08/06/2021
The term acute encephalitis syndrome (AES) was coined by the WHO in 2008.
The symptoms of AES include an acute onset of fever and associated clinical neurological manifestations such as mental confusion, disorientation, delirium, convulsions, or coma.
Early symptoms include headaches and vomiting, along with sudden hypoglycemia (drops in blood sugar levels), but may lead to coma, brain dysfunctions, and inflammation of the heart and lungs. The severe hypoglycemia can cause death. The syndrome is locally known as Chamki Bukhar in Bihar.
Cause s
The cause of the outbreak is unclear.
AES can be caused by different microorganisms including virus, bacteria, fungi, parasites and spirochetes, as well as chemicals and toxins. AES mostly affects children below 15. In India, AES was chiefly associated with Japanese encephalitis virus (JEV) before 1975. The JEV cases and outbreaks became more frequent and endemic regions developed between 1975 and 1999. After 1999, non-JEV cases and outbreaks of AES were increasingly reported caused by other viruses including Chandipura virus (CHPV), Nipah virus (NiV), and enteroviruses. After 2012, it is observed that the cause shifting to JEV.
High temperature
humidity
malnutrition
poor hygiene
and lack of awareness are known aggravating factors of AES
Cases of AES tend to occur during the country's monsoon season. In June 2019, the temperature in Muzaffarpur had remained above 40 °C (104 °F) and the rains were delayed which might have aggravated the situation. Poverty and malnutrition is widespread among children in the region. Malnourished children lack a buffer stock of sugar as glycogen in the liver which puts them at higher risk of hypoglycemia.
Lychee fruits, which naturally include toxins related to encephalitis, are suspected to have been a contributing factor in the outbreak.
The region is the largest producer of lychee fruits in India. A 2014 study published in Lancet found that the methylene cyclopropyl acetic acid and hypoglycin A found in unripe lychee (Litchi chinensis) fruit can cause hypoglycemia and cited them as plausible cause of AES outbreaks. A diet heavy on unripe lychee fruits without having an otherwise full meal later in the day may put malnourished children at risk of hypoglycemia.
