Global Policy Forum

By Lawrence Altman

As polio cases surge in Nigeria and the virus spreads to other countries, West and Central Africa are on the brink of the largest polio epidemic in recent years, alarmed officials of the World Health Organization and Unicef said yesterday.

The 60 cases just reported by Nigeria for the final week in April, the latest period for which information is available, constitute the largest weekly number for any country in recent years, the officials said.

Last weekend, genetic testing of a child who became paralyzed on May 20 confirmed that a 10th country, Sudan, had polio that had come from Nigeria. The W.H.O., a United Nations agency based in Geneva, called the new developments "a stark warning."

Even though caseloads outside Nigeria are relatively small, health officials say they may greatly understate polio's spread and the danger of an epidemic.

Only about 1 in 200 people infected by the virus develops paralysis; an overwhelming majority experience only diarrhea and other nonspecific gastrointestinal symptoms. Yet any infected individual can spread the disease. That signals the potential for a large epidemic as polio enters the season when transmission is highest, the officials say. The polio virus spreads through feces, and contamination occurs more often when sewage backs up during the rainy season in Africa and Asia.

"It's a totally unnecessary public health tragedy," Kul Gautam, deputy executive director of Unicef, told reporters in a telephone news conference. The threat comes just as the World Health Organization and its partners expected that their $3.1 billion program was about to make polio the second disease to be conquered around the world, after smallpox. Instead, Dr. Bruce Aylward, a polio official at the agency, said, "we could see thousands paralyzed at a time when the disease should be eradicated."

Health officials and other experts attribute the current outbreak in Nigeria and the virus's spread to other countries to a decision by the government of the northern state of Kano last August to stop immunizing children. Political and religious leaders there claimed that the vaccine made girls infertile.

Allegations about impurities in the vaccine have caused alarm and confusion among many people in Nigeria and elsewhere. Tests of the vaccine have refuted such claims, said Dr. David L. Heymann, the director of the World Health Organization's polio eradication program. The vaccine purchased by Unicef meets the organization's standards and has been used safely to eliminate the disease from many other countries.

In May, Kano's governor, Ibrahim Shekarau, pledged to resume vaccinations. But that has not happened, Dr. Heymann said. Meanwhile, polio has spread not only in Kano but from that state to other parts of Nigeria. The W.H.O. is considering other measures, including a travel advisory, Dr. Heymann said. But the effectiveness of such an advisory is uncertain, because the spread of most polio cases to other countries is believed to have resulted from people traveling across porous borders on the ground, not from air travel.

When the health agency and its partners began the polio eradication program in 1988, 125 countries reported a total of 350,000 cases a year. This year there have been 333 cases in 13 countries, and the disease is endemic is only six countries, the agency says. But the virus can spread as long as there is a case anywhere.

Polio is defined as endemic - meaning that the chain of transmission has not been stopped within 6 to 12 months - in six countries: Afghanistan (3 cases this year), Egypt (1), India (13), Niger (18), Nigeria (257) and Pakistan (15). In addition to Sudan, the virus has spread from Nigeria to the following nine countries since last August: Benin, Botswana, Burkina Faso, Cameroon, Central African Republic, Chad, Ghana, Ivory Coast and Togo. Polio has spread from one person to another in three countries that were once free of the disease: Burkina Faso, Chad and Ivory Coast.

Despite what they acknowledged was a serious setback, officials of the United Nations agencies and a major partner, Rotary International, maintained their optimism, saying they could still salvage their goal of eradicating the disease by the end of the year. But to do so, they said, will require an additional $100 million to immunize 74 million children in 22 African countries in a synchronized program in October and November. Those countries cover the area extending from Mauritania in the north to Congo in the south, and from Senegal in the west to Sudan in the east.

A program that immunized at least 90 percent of the children in vulnerable areas could stop transmission and still allow the health organization to meet its goal, Mr. Gautam asserted. Dr. Aylward said one reason for optimism was that large immunization programs had quickly controlled two major epidemics in 1999: 1,103 cases in Angola and 500 in Congo.

Although "the virus is gathering steam" now in Africa, he said, "we can still do it."

Dr. Jong Wook Lee, who became director general of the health organization last July and who once ran its polio surveillance and immunization program, has made eradication a top priority. Rotary International has contributed more than $600 million to the polio eradication coalition, which has raised $3.1 billion. Other partners include the Bill and Melinda Gates Foundation, the United Nations Foundation, the World Bank, various businesses and donor countries. Volunteers play a critical role; 20 million people have taken part in the immunization programs.

The eradication program seeks an additional $100 million from new and old sources, with the first $25 million needed by Aug. 1 to start the large immunization campaign. The Group of 8 countries have pledged to pay for program until it is completed, Dr. Heymann said. James Lacey of Rotary International said, "We cannot come this close to eradication and not finish successfully."