Campaign to kick polio out of Africa

Eradication effort, led by WHO, sets example for other health programmes

By Daničle Letoré*


Health professionals and political leaders in Africa are gearing up for the final push to wipe out the remaining pockets of polio on the continent. "Polio eradication by the year 2000 is within our grasp," says Dr. Ebrahim M. Samba, Regional Director for Africa of the World Health Organization (WHO). "We are reaching levels of immunization that have never before been achieved in Africa."

Poliomyelitis, commonly referred to as polio, is a disease that once struck across the world, each year paralyzing hundreds of thousands of children during the early years of their lives (see box). "Lameness surveys" carried out in the 1970s established that polio was endemic in Africa. Today, the poliovirus is confined to sub-Saharan Africa, but with major reservoirs in the Democratic Republic of Congo, Ethiopia, Nigeria, Somalia and Sudan. Remarkable progress has been made in combating polio country by country in the last decade, although much remains to be done.

The current drive for full eradication is critical, since the virus easily crosses borders and countries considered free of the disease may become re-infected as a result of international travel. The worldwide campaign led by WHO to completely eliminate the disease is now focusing on the only two major areas of virus transmission remaining globally: the Indian subcontinent and sub-Saharan Africa.

‘Kick polio out'


The goal of eradicating polio by the year 2000 was first set at a 1988 assembly of WHO member states. The following year, after another such assembly approved a Plan of Action for a Global Polio Eradication Initiative, the WHO Regional Committee for Africa took up the assembly's resolution, and in 1995 again urged the vigorous implementation of the strategies for the polio eradication initiative. The Organization of African Unity, at its annual summit meeting of African heads of state in 1996, endorsed the eradication initiative.

South African President Nelson Mandela personally led a region-wide social mobilization campaign to boost public awareness of the initiative. "We shall immunize every child in Africa to get rid of this terrible disease forever," Mr. Mandela declared at the launch of his "Kick polio out of Africa campaign." Since 1997, through an alliance with the African Football Confederation, leading players from across the continent have participated in public awareness campaigns by distributing posters, conducting radio interviews and holding public autograph sessions. Public service announcements over radio stations have spread news of the campaign to as many communities across Africa as possible.

The polio eradication initiative is based on a four-pronged strategy that has proven effective in other areas of the world (such as the Americas, which have been certified polio-free since 1994). "The backbone of the eradication initiative," says Dr. Bruce Aylward, global coordinator for the polio eradication initiative, "is routine immunization supplemented, particularly in those countries where routine immunization has not always been possible, by National Immunization Days." Such NIDs, he explains, have bolstered immunization programmes in many countries by providing training for vaccine budgeting, planning and social mobilization at the local level, refurbishing the systems for keeping the vaccine in cold storage, and helping educate communities about the importance of routine immunization.

NIDs aim to administer oral polio vaccine in two doses to all children under five years of age nationwide. Each participating child is immunized at two NIDs held one month apart. Within the next year, NIDs will be scheduled to ensure that immunization also occurs in countries of continuing conflict such as Sierra Leone, Liberia and the Democratic Republic of Congo, where massive immunization campaigns have had to be postponed.

In addition to routine immunization and NIDs, two other components are central to the eradication initiative: surveillance and "mopping up." According to Dr. Okwo-Bele, Regional Advisor for the Expanded Programme on Immunization in Africa, "Surveillance is a key factor in identifying and controlling disease. In 1997 and 1998 we have trained surveillance teams in 36 countries to be able to identify ‘acute flaccid paralysis,' a symptom that can often mean that poliovirus is present." In later stages of eradicating poliovirus from a particular geographic area, mopping up involves door-to-door campaigns in the remaining population pockets where surveillance has shown that the virus transmission persists.

Dramatic drop in cases


The first NIDs for polio eradication in Africa were carried out in 1995 in Algeria, Mauritania and Namibia. In 1997, 36 African countries participated in NIDs, immunizing more than 85 mn children under the age of five years. In just two years, the number of reported polio cases in Africa dropped dramatically — from 2,198 in 1995 to an estimated 879 in 1997.

These figures are likely to underestimate the actual number of cases, however, since surveillance systems are in the early stages of development. And although no wild poliovirus has been isolated in Eastern and Southern Africa since 1996, more sensitive surveillance is required in these regions before polio-free status can be confirmed.

"With the success of the NIDs, the emphasis is shifting to establishing the surveillance needed to guide polio eradication activities and eventually certify its success," says Dr. Okwo-Bele. "Every African parent and health worker must understand that acutely paralyzed children need to be brought to a health facility for investigation."

