More than 110 children have died this month from encephalitis, a type of brain disease that has afflicted the state of Bihar for more than two decades. Health experts have long been dumbfounded by the root of the encephalitis outbreak, commonly known as chamki bukhar or brain fever, in Bihar’s Muzaffarpur district.

So far, more than 535 cases of encephalitis have been reported in Muzaffarpur. As many as 166 people have been admitted in hospitals.

A multi-disciplinary group created by the Union health ministry said that it will look at the socio-economic and nutrition profiles of the households that have reported the cases. The group will also focus on issues such as the ongoing heat wave and the reported high percentage of hypoglycemia in the children who have died, and the health infrastructure.

What is AES?

Acute encephalitis syndrome (AES) is characterised as an acute onset of fever and a change in mental status (mental confusion, disorientation, delirium or coma). Early symptoms can be similar to those of flu, with patients suffering from high temperatures or headaches. But symptoms can worsen within hours, and can include serious complications like seizures, paralysis and coma. The disease most commonly affects children and young adults, says the National Health Portal (NHP).

Viruses are the main causative agents in AES cases, although other sources such as bacteria, fungi, parasites, spirochetes, chemicals, toxins and non-infectious agents have also been reported over the past few decades.

Japanese encephalitis virus (JEV) is the major cause of AES in India (ranging from 5 per cent to 35 per cent). Herpes simplex virus, Influenza A virus, West Nile virus, Chandipura virus, mumps, measles, dengue, Parvovirus B4, enteroviruses, Epstein-Barr virus and scrub typhus, S.pneumoniae are the other causes of AES in sporadic and outbreak form in India. Nipah virus, Zika virus are also found as causative agents for AES. The etiology in a large number of AES cases still remains unidentified.

AES due to JEV was clinically diagnosed in India for the first time in 1955 in Tamil Nadu. During 2018, 10,485 AES cases and 632 deaths were reported from 17 states to the National Vector Borne Diseases Control Programme (NVBDCP) in India, with a case fatality rate around 6 per cent, the NHP said.

Doctors and officials are testing children for a variety of conditions and many are divided on the cause of the disease. But dehydration as a heat wave sweeps India could be to blame, according to medical staff in Muzaffarpur.

How is litchi fruit connected to AES?

The AES cases in Muzaffarpur and adjoining litchi producing districts have been observed mostly during April to June, particularly in children who are undernourished with a history of visiting litchi orchards. Muzaffarpur is a major hub for growing litchis, which ripen at this time of year.

Researchers who conducted a study of 390 children who fell sick in 2014 in Muzaffarpur said that litchis contained methylene cyclopropyl-glycine, which can disrupt metabolism, lowering blood sugar levels. If a malnourished child consumes litchi, it can trigger hypoglycaemia or very low level of blood sugar.

Retired virologist T. Jacob John also raised the possibility that encephalitis cases in Muzaffarpur could be associated with litchis in a 2014 study published by Indian science journal Current Science.

The study by India’s National Centre for Disease Control and the US Centers for Disease Control and Prevention added that when the brain lacks glucose, it turns to other sources of energy, which are rapidly depleted, eventually pushing people into coma. Because of the toxin in litchi, the body’s natural mechanism to correct low blood glucose level is prevented, thus leading to a drop in fuel supply to the brain.

Experts says litchi does not cause any harm in well-nourished children, but only in malnourished children who had eaten it the previous day and had gone to bed with an empty stomach.

What are the measures taken by the govt?

Considering the complexity of the AES problem and to reduce morbidity, mortality and disability in children due to JE/AES, the government has developed a National Programme for Prevention and Control of JE/AES (NPPCJA), a multi-pronged strategy with convergence of the concerned ministries.

The major objectives of the NPPCJA are...

* Strengthen and expand JE vaccination in affected districts. JE mass vaccination campaign is done using a single dose of live attenuated vaccine (SA-14-14-2) in children between 1 and 15 years of age followed by routine immunisation. Two doses of JE vaccination are provided under universal immunisation, first at 9-12 months along with measles and second with DPT booster at 16-24 months in JE endemic areas. JE vaccination of adult population is also started in selected districts of few endemic states.

* Strengthen surveillance, vector control, case management and timely referral of serious and complicated cases.

* Increase access to safe drinking water and proper sanitation facilities to the target population in affected rural and urban areas.

* Estimate disability burden due to JE/AES, and to provide for adequate facilities for physical, medical, neurological and social rehabilitation.

* Improve nutritional status of children at risk of JE/AES.