38 TROPICAL MEDICINE AND HYGIENE 



of the vessels into the connective tissue, and are ultimately 

 extruded through the mucous membrane of the genito- 

 urinary system, biliary ducts, intestine, or the rectum. 



The common series of clinical manifestations or 

 dieases due to the S. hcematobium are the effects of the 

 passage of these eggs through the tissues of the host. 



The adult worm causes no disease, though the walls of 

 the vessels containing the worms appear to be thickened, 

 but the irritating effects of the eggs are considerable. 

 These effects are usually limited to the submucosa, and 

 consist of inflammatory growth, of the formation of granu- 

 lation tissue ; and sometimes also of hypertrophy of the 

 mucosa. This may be sufficiently abundant to form 

 visible masses or papillomata. These are common in 

 the rectum and at the orifice of the anus. Similar papil- 

 lomata are found in the ureters and pelvis of the kidneys. 

 Rarely they are found under the skin round the orifice of 

 the anus. The adult worms are often found in the liver. 

 The ova in the liver are usually those with the lateral 

 spine. Possibly the hepatic cirrhosis so common in the 

 African native may in some cases be due to this worm. 



Whether visible papillomata are found or not in the 

 alimentary canal, there is thickening of the submucosa, 

 and in this the eggs are found in enormous numbers. 

 The mucosa, as the eggs pass into and through it, 

 becomes definitely inflamed, and thick mucus is dis- 

 charged from the surface, usually with some blood. The 

 eggs are discharged at the same time. 



When this occurs in the rectum, the prominent sym- 

 ptoms of dysentery may be produced tenesmus, with 

 passage of blood and mucus, and severe pain. In many 

 cases the symptoms are not dysenteric, but partake more 

 of the nature of a chronic diarrhoea, with wasting and 

 marked anaemia. 



The most common and troublesome results met with 

 are those when the eggs are passed through the mucous 

 membrane of the bladder and ureters. In the inflamed 

 and thickened membranes this passage results in (i) 



