allegory No spoilers!

SEE ALL

BROWSE DICTIONARY

West Nile virus

Test Your Vocabulary

Merriam-Webster's New Words Quiz—Fall 2017 Edition!

  • young-plant-shoots
  • Which of the following is a new sense of the word bunny?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

alt-59c2960017c94
The Ambiguity of Pushing 'Up' and 'Back'

When you push a meeting, where does it go?

image536372841
Silent Letters

When each letter can be seen but not heard

alt-59c17b8172892
'So Long': A Common But Mysterious Goodbye

Its origins are surprisingly murky.

alt-59c13729150dc
"Immune to" or "Immune from"?

Nobody is immune to this question.

Ask the Editors

video-title-words-of-the-year-1066
Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

payday
How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless
Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals
Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!

You're going to have to memorize the dictionary again.

Take the quiz
stylized-drawing-of-woman-pole-vaulting-across-gap-to-get-trophy
Challenging Vocabulary Quiz Returns!

No tricks, just difficult words.

Take the quiz
How Strong Is Your Vocabulary?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Take the quiz
Bee Cubed
Bee Cubed

Listen to the words and spell through all three levels.

Play the game