Because viruses do not observe man-made borders, there is always a possibility that poliovirus may reappear in countries deemed polio-free and be exported to others through international travel and population migration. In 1993-94, polio spread from Angola to Namibia and from Zaire (as the Democratic Republic of Congo was then known) to Zambia and Tanzania. Laboratory tests identified a strain of poliovirus that travelled from Nigeria across West Africa.

Therefore, another important element in the fight against polio is a strong laboratory network, capable of isolating the different types of poliovirus, of which there are three. Such a network is instrumental in genetically mapping the virus, to trace its country of origin and determine appropriate immunization strategies. Over the last five years, WHO has been developing and strengthening a laboratory network in Africa. Today there are 10 national laboratories and three regional laboratories as part of the African Polio Laboratory "We are building national capacity by providing training throughout the laboratory network," states Dr. Okwo-Bele. "This has direct benefits for other healthcare programmes, allowing the region to improve disease diagnostics, help pre-empt future epidemics and encourage the roll-out of other vaccines."

Strong partnerships


Much of the work, however, could not be accomplished without the commitment of national governments and the help of WHO's partners. Rotary International, the worldwide business and professional organization, has provided funding as well as an invaluable number of volunteers to help carry out NIDs and social mobilization campaigns, and provide advocacy assistance. The UN Children's Fund and the US Centres for Disease Control and Prevention regularly provide technical help. Other governmental agencies such as the US Agency for International Development, the UK Department for International Development, Danish International Development Assistance and the Japan International Cooperation Agency have been instrumental in providing resources for the polio eradication campaign.

The campaign has been notable for its success in bringing together governments, donors, the media, industries, health workers, national and community leaders, citizens, volunteers and private voluntary organizations in an extraordinary international effort to wipe out polio. Through the campaign, neighbouring countries such as the Democratic Republic of Congo, Uganda, Zimbabwe and Zambia have worked together to immunize their children. Health workers have collaborated to develop innovative strategies to reach remote groups of people, such as forest-dwelling Pygmies in Uganda.

By strengthening primary healthcare services and bringing renewed enthusiasm and support for other immunization campaigns, the polio eradication campaign has brought significant additional benefits to the African region. In Zimbabwe, the polio model was used to carry out a measles control campaign. Botswana, Mauritania, Mozambique, Namibia and South Africa included measles vaccine in their polio NIDs. In East Africa, yellow fever control is benefiting from the infrastructure built up by the polio eradication initiative.

In Madagascar, "NIDs brought new life to the routine immunization programme and the whole health system — new refrigerators, greater staff involvement and government awareness that good health is good politics," notes Dr. Harry Hull, a WHO medical officer.

Dr. Samba cautions, however, that the gains already achieved against polio should not now lead to complacency. "We are at the most difficult stage of the initiative," he notes. "It is not a question of just maintaining immunization levels. We must now increase immunization activities (NIDs and mop-ups) in the face of disappearing disease. This requires tremendous political leadership and commitment, as well as increased funding. If these components are assured, we will win the battle against polio."

Vaccination key in eliminating polio

Poliomyelitis, the infectious disease commonly known as polio, is caused by three different types of poliovirus that can result in permanent paralysis or even death. Under certain conditions, poliovirus can be transmitted very easily and can survive for a limited time in the environment. Carried via contaminated drinking water or contaminated surfaces, such as unwashed hands, the virus passes through the stomach and establishes itself in the intestinal lining, where it infects cells and replicates.

Most poliovirus infections are without symptoms, however. Clinical symptoms manifest themselves in just 0.1 to 1 per cent of all cases of infection, ranging from fever, sore throat, headache, vomiting and minor muscle pain to meningitis (swelling of the brain) and paralysis. In cases where the infection spreads from the intestinal tract to the blood stream and the central nervous system, the poliovirus replicates in the motor neurons of the spinal chord, destroying cells and causing paralysis.

When the poliovirus causes paralysis, it most often affects the legs. Many victims of acute flaccid paralysis caused by the poliovirus recover at least partial muscle function. From 2 to 10 per cent of all cases of paralytic poliomyelitis are fatal, as the virus paralyzes the muscles required to breathe.

The natural occurrence of the disease (through "wild" poliovirus) has effectively been eliminated in the Western hemisphere through widespread vaccination. The polio vaccine takes two forms: an inactivated poliovirus, which is injected, and a live poliovirus, which is given orally. Because it is inexpensive and easily administered, the oral vaccine has been used extensively in the campaign to eradicate polio. Global eradication of polio is technically feasible, since the virus only affects humans (there are no enduring, environmental sources of the virus) and protection via immunization lasts a lifetime.

* Daničle Letoré is an Information Officer of the World Health Organization in Geneva.

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