It is characterized by an enlarged left lobe of the liver with a sharp edge and enlarged spleen with nodules. The enlargement of liver and spleen is usually mild, but in severe cases, they can enlarge to the level of the belly button and even into the pelvis. Chronic (fibrotic) hepatic schistosomiasis

This is a late stage liver disease that occurs mainly in young and middle-aged adults who have been chronically infected with a heavy infection and whose immune regulation of fibrosis is not functioning properly. It affects only a small proportion of people who are infected. Liver function and liver architecture are not affected unlike cirrhosis. The pathogenesis of this disease is caused by deposition of collagen and extracellular matrix proteins within the periportal space, which leads to liver portal fibrosis and enlarged fibrotic portal tracts (Symmers pipe stem fibrosis). The periportal fibrosis physically compress the portal vein leading to portal hypertension (increased portal venous pressure), increased pressure of the splenic vein, and subsequent enlargement of the spleen. Portal hypertension can also increase the pressure in portosystemic anastomoses (vessel connections between the portal circulation and systemic circulation) leading to esophageal varices and caput medusae. These portosystemic anastomoses also allows a pathway for the eggs to travel to locations such as the lungs, spinal cord, or brain. Co-infection with hepatitis is common in regions endemic to schistosomiasis with Hepatitis B or Hepatitis C, and co-infection with Hepatitis C is associated with more rapid liver deterioration and worse outcome.
Life Cycle
The excretion Schistosome eggs in urine or feces depending on species
The hatching of the eggs leading to release of the free-swimming, ciliated larvae called miracidia
Miracidia find and penetrate the snails, which are the intermediate hosts (specific species of snails is dependent on the species of schistosoma)
Within the snails, two successive generations of sporocysts occur
Sporocyts gives rise to the infective free-swimming larvae with forked tails called cercariae, and they leave the snails to enter the water
Cercariae finds the human hosts and penetrate their skin
Upon entrance into the human hosts, cercariae lose their tails and become schistosomulae
The schistosomulae travels to the lungs and heart via the venous circulation
They migrate to the portal venous system of the liver where they mature into the adult form with two separate sexes
The adult male and female are paired together, exits the liver via portal venous system, and travel to the venous systems of the intestines or bladder (species dependent) and produce eggs
S. japonicum - superior mesenteric veins (but can also inhabit inferior mesenteric veins)
S. mansoni - inferior mesenteric veins (but can also inhabit superior mesenteric veins)
S. haematobium - vesicular and pelvic venous plexus of the bladder (occasionally rectal venules)
S. intercalatum and S. guineensis - inferior mesenteric plexus (lower portion of the bowels compared to S. mansoni)Schistosomes can live an average of 3–5 years, and the eggs can survive for more than 30 years after infection. Other hosts
Schistosomiasis is also a concern of cattle husbandry and mice. O-methyl-threonine is weakly effective in mouse schistosomiasis but is not in use.