Polio is nearing eradication.

Reported polio cases worldwide have declined a remarkable 90 percent since 1988, when the World Health Organization (WHO) launched its global vaccination campaign to eradicate polio by the year 2000. Over the past decade reported cases of the disease dropped from more than 35,000 to just over 3,200 - the lowest case count on record (the actual number of polio cases is thought to be ten times the reported figure).

For much of the 20th century, and particularly prior to discovery of the polio vaccine in the 1950s, the poliomyelitis virus was considered one of the most deadly and crippling diseases of our time. Today, some 10 to 20 million people worldwide - including many children in the developing world - remain paralyzed from the virus, unable to walk without the help of leg braces or to breathe without devices such as the "iron lung."

If all goes as planned, however, the turn of the century should witness one of the most remarkable achievements in international health cooperation ever, the global eradication of polio. The virus is one of only a limited number of diseases that can actually be wiped out, because it is transmitted only through person-to-person contact and does not persist in the environment for long without a human host. Moreover, there exists a highly effective and cheap (about $1 per dose, or $3 per child) oral vaccine against polio, which usually provides life-long immunity to the disease.

Global polio eradication has been made possible as a result of social and political commitment by national governments. By 1998, 118 countries had conducted at least one round of National Immunization Days, during which all children under five are administered two doses of polio vaccine one month apart. Only 21 countries had participated a decade earlier. In 1997 alone, 450 million children - about two-thirds of the world's under-five population - were immunized during large-scale campaigns in 80 countries.

In 1998, a record 188 countries reported zero polio cases. A decade earlier, only 94 countries had eliminated polio within their borders. Despite the overall decline worldwide, 27 countries reported polio transmissions as of late 1998. The disease still has a foothold in South Asia (largely India, Pakistan, and Bangladesh) and Africa (particularly Nigeria and the Democratic Republic of Congo).

Among the greatest obstacles to polio eradication efforts are the lack of basic health infrastructure for vaccine distribution, and the crippling effects of civil war. In polio endemic countries such as Angola, Somalia, Sudan, and Sierra Leone, internal conflict has meant the suspension of immunization programs, severance of vaccine-supply lines, and destruction of health services. Last August, the Democratic Republic of Congo - a country that four years ago witnessed one of the largest polio epidemics of the century - was forced to postpone its scheduled National Immunization Day and later suspend its vaccination program altogether after health-care workers fled hospitals that had been devastated by the country's ongoing war.

As the target year for polio eradication nears, WHO and its partners in this global effort (among them Rotary International, vaccine manufacturers, and several governments) are worried that support for the project may wane before the biggest hurdles are overcome. In particular, funds are still lacking for the most challenging phase of the initiative, the door-to-door "mopping-up" campaigns needed to immunize children in high-risk districts. Although 50 to 80 percent of the costs of polio eradication are covered by the endemic countries themselves, WHO estimates that an extra $350 million in additional support will be needed before the year 2001.

If all goes well, the world will achieve official "polio-free" status by 2005, and child immunization efforts will end after an additional five-year period. With the demise of polio, countries are expected to save an estimated $1.5 billion per year by eliminating the costs of immunization and treating and caring for people affected by polio. Western Europe alone will save about $200 million annually, and the United States will save about $230 million.

Most significantly, polio eradication efforts have created a global disease-prevention network that can be used to combat a range of other common childhood killers - including measles, tetanus, tuberculosis, whooping cough, and diphtheria. Already, WHO is weighing the possibility of selecting two additional viral diseases, measles and rubella, as eradication targets for the next 10 to 15 years.