Polio is on the verge of being eliminated. Last year there were just over 200 cases of polio, and they occurred in just two remote parts of the world — northern Nigeria and the rugged Afghan-Pakistan border region.
A new $5.5 billion plan being pushed by the World Health Organization strives to eliminate polio entirely, phase out vaccination campaigns and secure polio vaccine stockpiles in case the virus somehow manages to re-emerge.
If the effort is successful, polio would be just the second disease in human history, after smallpox, to be eliminated by medical science.
"We've never been so close to eradication as we are now," says Hamid Jafari, the director of Global Polio Eradication at WHO.
A quarter of a century ago there were roughly 300,000 polio cases a year worldwide. By 2011 that number had dropped to 650, and last year it was down to 223.
The new Global Polio Eradication and Endgame Strategic Plan aims to bring the number of new wild polio cases down to zero by 2015 and eradicate the virus entirely by 2018. It targets "wild" polio from normal transmission and the handful of so-called "vaccine-derived" cases, which are caused by the vaccine.
The plan calls for an orchestrated global transition from the oral vaccine, which contains live polio virus (and thus can cause "vaccine-derived" polio paralysis), to an injected vaccine made from dead virus.
Jafari says previous attempts to wipe out polio have stumbled because they lacked global coordination or adequate funding. And the biggest risk to the new plan's success is "if it is not financed up front."
In the 1950s, polio was spread all around the globe. Terrified parents in the U.S. wouldn't allow their children to go swimming in late summer out of fear that they'd catch the incurable condition. Slowly polio has been eliminated from one part of the world after another. Now it continues to spread only in isolated parts of Nigeria, Afghanistan and Pakistan.
The WHO, UNICEF and the Bill & Melinda Gates Foundation, among others, have been pouring resources in to attack polio in these three countries.
Even though polio appears to be backed into a corner, Jafari says, it still has the potential to spread.
"Even as recently as 2011 we had an outbreak in China as a result as importation from Pakistan that killed many adults," he says. "Earlier this year the sewage sampling in Cairo detected wild polio virus that originated in parts of Pakistan."
The areas of Pakistan, Afghanistan and Nigeria where polio remains a problem are also areas torn by violence.
As recently as February 2013, nine female polio workers were gunned down in the northern Nigerian city of Kano.
Apoorva Mallya, who works on vaccine-delivery programs for the Gates Foundation, says these incidents are unfortunate, but he points out that polio has been eliminated in other places during times of conflict.
"In specific places like Somalia, Sudan, El Salvador — it was during active conflict polio was stopped in those countries," he notes.
Mallya says what's really impressive is that India hasn't reported a new case of wild polio in more than two years. He says the new strategic plan incorporates many of the techniques and tools that were used in India to finish off the virus.