FAITH LAPIDUS: This is SCIENCE IN THE NEWS in VOA Special English. I'm Faith Lapidus.

BOB DOUGHTY: And I'm Bob Doughty. On our program this week, we tell about efforts to defeat the disease polio.

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FAITH LAPIDUS: Poliomyelitis does not want to die. Sometimes the disease seems close to disappearing. Then new cases appear.

But American businessman and philanthropist Bill Gates continues to believe that wild polio can be stopped. Money from the Bill and Melinda Gates Foundation has helped finance efforts against polio for more than twenty years.

The foundation recently announced winners of its Grand Challenges Explorations program. Some of the winners were honored for their work with polio, including studies aimed at leading to new vaccines.

Each winner will receive a grant of one hundred thousand dollars. Entrants competing for the grants were urged to think "out of the box," to develop ideas that are non-traditional. The goal is to speed the day when the international coalition to defeat polio has no more work to do.

BOB DOUGHTY: Some of the Grand Challenges Explorations money is for research that could improve vaccine given to children in developing countries. The vaccine currently in use is swallowed. This oral vaccine contains a weakened version of the live poliovirus.

Changes in the live virus can cause paralysis, an extremely rare event. The virus infects one in every two hundred fifty million children who receive the oral vaccine. But researchers are working to prevent this tragedy from happening.

FAITH LAPIDUS: In general, the worldwide campaign against polio has made huge progress in the past twenty years. Polio vaccines have decreased the number of recorded cases by ninety-nine percent since nineteen eighty-eight. That was when the cooperative effort called the Global Polio Eradication Initiative began.

A vaccine is very important because antibiotic drugs do not help after someone is infected. Antibiotics can kill only bacteria, not viruses. There is no cure for polio. Care includes rest, fluids and medicines to control symptoms like high body temperature.

The wild polio virus passes freely from person to person. It spreads through fluids in the mouth and nose, waste material and water systems. The very rare vaccine-derived, or vaccine-linked, polio strikes when changes in genetic material affect the vaccine.

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BOB DOUGHTY: Polio is mainly a children's disease. But adults also get it. Many people are infected without knowing it. They may have only a higher than normal temperature and pain in the throat. But when polio attacks the central nervous system, the person may not be able to stand or walk. When the disease affects breathing, a patient can die.

Polio left an estimated three hundred fifty thousand patients with paralysis in nineteen eighty-eight. They lost the use of their arms or legs. Some no longer could breathe without help.

FAITH LAPIDUS: The Global Polio Eradication Initiative includes national governments and the United Nations Children's Fund. Another partner is America's Centers for Disease Control and Prevention.

Still another is the volunteer service group Rotary International. Rotary members have worked against polio for many years. The group also has organized programs to raise money for the anti-polio campaign. Violinist Itzhak Perlman and orchestra conductor James DePreist gave their most recent Concert to End Polio in Chicago, Illinois.

Both musicians have survived paralytic polio. Mr. Perlman was four years old when the disease struck. Mr. DePreist was in his twenties. Today each man walks with the aid of crutches or other devices.

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BOB DOUGHTY: Scientists say three polio viruses cause wild polio. Type one is the most dangerous. It can infect many people in a short time. Type one has caused about eighty-five percent of all polio cases. Type two wild polio disappeared worldwide in nineteen ninety-nine. Cases caused by type three poliovirus do not spread as fast as polio caused by type one.

Today, polio continues to strike in Nigeria, India, Afghanistan and Pakistan. Officials say several problems make it difficult for these nations to stop the spread of polio.

For example, five hundred thousand babies are born each month in parts of northern India. It is hard to reach and vaccinate all these children. Armed conflicts and other disputes in Pakistan and Afghanistan have interfered with -- or stopped -- anti-polio campaigns.

FAITH LAPIDUS: In two thousand three, Nigeria stopped providing vaccine against polio for almost a year. False reports about the vaccine caused the stoppage. The reports said the vaccine gave people the disease AIDS. Other reports said it prevented people from having children.

Nigeria had many cases of polio after the vaccinations ended. The disease also spread to other nations.

By August of two thousand seven, however, the polio news in the nation seemed hopeful. Nigeria had reported a major reduction in polio cases after January. Then unwelcome news came. Sixty-nine children in the northern part of the country developed paralytic polio.

BOB DOUGHTY: Some of the infected children had received the Sabin oral polio vaccine. The vaccine contains weakened poliovirus that protects well against type one poliovirus. But in Nigeria, some of the vaccine had made a harmful genetic change.

FAITH LAPIDUS: Critics have questioned the continued use of the Sabin oral polio vaccine in the international campaign against polio. They say its link to infection with the disease makes the vaccine unacceptable.

Nine years ago, American health officials stopped suggesting use of that vaccine. They said the reason was to end the possibility of paralytic polio linked to it.

Olen Kew is an expert in viruses for the Centers for Disease Control. Among his studies is the polio known as vaccine-associated-paralytic polio, or VAPP. He says the United States had about eight such cases a year before two thousand, when the oral polio vaccine was being used. About twenty percent of the cases were in children who had problems with their own natural defenses against disease.

BOB DOUGHTY: If there is any chance of a case of VAPP developing, why give Sabin oral polio vaccine? Experts say this vaccine works faster against the spread of type one polio. And it is not costly. Health care workers who direct its use need little training.

Olen Kew notes that many developing countries use the vaccine because children can receive it without injection. The Sabin oral polio vaccine also protects the intestines. That prevents the spread of the disease from person to person.

But the virus expert says, "There is always the risk that the weakened strains of the virus used in the vaccine will mutate into a form that can cause severe illness and even death."

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FAITH LAPIDUS: Jonas Salk developed the first major polio vaccine in the nineteen fifties. Albert Sabin then developed the Sabin oral polio vaccine in the nineteen sixties. Doctor Salk's polio vaccine was injected. An improved version of the Salk vaccine is now used in the United States.

Poliovirus was first identified in nineteen eight, long before Doctors Salk and Sabin produced their vaccines. The earlier scientists, the discoverers, recognized the sickness. But they could not stop people from getting infected with it.

For example, polio killed six thousand people in the United States in nineteen sixteen. Twenty-seven thousand other Americans suffered permanent damage.

BOB DOUGHTY: For years, polio remained a frightening health threat. Many victims were children and young adults. Families tried all kinds of ways to protect their children.

A teacher living in the United States remembers wanting to go swimming as a child. But her mother always said, "It is too dangerous during the polio season."

The mother was right. Hot summers were disastrous. In the summer of nineteen fifty-two, more than fifty-seven thousand people were infected with polio in the United States alone. Although parents worked hard to protect their children, the disease kept spreading.

FAITH LAPIDUS: Some polio victims of those earlier days have lived to become well known in sports, medicine, the arts and other fields. Doctors say they often see such bravery and energy in patients who had polio. But researchers are working for the day when not one more person will ever suffer from the disease.

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This program was written by Jerilyn Watson. June Simms was our producer. I'm Faith Lapidus.

BOB DOUGHTY:

And I'm Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.