Western equine encephalitis (WEE) is a virus spread by a bite from an infected mosquito. While WEE is rare, an infected person can become seriously ill and even die from the virus.
WEE is caused by being bitten by a mosquito that is infected with the virus.
Factors that may increase your risk of WEE include: Living in or visiting the plains regions of western and central United StatesDoing activities outdoors and not using insect repellent
Most people with WEE do not have any symptoms.
If symptoms do occur, they appear within 5-10 days after infection and include: HeadacheFeverNeck stiffnessChillsFatigueJoint and muscle painVomiting
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.
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In addition to taking your medical history and doing a physical exam, your doctor will ask you: What kind of symptoms you are experiencingWhere you have been living or travelingWhether you have been exposed to mosquitoes
Your doctor may need to test your bodily fluids. This can be done with: Blood testsCerebrospinal fluid analysis
Your doctor may need pictures of structures inside your head. This can be done with: MRI scanCT scan
Because the infection is viral, there is no specific treatment for WEE. Treatment will focus on managing your symptoms and related complications through: IV fluidsMedicine to control seizuresMedicine to decrease brain swellingMechanical ventilation
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: 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.
Reimann CA, Hayes EB, et al. Epidemiology of neuroinvasive arboviral disease in the United States, 1999-2007.
Am J Trop Med Hyg.
10/1/2013 DynaMed Systematic Literature Surveillance
https://dynamed.ebscohost.com/about/about-us: Reimer LJ, Thomsen EK, Tisch DJ, et al. Insecticidal bed nets and filariasis transmission in Papua New Guinea. N Eng J Med. 2013 Aug 22; 369(8):745-753.
Last reviewed November 2012 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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