Schistosomiasis is caused by several parasitic schistosome worms, leading to two major forms of clinical disease: urinary schistosomiasis, caused by Schistosoma haematobium, and intestinal schistosomiasis, caused by Schistosoma mansoni in Africa, Middle East, the Caribbean and Latin America or Schistosoma japonicum in Asia.
Infection with schistosomes can result in serious clinical disease when parasite eggs become trapped in the wall of the intestine or bladder, or in the liver. The immune response to the trapped eggs can lead to inflammation and fibrosis, an excess of fibrous connective tissue.
Urinary schistosomiasiscauses bladder wall disease, leading to ulcer formation, blood in urine and pain when urinating. Inflammations and ulcers of the bladder wall and urethra can lead to bladder obstruction, renal failure, lesions of the genital tracts, and an increased risk of bladder cancer.
In intestinal schistosomiasis, there is progressive enlargement of the liver and spleen and intestinal damage, which can have severe and sometimes fatal consequences. Schistosomiasis also causes chronic growth faltering and can contribute to anaemia, especially among children.