Seven Diseases Can be Eliminated Within a Generation

Released from Washington, D.C.

Seven crippling and sometimes deadly diseases can be eliminated as public health problems (reduced to very low levels, for example one case per 10,000 population, but requiring continued control measures) or eradicated (permanently reduced to zero, obviating the need for further control measures) within a generation, according to the World Health Organization (WHO). The diseases are guinea worm disease, polio, leprosy, measles, river blindness, Chagas disease and lymphatic filariasis.

The diseases, all of which are now found largely in developing nations, can be eliminated through a combination of immunization and vaccination, drug therapy, community training and education, and national disease tracking efforts. “This is a gratifying outcome of research conducted over many years; in order to reach the elimination goals it will be important to retain a problem-solving attitude,” says Tore Godal, M.D. Director of the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR).

The elimination and eradication goals are being pursued by non-governmental organizations, governmental organizations and technical partners, and in the process global partnerships are developing between these players. “The partnerships that are being created are important because they mobilize the resources necessary to put in place an infrastructure for surveillance and control that is necessary not only for eradication and elimination of seven diseases, but also for the continued fight against all infectious diseases,” says David Heymann, M.D., Director of WHO’s Division of Emerging and other Communicable Diseases Surveillance and Control.

Lymphatic Filariasis

Lymphatic filariasis is a disease which produces attacks of fever in its acute stages, and may cause elephantiasis, the huge enlargement of the arms, legs and genital organs which results in profound physical and psychological disability, in its chronic stages. The disease currently affects 120 million people in 73 countries. “We have learned that the disease can be controlled with just a single yearly [drug] treatment,” says Eric Ottesen, M.D., of WHO’s Control of Tropical Diseases (CTD) programme. “In addition, for elephantiasis, an extremely simple regimen of washing with soap and water, sometimes applying topical antibiotics, has been shown to produce dramatic results.”

Elimination of the disease is likely to be greatly facilitated by the support from SmithKline Beecham, most notably the donation of up to five billion doses of its drug albendazole, which, when combined with other drugs, can be 99 percent effective against the parasitic worms that cause the disease.

Costs per person treated have been estimated at just 5-10 cents, and this treatment has even greater health benefits for children and women of childbearing age since the drugs used also reduce concurrent intestinal worm infections, such as hookworm, which cause anemia, stunt growth and inhibit intellectual development. “What we need now is to build up a strong support system for the elimination of filariasis,” says Kazem Behbehani, Ph.D., Director of CTD.

Guinea Worm Disease

There has been spectacular progress towards the elimination of guinea worm disease (dracunculiasis) since the late 1970s; the annual number of cases has fallen worldwide from an estimated 10-15 million to 77,863 in 1997. Today the disease affects only those living in the poorest and most remote parts of 16 countries located in Africa south of the Sahara and in Yemen, and 109 countries have been certified free of dracunculiasis transmission. Over 50 percent of cases reported worldwide are in Sudan, which remains the major obstacle to complete eradication; campaigns are complicated by the lack of accessibility to endemic villages due to insecurity and the protracted course of the civil war.

The disease is caused by a parasitic roundworm, the adult female of which may be up to 1 meter in length. People become infected through drinking water contaminated by minute water fleas (cyclops), which are themselves infected by larvae of the worm. The parasite migrates through the body to eventually emerge through the skin (from the feet in 90 percent of cases), causing intolerable pain accompanied by fever, nausea and vomiting.

Although there are no drugs to treat or prevent dracunculiasis, transmission is easily interrupted through:

  • behavioral change of rural populations so that they drink clean water;
  • protection of wells, tanks and water sources; and
  • filtering water before drinking it, or (when possible) treating water with ‘temephos’ (a bio- degradable organophosphorous compound which is safe for mammals) to kill the water fleas.

These activities can be carried out by communities educated about preventing the disease, containing patients with emerging worms, and filtering drinking water. Community-based activities include identifying cases prior to emergence of the worm, or at the latest 24 hours after it appears, and initiating case management by disinfecting wounds, applying antibiotic ointment, and using occlusive bandages. Case-containment has been implemented in most endemic villages. In 1997, endemic countries reported 71 percent of cases as contained.

The estimated $40 million required to eradicate the disease over the next few years can hardly compare to the improved quality of life and huge savings in terms of agricultural productivity and access to food safety that will follow.

Polio

Polio, once one of the world’s most feared diseases, is on track for global eradication by the year 2000 in a campaign that has given 1.5 billion vaccinations to children in the developing world this decade. Globally, polio incidence has plummeted by almost 90 percent since the WHO launched its global polio eradication initiative in 1988, with the estimated number of cases dropping from 350,000 to some 35,000 in 1997. Fifty-three countries remain endemic for polio.

Polio is caused by a virus which invades the spinal cord. The virus selectively destroys the nerve cells that stimulate muscles to move. The result is a permanent paralysis of the affected muscles, most often the legs. Most polio victims are children less than three years of age, 10 percent of whom die. Where rehabilitation services are good, these children may live full and productive lives. Elsewhere, many remain totally dependent on their families. Worldwide 10-20 million people remain paralyzed from polio.

The global polio campaign calls for countries to conduct National Immunization Days, during which doses of oral polio vaccine are delivered to all children less than five years of age. Three to five years of these campaigns are required to eradicate polioviruses from most endemic countries. In addition, a sensitive surveillance system must be created to detect every case of polio, track the spread of the virus and provide the evidence necessary for certification.

