Additional Secretary (Health) R P Ojha said 12 children died in the Sri Krishna Medical College and Hospital and the charitable Kejriwal hospital at Muzaffarpur.
Altogether 92 children were admitted in various hospitals to symptoms of the AES, the health official said.
The details of those children undergoing treatment at the primary health centres, sub-primary health centres and Sadar hospitals were not available, Ojha said.
A team of National Institute of Virology, Pune, had visited the state to study the AES and taken cerebrospinal fluid and blood samples of the patients from Gaya, Muzaffarpur and Patna, he said, adding, it will submit its report in 10 days.
A central team of experts also visited Muzaffarpur and surrounding areas and studied the socio-economic situation and lifestyle of the people, besides hygiene and amenities, he said.
The state government has also set up patrolling teams in the AES-affected districts to provide help to the patients, he said.