NEW DELHI - India marked a year since its last new case of polio Friday, a major milestone in a country once considered the epicentre of the disease and one that gives hope the scourge can be eradicated worldwide.
There were 150,000 cases of the highly contagious virus in India in 1985,but the country has now gone 12 months since discovering a new case - in an 18-month-old girl in the eastern state of West Bengal.
India, which until recently accounted for half of all the polio cases in the world, is one of four countries - with Afghanistan, Pakistan and Nigeria - where the disease is still officially endemic.
But if all laboratory tests for the wild polio virus return negative in January, India will follow recent success stories Niger and Egypt and be removed from the endemic list by the World Health Organisation by mid-February.
There was cautious optimism in New Delhi as health workers and the government celebrated the milestone while stressing that the virus - which mainly affects young children and can cause paralysis and deformed legs - could resurface at any time.
"We are excited and hopeful, at the same time, vigilant and alert," Health Minister Ghulam Nabi Azad said in a statement to mark the occasion.
Since the last new case was reported on January 13 last year, another vast effort to immunise children has seen 2.3 million vaccinators travel across India to deliver 900 million doses.
"What India has achieved is reaching a first milestone in a very important process," Lieven Desomer, head of the polio unit at UN children's agency UNICEF in India, told AFP.
"It's not the end of the road, but it's something to be very proud of.
"Achieving this milestone is going to instil confidence in polio eradication efforts globally. If it can be done here, it can be done everywhere."
India will only be judged to have eradicated the disease if it stays polio-free for another two years.
Polio was one of the most feared diseases of the 20th century for children, but it has been successfully controlled through a programme of vaccination in most countries.
UNICEF figures show India, where the crowded and impoverished northern states of Uttar Pradesh and Bihar have historically been the hotspots, had 150,000 cases of the disease in 1985.
This had fallen to about 6,000 in 1991, to 741 in 2009 and to just 42 in 2010.
The decline worldwide, through a concerted effort by governments, UN agencies and private donors, has raised hopes polio might go the way of smallpox, the only disease successfully eradicated globally.
"If we can achieve that it will be of great benefit to the children of the world," said Desomer. "But the last bit is the toughest."
The precipitous fall in polio cases in India is attributed by UNICEF to a huge campaign by the Indian government, which is often pilloried by critics for its failure to tackle malnutrition and poor sanitation.
It represents a rare public health success story in a country where four in 10 children under five are underweight due to malnutrition and only a third of people have access to toilets.
"India's success (with polio) is arguably its greatest public health achievement," said World Health Organisation Director-General Margaret Chan.
Desomer estimated the Indian government contribution to polio eradication to be about $2 billion over the last 10-15 years.
The other two important factors in combating the virus were a new, more efficient oral vaccine introduced in 2010 and partnership comprising the government, private donors and UN agencies.
He singled out the Rotary International charity for helping kickstart efforts to eradicate polio in the 1980s, as well as more recent donations from the Bill and Melinda Gates Foundation.