Control of Neglected Tropical Diseases (NTD)

At least 1 billion people — one sixth of the world’s population, or 1 person in 6 — suffer from one or more neglected tropical diseases (NTDs), such as Buruli ulcer, cholera, cysticercosis, dracunculiasis (guinea-worm disease), foodborne trematode infections (such as fascioliasis), hydatidosis, leishmaniasis, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiasis, trachoma and trypanosomiasis, although there are other estimates that suggest the number could be much higher. Several of these diseases, and others such as dengue, are vector-borne. Often, those populations most affected are also the poorest and most vulnerable and are found mainly in tropical and subtropical areas of the world. Some diseases affect individuals throughout their lives, causing a high degree of morbidity and physical disability and, in certain cases, gross disfigurement. Others are acute infections, with transient, severe and sometimes fatal outcomes. Patients can face social stigmatization and abuse, which only adds to the already heavy health burden.

For a large group of these diseases – mainly helminthic infections – effective, inexpensive or donated drugs are available for their prevention and control. These tools, when used on a large scale, are able to wipe out the burden caused by these ancient scourges of humanity. For leprosy, treatment with effective antibiotics is leading to the elimination of such ancient disabling disease. There is also a cost-effective approach to treating yaws that could lead to elimination and final eradication of this debilitating disease that may cause gross deformation. In the case of blinding trachoma, the use of the recommended strategy (SAFE) of an effective antibiotic is enhancing the progress towards final elimination. Large-scale, regular treatment plays a central role in the control of many NTDs such as filariasis, onchocerciasis, schistosomiasis and soil-transmitted nematode infections. For example, regular chemotherapy against intestinal worms reduces mortality and morbidity in preschool children, improves the nutritional status and academic performance of schoolchildren, and improves the health and well-being of pregnant women and their babies.

There is second group of NTDs for which the only clinical option currently available is systematic case-finding and management at an early stage. These diseases include Buruli ulcer, Chagas disease, cholera and other diarrhoeal diseases, human African trypanosomiasis, and leishmaniasis. Simple diagnostic tools and safe and effective treatment regimens need to be developed urgently for some of these diseases. However, even for these infections, systematic use of the present, imperfect tools at an early stage can dramatically reduce mortality and morbidity. For others, vector control tools are available and present the main method of transmission control, as in the case of Chagas disease.

There are examples of great successes in the fight against both of these groups of NTDs. Since 1985, 14.5 million patients have been cured of leprosy through multidrug therapy; today, less than a million people are affected by the disease. Before the start of the Guinea-worm Eradication Programme in the early 1980s, an estimated 3.5 million people in 20 endemic countries were infected with the disease. In 2005, only about 10 000 cases were reported in 9 endemic countries, and the programme is moving towards eradication. Onchocerciasis has freed more than 25 million hectares of previously onchocerciasis-infected land available for resettlement and agricultural cultivation, thereby considerably improving development prospects in Africa and Latin America.

Increased awareness and advocacy are needed to draw attention to the realistic prospect of reducing the negative impact of NTDs on the health and social and economic well-being of affected communities. The WHO Department of Control of Neglected Tropical Diseases is committed to supporting Member States and partners to achieve this goal.