(CBS/AP) India once had a big polio problem. This Friday, the country will celebrate a full year since its last reported case of poliomyelitis.
And if no previously undisclosed cases of the crippling disease are discovered, India will no longer be considered endemic, leaving only Pakistan, Afghanistan and Nigeria on the list.
The news is a major achievement and morale boost to those who had begun to lose hope of ever defeating the disease, which the world had promised to eradicate by 2000.
"This is a game changer in a huge way," said Bruce Aylward, head of the World Health Organization's global polio campaign.
It also helps India - which bills itself as one of the world's emerging powers - shed the embarrassing link to a disease associated with poverty and chaos that most of the world had conquered long ago.
India's government has spent about $2.4 billion on the program to fight polio, and welcomes the milestone as a confirmation of its commitment.
"We are excited and hopeful. At the same time, vigilant and alert," Health Minister Ghulam Nabi Azad said in a statement. Azad warned that India still needs to push its vaccination campaign forward to ensure the elimination of any residual virus and prevent any spread from abroad.
The polio virus attacks the central nervous system, sometimes causing paralysis, muscular atrophy, deformation and, in some cases, death. It usually infects children in unsanitary conditions like India's. The country's dense population, high levels of migration and weak public health system had made India that "the perfect storm of polio," Aylward said. Even some vaccinated children fell ill with the virus because malnutrition and chronic diarrhea made their bodies too weak to properly process the oral vaccine.
In 2009, India had 741 cases. That plunged to 42 in 2010. Last year, there was a single case, which was the country's last reported polio victim.
Why the sudden success? Tighter monitoring has allowed health officials to quickly hit areas of outbreaks with emergency vaccinations. A new vaccine was also rolled out in 2010 that more powerfully targets the two remaining strains of the disease.
Philanthropist Bill Gates, whose foundation has made polio eradication a priority, hailed India's achievement as an example of the progress that can be made on difficult development problems.
"Polio can be stopped when countries combine the right elements: political will, quality immunization campaigns and an entire nation's determination. We must build on this historic moment and ensure that India's polio program continues to move full-steam ahead until eradication is achieved," he said in a statement.
Health officials want to make polio the second human disease eradicated, after smallpox. But while smallpox carriers were easy to find because everyone infected developed symptoms, only a tiny fraction of those infected with the polio virus ever contract the disease. So while no one in India is reported to have suffered from polio in a year, the virus - which travels through human waste - could still be lingering.
The country will not be certified as completely polio-free until at least three full years pass without a case. Public health advocates warn against complacency in the massive vaccination efforts.
"We are at a threshold. If we take a long step, we may be in trouble," said Dr. Yash Paul, a pediatrician in the northern city of Jaipur who was a member of the Indian Academy of Pediatrics' polio eradication committee until it was dismantled last year because the academy felt it was no longer needed.
The WHO program needs another $500 million to fund operations for the rest of the year, and some programs could run out of funding by March, he said.
"If we fail at this point, it's an issue of will," said Aylward.
More information about the global effort to eradicate polio can be found here.