NEW DELHI (AFP) - At least 215 people, mostly children, have died in an outbreak of Japanese encephalitis in an impoverished region of northern Indian and the death toll is likely to soar, officials said Saturday. Eastern parts of Indias most populous state are ravaged by encephalitis each year as malnourished children succumb to the virus which is transmitted by mosquitoes from pigs to humans but this is one of the worst outbreaks, officials said. Most of the deaths have occurred in the Gorakhpur district of Uttar Pradesh state since the monsoon struck the region in July, regional health officer UK Srivastava told AFP by telephone from Gorakhpur. The deaths of five more children on Friday pushed the toll to 211, with hundreds sick, some two to a bed, in hospitals in Gorakhpur, a deeply neglected area of 14m people, he said. A total of 1,299 patients had been admitted in hospitals until Friday in Gorakhpur, which is the epicentre of the outbreak, and more encephalitis patients are coming into our hospitals, Srivastava told AFP. We fear the total number of encephalitis cases will go up to at least 3,500 and the death rate will be at a ratio of around 20 percent, Srivastava said. Japanese encephalitis causes brain inflammation and can result in brain damage. Symptoms include headaches, seizures and fever. Health experts say 70m children nationwide are at risk of encephalitis. Unusually heavy monsoon rains coupled with overflowing rivers coursing through Gorakhpur are making it tougher for health workers battling encephalitis. We have begun spraying insecticides to wipe out populations of the culex mosquitos which transmits the disease and we are handing out chlorine to villagers to disinfect their drinking water supplies, Srivastava said. VS Nigam, in charge of Uttar Pradeshs encephalitis prevention programme, said a mammoth project to contain the disease ended with 35m children vaccinated in the states 34 districts. But as soon children are vaccinated against Japanese encephalitis, they fall sick with acute encephalitis syndrome because when one virus is suppressed by vaccines, others become dominant, he said from the state capital Lucknow. Its a large challenge, Nigam said, adding state health experts would meet national virologists next week in New Delhi for talks on way to prevent future outbreaks.