The Lancet Global Health, a leading medical journal, has published the results of a collaborative investigation by Indian and U.S. authorities revealing that lychee, a widely available fruit in India, had claimed 122 lives in Muzaffarpur, Bihar in 2014.
From 2013 to 2014 the National Centre for Disease Control, India (NCDC), the U.S. Center for Disease Control (CDC) and other Indian health officials investigated the recurring outbreak of an unexplained neurologic illness among young children in Muzaffarpur – the largest lychee farming region in India.
These recurring outbreaks begin each year in mid-May and peak in June, coinciding with the lychee harvesting season. Children from poor socioeconomic backgrounds in rural Muzaffarpur comprise most of those affected.
The illness is characterized by acute seizures and changed mental status and is associated with high mortality. The disease resembles encephalitis that causes inflammation of the brain.
The findings of that investigation, have, for the first time, comprehensively confirmed that this illness is associated with lychee fruit consumption and the effects of naturally occurring toxins.
According to the study, parents reported that children in the affected villages spent most of the day eating lychees from the surrounding orchards, often returning home in the evening “uninterested in eating a meal.”
The results said that children who fell ill were twice as likely to have skipped dinner, which, according to the researchers probably resulted in “night-time hypoglycaemia.”
When their blood sugar level dropped, the body would start to metabolize fatty acids to produce a necessary boost of glucose.
However, urine samples showed that two-thirds of the ill children showed evidence of exposure to toxins found in lychee seeds – present in higher levels in unripe fruits.
In the presence of these toxins “glucose synthesis is severely impaired,” the study said, leading to dangerously low blood sugar and brain inflammation in the children.
However, the researchers said there are still some questions surrounding the mystery. For example, while orchards surround many villages in the area, typically only one child in each village develops the illness. The report suggests it may be something to do with genetics.
“The synergistic combination of lychee consumption, a missed evening meal, and other potential factors such as poor nutritional status, eating a greater number of lychee and as yet unidentified genetic differences might be needed to produce this illness,” the study said.
The study added that similar outbreaks had been reported in another lychee cultivation area in West Bengal, and also beyond India in parts of Vietnam and Bangladesh.
Previous research had focused on pesticides rather than the fruit itself, but “the findings of our investigations might help to shed light on the cause of illness in the Bangladesh and Vietnam outbreaks,” the study said.