A total of $1 billion will be needed from the international community between now and 2005 to eradicate polio and then certify that the world is free; two-thirds of this amount during the next three years. The United States, Japan, the United Kingdom, Germany, Denmark, Australia and Canada are major financial contributors. The U.S. Government contributes about $72 million per year, including technical support, through the Agency for International Development and the Centers for Disease Control and Prevention. Starting in 1985, Rotary International, a service club with more than 1.2 million members in 155 countries, will contribute a total of more than $400 million of private resources by the end of the initiative.

Leprosy

The combination of three drugs known as MDT (multidrug therapy) has now cured more than 10 million leprosy patients. At the end of 1997, 99.3 percent of all registered patients were receiving MDT free of charge; and the WHO believes it is well on track to eliminating leprosy as a public health problem by the year 2000.

The therapy is highly effective. It cures leprosy completely; relapse rates are less than one percent; and no resistance to the three drugs together has been detected anywhere. The therapy has completely changed the global picture and made inroads into the burden of leprosy. But S.K. Nordeen, M.D., Director of WHO’s Action Programme for Elimination of Leprosy, has warned that many challenges remain before elimination can be achieved. In the next 2-3 years, highly endemic districts within countries — an estimated 800-1000 — will be identified and targeted for elimination.

During 1997, about 690,000 leprosy cases were detected, bringing the global total to some 830,000 known cases (a global prevalence of 1.4 per 10,000 population). It is estimated that 1.5-2 million patients, mostly living in inaccessible places with limited health care infrastructure, remain to be diagnosed and cured before the elimination goal can be achieved. The costs of reaching and treating these hidden patients could reach $250 million. Other research costs, including eradication research, will amount to about $22 million. Thus the global elimination strategy is very cost-effective; this is due to its community approach to case-finding, treatment and surveillance.

Measles

Measles is a very common viral disease of humans that most commonly affects children. Despite the fact that an effective and safe vaccine has been available for more than three decades, measles remains a major childhood killer, mostly in developing countries; it is still responsible for approximately 1 million deaths, half of them in Africa amongst the most disadvantaged community groups.

At the World Summit for Children in 1990, the goal of protecting 90 percent of the world’s children against measles by the year 2000 was established. The great strides in measles control and elimination in some countries give us good reason to be optimistic. For instance, in the USA, indigenous transmission of measles virus has been interrupted since 1993, although importation of measles virus into the country from Europe, Asia and Africa has resulted in sporadic outbreaks and epidemics. On a global scale, measles mortality and morbidity are estimated to have declined by 78 percent and 88 percent compared with pre-vaccination era figures.

The overall savings of successful global eradication would accrue every year in all countries. It is estimated that the US alone would save a minimum of $63 million per year, including about $50 million for domestic vaccine costs, $1.3 million on domestic research and about $11.7 million for the global measles control efforts. Prevention of future epidemics would result in additional savings of $150 million, not including costs associated with lost productivity.

River Blindness

Onchocerciasis, or river blindness, affects 18 million people in Africa, Latin America and the Arabian Peninsula. Today 350,000 people are blind as a result of the disease, their life expectancy reduced by more than a decade, while 6 million suffer from severe, maddening itching.

Transmission of the disease has now been virtually eliminated, through the Onchocerciasis Control Programme (OCP), in 11 affected West African countries, protecting 30 million of the 90 million people at risk on the continent. The OCP has relied for the last twenty years on vector control by aerial spraying of larvicides, a rather expensive control strategy; but today, NGOs and local governments distribute the drug ivermectin, donated by Merck, free of charge. This drug is effective against the microfilariae (larval parasites), which are responsible for producing the harmful symptoms. However, the adult parasites are not affected by ivermectin and live on in the body, so it is necessary to take ivermectin annually until the adult worm dies.

Another control programme, the African Programme for Onchocerciasis Control (APOC), was established in 1994 to eliminate the disease in the remaining 19 affected countries in Africa. This programme is based on Community-Directed Treatment, and depends on communities rather than trained mobile teams to distribute ivermectin. After training, community representatives travel to a central place in each district to pick up the medicine, and then return to their communities to organize distribution. “The new program is cheap because most of the work is done by communities themselves, with support from NGOs and local health services,” says Hans Remme, Ph.D., of the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR).

Chagas Disease

Some 16-18 million people in 21 Latin American countries are infected with Chagas disease, and about 45,000 people die from the disease each year. It is transmitted to humans via a parasite-carrying triatomine bug, which feeds on the blood of sleeping victims. The parasite can also be transmitted by blood transfusion and from mother to fetus.

The acute stage of the disease is sometimes fatal, developing within 2-3 weeks of infection and lasting up to 2 months. Symptoms at this stage consist of fever, lymph node swelling, enlargement of liver and spleen, rash and acute inflammation of the heart muscle. The chronic stage of the disease, which can last for years, eventually causes irreversible damage to the heart and intestines. Control relies on insecticides (to kill the bugs), improved housing and health education.

The six Southern Cone countries of Latin America — Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay — have made the political commitment to interrupt transmission of the disease by the year 2000; Uruguay has succeeded already. Control in these countries depends on insecticide treatment of houses. Scientists have developed a colorless latex-based paint which incorporates insecticides that remain effective for more than 2 years, and a fumigant canister that is currently being used in Argentina; these new control measures cost half as much as traditional spraying measures. In Andean and Central American countries, the control programmes are based on insecticide spraying and on blood screening to prevent transmission through transfusion.

Successful elimination of the disease will be the result of joint efforts by WHO, the Pan American Health Organization and the ministries of health in affected countries.

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