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 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.
Factors that may increase your chance of encephalitis include:
Newborns of mothers who have genital herpes simplex are at risk for herpes simplex encephalitis
The symptoms may range from mild to severe. Severe symptoms can include permanent neurological damage. Encephalitis can also lead to death.
Milder symptoms include:
More severe symptoms may include:
The doctor will ask about your symptoms and medical history. A physical exam will be done.
Tests may include:
Treatment is mostly supportive. It may include:
To help reduce your chance of getting encephalitis, take these steps:
Encephalitis Information Resource
National Institute of Neurological Disorders and Stroke
Canadian Neurological Sciences Federation
Herpes simplex encephalitis. EBSCO DynaMed website. Available at: http:// http://www.ebscohost.com. Updated February 21, 2013. Accessed May 30, 2014.
California encephalitis. EBSCO DynaMed website. Available at: http:// http://www.ebscohost.com. Updated February 21, 2013. Accessed May 30, 2014.
Eastern equine encephalitis. EBSCO DynaMed website. Available at: http:// http://www.ebscohost.com. Updated September 19, 2013. Accessed May 30, 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 May 1, 2014.
West Nile virus infection. EBSCO DynaMed website. Available at: http:// http://www.ebscohost.com. Updated August 9, 2013. Accessed May 30, 2014.
10/1/2013 DynaMed Systematic Literature Surveillance http:// http://www.ebscohost.com: 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 May 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.