It was reported that fifteen children have died in the past few days in a fresh outbreak of viral encephalitis in India's Uttar Pradesh state, taking this year's toll to 358 and over 6,500 children have died of encephalitis in India since the first case was detected in 1978.

The disease usually occurs during the monsoon season in Gorakhpur and adjoining areas and children are mostly affected.

More than 200 patients are still being treated at government hospitals.

Gorakhpur and adjoining districts which border Nepal in the foothills of the Himalayas are low-lying and prone to floods, providing a breeding ground for mosquitoes which commonly transmit the virus.

Doctors say affected patients come from between 10 and 12 districts in the region, and are mostly the rural poor.

The diseases cause headaches and vomiting and can lead to coma, brain dysfunction, seizure and inflammation of the heart and kidney.

Until 2005, doctors say that the majority of deaths were caused by Japanese encephalitis, a mosquito-borne virus.

But in the past seven years, children have been dying of other forms of viral encephalitis, the exact cause of which is unclear.

Doctors say children between the age of six months and 15 years are the worst affected.

A fifth of the children who survive have to live with neurological weaknesses, doctors say.

The government says it has tried to check the regular outbreak of encephalitis in the region and last week, India launched a vaccine against Japanese encephalitis as part of a national programme to fight the virus.