In many parts of Africa a small worm called bilharzia is found. There are two kinds of bilharzia: one which lives in a human being’s lower bowel, and one which lives in the bladder. Bilharzia is also the name of the disease the worm causes. Although it rarely kills people, it weakens them, and makes it easy for them to catch other diseases.
The bilharzia worms lay tiny eggs inside the infected person. If the infected person urinates or defecates into a stream or river or pond, the eggs hatch out into larvae which live for a short time in snails. These larvae attack a person by entering through the body while the person is bathing in water, or when standing in it. They enter the body and then enter the wall of the bowel or bladder causing bleeding, pain and damage to vital parts of the body.
The symptoms of the disease are well known. In the early stages, the infected person will feel feverish, will suffer from stomach pain and will have too much loose body waste. The infected person will also feel tired and will have little energy. If the disease continues for a long time, the intestines may be destroyed, and the liver may become hard.
Bilharzia can be cured. If treatment is given early enough, four out of every five cases can be cured by means of new medicines, but these medicines can cause bad side effects. However, prevention is better than cure.
A number of preventive measures can be taken. Firstly, a proper latrine should be used whenever possible. Rivers and streams should not be polluted. In addition, the water supply should be kept clear of weeds and reeds, which may harbor the bilharzia snails. All drinking water should of course be boiled. Finally, slowly moving streams or stagnant pools which may be infected with bilharzia should be avoided.
Text taken from http://www.col.org/bilharzia