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by Stahl RJ

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:
  • Living in or visiting the plains regions of western and central US
  • Doing activities outdoors and not using insect repellent

Symptoms

Most people with WEE do not have any symptoms.
If symptoms do occur, they appear within 5-10 days after infection and include:
  • Headache
  • Fever
  • Nausea and vomiting
  • Neck stiffness
  • Chills
  • Fatigue
  • Joint and muscle pain
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:
  • What kind of symptoms you are experiencing
  • Where you have been living or traveling
  • Whether you have been exposed to mosquitoes
Your doctor may need to test your bodily fluids. This can be done with:
  • Blood tests
  • Lumbar puncture to evaluate the fluid that surrounds the brain and spinal cord
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:
  • Stay inside between dusk and dark, when mosquitoes are most active.
  • Wear long pants and long-sleeved shirts when outside.
  • Use an insect repellent with DEET.
  • Repair screens to prevent mosquitoes from entering the house.
  • Use proper mosquito netting at night. Look for netting treated with insecticide.
  • Remove standing water (such as birdbaths, clogged gutters) to prevent mosquito breeding.

RESOURCES

Centers for Disease Control and Prevention
https://www.cdc.gov
National Institute of Allergy and Infectious Diseases
https://www.niaid.nih.gov

CANADIAN RESOURCES

Alberta Health
http://www.health.alberta.ca
Health Canada
https://www.canada.ca

References

About Western equine encephalitis. Minnesota Department of Health website. Available at: http://www.health.state.mn.us/divs/idepc/diseases/weencephalitis/basics.html. Accessed December 7, 2017.
Meningitis and encephalitis information page. National Institutes of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Meningitis-and-Encephalitis-Information-Page. Accessed December 7, 2017.
Mosquito avoidance. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115142/Mosquito-avoidance . Updated November 21, 2016. Accessed December 7, 2017.

Revision Information

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