Share this page

Health Library

Encephalitis

Pronounced: En-sef-uh-light-iss

Definition

Encephalitis is inflammation of the brain. The inflammation may involve the whole brain or just parts of the brain. Encephalitis may just occur in individuals (sporadic) or may affect many people in a particular area (epidemic).

Encephalitis

Nucleus factsheet image

Copyright © Nucleus Medical Media, Inc.

Causes

Encephalitis is most often caused by a viral infection. In the United States, the most common cause of sporadic encephalitis is the herpes simplex virus (HSV). Epidemic causes of encephalitis are usually mosquito- or tick-borne viruses.

The most common viruses that cause encephalitis include:

Not all encephalitis is caused by a virus. Some may be due to an overreaction of the immune system.

Risk Factors

Factors that may increase your chance of encephalitis include:

  • Living, working, or playing in an area where mosquito- or tick-borne viruses are common.
  • Not being immunized against diseases, such as:
    • Measles
    • Mumps
    • Chickenpox
    • Polio
    • Rotavirus
  • A suppressed immune system caused by certain medications, or health conditions, such as HIV infection
  • Having cancer—sometimes immune system overactivity may be the first sign of cancer

Newborns of mothers who have genital herpes simplex are at risk for herpes simplex encephalitis

Symptoms

The symptoms may range from mild to severe. Severe symptoms can include permanent neurological damage. Encephalitis can also lead to death.

Milder symptoms include:

  • Fever
  • Weakness, severe fatigue
  • Headache
  • Sensitivity to light
  • Stiff neck and back
  • Vomiting
  • Muscle aches
  • Rash
  • Yawning

More severe symptoms may include:

  • Changes in consciousness
  • Personality changes
  • Confusion
  • Irritability
  • Seizures
  • Loss of mobility
  • Progressive drowsiness
  • Trouble walking
  • Trouble speaking
  • Trouble swallowing
Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done.

Your bodily fluids may be tested. This can be done with:

Images may be taken of your head. This can be done with:

Your brain's electrical activity may be tested. This can be done with an electroencephalogram (EEG).

Treatment

Treatment is mostly supportive. It may include:

  • Antiviral drugs to shorten the duration of the illness
  • Steroids to reduce brain inflammation
  • Diuretics to decrease elevated intracranial pressure
  • Intubation with hyperventilation to decrease elevated intracranial pressure, and to maintain respiration and ventilation
  • Anticonvulsants to prevent and/or treat seizures
Prevention

To help reduce your chance of getting encephalitis, take these steps:

  • Make sure that you and your children are vaccinated against preventable viral illnesses
  • Protect yourself from mosquito bites:
    • Fix window screens.
    • Drain standing water around your home.
    • Wear long clothes after dark.
    • Use repellent when you are outside.
    • Use proper mosquito netting at night. Look for netting treated with insecticide.

RESOURCES:

The Encephalitis Society
http://www.encephalitis.info

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

CANADIAN RESOURCES:

Canadian Neurological Sciences Federation
http://www.cnsfederation.org

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

References:

Herpes simplex encephalitis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated February 1, 2013. Accessed September 23, 2014.

California encephalitis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated February 21, 2013. Accessed September 23, 2014.

Eastern equine encephalitis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated June 23, 2014. Accessed September 23, 2014.

NINDS meningitis and encephalitis information page. National Institute of Neurologic Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/encephalitis_meningitis/encephalitis_meningitis.htm. Updated April 16, 2014. Accessed September 23, 2014.

West Nile virus infection. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated June 23, 2014. Accessed September 23, 2014.

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 Aug 22; 369(8):745-53.



Last reviewed August 2014 by Rimas Lukas, 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.

Baptist Flame

Healthy Life Podcasts

Find A Doctor

Services

Locations

Baptist Medical Clinic

Patients & Visitors

Learn

Contact Us

Physician Tools

Careers at Baptist

Employee Links

Online Services

At Baptist Health Systems

At Baptist Medical Center

close ×