What explains the mysterious deaths of children in Muzaffarpur? How is it connected to litchis? And is this really new information?
Litchis. Credit: Reuters
New Delhi: Over the last few days, media outlets across the world, from India, the US and France, have carried reports on Bihar’s ‘killer litchis’. The reports are based on an article published in the medical journal The Lancet Global Health, which details the results of an investigation conducted by India’s National Centre for Disease Control (NCDC) and the the US Centers for Disease Control and Prevention (CDCP). The study claims to have finally discovered the cause for the sudden neurological illness faced by children in the state’s rural areas in the summer months, noticed every year since 1995. This was earlier seen as one of the world’s ‘most mysterious outbreaks‘, making finding the cause all the more newsworthy.
Starting around mid-May every year and going on till the monsoon, children who were seen to be perfectly healthy the day before would fall ill suddenly, often in the middle of the night, having seizures and even slipping into a coma. Parents would then take them to local hospitals – where the team from the NCDC and the US CDCP conducted their study – and where doctors would work to keep patients hydrated but were unable to do much as the cause of the illness was unknown. According to the article, close to a third of the children the team saw in a Muzaffarpur hospital in 2014 died of the illness.
The disease has been known for its high mortality rate and had previously been seen as a form of encephalitis because of similar symptoms. The cause has been variously ascribed to pesticides used in the nearby litchi orchards, malnutrition, infections carried by rodents and insects and heat stroke.
The discovery
The region where this annual mystery outbreak takes place is known for its litchis, and it turns out that’s where the key to the mystery lay. The fruit’s seed contains natural methylenecyclopropylglycine (MCPG), a homologue of hypoglycin A, according to the study. MCPG limits the body’s ability to produce glucose, leading to low blood sugar levels. Unripe litchis are most dangerous and contain higher levels of this substance. In a large number of cases, children had not eaten dinner after they had consumed litchis, meaning that the body had nothing with which to counteract the effect of the litchis.
Four clues led the scientists to link the illness with the fruit and this particular substance in it: the children showed no sign of having an infection; most of the victims had low blood sugar levels when they reached medical centres; previous knowledge of an outbreak caused by the ackee fruit in the West Indies that contains hypoglycin A; and the fact that affected children had huge metabolic imbalances. And the investigators had found their answer:
To prevent illness and save lives in Muzaffarpur, we recommended minimising litchi consumption among young children, ensuring children in the area receive an evening meal throughout the outbreak season, and implementing rapid glucose correction for children with suspected illness.
The controversy
But is this discovery really as path-breaking as the Lancet article makes it out to be? A scientist who worked on the disease before has said that the article has raised ethical questions on whether the authors have properly cited the influence of his work on theirs. “Not giving due credit for work done by others is not acceptable in science,” Dr T. Jacob John, a virologist who was earlier attached to the Christian Medical College, Vellore, told The Hindu. “They quote our study but don’t honestly say what we have found. If they did that then they can’t claim originality. They have done a large case-control study but borrowed all important information connected with the illness from us.”
John and his team had published an article in the journal Current Science in 2014 that laid out the similarities between the ackee fruit and litchis, also showing similarities between the illness outbreak caused by the ackee and what was being observed in Muzaffarpur. The fact that skipping an evening meal could intensify the problem was also highlighted in his paper.
The authors have refuted this claim, saying that they cited John’s papers and added new information to what was already found. “There are a few key findings in our study that have not been, to our knowledge, reported previously. First: the evidence of the metabolites of hypoglycin A and MCPG in the specimens of affected children, and the demonstrated metabolic abnormalities that resulted due to the effects of these toxins. And, second, a statistically significant epidemiological association between illness and litchi consumption, as well as the modifying effect of the absence of an evening meal,” Dr Padmini Srikantiah, of the US CDCP, Atlanta, told The Hindu.
Several of the claims made in the Lancet paper, though, do seem to have already existed in John’s paper: the lack of infection, the low blood sugar, the inconsistent presence of fever. “Our hypothesis is that the Muzaffarpur illness is caused by MCPG in litchi,” said the paper. After their observations, John said, the Bihar government introduced interventions such as telling parents to try and restrict litchi consumption and ensure that children ate an evening meal. He and his team also injected dextrose into children when they reached the hospital with symptoms, leading to a reduction in deaths, he added.
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