Encephalitis

Yahoo News
Encephalitis literally means an inflammation of the brain, but it usually refers to brain inflammation caused by a virus. It's a rare disease that only occurs in approximately 0.5 per 100,000 individuals - most commonly in children, the elderly, and people with weakened immune systems (i.e., those with HIV/AIDS or cancer).

Although several thousand cases of encephalitis (also called acute viral encephalitis or aseptic encephalitis) are reported to the U.S. Centers for Disease Control and Prevention (CDC) every year, experts suspect that many more may go unreported because the symptoms are so mild.

What Are the Signs and Symptoms?
Symptoms in milder cases of encephalitis usually include:

* fever
* headache
* poor appetite
* loss of energy
* just a general sick feeling

In more severe cases of encephalitis, a person is more likely to experience high fever and any of a number of symptoms that relate to the central nervous system including:

* severe headache
* nausea and vomiting
* stiff neck
* confusion
* disorientation
* personality changes
* convulsions (seizures)
* problems with speech or hearing
* hallucinations
* memory loss
* drowsiness
* coma

It's harder to detect some of these symptoms in infants, but there are still some important signs to look for including:

* vomiting
* a full or bulging soft spot (fontanel)
* crying that doesn't stop or that seems worse when an infant is picked up or handled in some way body stiffness

Because encephalitis can follow or accompany common viral illnesses, there are sometimes characteristic signs and symptoms of these illnesses beforehand. But often, the encephalitis appears without warning.

What Causes It?
Because encephalitis can be caused by many types of germs, the infection can be spread in several different ways.

Of the many different kinds of viruses that can cause encephalitis, one of the most dangerous and the most common cause of encephalitis is the herpes simplex virus (HSV). HSV is the same virus that causes cold sores around the mouth, but when it attacks the brain it may be fatal in as many as half of newborns who become infected and up to 28% of individuals after the newborn period. Fortunately, HSV encephalitis is very rare.

Some forms of encephalitis are transmitted by insects. Lyme disease, which is transmitted by ticks, can lead to encephalitis. Encephalitis that occurs as a complication of Lyme disease or rabies can be spread by ticks and animals, respectively.

Mosquitoes can also transmit the viruses for several types of encephalitis, including West Nile encephalitis, St. Louis encephalitis, and Western Equine encephalitis. Over the last several years in the United States, there's been concern about the spread of
West Nile virus, which is transmitted to humans by mosquitoes that pick up the virus when they bite infected birds.

Milder forms of encephalitis can follow or accompany common childhood illnesses, including measles, mumps, chickenpox, rubella (German measles), and mononucleosis. Viruses like chickenpox spread mostly via the fluids of the nose and throat, usually during a cough or sneeze.

Less commonly, encephalitis can result from a bacterial infection, such as bacterial meningitis, or it may be a complication of other infectious diseases like rabies or syphilis. Certain parasites, like toxoplasmosis, can also cause encephalitis in people with weakened immune systems.

Is It Contagious?
Brain inflammation itself is not contagious, but any of the various viruses that cause encephalitis can be. Of course, just because a child gets a certain virus does not mean that he or she will develop encephalitis. Still, to be safe, children should avoid contact with anyone who has encephalitis.

How Is It Diagnosed?
Doctors use several tests to diagnose encephalitis, including:

* imaging tests, such as computed tomography (CT) scans or magnetic resonance imaging (MRI), to check the brain for swelling, bleeding, or other abnormalities
* electroencephalogram (EEG), which records the electrical signals in the brain, to check for abnormal brain waves
* blood tests to confirm the presence of bacteria or viruses in the blood, and whether a person is producing antibodies (specific proteins that fight infection) in response to a germ
* lumbar puncture, also known as a spinal tap, in which cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) is checked for signs of infection

How Is It Treated?
Some children with very mild encephalitis can be monitored at home, but most will need care in a hospital, usually in an intensive care unit. Doctors will carefully monitor their blood pressure, heart rate, and breathing, as well as their body fluids, to prevent further swelling of the brain.

Because antibiotics aren't effective against viruses, they aren't used to treat encephalitis. However, antiviral drugs can be used to treat some forms of encephalitis, especially the type caused by the herpes simplex virus. Corticosteroids may also be used in some cases to reduce brain swelling. If a child is having seizures, anticonvulsants may also be given.

Over-the-counter medications, like acetaminophen, can be used to treat fever and headaches. Most people with encephalitis make a full recovery. In a small percentage of cases, swelling of the brain can lead to permanent brain damage and lasting complications like learning disabilities, speech problems, memory loss, or lack of muscle control. Speech, physical, or occupational therapy may be necessary in these cases.

Rarely, if the brain damage is severe, encephalitis can lead to death. Infants younger than 1 year and adults older than 55 are at greatest risk of death from encephalitis.