Prelims cum Mains Social Issues

How litchi toxin is causing the deaths?

The News

  • The recent spike in deaths due to acute encephalitis syndrome (AES) in northern districts of Bihar is associated with a condition called hypoglycemic encephalopathy.

Background

  • Districts in North Bihar including Muzaffarpur, Vaishali, Sitamarhi, Samastipur, Sheohar, East and West Champaran are witnessing upsurge in the Acute Encephalitis Syndrome cases.
  • Acute Encephalitis Syndrome is a spectrum of diseases classified based on similar clinical syndromes.
  • It is primarily a neurological condition characterized by sudden onset of fever and altered consciousness.
  • It can be caused by different viruses, bacteria, fungus, parasites, spirochetes, toxins etc.

 

In focus: Hypoglycemic Encephalopathy

Introduction

  • While encephalitis causes 15% of the AES cases, the recent outbreak of AES in Bihar is associated with a biochemical found in litchi that is known to cause hypoglycemia in undernourished children.
  • The AES condition caused due to litchi is called Hypoglycemic Encephalopathy.

Difference between Encephalitis and Hypoglycemic Encephalopathy

Causes

  • Encephalitis is a mosquito borne viral disease transmitted by Culex Mosquitoes.
  • Hypoglycemic Encephalopathy is caused mainly by a toxin that hinders synthesis of glucose in the body.

Symptoms

  • In case of encephalitis, fever precedes brain dysfunction.
  • On the other hand, in cases of hypoglycaemic encephalopathy, fever is after the onset of brain dysfunction.
  • Under encephalitis, blood sugar level is normal in children.
  • Under hypoglycaemic encephalopathy, hypoglycemia is the main cause of death.

Image result for Hypoglycemic Encephalopathy

Litchi and Hypoglycemic Encephalopathy

Evidence

  • A study in 2015 established a relationship between consumption of litchi and AES.
  • Most of these cases are associated with exposure to a toxin in litchi (hypoglycin A and methylene cyclopropylglycine (MCPG).
  • In 2017, another team of researchers confirmed the role of the toxin methylene cyclopropyl glycine (MCPG).

Glucose synthesis in the body

  • In normal circumstances, after a period of fasting, the blood sugar level in the body dips.
  • In such a situation, glycogen (a polysaccharide) in the liver is broken down into simple sugar glucose restoring the sugar levels in the blood.
  • When glycogen reserve in the liver is exhausted, the body oxidizes the fatty acid into glucose.

MCPG and hypoglycemia

  • Methylene cyclopropyl glycine (MCPG) present in litchi blocks the fatty acid oxidation leading to hypoglycemia.
  • Thus in case of under-nourished children, who have low/no glycogen in the liver, fatty acid oxidation into glucose is hindered by MCPG after a prolonged period of no food intake.
  • Low sugars level in blood results in lack of supply to brain leading to drowsiness, disorientation and even unconsciousness.
  • Besides when fatty acid conversion is halted, amino acids are released to brain cells.
  • The amino acids cause brain oedema (filling up of water) resulting in swelling of the brain cells resulting in seizures, coma and finally death.

 

Prevention and Treatment

  • Undernourished children should not go empty stomach.
  • Ensure they do not eat litchi empty stomach.
  • Infusion of 10% dextrose restores blood sugar and also stops the production of amino acid that causes swelling of brain cells.
  • 3% saline solution reduces brain oedema through the process of osmosis.

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