SCHISTOSOMIASIS: AN OVERVIEW OF BIOLOGY, PATHOGENESIS, DIAGNOSIS AND CONTROL

Schistosomiasis is a serious neglected tropical disease which is caused by dioecious trematode parasites belonging to the genus Schistosoma. In man, there are five medically important species: S. mansoni, S. haematobium, S. japonicum, S. intercalatum, and S. mekongi. The importance of these parasites is not due to the adults themselves but due to the host’s inflammatory reaction to the eggs which have become trapped in the host tissues. The differences between the various species involve the geographical distribution, snail intermediate hosts, definitive host range, egg morphology, major pathology, and zoonotic capability. The major pathologies of S. mansoni and S. japonicum involve the intestines and the liver/spleen while the S. haematobium is the classic cause of urogenital schistosomiasis and causes bladder pathology and squamous-cell carcinoma.