US researchers have found that the mysterious and sometimes fatal brain disease that has afflicted children in northeastern India for several years could be linked to a toxic substance in litchi fruits. However, investigators feel the need for more research to uncover the cause of the illness, which leads to seizures, altered mental state and death in more than a third of cases.
The report by the US Centers for Disease Control and Prevention (CDC) states that the disease outbreaks have coincided with the month-long litchi harvesting season in and around the Muzaffarpur district of Bihar state since 1995. A study that compared sick children to a control group in the area found that those who got sick were more than twice as likely to have spent time in orchards or agricultural fields. These findings raised concern for the possibility of a toxin-mediated illness. According to the CDC's Morbidity and Mortality Weekly Report, the 2013 and 2014 Muzaffarpur investigations indicate that this illness is an acute non-inflammatory encephalopathy.
Researchers are studying a component, known as methylenecyclopropylglycine (MCPG), found in litchi seeds near the homes of affected children and known to cause hypoglycemia in animal studies. They have also collected environmental samples from their homes and water supplies to search for pesticides. Researchers think that MCPG may cause severe hypoglycemia and illness much the same way as a similar toxin, hypoglycin A, which has caused acute encephalopathy in the West Indies and West Africa after consumption of unripe ackee, a fruit in the same botanical family as litchi.
Outbreaks of neurological illness have also been observed in litchi-growing areas of Bangladesh and Vietnam, raising further interest in a possible association between litchis and this illness.
Until researchers uncover the cause, the CDC has urged parents to seek immediate medical care for their children if they show symptoms, and recommended doctors to promptly keep a check on hypoglycemia and correct it as soon as possible.