Fifty years after the first polio vaccine was created, the world is close to eradicating the disease from the planet. The challenge for health officials now, however, is eliminating the disease in countries where transmission has never fully been broken while fighting the re-emergence of the disease in previously polio-free nations.
The Global Polio Eradication Initiative, known as the largest public health initiative in history, was created in 1988. Since its inception, polio cases have plummeted from 350,000 in 1988 to 784 in 2003, according to the United Nations Children's Fund, otherwise known as UNICEF. Currently, polio remains endemic in only six nations: India, Pakistan, Nigeria, Afghanistan, Niger and Egypt. However last year, a polio outbreak emerged in West Africa that has so far spread to 16 previously polio-free nations. Affecting mainly children younger than 3, polio is a highly infectious disease that attacks the nervous system and can cause total paralysis.
Many of those infected with polio never produce symptoms of illness and therefore the disease can spread quickly and undetected.
"Polio right now is a disease of poverty," said Claire Hajaj, UNICEF's communications officer for polio eradication. "In those countries (where it is endemic), it attacks the poorest people. It thrives on children with low immune systems and little in the way of health care."
For every one case of paralytic polio, there are between 200 and 1,000 cases of infected children, Hajaj said. Children in polio-free nations can be exposed to infection in regions where routine immunization rates are low or where average rates of immunization are high, but some children remain unimmunized -- "and polio will always find those pockets," Hajaj said. Such a situation occurred in Indonesia, where a total of 39 cases of polio were confirmed as of mid-June, according to the World Health Organization. Before the polio re-emergence, Indonesia had been polio-free for a decade.
"Polio knows no borders," Hajaj said. "It can pass slowly and steadily or it can jump on an airplane and be with you in five minutes. Should the world be afraid of the re-emergence of polio? Absolutely."
To combat polio's importation into polio-free nations, countries such as Somalia are launching massive immunization drives to protect children from nearby outbreaks in Yemen and Ethiopia, where the disease has caused paralysis in more than 200 children, WHO reported. In May, Yemen received millions of doses of oral polio vaccine in an effort to stop the outbreak and immunize every child younger than 5 in the country. According to WHO, previously polio-free countries can stop polio outbreaks if high-quality immunization campaigns are put in place quickly. However, countries in which polio is indigenous -- or where transmission has never been stopped -- present the biggest challenge to global eradication.
"The big epidemiological challenge is stopping transmission in the last remaining reservoirs where it never stopped," Hajaj told The Nation's Health. "Importation (of polio) is a real problem -- it's alarming and it drains the (eradication) campaign financially. But all of these countries have stopped polio before and they can stop it again."
Hajaj said the eradication initiative has set a goal of making the globe polio-free as of 2008. Because a nation must go three years without polio to be declared polio-free, polio transmission must be stopped by the end of this year to reach such a goal. While reports from Asia look encouraging, Africa's progress will be reassessed in the fall, Hajaj noted. The recent polio outbreak in Africa has hampered progress on the continent and civil unrest in nations such as Sudan and Cote d'Ivoire are making it difficult to reach children there, UNICEF reported.
Nonetheless, sustaining key immunization ingredients to successfully combat the disease will ensure eradication moves forward, Hajaj said. Those ingredients are sufficient funding, political commitment down to the community level and community participation in changing people's behaviors and understanding of polio and its vaccine. Insufficient funding, however, could present one of the biggest threats to successfully eliminating polio.
"Right now, we're definitely being squeezed," Hajaj said. "We are really close to an enormous public health victory and we need to seize that while the opportunity is before us."
The global eradication initiative faces a $50 million funding gap in the last part of 2005 and will need $200 million in 2006 to be able to respond to outbreaks like the one in Yemen and maintain current activities. Without additional funds, a $4 billion investment by the global community to wipe out polio could be threatened, UNICEF reported.
"It's kind of frustrating because you can see the finish line, but you're not quite there yet," said Denise Johnson, MS, acting chief of the polio eradication branch at the Centers for Disease Control and Prevention's Global Immunization Division.
Johnson said it is not unusual to witness outbreaks near the end of an eradication program and the biggest concerns are still with nations that have never interrupted polio transmission. But without adequate funding, difficult decisions have to be made as to where to cut back, "which means you don't do activities in areas where you should," Johnson said. As long as polio still exists somewhere in the world, it poses a threat to the United States -- even though that threat is extremely minor, she said. The Americas have been certified polio-free since 1994.
"We want to make sure that we prevent polio from coming back, from being imported back into the United States," Johnson told The Nation's Health. "All kinds of diseases move much more freely now...and we probably won't have an outbreak here because we have good routine immunization in the United States, but even one paralyzed child is too much."
In addition to almost wiping out a devastating childhood disease, the global polio eradication effort has also helped strengthen and build health care capacity in many developing nations, Johnson said. Vitamin A capsules are often given to children along with polio vaccines to bolster their immune systems and polio vaccinators supported the first birth registration campaign in post-Taliban Afghanistan, according to UNICEF. Polio education has also boosted health and hygiene awareness in poor communities, and systems set up to administer polio vaccines have paved the way for immunization campaigns targeting other diseases.
"Vaccines are one of the greatest gifts we have this century and such a valuable asset to our public health toolkit," Johnson said. "It was a wonderful discovery that's made an enormous impact on the world."
For more information on the Global Polio Eradication Initiative, visit www.polioeradication.org
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