Sixty years after the first successful polio vaccine trial, the disease has been wiped out in much of the world, but violence, conspiracy theories and lack of cash keep it from disappearing.
"The world is closer than ever to eradicating polio," said Oliver Rosenbauer, spokesman for the World Health Organization's Global Polio Eradication Initiative.
In 2012, there were just 223 infections worldwide, compared to 360,000 in 1988, when the United Nations launched a campaign to eliminate the highly contagious illness that causes paralysis and sometimes death, particularly in young children.
All but six of last year's cases were in three countries: Nigeria (122), Pakistan (58) and Afghanistan (37), according to the WHO.
The success seen in India, which has had no new cases in two years, shows that eradicating polio is "technically feasible," Rosenbauer told AFP.
"So now the question is, does the world want to do this? Does it have enough political will to do this?"
If the virus is not eliminated, the number of cases could return to a level of 200,000 new infections annually within 10 years, he warned.
But efforts to end the disease face mounting risks brought on by violence against vaccine workers in the disease's last bastions.
In Nigeria and Pakistan, some religious figures say the vaccine contains pork, which Muslims are forbidden from consuming, or that it renders people infertile as part of an alleged Western plot to sterilize Muslims.
Dozens of health workers have been killed in attacks on vaccination stations in recent months, particularly in remote areas—with at least 10 killed in northern Nigeria and 20 in Pakistan since December.
In Pakistan, some believe the CIA used polio vaccines as a cover for a campaign to obtain DNA samples from people in order to root out Al-Qaeda chief Osama bin Laden, who was killed in a US raid in 2011.
"There is no question that these groups fighting the polio vaccination effort are a challenge to polio eradication," said Carol Pandak, who heads an anti-polio program at the charitable organization Rotary International.
In order to break down hostilities, international polio workers have held meetings with local religious leaders and the governments of the countries concerned.
The goal is to communicate on a local level "so they can learn more about the benefits of immunization and we can hear their concerns," said Pandak.
But money remains a problem. Pandak said the global anti-polio campaign is short 660 million dollars in 2013, or more than half the annual budget of a billion dollars that experts say is necessary.
The funds come mainly from G8 countries, the Bill and Melinda Gates Foundation, Rotary International and other donors.
Eradicating polio could lead to success against other illnesses, such as measles, according to Walter Orenstein, chairman of the WHO's Technical Consultative Group on the Global Eradication of Poliomyelitis.
"I think the polio effort has the potential to draw in a lot of expertise to tackle other diseases in the future," he told AFP.
American Jonas Salk developed the first polio vaccine, testing it on volunteers, including himself and his family, before announcing the first successful trial results in 1953.
In 1955, the vaccine was declared safe and effective for release on the world market.
"The success of the polio vaccine required a real coordinated effort," said Orenstein.
"The polio virus is an enemy of humankind. By eradicating it, it's a gift from this generation to all future generations."