Every spring since 1995, children in the town of Muzzafarpur, India would fall ill. They would experience seizures and fall comatose. Many of them would die – about 40 per cent – and no one could explain why.
And just as suddenly as the outbreak sprang up in mid-May, it would disappear in July.
In 2014, doctors at India’s National Center for Disease Control and the American Centers for Disease Control and Prevention embarked on a study to pinpoint the culprit behind the mystery disease. A new report published in the medical journal The Lancet Global Health reported that the consumption of lychee fruit on an empty stomach was to blame.
Muzzafarpur is India’s largest lychee farming region. It accounts for 70 per cent of the country’s lychee harvest.
Investigators looked at the hundreds of children admitted to local hospitals in 2014 with similar symptoms. Of the 390 children admitted, 122 died.
The researchers checked for signs of infection and elevated pesticide levels and came up short. Then they tested blood glucose levels of the affected children and compared them to the levels of children who did not exhibit the mystery illness symptoms. The glucose levels in the sick children were very low in comparison.
“It seemed to be a little signal,” CDC epidemiologist Padmini Srikantiah told the The New York Times. “One of the things we heard multiple times from the children’s mothers was that they didn’t really eat dinner properly.”
In addition, they found high levels of hypoglycin A and methylenecyclopropyl glycine (MCPG) in two-thirds of the children’s urine. Both are naturally-occurring toxins found in fruit that can cause glucose deficiency and “metabolic derangement.”
In the study, the researchers said many of the children’s parents reported that their kids would frequently go to neighbouring orchards and eat lychee fruit. They’d lose their appetite and would not want to eat dinner.
They concluded that “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.”
Following the study, the Indian government issued a public health recommendation to minimize the consumption of lychee fruit among children in the affected regions, and to ensure they eat dinner during the outbreak period. The cases of illness reportedly fell to less than 50 in the past year.
The researchers said they believe their study may help shed light on similar outbreaks in lychee-growing regions in Bangladesh and Vietnam, although thorough investigations in those areas are yet to be done.