More than 300 people have died from an encephalitis outbreak since July. Despite all efforts to control the disease, the number of people who have been affected has increased, health officials said on Tuesday.

Top medical official of Uttar Pradesh in the northern state of Anant Kumar Singh said, there were more than 10 million children who were vaccinated against the killer virus.

"In total, 42 districts are prone to the virus, but due to a shortage of vaccine, only 18 have been fully covered," Singh said.

India is one of the most populous countries in the world with 180 million residents and also one of the world's poorest countries. The encephalitis disease claimed more than 400 lives in 2006 and 1,400 in 2005. Some of the effects of the virus include brain damage.

Encephalitis or brain fever virus often passed from pigs to human beings. It is endemic to the eastern part of the state.