Transmission

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Transmission Cycle

Image of the West Nile virus transmission cycle. The image is divided into two sides with a box in the middle. Inside the box there are images of mosquitoes on the top and birds on the bottom with arrows going from the mosquitoes to the birds and then from the birds to the mosquitoes. Mosquitoes transmit disease and birds are amplifier hosts. There is an arrow going from the mosquitoes to the left side of the image where a horse is in a field outside. The horse is a dead end host. There is also an arrow going from the mosquitoes to the right side of the image where there is a woman planting flowers outside of her house. The woman is also a dead end host.

West Nile Virus Transmission Cycle pdf icon[PDF – 1 page]

West Nile virus is most commonly spread to people by the bite of an infected mosquito.

Mosquitoes become infected when they feed on infected birds. Infected mosquitoes then spread West Nile virus to people and other animals by biting them.

In a very small number of cases, West Nile virus has been spread through:

West Nile virus is not spread:

  • Through coughing, sneezing, or touching
  • By touching live animals
  • From handling live or dead infected birds. Avoid bare-handed contact when handling any dead animal. If you are disposing of a dead bird, use gloves or double plastic bags to place the carcass in a garbage can.
  • Through eating infected animals, including birds. Always follow instructions for fully cooking meat.
Page last reviewed: July 7, 2021
Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD)