Worms residing in blood vessels of the bladder cause a chronic disease known as urinary schistosomiasis. The disease is commonly found in African and Eastern Mediterranean countries, especially in poor, rural areas. Humans become infected when they come into contact with contaminated water. The infection occurs when small larvae shed from snails in infected waters get into the individual through the skin and develop into adult worms that travel to the blood vessels of the bladder. There they can produce a large number of eggs, and the worm can live for three to five years. It is mainly the eggs that cause the disease. The main symptoms are blood in the urine and pain when passing urine. The eggs also cause tissue damage, and the severity of disease depends upon the intensity of the infection. Sometimes the infection can lead to bladder cancer or other kidney problems, including kidney failure. There are a number of measures that have been introduced to try to reduce the risk of infection. These include health education, improving clean water supplies and sanitation, environmental control measures to reduce numbers of intermediate host snails, and drug treatments. The review looked at the efficacy of drugs to reduce the ill-health associated with these infections. The review identified 24 trials involving 6315 people. Praziquantel and metrifonate were both found to be efficacious with few adverse events, although adverse outcomes were poorly assessed. Evidence on the artemisinins was inconclusive, and further research is warranted on combination therapies.
Danso-Appiah, A.; Utzinger, J.; Liu, J.; Olliaro, P. Drugs for treating urinary schistosomiasis. Cochrane Database of Systematic Reviews (2008) (Issue 3) Art. No.: CD000053. [DOI: 10.1002/14651858.CD000053.pub2]