West Nile virus (WNV) is an infection from a mosquito. Rarely, it can lead to serious problems, or death.
The infection is caused by a virus. The virus is spread to humans from the bite of an infected mosquito. Rarely it has spread from an infected blood transfusion, organ transplant, and breastfeeding.
Things that raise the risk of WNV are:
Severe WNV is more common in men and people over 50 years old. Other things that raise the risk of severe WNV are:
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Most people with WNV have no symptoms. Others develop flu-like symptoms such as:
Symptoms can last from a few days to several weeks.
A small number of people with WNV develop serious symptoms, such as:
The doctor will ask about your symptoms, travel, and health history. A physical exam will be done.
WNV is often diagnosed with:
Other tests may be done, depending on symptoms.
There is no specific treatment for WNV. Treatment depends on how severe the disease is. The goal is to manage symptoms and problems. In severe cases, hospital care is needed.
Depending on the symptoms, options may be:
Treatment for severe symptoms may include:
WMV can be prevented by avoiding mosquito bites. Things that may help are:
Centers for Disease Control and Prevention
Infectious Diseases Society of America
Alberta Ministry of Health
Mosquito avoidance. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/mosquito-avoidance. Accessed April 5, 2021.
Sejvar JJ. West nile virus infection. Microbiol Spectr. 2016;4(3).
West Nile virus infection. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/west-nile-virus-infection . Accessed April 5, 2021.
West Nile virus: What you need to know. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/westnile/index.html. Accessed April 5, 2021.
Last reviewed December 2020 by
EBSCO Medical Review Board
David L. Horn, MD, FACP
Last Updated: 4/5/2021