By Geeta Pandey
BBC News, Delhi
Officials in India say they are worried over the growing number of polio cases in the country.
A health worker in India gives polio drops to a baby
They say 119 new cases have been reported in the past month, taking the total number of infections to 416.
The disease, which attacks children under five years, affects the nervous system and can result in paralysis.
With almost one-third of the total 1,449 cases in the world, India is seen as a big stumbling block in the struggle against polio.
Particularly dismal has been the case of the northern state of Uttar Pradesh where 358 polio cases have been recorded.
Earlier it was believed that the virus was confined to some pockets of western Uttar Pradesh, but health ministry officials say now it has spread to 41 of the 70 districts in the state.
The neighbouring state of Bihar comes second with 28 infections.
With new cases being reported from the capital, Delhi, and in the western city of Mumbai, experts say the virus has now travelled out of the region and is afflicting children in the whole of northern and western India.
Officials blame it on people moving out of the worst-affected states to other parts of the country.
"It is the migrants who have taken it out of Bihar and Uttar Pradesh. All the cases found in Delhi or Mumbai can be linked to the state as these children had travelled there in the last few months," a spokesman for the health ministry told the BBC.
Experts say the spread of the virus is dependent on three factors - lack of nutrition, environmental causes and poor hygiene and sanitation.
They say almost all the cases have been reported from areas where sanitation is an issue and most of the children belong to poor families unable to give them a nutritious diet.
In the developed countries, a child needs three doses for immunisation. But in India, a child may need up to 10 doses, they say.
Officials have confirmed that one child in Delhi has contracted the virus despite being given nine shots of the vaccine.
"We're still in the process of examining how that happened, but she may have had diarrhoea at the time she was given the vaccine. In such a situation, her body will expel the medicine and it will not have the desired affect," says the health ministry spokesman.
Last month, India's health minister held an emergency meeting of officials from the states affected by the disease.
Last year, only 66 cases of polio were recorded in India and officials say the current numbers are giving them sleepless nights.
A huge pulse polio campaign is being launched in November and officials say they hope the virus will be contained soon.
Although polio has no cure, it is easily preventable through vaccine.
Before 1988, when the World Health Organisation (WHO) launched a global anti-polio campaign, there were more than 350,000 cases worldwide.
Today the disease has been eradicated in much of the world but is still found in some countries.
A strain of the disease, which originated in Uttar Pradesh state, has also travelled to the neighbouring countries of Nepal and Bangladesh.
It has also infected people in faraway African countries like Angola, Namibia and Congo.
India's failure to contain the virus has caused serious concern to the World Health Organisation in Geneva. It has written to India's health minister, seeking a meeting with him.