The Bill & Melinda Gates Foundation, Rotary International and the British and German governments today pledged $630 million over the next five years to vaccine and other programs designed to wipe out polio.

"I am urging everyone to redouble their commitment and see the eradication effort to the end," Bill Gates said today during a teleconference with reporters. Gates said he's confident that polio will become the second viral disease that humankind eradicates (the first being smallpox in 1979), but he was loath to predict when that might happen.

The Gates Foundation, which has contributed $655 million toward polio eradication since 1999, today pledged an additional $255 million over the next five years. Rotary has promised $100 million, and the U.K. and Germany are forking over $150 million and $130 million, respectively. This money will go to a variety of resources and activities essential to the eradication effort, from purchasing vaccines to training programs for health workers.

A disease that attacks the nervous system, polio most commonly strikes children under age five, causing nothing more than flulike symptoms in most but permanent paralysis in others. One in every 200 cases results in paralysis, according to the World Health Organization (WHO). The virus is easily spread through dirty drinking water in areas with poor sanitation systems and continues to thrive in four countries—Nigeria, India, Afghanistan, and Pakistan, where it annually paralyzes about 2,000 children.

The disease came close to being wiped out in the U.S. in the 1960s, but there were sporadic outbreaks in pockets where the vaccine was shunned—such as among the Amish in Lancaster County, Pa., in 1979. The WHO finally declared the Americas polio-free in 1994.

Since 1988, the WHO, the U.S. and other governments as well as charitable orgs such as Gates and Rotary have contributed $6 billion to eradicating polio. The international effort has cut polio cases by over 99 percent, from some 350,000 in 1988 to about 1,600 last year.

The infusion of new funds will focus on overcoming specific hurdles in each of the four countries where the disease still exists. Afghanistan, for instance, is embroiled in a war, which makes it dangerous for vaccinators to distribute the medicines, and Nigeria has fallen behind in its eradication campaign, because local government officials in some of the country's northern states have failed to provide training for health workers or programs to educate parents on the import of vaccinating their children.

"We need new efforts from the leaders in these countries where polio is still endemic," Gates said. "There's no target date yet for eradication because nobody knows what it will take."

Image Credit ©WHO/T. Moran