In June 2019, an outbreak of acute encephalitis syndrome (AES) occurred in Muzaffarpur and the adjoining districts in Bihar state of India resulting in deaths of more than 150 children, mainly due to hypoglycemia. In subsequent months more cases and deaths were reported. The cause of outbreak is unclear. Malnutrition, climate, hygiene, inadequate health facilities, and lack of awareness are considered as contributing factors. The lychee fruit toxins are also cited as plausible cause of AES.