What is Encephalitis?

Encephalitis is a term used to describe an acute inflammation of the brain. A large number of infectious germs can cause encephalitis. Common viruses that cause encephalitis include rabies, herpes, polio, measles, West Nile virus, St. Louis encephalitis, Eastern and Western equine encephalitis, Japanese encephalitis, tick-borne encephalitis and other groups of viruses, such as enteroviruses that are found in the intestinal tract. Many bacteria and parasites, such as malaria, also can cause encephalitis. 

How do you get Encephalitis?

A variety of insects (especially mosquitoes and ticks) can transmit some of the germs that cause encephalitis. Other germs, such as rabies, are spread by animal bites that result in encephalitis. Some infectious agents that cause encephalitis can be spread by contaminated food or water.

Susceptibility and Resistance

Generally, all people are susceptible, but vaccination against some of the viruses creates effective immunity against those germs.

Incubation Period

The incubation period for Encephalitis is 1-90 days.

What are the Symptoms?

Encephalitis is usually characterised by a sudden fever, headache, confusion, and sometimes seizures. Younger children or infants usually become irritable with a fever and poor appetite. Drowsiness and confusion are often present. A stiff neck indicates that the membrane covering the brain is inflamed (meningitis).

Preventative Measures

Prevention of encephalitis depends on the germ causing the infection. For example, protecting against mosquito bites is very effective in preventing a large number of viral infections (e.g.,Japanese encephalitis, West Nile virus, etc.). Vaccination against a variety of viral infections (e.g., polio, measles, etc.) will prevent encephalitis. Some medications may be helpful to prevent encephalitis caused by bacteria and parasites (e.g. malaria). Avoid contaminated food and water to prevent encephalitis caused by enteric (intestinal) viruses.


Treatment depends on the type of germ causing the infection and usually consists of relieving the symptoms. For encephalitis caused by viruses, there are very few drugs that are effective against a limited number of viruses. For bacterial infections, antibiotics are necessary. Steroids (e.g. methylprednisolone) are often used to reduce brain swelling and inflammation. Sedatives may be needed for irritability or restlessness.



Where Does It Commonly Occur?

The illness, encephalitis, occurs worldwide.