With India polio-free for the past year, there are now only three countries where polio is endemic: Afghanistan, Pakistan and Nigeria.
Global health experts caution that the challenges there are massive, making the World Health Organization's stated goal of a polio-free world by 2012 virtually unattainable.
"What do polio-endemic Afghanistan, Pakistan and Nigeria have in common?" asks Peter Singer, director of the McLaughlin-Rotman Centre for Global Health in Toronto.
"They're governance-challenged and conflict-prone, meaning that eradication will require not only vaccines but also social innovation, determination, and a lot of hard work."
Worldwide eradiation efforts began in 1988. At the time, some 350,000 people a year contracted polio, most of them children, and millions were living with disabilities as a result. The goal was to eliminate "the Great Crippler" by the year 2000.
Raising money and manufacturing vaccines proved relatively easy. After all, while polio was rare in the Western world, memories of its devastation were still fresh. And the notion of eliminating a killer virus forever – as had been done with smallpox – was a tantalizing prospect.
Some of the biggest and most powerful health groups on the planet got on board: The World Health Organization, Unicef, the U.S. Centers for Disease Control and Prevention, and the irrepressible Rotary International. The cash-rich Gates Foundation became a partner later.
Success came quickly.
The Americas (including Canada) were declared polio-free in 1994, followed by the Western Pacific (including China) in 2000 and Europe in 2002.
In 2001, there were a mere 483 cases worldwide, and they were concentrated in a few hot spots in Africa and south-east Asia, and a plan began for declaring the world polio-free.
The initial deadline was missed but confidence remained. Then efforts stalled. A polio-free world would have to wait until 2004, then 2008, 2010 and 2012.
"Realistically, eradication isn't going to happen until 2015 or 2016," said Dr. Luis Barreto, a global health consultant and former vice-president of immunization policy and scientific affairs at Sanofi Pasteur Ltd. Canada.
War and natural disasters interfered with vaccine campaigns; greater ease of travel brought polio back to countries where it had been wiped out, and the logistics of mass vaccination remained difficult, particularly in the poorest corners of the world.
The eradication campaign was also, to put it bluntly, badly managed, rife with incompetent managers, nepotism and corruption, according to a stinging report issued last year by a blue-ribbon panel led by Sir Liam Donaldson, the former chief medical officer of Britain.
They were particularly critical of Pakistan, whose "progress now lags behind every country in the world." Without urgent and fundamental change, it is a safe bet that it will be the last country on earth to host polio."
In other words, the world will not be polio-free until Pakistan follows the lead of its neighbour (and often enemy) India and pulls out all the stops.
"The number one thing missing is political will," Dr. Barreto said. "But it's not just political will that's required."
As long as polio exists in the wild, the risk of resurgence exists, and children have to be immunized – some 400 million a year.
"People don't realize just how difficult eradication is," Dr. Barreto said. "But it will get done eventually."
The greatest danger, in the meantime, is complacency. As India, the long-time epicentre of the polio epidemic, celebrates, the world could wrongly assume that the war is won when some key battles still remain.