Schistosomiasis and Soil Transmitted Helminthiases (STH) control

Schistosomiasis

Schistosomiasis, or bilharzia, is a parasitic disease caused by trematode flatworms of the genus Schistosoma. Larval forms of the parasites, which are released by freshwater snails, penetrate the skin of people in the water. In the body, the larvae develop into adult schistosomes, which live in the blood vessels. The females release eggs, some of which are passed out of the body in the urine or faeces. Others are trapped in body tissues, causing an immune reaction.

In urinary schistosomiasis, there is progressive damage to the bladder, ureters and kidneys. In intestinal schistosomiasis, there is progressive enlargement of the liver and spleen, intestinal damage, and hypertension of the abdominal blood vessels.

In Africa, schistosomiasis affects at least 160 million people and an estimated 70 million people exhibit symptoms of urinary schistosomiasis.

Helminthiasis

Helminthiasis is infestation with one or more intestinal parasitic worms (roundworms (Ascaris lumbricoides), whipworms (Trichuris trichiura), or hookworms (Necator americanus and Ancylostoma duodenale)). Infected people excrete helminth eggs in their faeces, which then contaminate the soil in areas with inadequate sanitation. Other people can then be infected by ingesting eggs or larvae in contaminated food, or through penetration of the skin by infective larvae in the soil (hookworms). Soil-transmitted helminths produce intestinal manifestations (diarrhoea, abdominal pain), general malaise and weakness, that may affect working and learning capacities and impair physical growth. Hookworms cause chronic intestinal blood loss that results in anaemia.

Soil-transmitted helminthiasis is widespread in most poverty-stricken areas in the developing world; schistosomiasis occurs in focal pockets and is closely linked to the presence of water bodies that harbour susceptible species of snails.

More than 400 million people are affected by STH in the Region. WHO / AFRO member states and its control have endorsed the World Health Assembly Resolution WHA 54.19 of 2001 which called for joint implementation of control of schistosomiasis and STH. The diseases have long been recognized as a major public health problem, but limited funds and low priority are often accorded resulting in its exclusion from most Health Sector Strategic Plans in the Region and consequently there has not been any large scale control program until recently. However, since 2001, the prospects for control were improved because of the strategy of mass drug administration (MDA) was simplified using the dose pole.

The aim of the programs in the African Region countries is to control morbidity by maximizing annual mass de-worming coverage to reach all persons residing in the endemic areas following WHO guidelines. Supportive control activities include intensive health education to the affected communities and limited provision of sanitary facilities and safe water especially in schools. Integrating de-worming into already existing and successful disease control campaigns might be the only way to sustain the programs.