What is encephalitis?

Encephalitis is a potentially serious disease marked by irritation and inflammation of the brain. This swelling or inflammation is called cerebral edema and can lead to the destruction of nerve cells, bleeding into the brain (intracerebral hemorrhage), and brain damage.

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While encephalitis can be a mild disease, people most at risk of developing a serious case of encephalitis include infants, young children, the elderly, and people with weakened immune systems. Encephalitis is rare in the United States.

Encephalitis is most often caused by viral infections. You can be exposed to viruses and other pathogens that cause encephalitis in various ways. Viruses, bacteria and parasites can be transmitted by breathing in air droplets from an infected person, swallowing contaminated food or drink, or making person-to-person contact. Encephalitis can result from viruses that cause childhood infections, such as measles and mumps. These illnesses used to be very common, but are less frequent now because of childhood immunizations. Pathogens can also be transmitted by a bite from a rabid animal or from a tick, mosquito, or other blood-sucking insect.

Once any of these pathogens enter your body, they can spread to the bloodstream where they are carried to the nervous system. In the nervous system, they multiply and cause infection and inflammation of the brain. Other causes of encephalitis include autoimmune disorders, allergic reactions to vaccines, and certain cancers.

Typical symptoms of encephalitis include a low-grade fever, mild headache, low energy, and poor appetite. Treatment of encephalitis varies depending on the type and severity of encephalitis. Almost all people with mild cases of encephalitis will recover, but more severe cases of encephalitis can be life threatening if they are not quickly diagnosed and treated.

Encephalitis is a disease that can cause serious complications, such as problems with vision, memory and speech, and can be life threatening in some cases. Seek prompt medical care if you have been exposed to someone who has encephalitis.

Seek immediate medical care (call 911) if you, or someone you are with, have symptoms of encephalitis, such as fever, severe headache, change in consciousness, hallucinations, seizure, muscle weakness or paralysis, changes in mental function, and changes in speech, hearing or vision.

SYMPTOMS

What are the symptoms of encephalitis?

Symptoms of encephalitis vary depending on the type of encephalitis and individual factors. Cases can range from mild to severe, with mild cases resembling a cold or the flu. Symptoms of mild cases of encephalitis can also mimic symptoms of other diseases, such as influenza or meningitis.... Read more about encephalitissymptoms

CAUSES

What causes encephalitis?

In the United States, the most common cause of encephalitis is a viral infection by enteroviruses, herpes simplex viruses, or arboviruses. In most cases, these viruses result in a cold-like or mild illness, but once in the body, these pathogens can spread to the bloodstream where they are carried to the nervous system. In the nervous system, they multiply and cause infection and inflammation of the brain.... Read more about encephalitiscauses

TREATMENTS

How is encephalitis treated?>

Treatment of encephalitis varies depending on the type of encephalitis, your age, and other factors. General treatment of all forms of encephalitis includes easing symptoms and keeping your body well hydrated so you can keep your body strong and get the rest you need to recover. Treatment includes:... Read more about encephalitistreatments

Medical Reviewer: McDonough, Brian, MD Last Annual Review Date: Jun 27, 2011 Copyright: © Copyright 2011 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Brain and Nerves