Neglected tropical diseases (NTDs) are a diverse group of communicable diseases that prevail in tropical and subtropical conditions in 149 countries and affect more than one billion people, costing developing economies billions of dollars every year. They mainly affect populations living in poverty, without adequate sanitation and in close contact with infectious vectors and domestic animals and livestock.
Some Neglected Tropical Diseases are:
• Dengue: A mosquito-borne infection causing flu-like illness that may develop into severe dengue and cause lethal complications.
• Rabies: A preventable viral disease transmitted to humans through the bites of infected dogs that is invariably fatal once symptoms develop.
• Trachoma: A chlamydial infection transmitted through direct contact with infectious eye or nasal discharge, or through indirect contact with unsafe living conditions and hygiene practices, which left untreated causes irreversible corneal opacities and blindness.
• Buruli ulcer: A debilitating mycobacterial skin infection causing severe destruction of the skin, bone and soft tissue.
• Yaws: A chronic bacterial infection affecting mainly the skin and bone.
• Leprosy: A complex disease caused by infection mainly of the skin, peripheral nerves, mucosa of the upper respiratory tract and eyes.
• Chagas disease: A life-threatening illness transmitted to humans through contact with vector insects (triatomine bugs), ingestion of contaminated food, infected blood transfusions, congenital transmission, organ transplantation or laboratory accidents.
• Human African trypanosomiasis (sleeping sickness): A parasitic infection spread by the bites of tsetse flies that is almost 100% fatal without prompt diagnosis and treatment to prevent the parasites invading the central nervous system.
• Leishmaniases: Disease transmitted through the bites of infected female sandflies that in its most severe (visceral) form attacks the internal organs and in its most prevalent (cutaneous) form causes face ulcers, disfiguring scars and disability.
• Taeniasis and neurocysticercosis: An infection caused by adult tapeworms in human intestines; cysticercosis results when humans ingest tapeworm eggs that develop as larvae in tissues.
• Dracunculiasis (guinea-worm disease): A nematode infection transmitted exclusively by drinking-water contaminated with parasite-infected water fleas.
• Echinococcosis: Infection caused by the larval stages of tapeworms forming pathogenic cysts in humans and transmitted when ingesting eggs most commonly shed in faeces of dogs and wild animals.
• Foodborne trematodiases: Infection acquired by consuming fish, vegetables and crustaceans contaminated with larval parasites; clonorchiasis, opisthorchiasis and fascioliasis are the main diseases.
• Lymphatic filariasis: Infection transmitted by mosquitoes causing abnormal enlargement of limbs and genitals from adult worms inhabiting and reproducing in the lymphatic system.
• Soil-transmitted helminthiases: Nematode infections transmitted through soil contaminated by human faeces causing anaemia, vitamin A deficiency, stunted growth, malnutrition, intestinal obstruction and impaired development.
A report on Neglected Tropical Diseases released by the World Health Organisation has outlined the breathtaking economic cost that developing countries such as India face in coping with diseases such as hookworm infection, lymphatic filariasis and visceral leishmaniasis, commonly known as kala-azar.
Effective control against NTDs can be achieved when several public health approaches are combined. Interventions are therefore guided by local epidemiology and availability of appropriate detection, prevention and control measures that can be delivered locally.