NEGLECTED TROPICAL DISEASES

ANCIENT COMPANIONSOF POVERTY

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Innovative and Intensifi ed Disease Management focuses on diseases for which cost-effective control tools do not exist. These diseases include Buruli ulcer, Chagas disease, human African trypanosomiasis and leishmaniasis. Oman, 2009.

Preventive Chemotherapy and Transmission Control uses safe and effective drugs to treat diseases through large-scale preventive chemotherapy. The diseases include lymphatic fi lariasis, onchocerciasis, schistosomiasis, trachoma and STH. Rep. of Korea, 2008.

Neglected Zoonotic Diseases are endemic in many developing countries. Common diseases are anthrax, bovine tuberculosis, brucellosis, cysticercosis, echinococcosis and rabies, and their control helps save lives and alleviate poverty in rural communities. Chile, 2007.

Neglected tropical diseases debilitate, deform, blind and kill ...

Neglected tropical diseases: ancient companionsof poverty

Neglected tropical diseases are a group of infectious diseases that thrive in impoverished settings, especially in the heat and humidity of tropical climates. Most are diverse parasitic diseases, spread by vectors ranging from mosquitoes to blackfl ies to snails, sandfl ies, tsetse fl ies, bugs and common house fl ies. Other diseases such as dracunculiasis, fascioliasis and helminthiases are spread by contaminated water and soil infested with the eggs of worms. Transmission cycles are perpetuated under conditions of environmental contamination and poor standards of living and hygiene.

Once widely dispersed, these diseases are now concentrated in settings of extreme poverty in remote rural areas of Africa and Latin America, and also in urban slums or in confl ict zones. Of the world’s poorest 2.7 billion people (defi ned as those who live on less than US$ 2.00 a day), more than 1 billion are affected by one or more neglected tropical disease.

In many parts of the world, these diseases gradually disappeared as standards of living and hygiene improved.

Cycle of suffering and disability

Neglected tropical diseases are not highly visible. Except for dengue, they do not cause explosive outbreaks that attract media attention. They cause disabling infections that sometimes kill but more often disfi gure. In most cases, individuals are affected simultaneously by 5–7 of these diseases. Some diseases diminish the economic productivity of young adults, impair childhood growth and development, cause adverse pregnancy outcomes and affect individuals in the prime of life.

These diseases cause blindness, disability, deformities or otherwise maim those who are infected. The development of these diseases is insidious. Severe impairments often occur after years of silent infection so patients may have been unaware of the need to seek care. Other neglected tropical diseases, such as dengue and dengue haemorrhagic fever, human Africantrypanosomiasis and Buruli ulcer, and zoonoses such as rabies, anthrax and brucellosis, can kill within days, weeks or months once an advanced stage of disease is reached.

Tool-ready and tool-defi cient diseases: a new approach

Since 2003, the World Health Organization (WHO) has moved away from using a disease-centred approach towards treating neglected tropical diseases as a group, based on disease biology and through the use of large-scale integrated programmes involving safe, inexpensive and effective medicines.

The tool-ready diseases, which affect the largest number of people globally, are those for which powerful control strategies are available and for which well developed implementation strategies are immediately feasible. Through the use of preventive chemotherapy, single-dose oral medicines such as ivermectin are being used to simultaneously control and eliminate lymphatic fi lariasis and onchocerciasis. Other medicines such as albendazole, ivermectin and praziquantel make the prevention,control and possible elimination of worm infections more likely than ever before.

Control strategies for diseases defi ned as tool-defi cient rely on costly and diffi cult-to-manage tools. For most of these diseases, such as Buruli ulcer, Chagas disease, human African trypanosomiasis and leishmaniasis, early detection and treatment

are vital to avoiding irreversible disability or death. Simple, safe and cost-effective tools and approaches must be developed, including pesticide products, and they must be made accessible.

Neglected tropical diseases mainly:

• affect people in remote rural areas or urban slums who have no political voice;

• are linked to poverty and occur in areas where safe drinking-water is lacking; where education is poor; and where there is poor sanitation, substandard housing and reservoirs for insects and other vector-borne diseases;

• affect low-income countries where people are simultaneously affected by several diseases;

• are mostly disabling and disfi guring but also deadly;

• have low priority in national health programmes, and data and statistics to help prepare control strategies are limited;

• remain hidden, and cause social stigmatization and discrimination;

• affl ict people, particularly children and women, with lifelong consequences, including severe physical pain, irreversible disability and gross disfi gurements.

