The fatal 'mystery fever' on Tuesday claimed one more life in Bihar's Muzaffarpur district, taking the death toll to 46, even as ambiguity still prevails over the disease with scientists ruling out encephalitis.

Chief Medical Officer K P Singh said one more child died at Kejriwal hospital during the day.

Two more children were being treated at the Srikrishna Medical College Hospital and the Kejriwal hospital, he said.

A central team which visited the hospitals last week had initially diagnosed the disease as encephalitis and sent the blood samples to Pune's National Institute of Virology for further tests.

NIV scientists, however, in a report to district magistrate S K Mall, ruled out Japanese encephalitis, Chandipura Virus encephalitis and Nipah virus encephalitis in the nine samples they tested.

As a precautionary measure, Methylene and DDT were being sprayed on a large-scale in the 63 affected villages, officials said.

"At present, we are just resorting to symptomatic treatment," Dr Braj Mohan, Head of Paediatrics at the Srikrishna Medical College Hospital, said.