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Western Equine Encephalitis

(WEE)

Definition

Western equine encephalitis (WEE) is a virus spread by a bite from an infected mosquito. While WEE is rare, an infection can be serious or fatal.

Causes

WEE is caused by a virus. The virus is passed through the bite of an infected mosquito.

Risk Factors

Factors that may increase your chance of WEE include:

Symptoms

Most people with WEE do not have any symptoms.
If symptoms do occur, they appear within 5-10 days after infection and include:
WEE can lead to more serious, life-threatening symptoms like inflammation of the brain (encephalitis), seizures, and coma . These serious symptoms are more common in infants and older adults.
Encephalitis
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Diagnosis

In addition to taking your medical history and doing a physical exam, your doctor will ask you:
Your doctor may need to test your bodily fluids. This can be done with:
Imaging tests to evaluate the brain can be done with:

Treatment

Because the infection is viral, there is no specific treatment for WEE. Treatment will focus on managing your symptoms and related complications through:

Prevention

There is no vaccine for humans. There is a vaccine for horses. Prevention of WEE focuses on controlling mosquitoes and avoiding mosquito bites. Steps you can take to avoid mosquito bites include:

RESOURCES

Centers for Disease Control and Prevention http://www.cdc.gov

National Institute of Allergy and Infectious Diseases http://www.niaid.nih.gov

CANADIAN RESOURCES

Health Canada http://www.hc-sc.gc.ca

Healthy Alberta http://www.healthyalberta.com

References

Fact sheet: Western equine encephalitis. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncezid/dvbd. Updated November 7, 2005. Accessed January 4, 2013.

Meningitis and encephalitis fact sheet. National Institutes of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/encephalitis%5Fmeningitis/detail%5Fencephalitis%5Fmeningitis.htm. Updated February 16, 2011. Accessed January 4, 2013.

Reimann CA, Hayes EB, DiGuiseppi C, et al. Epidemiology of neuroinvasive arboviral disease in the United States, 1999-2007. Am J Trop Med Hyg. 2008;79(6):974-979.

Western equine encephalitis fact sheet. Minnesota Department of Public Health website. Available at: http://www.health.state.mn.us/divs/idepc/diseases/weencephalitis/wee.html. Accessed January 4, 2013.

10/1/2013 DynaMed Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Reimer LJ, Thomsen EK, Tisch DJ, et al. Insecticidal bed nets and filariasis transmission in Papua New Guinea. N Eng J Med. 2013;369(8):745-753.

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