“Together, we are upholding a fundamental principle of health development: equity. Access to life-saving and health-promoting interventions should not be denied for unfair reasons, including an inability to pay ...

These diseases have international importance in sectors well beyond health.”

Dr Margaret Chan, WHO Director-General, in her address to the fi rst WHO Global Partners Meeting, 19 April 2007

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A young African woman returns from hospital after being successfully treated for a neglected tropical disease.

Blinding trachoma is a bacterial infection caused by Chlamydia trachomatis. It is spread through contact with eye discharge from an infected person and is also transmitted through eye-seeking fl ies. Untreated, this condition leads to the formation of irreversible corneal opacities and blindness.

Buruli ulcer is a severe skin disorder that is caused by the bacterium Mycobacterium ulcerans, which belongs to the same family of organisms as those that cause leprosy and tuberculosis. Left untreated, it causes destruction of the skin and, in some cases, of bone, eyes and other tissue.

Chagas disease (American trypanosomiasis) is mainly a chronic condition caused by a protozoan parasite transmitted by the infected faeces of blood-sucking bugs, through transfusion of infected blood, by organ transplantation or congenitally from an infected mother to her fetus.

Dengue is a mosquito-borne viral disease. The more severe forms of the disease are dengue haemorrhagic fever or dengue shock syndrome; these are usually fatal within 12–24 hours.

Dracunculiasis (guinea-worm disease) is transmitted by contaminated drinking-water. It is characterized by the emergence of a one-metre-long worm from a skin ulcer usually, but not necessarily, in the leg.

Human African trypanosomiasis (sleeping sickness) is spread by the bite of the tsetse fl y in impoverished rural areas of sub-Saharan Africa. A person may be infected for months or years without major signs or symptoms. When symptoms do emerge, the patient is often at a fatal stage of the disease and there is involvement of the central nervous system.

Leishmaniasis is transmitted by the bite of the sandfl y. Visceral leishmaniasis, which attacks the internal organs, is the most severe form. Left untreated, it is usually fatal within two years. Cutaneous leishmaniasis commonly causes ulcers of the face, arms and legs and leaves severe and permanently disfi guring scars and disability.

Leprosy is a chronic infection caused by the bacillus y Mycobacterium leprae. The disease mainly affects the skin, peripheral nerves, mucosa of the upper respiratory tract and the eyes. Once regarded as mutilating, contagious and incurable, the disease can now be easily cured using multidrug therapy.

Lymphatic fi lariasis (elephantiasis) is a severely debilitating, disfi guring and stigmatizing disease caused by parasitic worms. It usually causes abnormal enlargement of the limbs and the genitals.

Onchocerciasis (river blindness) is caused by a fi larial worm that is transmitted to humans through the bites of infected blackfl ies. The larvae mature to adult worms; these move through the body and, when they die, they cause a variety of conditions, including blindness.

Rabies is a viral zoonotic disease mainly transmitted to humans through the bite of an infected dog. Rabies has a long incubation period and always kills within a few days after onset of symptoms. Human rabies can be prevented by proper wound care and administration of rabies biologicals immediately after a bite.

Schistosomiasis (bilharziasis) is a parasitic disease that leads to chronic ill-health. Infection is acquired from contaminated fresh water that contains the larval forms of blood fl ukes, known as schistosomes.

Vector control management develops and promotes strategies and guidelines based on the principles of integrated vector management, including sound management of pesticides. Ethiopia, 2005.

“Neglected tropical diseases Hidden successes, Emerging opportunities”

A commonly accepted definition of “neglected” is: 1. failure to give proper care or attention to; 2. failure to do something.

“the enjoyment of the highest attainable standard of health is one of the fundamental rights of every human being ...”

WHO Constitution, 1948

Decisive action

The prospects for controllingneglected tropical diseases provide unprecedented opportunities to make a real impact on the lives of the world’s poorest and most vulnerablepeople. Effective drugs are availableat no cost or very low cost. Delivery strategies have been devised that are compatible with conditionsin very-low-income settings. Interventions can be integrated or bundled, and existing delivery systems can be used, thusincreasing operational effi ciency.

WHO hopes to controlneglected tropical diseases by 2015, and even to eliminate some by that date, in order to alleviate the burden of avoidable mortality and morbidity among the world’s poorest people.

“Neglected tropical diseases Hidden successes, Emerging opportunities”

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© World Health Organization 2009. All rights reservedWHO/HTM/NTD/2009.1

DISEASES NEGLECTED

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