Chapter 6 of 16
The end of the line for some infectious diseases?
Graphs: Nearly eradicated or eliminated -
Initiative: Partnerships for long-term goals
|Throughout history only
one infectious disease - smallpox - has ever been eradicated. Today, two more diseases
- polio and guinea-worm disease - are on the verge of eradication. Several more are
gradually being brought under control or reduced to a level manageable within the existing
But progress is not always straightforward. Environmental change, internal conflict, mass population movements and the collapse of basic health services can rapidly overwhelm efforts to control infectious diseases. And, in the final stages when a disease becomes less visible, progress is often hampered by complacency. Success can never be taken for granted.
Today efforts are being stepped up to ensure that polio is eradicated by the year 2000. Prospects are good. Over the past decade the number of reported cases fell from 35 000 cases to about 5 000. The disease has been eradicated throughout the Americas and transmission now appears to have been halted in the Western Pacific Region, including China.
Mass immunization campaigns which reach hundreds of millions of children in a few days have had a dramatic impact on the disease. Children have been reached in some of the remotest corners of the world. Health workers have used camels, horses, dug-out canoes, boats and motor-bikes to get the vaccines through. In many countries polio immunization campaigns have been used to deliver vitamin A supplements as well, increasing the impact of immunization on child health. These efforts to reach neglected groups were made possible with the support of partners such as Rotary International and the Centers for Disease Control and Prevention (CDC).
But problems remain. Polio is still widespread in a few heavily populated countries. Worst affected are Afghanistan, Democratic Republic of Congo, India, Nigeria and Pakistan. Many polio cases still go undetected due to poor reporting systems. Conflict is another frequent constraint, hampering vital mass immunization campaigns in war-torn countries and triggering a polio outbreak in Angola in early 1999.
There is concern at the shortfall in funding needed to carry out the final mass immunization campaigns. Once polio has been eradicated, savings on vaccination costs worldwide will amount to $1.5 billion a year. The United States alone will save around $250 million a year - the amount it now spends on polio immunization every year to prevent the re-importation of a disease it has already eradicated.
Guinea-worm disease is also on the way out. Over the past decade the number of cases has been reduced by 90%. The strategy used involves health education, case containment and provision of safe drinking water. Guinea-worm disease is now restricted to 14 countries in Africa.
Principal partners in guinea-worm eradication are UNICEF, the Carter Foundation and CDC, all working together to intensify eradication efforts. Over 100 countries have been freed of the disease, but stumbling blocks remain. War and social upheaval have frequently hampered efforts to eradicate guinea-worm disease. In one country the number of cases actually increased between 1996 and 1998.
Today there are fears that lack of resources could lead to a resurgence of both polio and guinea-worm disease in areas that are now almost free of these diseases - reversing hard-won gains. Success can breed complacency. A disease can rapidly become yesterday's story once it has low visibility and limited impact.
Efforts are also under way to control or eliminate a range of other diseases. Neonatal tetanus has been eliminated in over 100 countries but the disease continues to kill almost 300 000 newborn babies every year, and tetanus kills about 40 000 mothers as well. The disease could be eliminated through immunizing women with tetanus toxoid during pregnancy and ensuring they have access to a safe delivery. But in 1997, only 64% of pregnant women were immunized and, of the almost 50 countries where the disease is still a public health problem, only 17 had national plans to eliminate the disease.
Almost ten million people have been cured of leprosy over the past 15 years in an effort to eliminate the disease by the year 2000. Today virtually every registered patient is receiving multi-drug therapy. The number of countries where the disease is a public health problem has been reduced from 122 in 1985 to only 28. But leprosy remains a serious problem in 16 countries which together account for over 90% of all cases.
Today the efforts of WHO and its principal partners - the International Federation of Antileprosy Associations and the Nippon Foundation - are being stepped up to reach neglected groups in remote areas. About half a million new cases are reported every year. While global targets may be met by the year 2000, in some countries intensified efforts will have to continue for some time.
Global efforts to control measles are being hampered by continuing low immunization coverage rates in some countries. In Africa, fewer than two in three children today are immunized against measles. And in ten countries fewer than half of all children are protected.
Mass vaccination campaigns are now being carried out in the highest-risk areas in some regions - especially densely populated deprived urban areas. In the Americas, where the disease is targeted for elimination by the year 2000, over 90% of children are now immunized against measles.
Efforts are also under way to eliminate lymphatic filariasis as a global public health problem. The elimination initiative has been made possible by greatly improved diagnostic techniques and dramatic advances in treatment methods - both for controlling the spread of the disease and for alleviating the suffering involved. In addition, partnerships with pharmaceutical manufacturers SmithKline Beecham and Merck are ensuring that drugs are available wherever they are needed.
In Latin America, countries have made a political commitment to eliminate Chagas disease. The first initiative was launched in 1991 by Argentina, Brazil, Bolivia, Chile, Paraguay and Uruguay. So far Uruguay has been successful. The strategy used involves screening blood donations and vector control.
More recently, the Andean and Central American group of countries have launched similar elimination efforts. One of the key tools being used is a low-cost colourless latex-based insecticide paint developed within this region.
Onchocerciasis (river blindness) has been virtually
eliminated in 11 countries in West Africa through a 20-year programme initially involving
vector spraying and now providing once-yearly community-based treatment with the drug
ivermectin - supplied free by the manufacturer Merck. In 1994, with partners including the
World Bank, the African Programme for Onchocerciasis Control was established to ensure
that the disease is eliminated in the remaining 19 African countries where it is a serious
|© World Health Organization 1999
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