Definition
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.
Causes
WEE is caused by being bitten by a mosquito that is infected with the virus.
Risk Factors
Factors that may increase your risk of WEE include:
- Living in or visiting the plains regions of western and central United States
- 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
- Neck stiffness
- Chills
- Fatigue
- Joint and muscle pain
- Vomiting
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.
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
- Cerebrospinal fluid analysis
Your doctor may need pictures of structures inside your head. This can be done with:
- MRI scan
- CT scan
Treatment
Because the infection is viral, there is no specific treatment for WEE. Treatment will focus on managing your symptoms and related complications through:
- IV fluids
- Medicine to control seizures
- Medicine to decrease brain swelling
- Mechanical ventilation (breathing support)
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:
- 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.
- Remove standing water (eg, bird baths, clogged gutters) to prevent mosquito breeding.