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Polio, the Virus - 2002-11-20

This is the first in a five-part series on global polio eradication based on interviews in Washington, in Atlanta at the Centers for Disease Control and Prevention, and at National Immunization Days in northern Nigeria.

Fifty years ago, a worldwide epidemic of polio was in full swing. In the United States alone, 58,000 cases of this highly infectious and crippling disease were reported in 1952.

Vaccines, which can prevent but not cure polio, halted its spread in the United States and much of the world. But polio remained a threat in many parts of the world. A global immunization campaign to eradicate polio - the largest public health initiative in history - began in 1988. It has put an end to the disease in all but a few developing countries.

Nigeria is one of the last remaining reservoirs of the poliovirus. An army of vaccinators is at work to immunize every child in a door-to-door campaign.

Polio eradication in Nigeria starts with a ceremony in a large, dusty lot at the Community Islamic Center in Rogo, Nigeria. Banners and posters announce the latest campaign. Men in long-flowing white robes and women in bold African prints take their seats under the shade of circus tents.

Islamic religious leaders from nearby villages are here with government officials, health workers, international aid advisors and dozens of women with babies in their laps. Uniformed policemen stand guard to hold back a crowd of curious townspeople gathered to watch the event.

They have come to Rogo, a small community of mostly Muslim residents in Northern Nigeria, to celebrate the kick-off of National Immunization Days, a weeklong campaign that promises to deliver the oral polio vaccine, village by village, door-to-door, to the more than 40 million Nigerian children under the age of five.

There are speeches and songs. A roving group of musicians carrying instruments made from dried gourds chants an important message: "Please madam, immunize your children, because if you don't, you have cheated them, and you have cheated yourself."

Polio is a highly infectious viral disease that invades the nervous system and can cause paralysis, even death. It commonly attacks young children and is spread by food or water contaminated with feces. Although the advent of vaccines in the 1950s brought the global polio epidemic to a halt, many developing countries continued to suffer from the disease. During the 1980s, they accounted for 95 percent of the polio cases worldwide.

Stephen Cochi is director of the Global Immunization Division of the U.S. Centers for Disease Control and Prevention in Atlanta. He said that on average in a susceptible population, one in 200 polio-infected children develops an irreversible paralysis. The others become carriers of the virus and are contagious for about two weeks. "But it spreads silently, and that makes it difficult to stop the spread of the virus, because it is already widespread in a community when you first get this signal of paralyzed children manifesting the fact that they have the virus," he explained.

That is why one case is considered an epidemic. Mr. Cochi added that without a human host, polio cannot survive - a major reason that effective immunization has sped the eradication effort. "The polio virus is, as we say, on the ropes," he said. "It is making its last stand in the world. Before the vaccine era, polio had conquered the world. Polio existed everywhere in the world."

The global initiative to eradicate polio launched in 1988 is being led by the United Nations' World Health Organization, UNICEF, the private Rotary International and the Centers for Disease Control and Prevention in Atlanta. Their combined assault on polio has yielded results. "We've come a long way in a very short time since then. From 350,000 [cases] in 1988, we are down to 483 cases last year, in 2001," said Mr. Cochi. "That's more than a 99.8 percent reduction. We've gone from 125 countries to less than 10 countries today. It only exists in some of the most difficult to access parts of the world and in areas where the infrastructure to deliver polio vaccine is the weakest."

The largest reservoirs of the disease are in India, Pakistan and Nigeria. These nations share conditions that support polio transmission - low rates of immunization, poor sanitation, a dense population and a weak public health network.

Still, experts say global polio eradication is doable. World Health Organization officials expect to reach that goal by 2005.

In part 2, we take a closer look at the polio eradication campaign in Nigeria, and its focus on health worker training and door-to-door immunization.

Photos for this series provided by Rosanne Skirble.