15 children have succumbed to suspected encephalitis in the last week in Bihar's Muzaffarpur and Gaya districts, report said.
The mosquito-borne disease, which claimed nearly 150 lives last year, has returned with a vengeance.
Eleven children have died in Muzaffarpur and four in Gaya. Over two dozen children have been admitted to hospitals in both places.
According to officials, 24 children have been admitted for treatment in hospitals in Muzaffarpur, about 70 km from here.
Muzaffarpur civil surgeon Gayan Bhusan said the children died after contracting high fever followed by convulsions.
"Nearly half a dozen children are battling for life in one Gaya," said A.K. Ravi, a child specialist at one hospital.
Encephalitis is a condition of acute inflammation of the brain resulting either from a viral infection or when the body's immune system mistakenly attacks the brain tissue.