A team of American and Indian scientist who had been jointly investigating the case has claimed that when eaten on an empty stomach, the amino acid present in the lychee fruit was dramatically lowering blood glucose levels, sending children into hypoglcaemia causing sudden seizures leading to death in 40% of cases.
Scientists say that consumption of lychee alone is not the cause of the illness but lychee consumption in huge quantity combined with skipped evening meal affect glucose synthesis causing the illness.
“Parents in affected villages report that during May and June, young children frequently spend their day eating litchis in the surrounding orchards; many returned home in the evening uninterested in eating a meal. Skipping an evening meal is likely to result in night-time hypoglycaemia, particularly in young children who have limited hepatic glycogen reserves, which would normally trigger β-oxidation of fatty acids for energy production and gluconeogenesis. However, in the setting of hypoglycin A/MCPG toxicity, fatty acid metabolism is disrupted and glucose synthesis is severely impaired, which can lead to the characteristic acute hypoglycaemia and encephalopathy of the outbreak illness,” reads the study published by The Lancet.
Investigations into the mystery illness had begun as early as 1995. The illness was ascribed to various phenomena like heat stroke, infections borne by rats, bats and flies and even pesticides used in the ubiquitous lychee orchards in the region.
The joint investigation team of India’s National Center for Disease Control and the India office of the Centers for Disease Control and Prevention in Atlanta was prompted to suspect the lychee fruit when they compared the illness with the “Jamaican vomiting sickness” which had similar symptoms and is ascribed to hypoglycin, a toxin found in the ackee fruit that inhibits the body’s ability to synthesize glucose, leading extremely low blood glucose levels. When they tested the lychee fruit they detected the same toxin. This led to health officials in India closely examining what the afflicted ate eaten, drunk and breathed. They urged parents to be sure not to feed unripe lychees to young children on empty stomach and to limit their consumption of the fruit otherwise as well. In two seasons, the number of reported cases per year dropped to less than 50 from hundreds, thus establishing that consumption of the fruit combined with skipping evening meal was the reason behind the deaths.