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West Nile

West Nile virus (WNV) can cause a fatal neurological disease in people who are bitten by an infected mosquito.1

Areas of risk

map chikungunya

West Nile virus is found in Africa, Europe, the Middle East, North America, and Western Asia1

Key facts

Mosquitoes become infected when they feed on birds infected with WNV.

These mosquitoes then spread the virus to people and other animals.1

West Nile virus is the leading cause of mosquito-borne disease in the US.2

prevention guidance

In 2022, 1,035 cases of West Nile were reported to the CDC.

71% of WNV cases were neuroinvasive.3

Severe West Nile virus4

~1 in 150

people who are infected develop severe symptoms affecting the central nervous system

~1 in 10

people with disease affecting the central nervous system die

West Nile at a glance

Primary vector5,6

Culex

Biting habits:

  • Evening to morning

Symptoms4

Most common:

  • Fever

Other:

  • Headache
  • Body aches
  • Joint pain
  • Vomiting
  • Diarrhea
  • Rash

References: 1. West Nile virus. World Health Organization. Accessed March 13, 2023. https://www.who.int/en/news-room/fact-sheets/west-nile-virus 2. West Nile virus. Centers for Disease Control and Prevention. Updated December 15, 2022. Accessed March 13, 2023. https://www.cdc.gov/westnile/index.html 3. West Nile Virus – Preliminary Maps & data for 2022. Centers for Disease Control and Prevention. Updated December 13, 2022. Accessed March 13, 2023. https://www.cdc.gov/westnile/statsmaps/preliminarymapsdata2022/index.html 4. Symptoms, diagnosis, & treatment. West Nile virus. Centers for Disease Control and Prevention. Updated October 14, 2022. Accessed March 13, 2023. https://www.cdc.gov/westnile/symptoms/index.html 5. Mosquito-borne diseases. Baylor College of Medicine. Accessed March 13, 2023. https://www.bcm.edu/departments/molecular-virology-and-microbiology/emerging-infections-and-biodefense/mosquitoes 6. Mosquito bite prevention (United States). Centers for Disease Control and Prevention. October 13, 2016. Accessed March 13, 2023. https://www.cdc.gov/chikungunya/pdfs/fs_mosquito_bite_prevention_us.pdf