The amino acid is also found in other fruits of the same family like rambutan, longan and ackee.
An global team of scientists reviewed both the literature and the 2014 outbreak, and found that chemicals in the lychee fruits themselves probably caused the illness-most frequently, in kids who had forgone dinner the night before. The study also recommended that authorities must ensure that children consume an evening meal during the outbreak period, and to rapidly assess and correct blood glucose levels in any child suspected of having the outbreak of the illness.
Heat, humidity, malnourishment, the monsoon and pesticides have all been considered at one stage to be contributing factors to the illness - said to resemble encephalitis symptomatically, a disease that causes inflammation of the brain.
Three years ago, Dr Rajesh Yadav, an investigator with the India Epidemic Intelligence Service, moved to the city of Muzaffarpur, the site of one of the country's most mysterious outbreaks. Children living in that area often spend the day at orchards eating large amounts of lychees, CNN noted, then come home not hungry for anything else.
Children aged 15 years or younger who were admitted to two hospitals in Muzaffarpur in 2014 with new-onset seizures or altered sensorium were included in the study. "Guidance should be developed for the consumer, especially children but also adults who have a susceptible metabolic profile or who eat fruit after fasting".
On Tuesday, a joint investigation published by India's National Center for Disease Control and the India office of the Centers for Disease Control and Prevention in Atlanta published a report identifying the cause of this phenomenon.
Speaking in numbers, the report said that of the 390 admitted, 122 (31%) died, while on admission 204 (62%) showed lowblood glucose level. This leads to dangerously low blood sugar levels, or hypoglycemia.
But other researchers believe that the study definitely ties the disease to the lychee, according to a commentary written by Peter Spencer and Valerie Palmer from Oregon Health and Science University.
The research suggests Lychees contain toxins that hinder the body's ability to produce glucose, which in turn affects young children whose blood sugar levels were already low because they were not eating dinner.
Finally, the scientists found cases of a chemical called hypoglycin A that caused neurological symptoms in people who ate another fruit related to the lychee, the ackee fruit.
In 2015, when health officials instructed parents to feed a healthy evening meal to their children instead of the fruit, the number of deaths subsequently dropped down to nearly 50 per cent.