What is encephalitis?

Encephalitis is an inflammation (irritation and swelling) of the brain tissue. It can occur as a primary illness or as a result of another illness elsewhere in the body. Frequently caused by an infection with a virus, encephalitis can be mild or severe, but severe cases are rare.

Who gets encephalitis?

Anyone can get encephalitis, but young children, older adults, and persons with weakened immune systems are more at risk.

How is encephalitis spread?

Primary encephalitis occurs when a virus directly infects the brain. Viruses that are carried by infected mosquitoes and ticks can cause primary encephalitis. Other viruses can cause an illness and then encephalitis can develop as a complication of the viral illness. When encephalitis develops after another infection, it is called post-infectious encephalitis. Post-infectious encephalitis most commonly follows a bout of chickenpox, mumps, or measles.

What are the symptoms of encephalitis?

Encephalitis frequently causes headache, fever, confused thinking, seizures, or problems with vision, speech, or movement. Infants and young children might have nausea, vomiting, body stiffness, constant crying, and poor feeding.

How soon after exposure do symptoms appear?

Encephalitis can occur within two to three weeks after a viral illness. Symptoms begin within a few days to one or two weeks after the bite from an infected mosquito.

How is encephalitis diagnosed?

Medical evaluation and special tests are needed to confirm the diagnosis. Anyone with a severe headache, fever, and altered mental status should seek medical care immediately.

What is the treatment for encephalitis?

Doctors might prescribe antiviral drugs, anti-inflammatory drugs, or other treatments for the symptoms as needed. A person with encephalitis needs hospital care.

How can encephalitis be prevented?

The way to prevent encephalitis is to prevent the viral illness that can lead to a complication like encephalitis. This can be done through practicing good hand washing and staying up-to-date on all recommended vaccines. Take measures to protect yourself against mosquito and tick bites, such as by wearing appropriate clothing, avoiding mosquito- and tick-infested areas, wearing insect repellent, and keeping the area around the home free of stagnant or standing water.

What should I do if I've been in contact with a person who has encephalitis?

You will not catch encephalitis from someone else. If the encephalitis resulted from another disease, such as measles, and you had contact with the person while he or she was sick, you may need some protection from that disease (for example, vaccination). Your healthcare provider or health department can give you advice about this.

How can I get more information about encephalitis?

September 2018

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