The celebration started January 15, 2004, when health ministers of the last six countries where the poliovirus still circulated--Afghanistan, India, Pakistan, Egypt, Nigeria and Niger--gathered in Geneva to commence a very public countdown. After 15 years and some $3 billion, the Global Polio Eradication Initiative was going to halt all transmission of the "wild" virus by the end of the year and thereafter consign polio to the same fate as smallpox, declared officially banished in 1980.

Unfortunately, polio has proved to be a much trickier disease, and the world is a different place than it was in the 1970s. Rather than having been eliminated, polio is now present in 10 countries. The polio program has succeeded in many difficult areas, says University of Pittsburgh professor D. A. Henderson, who led the smallpox eradication program and guided polio eradication in the Americas. "But at this time they're running into some very heavy weather," he warns.

Polio's perfect storm started in the summer of 2003 in northern Nigeria. In the Kano state, politicians and clerics claimed that the polio vaccine was a "Western" ploy, tainted with HIV or with hormones meant to render Muslim women infertile. The resulting resistance to the eradication program led to immunizations being suspended for 11 months. By the summer of 2004, outbreaks in Nigeria had spread to 10 surrounding nations that had been polio-free for years, leaving nearly 700 children paralyzed and reestablishing polio in four countries.

A massive mop-up campaign began in October, involving one million volunteers in 23 African countries attempting to vaccinate 80 million children by year's end. The unexpected setback cost the cash-strapped eradication program an additional $100 million. The goal for ending wild-virus transmission worldwide has now slipped to the end of 2005.

"It's certainly biologically feasible" to meet the new target date, says David L. Heymann of the World Health Organization. Since Heymann took over the polio program in mid-2003, the veteran epidemiologist has observed that political will is the real wild card [see "A Strategy of Containment," by Christine Soares; Scientific American, March 2004]. So he has spent much of his tenure traveling to drum up political support for polio eradication.

One of Heymann's first big accomplishments was gaining an endorsement from the Organization of the Islamic Conference (OIC), a confederation of 56 Muslim nations. Polio has hit the group hard: five of the six original endemic countries and two where wild virus was reestablished are members. Malaysia and the United Arab Emirates, both in the OIC, each made $1-million contributions to the eradication program last year. The organization's support also softened opposition in Nigeria. By last spring, Kano officials agreed to resume vaccinations but made a show of purchasing the vaccine from Muslim Indonesia, and sending it to India to be safety-tested. (Ironically, India, where polio is still endemic, has yet to resolve two past incidents of locally manufactured vaccine being contaminated--either accidentally or intentionally--by a virulent wild strain of the poliovirus.)

Meeting an end-of-2005 target in Africa will require a "heroic effort," according to Henderson. The 13 African countries where outbreaks occurred last year cover an area bigger than the 48 contiguous states and have a population of some 300 million people. Because polio only causes a detectable "acute flaccid paralysis" in one of every 200 victims, it is much harder to ferret out than smallpox, Henderson adds, and 800 documented cases in Africa mean that 160,000 people were probably infected.

India, Pakistan and Afghanistan are in far better shape. By early November, India had detected only 81 cases. According to Heymann, all three Asian countries should "finish up" efforts to halt wild-virus transmission early in 2005. Doing the same in Africa by the end of the year is essential, he says: "If countries don't do it now, it won't happen. This is the best chance we'll ever have."

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