World Health Organization and partners unveil new coordinated approach to treat millions suffering from neglected tropical diseases
Note to editors
NEGLECTED TROPICAL DISEASES INCLUDE
Lymphatic filariasis: It is estimated that 1.2 billion people in 83 countries live in areas endemic for lymphatic filariasis and about 120 million people are affected by the disease. Filarial infection may be clinically asymptomatic; the disease may also present as one or more acute manifestations (fever, local swelling, tropical pulmonary eosinophilia syndrome, lymphangitis). Chronic complications include lymphoedema or elephantiasis of the limbs, damage to the genital organs (including hydrocele in men), and damage to the kidney (including chyluria) and lymphatic system. The causal agents of lymphatic filariasis are the filariae Wuchereria bancrofti, Brugia malayi and Brugia timori.
Schistosomiasis: It affects about 200 million people worldwide, and more than 650 million people live in endemic areas. Urinary schistosomiasis is caused by Schistosoma haematobium and intestinal schistosomiasis by any of the organisms S. intercalatum, S. mansoni, S. japonicum, and S. mekongi. Disease is caused primarily by schistosome eggs, which are deposited by adult worms in the blood vessels surrounding the bladder or intestines. The classical sign of urinary schistosomiasis is haematuria (blood in urine). Bladder and ureteral fibrosis and hydronephrosis are common findings in advanced cases, and bladder cancer is a possible late-stage complication. Intestinal schistosomiasis has a nonspecific clinical picture of abdominal pain, diarrhoea, and blood in the stool. Liver enlargement is common in advanced cases and frequently associated with ascites and other signs of increased portal pressure. In such cases there may also be splenomegaly.
Onchocerciasis: Onchocerciasis is endemic in 30 countries in Africa, 6 countries in the Americas, and in Yemen in the Arabian peninsula. It is estimated that 100 million are at risk of infection while 37 million are estimated to be infected. The causal agent of onchocerciasis is Onchocerca volvulus, a nematode filaria. Symptoms begin 1–3 years after infection, usually at the time when adult females begin to produce microfilariae. These include: rashes, papular skin lesions, subcutaneous nodules, intense itching and depigmentation of the skin, lymphadenitis, which results in “hanging groin” and elephantiasis of the genitalia, and general debilitation. Eye lesions lead to serious visual impairment including blindness.
Soil-transmitted helminthiasis (ascariasis, trichuriasis, hookworm infections): Soil-transmitted helminthiasis affects more than 2 billion people worldwide. Recent estimates suggest that Ascaris lumbricoides infects 1.221 billion people, Trichuris trichiura 795 million, and hookworms (Ancylostoma duodenale and Necator americanus) 740 million. The causal agent of soil-transmitted helminthiasis is any of the following worms: Ascaris lumbricoides, Trichuris trichiura and the hookworms. Infection is caused by ingestion of eggs in contaminated soil or food (Ascaris lumbricoides and Trichuris trichiura) or by active penetration of the skin by larvae in the soil (hookworms). Soil-transmitted helminths produce a wide range of symptoms that include intestinal manifestations (diarrhoea, abdominal pain), general malaise and weakness that may affect working and learning capacities, and impaired physical growth. Hookworms cause chronic intestinal blood loss that results in anaemia.
Trachoma: Trachoma affects about 84 million people of whom about 8 million are visually impaired. It is caused by Chlamydia trachomatis – a microorganism which spreads through contact with eye discharge from the infected person (on towels, handkerchiefs, fingers, etc.) and through transmission by eye-seeking flies. After years of repeated infection, the inside of the eyelid may be scarred so severely that the eyelid turns inward and the lashes rub on the eyeball, scarring the cornea (the front of the eye). If untreated, this condition leads to the formation of irreversible corneal opacities and blindness.