Thanks to a worldwide program designed to fight polio, the numbers of people with this terrible illness have dwindled. But this initiative has not yet succeeded in making the disease disappear altogether. In January, the US-based Bill & Melinda Gates Foundation and Rotary International, along with the governments of Great Britain and Germany, jointly announced a donation of more than $630 million to help propel the program forward toward its ultimate goal.

Since the Global Polio Eradication Initiative was launched worldwide, polio cases have been reduced by more than 99%—from over 350,000 in 1988 to around 1,600 in 2008. However, the initiative failed to meet the initial target date of 2000 for worldwide eradication, and the World Health Organization (WHO) has not set another official global target date for eradicating polio. “When they set [the 2000 deadline], it initially seemed a good idea. But [it] proved counterproductive, because funding increased in the run-up to the deadline and flatlined after the deadline was missed,” says Amir Attaran of the University of Ottawa, Canada.

Policymakers need to remember any eradication campaign is a “high-stakes gamble,” says Scott Barrett, professor at the Johns Hopkins University School of Advanced International Studies in Washington, DC.

“[The gamble] paid off for smallpox,” says Barrett. “Smallpox eradication is probably the best investment the world ever made.” However, polio—which causes paralysis in less than one out of every 100 cases—is much more difficult to detect than smallpox, Barrett adds. And polio is endemic in war-torn countries, which makes vaccine delivery difficult.

A dose of hope: An Afghan boy is vaccinated against polio Credit: Associated Press

There are four countries with endemic polio: Nigeria, India, Pakistan and Afghanistan. According to Oliver Rosenbauer, a WHO spokesperson, political support—particularly from local governments—coupled with the recent boost in funding will make eradication possible. “If these two things come together, we know [eradication] will happen because we've seen it work.”