The official death toll from Japanese encephalitis passed 500 on Wednesday in northern India where more than 2,000 children were fighting for their lives against the mosquito-borne disease. All but three of the dead were children, according to official figures, and doctors said many more deaths have gone unreported.
At least 40 more deaths were reported in the previous 24 hours in Uttar Pradesh state, adding to an earlier toll of 468, health officials said.
The encephalitis outbreak which erupted at the end of July has been centred in Gorakhpur, close to the border with Nepal, where more than 400 have died, a spokeswoman for the government's epidemic health control room told AFP.
"We are still computing the casualty figures but the maximum number of deaths have occurred in Gorakhpur," she said, asking not to be named.
Some 2,100 patients were battling encephalitis in various hospitals across Uttar Pradesh, India's most populous state with 180 million people.
The illness has been reported in 25 of the 70 districts of the state.
"This is a man-made disaster," said T.N. Dhole, a senior microbiologist at the state-owned Sanjay Gandhi Post-Graduate Institute in state capital Lucknow.
Worst-hit Gorakhpur district is crowded with 3.86 million people, Dhole said, adding 20 percent of them were in the "vulnerable" age group."
"The environment is dirty and the situation has been compounded by government neglect," Dhole said.
"It's too late to do anything except for massive fogging (spraying of insecticides) in these areas," he said. "But the state government is just planning what to do. They just don't have the money."