Cause of AES that has killed over 100 children in Bihar remains unknown
AES cases in Bihar’s litchi-cultivation region were misdiagnosed as Japanese encephalitis (JE) till late 1990s since the symptoms and the seasonal outbreak of the two diseases are similar.Updated: Jun 18, 2019 07:48 IST
The Acute Encephalitis Syndrome (AES), which has killed over 100 children in Bihar’s Muzaffarpur, preys on poor and malnourished children.
AES cases in Bihar’s litchi-cultivation region were misdiagnosed as Japanese encephalitis (JE) till late 1990s since the symptoms and the seasonal outbreak of the two diseases are similar.
JE cases have dropped drastically since India started vaccinating at-risk populations against the disease in 2006. The AES cases and deaths now outstrip JE. In 2018, AES infected 11,388 and killed 636. As many as 1,678 JE cases and 182 deaths were also reported that year.
Muzaffarpur’s Sri Krishna Medical College and Hospital paediatrician Dr G S Shahni published a paper in 2012, stating that all 55 AES samples sent to Pune’s National Institute of Virology had tested negative for any virus. This established the non-infectious origin of the disease. He proposed heat stroke as the probable reason for the syndrome.
In 2013, Dr T Jacob John of Christian Medical College, Vellore, proposed the hypothesis of toxic origin found in unripe lychee seeds. He proposed that the toxin present in lychee (methylene cyclopropyl glycine, or MCPG) could possibly be the reason for these symptoms in severely malnourished children, who develop severe hypoglycaemia and go into coma and shock, which leads to death. Hypoglycaemia is aggravated by heat, which causes acute complications, say other doctors.
In 2014, the Centers for Disease Control and Prevention, United States, conducted an investigation of 390 cases and found no confirmatory proof of any infection, which led them to call AES “non-infectious encephalopathy”.
The various non-infectious hypotheses proposed for this disease are pesticides/herbicides used to spray lychee orchards or agricultural fields; the toxin in lychee known as MCPG and hypoglycine, which cause hypoglycaemia in children who are starved, because of the lack of proper care by parents during peak litchi cultivation season.
A 2017 Lancet paper proposed all these theories behind the mysterious disease but ended up hinting at litchi toxin being the prime cause of the disease. But since the fruit is not just grown in Muzaffarpur, nor is intense heat confined to the region, acute malnutrition is likely to be the aggravating factor behind vulnerability of children to the disease.
The National Family Health Survey, 2015-16, pointed out a high rate of malnutrition in children under five in Bihar, manifested mainly through wasting (acute malnutrition ) and stunting (chronic malnutrition).