Encephalitis is a rare infectious disease of the brain which involves the inflammation (swelling) and irritation of the brain. It is a serious condition which causes neuropsychological dysfunction. Encephalitis can be either primary (direct infection of the brain) or secondary (an infection which starts elsewhere and spreads to the brain).

According to Center for Disease Control and Prevention (CDC), encephalitis occurs in 0.5 in 10,00,000 individuals and is commonly observed in children.


The initial encephalitis symptoms are mild, but they can become severe and serious within hours or days of infection

Initial symptoms of encephalitis (flu-like)

  • Nausea and vomiting
  • Fever (a temperature equal to or more than 38OC)
  • Headache
  • Joint pain

Later symptoms of encephalitis (severe and serious)

  • Seizures (fits)
  • Loss of consciousness
  • Changes in behavior and personality
  • Confusion, drowsiness, and disorientation

Other symptoms of encephalitis include:

  • Photophobia (sensitivity to light)
  • Hallucinations (an apparent perception of something not present)
  • Inability to speech
  • Inability to control physical movements
  • Numbness in certain parts of the body
  • Visual disturbances (partial or total loss can also occur)
  • Neck stiffness and pain

Risk factors

You are at an increased risk for encephalitis based on

  • Age: Encephalitis is more common in children who are in their first year of life. It is also more likely in older adults and is also very severe in this population.
  • Compromised immune system: People with a weak immune system such as those with HIV/AIDS are at an increased risk of encephalitis.
  • Season: Spring season is very favorable for mosquitoes, ticks, etc. and can increase the risk of spread of the infection.
  • Geographical areas: In certain geographical areas, the prevalence of mosquitoes and ticks is high which pose and increased risk for encephalitis.


As is it mostly a viral infection, antiviral agents are used in the encephalitis treatment of acute stages. Along with these medications, the patients with viral infections are also administered IV fluids and are monitored regularly for the extent of swelling.

  • To control the seizures, anticonvulsants such as lorazepam may be given.
  • Diuretics may be given to lower the intracranial pressure in the brain.
  • In the case of herpes viral infection, immediate death can occur if a prompt treatment is not provided. Therefore, the doctor immediately starts treatment with intravenous acyclovir.

Additionally, the below measures are taken as a part of treatment

  • Mechanical ventilation
  • Luke warm sponge baths
  • Administration of fluids (oral or IV)
  • Resting the patient
  • Administration of pain killers and sedatives


Complications are more likely in older individuals with encephalitis and those who do not receive treatment right away after the diagnosis. The below complications can result from untreated encephalitis

  • Increased intracranial pressure
  • Loss of memory
  • Intellectual disability
  • Problems with speech and hearing
  • Breathing difficulty
  • Paralysis
  • Seizures
  • Coma
  • Death

Your doctor initially checks your signs and symptoms based on which one or more of the following tests are performed to test for encephalitis.

Test type Purpose of the test
Blood tests To detect the presence of infection in the blood
Lumbar puncture To test the signs of infection in the spinal fluid
Imaging studies (CT, MRI) Detect changes in the brain structure To exclude other conditions such as stroke or tumor with similar symptoms
Electroencephalograph (EEG) To record activity of the brain
Biopsy To test for infection in the collected sample of brain tissue It is rarely performed.

Below are the suggestions to prevent encephalitis:

  • Get vaccinated. Vaccination is found to be effective in preventing or reducing the cases of encephalitis caused by the viruses such as measles, mumps, rabies, polio, rubella and varicella.
  • Avoid spending long hours outdoors during the peak time (such as dusk) for the insects.
  • Wear long shirts and pants to avoid insect bites.
  • You may also use an insect repellant especially if you stay in the areas of high incidence of these cases.
  • Maintain good hygiene. Wash your hands regularly with antiseptic soap.
  • Do not share utensils, tableware and beverages.
  • Do not allow stagnant water in your surroundings.
  • The most significant cause of encephalitis is the viral infection which causes viral encephalitis or viral meningoencephalitis. Several viruses can cause encephalitis such as adenovirus, herpes simplex virus, cytomegalovirus, echovirus, coxsackievirus, etc. The most common virus is the herpes simplex virus which causes severe encephalitis in all the age groups.

    The exposure can occur through:

    • Breathing the droplets released by the infected person through sneezing
    • Contaminated food and water
    • Mosquitoes, ticks, and other insects
    • Physical contact

    The viruses are specifically located in particular areas and are predominantly present during certain seasons.

    As the virus enters the brain, it causes inflammation of the brain tissue. This destroys the nerve cells thereby causing bleeding in the brain and its damage.

    Other causes of encephalitis are:

    • Autoimmune diseases (causes autoimmune encephalitis)
    • An allergic reaction to vaccines
    • Bacteria which cause Lyme disease, tuberculosis, and syphilis
    • Parasites such as toxoplasmosis, cysticercosis, and roundworms can cause encephalitis in people with a weak immune system
    • Some cancer patients can also develop encephalitis