|This transmission electron micrograph (TEM) revealed the presence of West Nile virus virions, in an isolate that was grown in a cell culture.|
What Is West Nile Virus?
West Nile virus (WNV) is a potentially serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. This fact sheet contains important information that can help you recognize and prevent West Nile virus.
How Does West Nile Virus Spread?
- Infected Mosquitoes: Most often, WNV is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite.
- Transfusions, Transplants, and Mother-to-Child: In a very small number of cases, WNV also has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby.
- Not through touching: WNV is not spread through casual contact such as touching or kissing a person with the virus.