The neglected diseases
■ Dengue: A mosquito-borne infection causing a flu-like illness that may develop into severe dengue and cause lethal complications. A partially effective vaccine became available in 2016 but there are no anti-viral therapies.
■ Rabies: Transmitted to humans through the bites of infected dogs, it’s invariably fatal once symptoms develop. Each year, 15 million people are vaccinated against rabies.
■ Trachoma: Infection transmitted through direct contact with eye or nasal discharge. Left untreated, it causes irreversible corneal opacities and blindness. Up to 80 million people are infected every year but can be treated with antibiotics and improved hygiene.
■ Buruli ulcer: A debilitating mycobacterial skin infection causing destruction of the skin, bone and soft tissue. Affects 80,000 people a year. Treatment comprises a combination of antibiotics and complementary treatments.
■ Yaws: A chronic bacterial infection that affects skin and bone. Primarily affects children in tropical forested areas. There is no vaccine.
■ Leprosy: A complex disease caused by infection mainly of the skin, peripheral nerves, mucosa of the upper respiratory tract and eyes. Leprosy is curable with a combination of drugs. The number of people with leprosy has dropped from more than five million over the past 40 years to around 200,000.
■ Chagas disease: A lifethreatening illness transmitted through contact with insects, ingestion of contaminated food, infected blood transfusions and congenital transmission. Chagas can be treated with two antiparasitic medicines that are nearly 100 per cent effective.
■ Human African trypanosomiasis (sleeping sickness): A parasitic infection spread by the bites of tsetse flies. Almost 100 per cent fatal without rapid diagnosis and treatment. Six medicines are donated by their manufacturers.
■ Leishmaniases: Transmitted through the bites of infected female sandflies. In its most severe (visceral) form, attacks the internal organs and in its most prevalent (cutaneous) form, causes face ulcers, disfiguring scars and disability. Treatment can’t provide a sterile cure and the parasite can cause a relapse.
■ Taeniasis and neurocysticercosis: Caused by adult tapeworms in human intestines. Leads to cysts in the brain and tissues, and seizures.
The WHO says that improved, rapid diagnostic tools are still needed.
■ Dracunculiasis (guinea-worm disease): A nematode infection transmitted by drinking-water contaminated with parasite-infected water fleas. No drug treatment is available.
■ Echinococcosis: Infection caused by the larval stages of tapeworms, which form pathogenic cysts in humans. Transmitted by ingestion of eggs, most commonly shed in the faeces of dogs and wild animals. Expensive, complicated treatment includes surgery and/or prolonged drug therapy.
■ Foodborne trematodiases: Infection acquired by consuming fish, vegetables and crustaceans contaminated with larval parasites. Treatment can be offered through preventive chemotherapy.
■ Lymphatic filariasis (Elephantiasis): Infection transmitted by mosquitoes that causes abnormal enlargement of limbs and genitals. Available medicines have limited effect.
■ Onchocerciasis (river blindness): Infection transmitted by the bite of infected blackflies. Can lead to blindness. Medicine needed at least once yearly for up to 15 years.
■ Schistosomiasis (Bilharzia): Trematode infection transmitted when larval forms released by freshwater snails penetrate human skin. Treatment with Praziquantel is effective, safe and low-cost.
■ Soil-transmitted helminthiases: Nematode infection transmitted through soil contaminated by human faeces causing anaemia, vitamin A deficiency, and stunted growth. WHO-recommended medicines are effective, inexpensive and easy to administer.
■ Mycetoma: a chronic inflammatory skin disease which usually affects the lower limbs. Infection is thought to be caused by fungi or bacteria from thorn pricks. Treatment involves a longterm antibiotics or antifungal combination but has many side effects, is expensive and rarely available.
■ Chromoblastomycosis and other deep mycoses, scabies and other ectoparasites: Globally estimated to affect more than
200 million people at any time. Treatment involves application of a topical scabicide.