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Acute Encephalitis Syndrome

1. Acute encephalitis syndrome (AES) has surfaced in a few districts of Bihar and has claimed the lives of over 100 children.

2. Most of the deaths have been attributed to low blood sugar level (hypoglycaemia).

Which are the reasons for this?

1. Hypoglycaemia (low blood sugar level) was reported in a “high percentage” of children who died in Muzaffarpur.

2. In 2017, an India-U.S. team confirmed the role of the toxin called methylene cyclopropyl glycine (MCPG).

3. Early morning, it is normal for blood sugar to dip after several hours of no food intake.

4. Undernourished children who had gone to sleep without a meal at night develop hypoglycaemia.

5. The brain needs normal levels of glucose in the blood. The liver is unable to supply the need.

6. So, the alternate pathway of glucose synthesis, called fatty acid oxidation, is turned on. That pathway is blocked by MCPG.

7. Litchi does not cause any harm in well-nourished children, but only in undernourished children who had eaten litchi fruit the previous day and gone to bed on an empty stomach.

Why does it affect only young children?

1. AES is a basket term used for referring to children with clinical neurological manifestations.

2. This includes mental confusion, disorientation, convulsion, delirium or coma.

3. 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.

4. Malnourished children between two to 10 years fall ill and die due to hypoglycaemic encephalopathy.

5. It is not known why older children or adults do not suffer the same way.

6. It has also been documented that most of the children falling ill are from families camping in orchards to harvest the fruits.

7. These children tend to collect and eat the fruits that have fallen on the ground.

8. Hypoglycaemic encephalopathy outbreaks are restricted to April-July, with a peak seen in June because litchi is harvested during this period.

How is encephalitis different from hypoglycaemic encephalopathy?

1. Fever on the first day is one of the symptoms of encephalitis before brain dysfunction begins.

2. While fever is seen in children in the case of hypoglycaemic encephalopathy, fever is always after the onset of brain dysfunction (actually due to brain dysfunction).

3. Not all children exhibit fever. Some children have no fever, while others may have a mild or very high fever.

4. The blood sugar level is usually normal in children with encephalitis but is low in children with hypoglycaemic encephalopathy.

5. In the case of encephalitis, fever (due to virus infection) for a day or two is followed by the onset of symptoms caused by the brain getting affected.

6. However, in hypoglycaemic encephalopathy, children go to bed without any illness but manifest symptoms such as vomiting, convulsion and semi-consciousness early next morning.

7. The most important difference between the two is the presence of white blood cells in the cerebrospinal fluid.

8. In encephalitis, there are more white blood cells per unit volume of cerebrospinal fluid, which is a reflection of inflammation in the brain.

9. In contrast, no increase in white blood cells is seen in hypoglycaemic encephalopathy as there is no inflammation in the brain.

What needs to be done to cure or prevent?

1. Making sure that undernourished children do not eat plenty of litchi fruit.

2. Ensuring that they eat some food and not go to bed on an empty stomach.

3. A full and complete recovery can be achieved if children with hypoglycaemic encephalopathy are infused with 10% dextrose within four hours after the onset of symptoms.

4. Infusing 10% dextrose not only restores blood sugar to a safe level but also stops the production of amino acid that is toxic to brain cells by shutting down the body’s attempt to convert fatty acid into glucose.