Mosquito-Borne Viral Encephalitis
How to Say It: En-sef-uh-LITE-is
by Amy Scholten, MPH
Mosquito-borne viral encephalitis is inflammation of the brain. This condition is from viruses carried by mosquitoes. Examples of these viruses are:
The most common cause is a bite from an infected mosquito. Rarely, there may be other causes. One example is a blood transfusion with infected blood.
Things that raise the risk are:
The risk of serious symptoms is highest in those age 50 years and older. It is also higher in those with weak immune systems.
Most people with viruses from mosquitoes do not have symptoms.
If symptoms happen, they are often mild. They may be:
A small number of people develop encephalitis. Symptoms can be serious and even fatal. They may be:
The doctor will ask about your symptoms, travel, and health history. A physical exam will be done.
Blood tests will be done. They are often used to diagnose viruses from mosquitoes. The doctor may also order other tests, such as:
Treatment focuses on support, such as:
Severe symptoms need hospital care. This may include:
The risk of mosquito-borne viral encephalitis can be reduced. The best way is to avoid mosquito bites. Things that may help are:
Centers for Disease Control and Prevention
National Institute of Neurological Disorders and Stroke
Alberta Ministry of Health
Alpern JD, Dunlop SJ, et al. Personal protection measures against mosquitoes, ticks, and other arthropods. Med Clin North Am. 2016;100(2):303-16.
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Meningitis and encephalitis information page. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Meningitis-and-Encephalitis-Information-Page. Accessed April 6, 2021.
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West Nile virus. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/westnile/index.html. Accessed April 6, 2021.
Last reviewed December 2020 by EBSCO Medical Review Board David L. Horn, MD, FACP
Last Updated: 4/6/2021
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