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Acute Encephalitis Syndrome (AES)

Topics Covered: Issues related to Health.

Acute Encephalitis Syndrome (AES):


First AES case of the year suspected in Muzaffarpur.

  • Usually AES, locally called chamki bukhar, surfaces during summer in the flood-prone districts of north Bihar.


AES cases were reported from five north Bihar districts in 2019. More than 150 children died. More than 600 children suffering from AES were admitted in the hospitals, including SKMCH and nearly 450 recovered.

About AES:

Acute encephalitis syndrome is a basket term used for referring to hospitals, children with clinical neurological manifestation that includes mental confusion, disorientation, convulsion, delirium, or coma.

  • Meningitis caused by virus or bacteria, encephalitis (mostly Japanese encephalitis) caused by virus, encephalopathy, cerebral malaria, and scrub typhus caused by bacteria are collectively called acute encephalitis syndrome.
  • The disease most commonly affects children and young adults and can lead to considerable morbidity and mortality.


It is characterized as acute-onset of fever and a change in mental status (mental confusion, disorientation, delirium, or coma) and/or new-onset of seizures in a person of any age at any time of the year.

Cause of the disease:

Acute Encephalitis Syndrome (AES) is considered a very complex disease as it can be caused by various agents including bacteria, fungi, virus and many other agents.

  • Japanese encephalitis virus (JEV) is the major cause of AES in India (ranging from 5%-35%).
  • Nipah virus, Zika virus are also found as causative agents for AES.

How is it related to litchi fruits? How it affects?

In India, AES outbreaks in north and eastern India have been linked to children eating unripe litchi fruit on empty stomachs.

Unripe fruit contain the toxins hypoglycin A and methylenecyclopropylglycine (MCPG), which cause vomiting if ingested in large quantities.

  • Hypoglycin A is a naturally occurring amino acid found in the unripened litchi that causes severe vomiting (Jamaican vomiting sickness), while MCPG is a poisonous compound found in litchi seeds.

Why it affects undernourished children?

Blood glucose falls sharply causing severe brain malfunction (encephalopathy), leading to seizures and coma, and death in many cases.

  • This is because under-nourished children lack sufficient glucose reserve in the form of glycogen and the production of glucose from non-carbohydrate source is blocked midway leading to low blood sugar level.
  • This causes serious brain function derangement and seizures.

Measures needed:

  1. Increase access to safe drinking water and proper sanitation facilities.
  2. Improve nutritional status of children at risk of JE/AES.
  3. Preparative measures to be in place before the possible outbreaks.
  4. Vector control.
  5. Better awareness generation among children, parents through Anganwadi workers etc.



Prelims Link:

  1. AES is caused by?
  2. Diseases caused by virus vs bacteria vs fungi.
  3. What is hypoglycaemia?
  4. What is JE?
  5. How eating litchi fruits aggravate the problem in malnourished children?

Mains Link:

What is Acute encephalitis syndrome? Discuss the causative agents, do you think authorities failed at several levels in preventing deaths due to encephalopathy in Bihar? Suggest what needs to be done?

Sources: Down to Earth.