Waking up to MCPG toxin’s role in causing litchi mystery disease

litchi1There is evidence that as late as March 2014, Delhi’s National Centre for Disease Control, India (NCDC) and Centres for Disease Control and Prevention, Atlanta (CDC) researchers were in the dark about the possible role of methylenecyclopropylglycine (MCPG) toxin present in litchi in causing illness in children aged 15 years or younger in Muzaffarpur, Bihar and killing many children each year between May and June.

Scientists from NCDC and CDC had published a paper on January 30 in the journal Lancet Global Health wherein they state that consumption of litchi, which has the MCPG toxin, and skipping evening meal result in very low blood glucose level (less than 70 mg/dL) and acute encephalopathy and causes death in many cases.

It has now come to light that an article in NCDC’s July-September 2013 newsletter and a March 2014 presentation (Summary of 2013 investigation on acute encephalopathy outbreak) made on behalf of the NCDC-CDC surveillance team about the litchi mystery disease do not make any mention of MCPG toxin present in litchi and its possible role in causing illness. The article is written by Dr. Padmini Srikantiah of CDC Atlanta and the corresponding author of the Lancet paper.

According to the article in the July-September 2013 newsletter, the focus of the investigation during May-July 2013 was on the role of several viruses. There is no mention of MCPG toxin present in litchi or any investigation of its role in causing the illness. Even the March 2014 presentation does not mention MCPG toxin.

But two months after Dr. T. Jacob John, a virologist who was earlier attached to the Christian Medical College, (CMC) Vellore and his team, published a paper on May 10 in the journal Current Science hypothesising that MCPG in litchi may be causing the illness, an article in the July-September 2014 newsletter cites the possible role of MCPG. The article is written by Dr. Srikantiah and Aakash Shrivastava, who is the first author of the January 30 Lancet paper.

The 2014 article says: “One specific hypothesis generated from the 2013 findings included the potential presence of a toxin (MCPG) with hypoglycemic activity that is found in the litchi seed.” They also cite MCPG’s “potential” to cause acute hypoglycemia and encephalopathy in animals, akin to ackee poisoning seen in the Caribbean.

All the details about the MCPG toxin mentioned by the Lancet authors in the 2014 newsletter article have already been stated in the May 2014 paper by Dr. John and Dr. Mukul Das from the Indian Institute of Toxicology Research, Lucknow.

“This fits with my assessment that they got the idea from us,” Dr. John says. Dr. Srikantiah and Dr. Shrivastava did not respond to emails.

In a paper published in January 2015 in Morbidity and Mortality Weekly Report (MMWR), the authors of the Lancet paper state: “In Muzaffarpur, MCPG is hypothesized to cause acute hypoglycemia and illness”. However, the MMWR paper does not cite the May and August 2014 papers in Current Science, where the hypothesis of MCPG toxin in litchi possibly causing the illness was the first published by Dr. John’s team.

Published in The Hindu on February 11, 2017