Partners in the effort to finally rid the world of polio are taking another step today, launching an emergency action plan strategists hope will propel the long overdue program across the finish line.

The plan is aimed at keeping polio on the radar of world leaders while improving the performance of the armies of public health officials and volunteers working to eradicate the disease. Its launch is expected to be followed Friday by a vote from the World Health Assembly to declare polio a "programmatic emergency for global public health." The World Health Assembly is the annual general meeting of the member states of the World Health Organization.

"Polio eradication is at a tipping point," says the action plan, which warns that if vaccination levels don't rise substantially in the three remaining countries where polio transmission has never been stopped, "polio eradication will fail."

The renewed polio efforts come at a time when only four countries in the world are reporting spread of the paralyzing viruses. Three -- Pakistan, Afghanistan and Nigeria -- are listed as endemic countries, places where polio transmission has never been halted. The fourth country, Chad, has previously interrupted spread of polioviruses but transmission was re-ignited when viruses from outside the country triggered a new outbreak.

The low number of active countries -- the lowest ever -- and cases so far this year has put the program on new ground, says Dr. Bruce Aylward, a Canadian who serves as the WHO's assistant director-general for polio, emergencies and country collaboration.

To date this year there have been 60 cases of paralytic polio, compared to about 155 last year at this time.

"We've got one-third the number of cases and one-third the number of countries as well," Aylward said in an interview from Geneva. "So we're in a very different place."

Different in some respects, and yet it must seem frustratingly familiar in others.

For the third time, the polio eradication program finds itself approaching a self-imposed deadline, a point by which it had promised to have stopped polio transmission. Like the two before it, this deadline is likely to be missed.

The eradication effort, which began in 1988 as a partnership between the WHO, UNICEF, the service club Rotary International and the U.S. Centers for Disease Control, was originally meant to reach its goal in the year 2000.

Despite coming heartbreakingly close, the original deadline had to be pushed back to 2005. After that deadline too passed, the eradication partners refrained from setting a new deadline for several years. But a few years ago, in the face of concern the job would never get done, a new target was set. Spread of polioviruses would be halted worldwide by the end of 2012.

Will the program fail to reach the latest goal? "High risk," Aylward admits. But he insists the emergency plan, if it works, could get enough children in the four remaining countries vaccinated that the end will be in sight, even if it doesn't happen this year.

Deadlines are a tool to keep funders committed to the effort, but they are a double-edged one. Deadlines missed, especially at this stage, could hurt efforts to raise the seemingly endless funds needed to stop polio. To date, the world has spend about US$9 billion on trying to get rid of polio, and several billions more will be spent before the job is complete.

"I do think we have a solid number of donors that continue to support the program. But it's true that there are challenges in missing deadlines," says Carol Pandak, manager of PolioPlus, Rotary's polio eradication program. By the time polio is eradicated, Rotary will have raised $1.2 billion for the effort.

Still, Pandak says positive signs from one or two of the remaining countries would likely shore up confidence, especially coming in a year when the program had its biggest coup in over a decade.

In January, India -- long thought to be the eradication program's Waterloo -- marked a year without a case of polio. (That streak continues.) That milestone took India off the list of polio endemic countries. All involved in the fight against polio are drawing on the optimism India's success created.

"Significant progress in another one of the polio endemic countries I think would go a far way to secure support for the program," says Pandak. "And that would be a huge message and a boost to the program. So we need Nigeria or Pakistan to do much better."

So far this year Nigeria has plenty of room for improvement. It has had 35 cases, up substantially from nine last year at this time. Pakistan, where efforts faltered last year, is doing better. It has had only 16 cases, down from 40 at this time last year.

As it struggles to keep donor governments giving to a cause they were repeatedly assured would be history by now, the polio program faces a huge funding gap. It is short between $600 million and $950 million for this year and next year alone. Where the shortfall will actually come in on that spectrum depends on whether donors who have given "relatively firm" commitments of a total of $350 million make good on the promises, Aylward says.

The funding crunch is hurting efforts to keep immunity levels high enough globally to prevent more cases of renewed spread, as was seen in Chad. "We have cancelled (vaccination) campaigns already this year in 24 countries and it could be as many as 30 countries by the end of the year unless we're able to close the financing gap," Aylward says.

A panel of experts that critiques the eradication efforts calls the decision to cut back vaccination campaigns "an extreme and unacceptable risk."

"It would leave whole swathes of West Africa at high risk of importing polio from Nigeria," the group, called the Independent Monitoring Board, wrote last week in a letter to WHO Director General Dr. Margaret.

"This would not only spell disaster for the countries affected; it could set this global endeavour back by many years, and vastly increase the eventual cost of achieving eradication."

The board's letter warned that cutting back on vaccination rounds at this time risks triggering an explosive resurgence of polio that would see a multitude of countries "under attack from a disease that they thought their children were protected from."