AES patients at Sri Krishna Medical College and Hospital, Muzaffarpur on June 23. (Express photo: Ritesh Shukla) AES patients at Sri Krishna Medical College and Hospital, Muzaffarpur on June 23. (Express photo: Ritesh Shukla)

Muzaffarpur in Bihar is famous for litchis and infamous for children dying due to annual seasonal brain disease outbreaks. The common brain diseases in children with high mortality are meningitis, encephalitis and encephalopathy. These three have clear-cut differences and very different treatments. Trained paediatricians know how to distinguish the three. If diagnostic criteria are not applied for various reasons, then the three are not distinguished by doctors. That is when an easy diagnostic term covering all three — “acute encephalitis syndrome” (AES) — becomes handy.

Meningitis is most unlikely in large annual seasonal outbreaks. Encephalitis outbreaks in various parts of India are caused by the Japanese Encephalitis (JE) virus, transmitted by Culex mosquitos. The pre-monsoon months of April-May-June have low mosquito density so JE can also be readily excluded. JE occurs in other districts in Bihar, but not in Muzaffarpur, as the ecology is not conducive for Culex breeding.

The disease description that one, only under-nourished children are affected; two, only children between two and 10 years are affected and three, the onset of convulsions and unconsciousness is always between 4 am and 7 am are clear pointers against any virus infection causing the disease. Viruses, including JE, do not respect nutritional status, age and diurnal rhythm.

This inevitably leads us to conclude that the outbreak disease is encephalopathy. The early morning onset and frequent finding of low blood glucose level (hypoglycaemia) point to a biochemical disease related to glucose metabolism. Several hours after food intake (early morning) is when the body tends to develop hypoglycaemia.

If the fasting interval is longer than 6-7 hours, because some children were not given a night meal, the situation becomes more severe. That was a common story when I investigated the problem. Malnourished children do not have glucose reserves in the liver, which makes matters worse. In 2016 and 2017, a simple intervention — all grass root health workers consistently teaching rural families not to allow children sleep without a cooked meal — had brought down the case numbers drastically. I suspect this was not sustained in 2018 and 2019.

The disease is not simple hypoglycaemia. In addition, there is brain swelling caused by toxic damage to brain cells — encephalopathy, specifically, “hypoglycaemic encephalopathy”. The toxic substance for brain cells are amino-acids made within the body while attempting to synthesise glucose from fatty acids, but blocked halfway by an external stimulus. When fatty acid oxidation is blocked, amino-acids accumulate and cause encephalopathy.

If doctors had treated the sick and unconscious children with a 10 per cent glucose infusion within four hours of onset, all the children would have recovered. In 2013, all 32 primary health centre doctors in the area were taught this life-saving remedy. Before giving glucose they had to collect a blood sample to measure blood glucose level just to confirm that the child had hypoglycaemia. Doctors were used to 5 per cent glucose to correct hypoglycaemia. The high blood glucose level created with 10 per cent glucose actually turns off the fatty acid oxidation cycle immediately, so no more amino acids accumulate to further damage brain cells.

This year, apparently, many doctors were new and were not taught about the urgency to give 10 per cent glucose. Many children were referred to Muzaffarpur medical college, and the long delay in reaching there resulted in many deaths. Prevention is simple, as is treatment.

Where do litchis fit in? The external stimulus that blocks the fatty acid oxidation cycle for glucose synthesis is methylene cyclo-propyl glycine, present in the edible pulp of lychees. Normally-nourished children or adults suffer no adverse effects from litchis. Only when malnutrition and skipping the night meal come together does the litchi eaten the previous day become the last straw.

The socio-behavioural risk factors are the real cause of the outbreak. Where litchi orchards and gross malnutrition are not superimposed, like in Punjab and Haryana, hypoglycemic encephalopathy is not a problem. Blame the overload on the camel more than the last straw. Blame chronic malnutrition and prolonged fasting for the disease more than the litchi.

The writer, a paediatrician-cum-virologist, has been president of Indian Academy of Pediatrics and retired from the Christian Medical College, Vellore. He investigated the Muzaffarpur disease in 2012, 2013 and 2014

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