Reports are calling it a “deadly fruit,” as investigators recently discovered lychee is behind the mysterious outbreak that has taken hundreds of children’s lives every year in Muzaffarpur, India. The discovery, published Tuesday in the Lancet Global Health journal, is a celebration of scientific collaboration and quality sleuthing. However, others say what comes next could have an even greater global impact.
Since 1995, doctors in Muzaffarpur have been stumped by the annual flood of children into their wards in mid-May, at the peak of summer. Children, who were healthy the night before, were suddenly struck by encephalitis – or brain swelling – seizures, vomiting and even comas.
The diagnoses ranged from heat stroke to pesticides to infections carried by rats, bats or flies. But in 40 percent of cases, the children died, often within hours. Then, as quickly as it came, the outbreak disappeared with the onset of monsoon rains in July – that is, until the next year.
For two years, investigators from India’s National Center for Disease Control and the India office of the Centers for Disease Control and Prevention (CDC) based in Atlanta hunted down the culprit, which it turns out is lychees eaten on an empty stomach by malnourished children.
Muzaffarpur is famous for its lychee production, producing as much as 70 percent of India’s harvest. The fruit is widely consumed by everyone in the region, and children often eat ones that are unripe or that have fallen off the trees.
Unfortunately, lychees – especially unripe ones – contain high levels of two toxins that inhibit the body’s ability to produce glucose: hypoglycin A and methylenecyclopropyl glycine (MCPG). When investigators realized that the patients did not have suffer from an infection, but did all have low blood sugar levels, their search lead them to unripe ackee fruit, which also has high level of hypoglycin and was found to be responsible for “Jamaican vomiting sickness” in the 1950s.
However, eating lychees did not adversely affect everyone. Investigators reported that 16 percent of the patients they studied were wasted, and 65 percent of them were stunted. Often mothers said the child did not eat an evening meal.
“After identifying the connection [in 2015], there was a mass campaign to educate mothers to feed their children in the night and not allow them to consume litchi which has helped,” Arun Shah, a pediatrician from Muzaffarpur who worked on a concurrent study, told Scroll.in. “The problem is nutrition. If these children were well fed, the toxin would have not killed them.”
Over the next two seasons, the reported cases dropped from hundreds per year to less than 50.
“It was an unexplained illness for so many years,” said Padmini Srikantiah, a senior epidemiologist with the CDC and senior author of the paper, told the New York Times. “This is kind of emblematic of why we collaborate, to build this kind of systematic approach.”
However, some say this success should also serve as a lesson for global collaboration. Unripe ackee fruit was known for decades to cause “Jamaican vomiting sickness,” but that knowledge did not reach certain places like Muzaffarpur until now, noted Oregon Health and Science University’s Peter Spencer, professor of neurology and Valerie Palmer, senior research associate, in a comment published alongside the paper.
Especially as commercial lychee production expands, “researchers need to work with the [lychee]industry to determine how levels of hypoglycaemic acids vary across cultivars, soil, climate, and harvest conditions,” Spencer and Palmer said. “Guidance should be developed for the consumer, especially children but also adults who have a susceptible metabolic profile or who eat fruit after fasting.”
While Western consumers are not at high risk because they’re usually well-fed and high import prices mean lower consumption, areas of particular concern include parts of Bangladesh, China, Nepal, the Philippines, Thailand and Vietnam.
Of course, the industry is concerned that their product is now being labeled as “deadly,” but according to Spencer, ongoing research is looking for ways to use its glucose-lowering agents to fight metabolic syndrome that leads to diabetes and stroke. That is something lychee lovers can look forward to – after a good meal.