India has marked three years since its last reported polio case, putting the country on course to being formally declared free of the disease later this year.
India has made great strides against polio in recent years through a rigorous vaccination campaign. But for many in the country where polio victims with withered, twisted limbs are a common sight on the streets, the advances have come too late.
Polio usually infects children under five 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.
The milestone was significant, but the World Health Organisation stills need to confirm there are no undetected cases before making the official declaration that India is polio-free in March.
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 five that much more difficult.
An army of nearly 2.5 million volunteers, doctors and medical workers carried out a campaign across the country to vaccinate children over 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 neighbouring Pakistan. Indian health authorities have set up polio immunisation booths at the two border crossings with Pakistan and all children who enter by road and train are being given vaccines.