Encephalitis Symptoms and causes


Encephalitis is an inflammation of the brain tissue. The most common cause of encephalitis is viral infections. In some of the cases it can be caused by bacteria or even fungi.

There are two main types of encephalitis: primary and secondary. Primary encephalitis occurs when a virus directly infects the brain and spinal cord. Secondary encephalitis can occurs when the infection starts in the body then  travels into the brain.

Encephalitis is a rare yet serious disease that can be life-threatening. You should see the doctor immediately, if you have the symptoms of encephalitis.

Symptoms of encephalitis:

The symptoms of encephalitis can range from mild to severe.

  • Mild symptoms include:
  • Fever
  • Headache
  • Vomiting
  • Stiff neck
  • Lethargy (exhaustion)

Severe symptoms include:

  • Fever of 103°F (39.4°C) or higher
  • Confusion
  • Drowsiness
  • Hallucinations
  • Slower movements
  • Coma
  • Seizures
  • Irritability
  • Sensitivity to light
  • Unconsciousness

Infants and young children show different symptoms. Call a doctor immediately if your child is experiencing any of the following:

  • Vomiting
  • Bulging fontanel (soft spot in the scalp)
  • Constant crying
  • Body stiffness
  • Poor appetite


Many different viruses can cause encephalitis. It’s helpful to categorize the potential causes into three groups: common viruses, childhood viruses, and arboviruses.

Common viruses:

The most common virus that causes encephalitis in developed countries is herpes simplex. The herpes virus typically travels through a nerve to the skin, where it causes a cold sore. In rare cases, however, the virus travels to the brain.

This form of encephalitis usually affects the temporal lobe, the part of the brain that controls memory and speech. It can also affect the frontal lobe, the part that controls the emotions and behaviour. Encephalitis caused by herpes is dangerous and can lead to severe brain damage and death.

Other common viruses that can cause encephalitis include:

  • Mumps
  • Epstein-barr virus
  • HIV
  • Cytomegalovirus

Childhood viruses:

Vaccines can prevent childhood viruses that  cause encephalitis. Some of the viruses occur in the childhood and can cause encephalitis are as follows:

  • Chicken pox (very rare)
  • Measles
  • Rubella


Arboviruses are viruses carried by insects. The type of arbovirus that’s transmitted depends on the insect.

Risk factors for encephalitis:

The groups most at risk of encephalitis are:

  • Older adults
  • Children under the age of 1
  • People with weak immune systems

There is a higher risk of getting encephalitis if you live in an area where  mosquitoes or ticks are common. Mosquitoes and ticks can carry the viruses that can also cause this encephalitis. You are more likely to get an encephalitis during summer, when these insects are most active.


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