"Three blocks in the district have been declared high risk zones," he said, adding that the H5N1 virus was detected in chickens last week.
Kumar added that during a visit to Purnea Wednesday, he had directed officials to launch a continuous sanitation drive in the neighbouring districts too.
Purnea District Magistrate Manish Verma said culling operation had almost been completed for now.
"Now the situation is under control but more birds would be culled as a precautionary step. The administration had issued bird flu alert as a preventive measure. We are fully prepared to deal with an outbreak," he said.
Verma said 15 teams of officials have been formed to check the spread of bird flu and ensure that birds and eggs from the district were not sent outside Purnea, about 350 km from Patna.
An official of the animal husbandry department said the state government had also alerted neighbouring districts of Kishanganj, Katihar and Araria to take emergency measures.