While three children died at Kejriwal hospital, another died at Sri Krishna Medical College and Hospital in Muzaffarpur during the past 24 hours, they said.
Around 30 others were still being treated at the two hospitals, sources said. At least 22 children below the age of six years have died and 35 others hospitalised due to the disease during the past one week in Bihar's Muzaffarpur district till yesterday, officials said.
The state health department has sent a team of experts from Regional Malaria Research Institute (RMRI) in Patna to the district. The team had already collected the blood samples and returned to the state capital, Principal secretary (health), Amarjeet Sinha said.
The blood samples were sent to a specialised laboratory in Pune for examination, he said.
Meanwhile, Chief Minister Nitish Kumar has urged Union Health Minister Ghulam Nabi Azad to dispatch a central team of medical experts to diagnose the disease and work out the prevention immediately.