Children Dying Beneath the Lychee Trees of Bihar, India

Lychee orchards in Muzaffarpur（Image source：Tanmay Tarun， CC BY-SA 4.0 ）

In Muzaffarpur, a district in the Indian state of Bihar known for its extensive orchards of lychee (Litchi chinensis), the region has long been celebrated as the "Lychee Kingdom." The arrival of summer should normally bring the sweetness of ripening fruit and the joy of harvest. Yet over the past decade, this season has also become associated with a troubling pattern of illness.

The tragedy began with children who suddenly developed severe symptoms in the early morning hours. They would appear confused and disoriented, accompanied by fever, seizures, and vomiting. Even after being rushed to hospitals, many young lives were lost within a short time. The first major incident occurred in 2011, when fourteen children died from an unknown cause. In 2014 the disaster struck again, claiming even more lives. After extensive investigation, researchers eventually identified the likely culprit: the locally grown lychee fruit itself. The condition became popularly known as “lychee illness,” and in medical terms it is described as MCPG-associated encephalopathy.

Behind this tragedy lies a toxin naturally present in lychee fruit: methylene cyclopropyl-glycine (MCPG). This compound is found primarily in unripe lychee pulp and seeds. Inside the human body, MCPG interferes with two key metabolic processes: gluconeogenesis and fatty-acid β-oxidation. For children who are already malnourished and possess very limited glycogen reserves in the liver, this disruption can be devastating.

Because their bodies lack sufficient glycogen stores, and because MCPG blocks the production of new glucose, blood sugar levels can fall rapidly. Severe hypoglycemia then develops, leading to symptoms such as coma, seizures, and encephalopathy, which may cause death within a short time. Lychees also contain another compound, hypoglycin A, which produces a similar metabolic effect, although its concentration in lychee is extremely low and is not considered the primary cause of the illness.

Molecular structure of MCPG, Courtesy ofAsthana S et al

Yet the question remained: was lychee alone responsible?

A research team from India's National Institute of Nutrition conducted a comprehensive investigation. They collected lychee samples and urine samples from affected children in Muzaffarpur in an attempt to unravel the mystery behind these seasonal deaths. Using thin-layer chromatography and mass spectrometry, they analyzed the fruit pulp, peel, and seeds. The results clearly confirmed the presence of MCPG in multiple parts of the fruit.

However, the investigation revealed another troubling factor. High concentrations of organophosphate pesticide metabolites were detected in the urine of the children. One metabolite in particular, diethyl phosphate (DEP), appeared at extremely high levels. In one case, the DEP concentration reached 3,327 ng/ml—far exceeding typical human exposure levels considered safe.

This discovery suggested that the children had not only ingested lychee toxins but had also been exposed to significant pesticide contamination. Chemicals such as cypermethrin, chlorpyrifos, and imidacloprid are widely used in lychee orchards to protect the fruit from bats and insects. In many cases the fruit is harvested before sufficient time has passed for pesticide residues to degrade, allowing these compounds to enter the body when the fruit is eaten.

In some cases, exposure may have occurred even more directly. Several of the affected children—or members of their families—worked in lychee orchards and were involved in spraying or handling pesticides. Clothing, skin contact, and the surrounding environment could therefore serve as secondary sources of pesticide exposure. Among fourteen documented cases, three children had personally applied pesticides in the orchards, and eight lived with family members who worked with agricultural chemicals. The correlation between pesticide exposure and illness was therefore striking.

Researchers proposed that these two factors may act together. When MCPG disrupts the body's ability to maintain blood glucose levels, the nervous system becomes highly vulnerable. At the same time, neurotoxic compounds in pesticides can further damage neural function. Organophosphate pesticides inhibit the enzyme acetylcholinesterase, causing the neurotransmitter acetylcholine to accumulate in nerve synapses. This leads to excessive neural stimulation, seizures, and potentially respiratory paralysis.

For malnourished children whose liver function and metabolic reserves are still developing, the combined effect of hypoglycemia and neurotoxic pesticide exposure can produce a deadly outcome.

Experimental studies examining MCPG toxicity in mice have also been used to estimate safe levels of lychee consumption. When these results are translated into approximate human equivalents, the tolerable intake for children aged one to five years corresponds to roughly 0.59 to 1.17 kilograms of lychee pulp per day. For a 60-kilogram adult, the estimated safe upper limit is approximately 3.9 kilograms of lychee pulp per day.

In light of these findings, researchers have called for several preventive measures in Muzaffarpur and other lychee-growing regions. Children should be discouraged from eating unripe lychees, especially on an empty stomach. Agricultural authorities should enforce strict regulations regarding pesticide application and ensure adequate intervals between pesticide spraying and fruit harvesting. Equally important is improving the nutritional status of children in impoverished communities, allowing them to maintain sufficient glycogen reserves and better withstand metabolic stress caused by toxins such as MCPG.

It is also important to clarify a point that sometimes confuses readers: the lychees involved in this event are the same species commonly consumed worldwide, Litchi chinensis. The difference lies not in the species itself but in factors such as fruit maturity, nutritional status of the children, and environmental exposure to pesticides.

Author: Shui-Ye You

References:

1. Sinha SN et al. (2020). A recurring disease outbreak following litchi fruit consumption among children in Muzaffarpur, Bihar—A comprehensive investigation on factors of toxicity. PLOS ONE.

2. Tripathi J et al. (2019). Determination of tolerable dose of litchi fruit considering reported hypoglycin A and MCPG contents through biochemical and histopathological evaluations in mice. Current Science.