India on Monday marked three years since its last polio case was reported, a major milestone in eradicating the crippling disease.
The marker puts the country on course to being formally declared polio-free in March. The World Health Organization stills need to confirm there are no undetected cases before making the official declaration.
Polio is a vaccine-preventable disease that has been eradicated in most countries. But it still causes paralysis or death in some parts of the world, including Nigeria, Pakistan and Afghanistan.
Polio usually infects children under age 5 when they drink contaminated water. The virus attacks the central nervous system, causing paralysis, muscular atrophy, deformation and, in some cases, death.
"India was once thought to be the most difficult country in which to achieve polio eradication," Global Polio Eradication Initiative said in a statement.
Widespread poverty, dense population, poor sanitation, high levels of migration and a weak public health system made the task of reaching out to every child under age 5 that much more difficult.
Despite India's success against the disease, there are many people for whom the vaccination campaigns have come too late. Polio victims with withered, twisted limbs are a common sight on the streets of Indian cities.
Sonu Kumar did not have access to the polio vaccine when he was struck by the disease as a 10-year-old boy.
"My parents were very poor and couldn't afford medical treatment for me," said Kumar, who is paralyzed from the waist down. The 24-year-old begs outside a temple in central Delhi and uses a wheelchair to move around.
Some years ago, Kumar saw a TV advertisement by a charity organization offering free treatment for polio victims in a western Indian city. Doctors who examined him said it was too late for him to get medical help.
For India, the victory against polio is its second major health achievement. In 1980, it succeeded in eliminating smallpox through a sustained immunization campaign.
An army of nearly 2.5 million volunteers, doctors and medical workers carried out a rigorous campaign across the country to vaccinate children over a period of three years to wipe out the scourge. The number of polio cases came down from 741 in 2009 to 42 in 2010. The last case of polio was reported in eastern India in 2011.
In 2012, WHO removed India from a list of countries with active endemic wild polio transmission after it passed one year without registering any new cases.
Health officials remained concerned about the possibility of the virus entering the country from neighboring Pakistan, where a spate of cases has been reported. Indian health authorities have set up polio immunization booths at the two border crossings with Pakistan and all children who enter by road and train are being given vaccines.
Last month, New Delhi announced that travelers from Pakistan would have to show proof that they have been administered the oral polio vaccine at least six weeks prior to their departure for India. Travelers to India from Kenya also were told to get an additional dose of oral polio vaccine at least six weeks before they depart.
Although polio was eliminated in Kenya in 1984, some 10 cases were reported last year mostly in northern Kenya, where there is an influx of refugees.
India's health ministry was still waiting Monday for the last reports from different parts of the country to come in before making a formal declaration. However, Junior Home Minister R.P.N. Singh already tweeted: "Proud day for all of us as Indians ... India is polio free for three years."