Encephalitis is an inflammation (swelling and irritation) of the brain. In
most cases, a
causes this inflammation.
Encephalitis is also called acute viral encephalitis or aseptic
Who Gets Encephalitis?
Encephalitis (in-seh-fuh-LYE-tus) is a rare disease. Most cases happen in children,
the elderly, and people with a weakened immune
system (from HIV/AIDS, cancer, etc.).
Several thousand cases of encephalitis are reported to the Centers for Disease
Control and Prevention (CDC) every year. But health experts think that many more cases
happen that aren't reported because symptoms vary and can be mild.
What Are the Signs & Symptoms of Encephalitis?
Symptoms in mild cases of encephalitis usually include:
loss of energy
a general sick feeling
Serious cases of encephalitis can cause:
a high fever
nausea and vomiting
problems with speech or hearing
Because encephalitis can happen during or after common viral illnesses, symptoms
of these illnesses can start before encephalitis happens. But often, it appears without
What Causes Encephalitis?
Three groups of viruses are common causes of encephalitis:
Herpes viruses, such as chickenpox, EBV (Epstein-Barr virus, which causes mono),
and herpes simplex (which causes cold
Viruses that cause once-common childhood infections, such as measles, mumps, and
German measles. Thanks to immunizations, it's rare today for someone to develop encephalitis
from these illnesses.
Less often, encephalitis can be:
caused by an infection from
, such as bacterial meningitis
a complication of other infectious diseases like syphilis
due to a parasite, like toxoplasmosis (found in infected cat feces) in people
with weakened immune systems
Is Encephalitis Contagious?
Brain inflammation itself is not contagious. But the viruses that
cause encephalitis can be. Of course, getting a virus does not mean
that someone will develop encephalitis.
How Is Encephalitis 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
electroencephalogram (EEG), which records the electrical signals in the brain,
to check for unusual brain waves
blood tests to look for bacteria or viruses in the blood. These also can show
if the body is making antibodies (specific proteins that fight infection) in response
to a germ
lumbar puncture, or spinal tap, which checks cerebrospinal
fluid (the fluid that surrounds the brain and spinal cord) for signs of infection
How Is Encephalitis Treated?
Most people with encephalitis need care in a hospital, usually in an intensive
care unit (ICU). Doctors will watch their blood pressure, heart rate, breathing, and
body fluids to prevent further swelling of the brain.
Antiviral drugs can treat some forms of encephalitis, such as the type caused
by the herpes simplex virus.
Corticosteroids may be used to reduce brain swelling.
Anticonvulsants might be given to someone having seizures.
Over-the-counter (OTC) medicines, like acetaminophen, can help with fever and
Antibiotics don't work against viruses, so aren't used to treat most forms of
Many people with encephalitis make a full recovery. In some cases, brain swelling
can cause lasting problem like learning disabilities, speech problems, memory loss,
or lack of muscle control. Speech therapy, physical
therapy, or occupational therapy can help in these cases.
How Long Does Encephalitis Last?
Most of the time, the
phase of the illness (when symptoms are the most severe) lasts up to a
week. Full recovery can take longer, often several weeks or months.
Can Encephalitis Be Prevented?
The best way to prevent encephalitis is to avoid getting infected with the viruses
or other germs that can cause it. Regular hand
washing will help limit the spread of some of these germs. Staying as healthy
as possible by eating a balanced diet and getting plenty of rest can help keep your
immune system in shape. Immunizations are also an important way to protect people
from diseases like chickenpox and measles.
In areas where viruses and other germs are transmitted by insect bites, protect
yourself by wearing long sleeves and pants and applying an insect repellent. Also,
try to avoid unnecessary outdoor activities at dawn and dusk when mosquitoes are most
likely to bite.
When Should I Call the Doctor?
Get medical care right away if you have any of these symptoms: