Dormancy Period: 30 years or longer, with a large host of related diseases.

Each pair of flukes deposits around 1500–3500 eggs per day in the vessels of the intestinal wall. The eggs infiltrate through the tissues and are passed in the feces. The severity of S. japonicum arises in 60% of all neurological diseases in schistosomes due to the migration of schistosome eggs to the brain.

Individuals at risk to infection from S. japonicum are farmers who often wade in their irrigation water, fishermen who wade in streams and lakes, children who play in water, and people who wash clothes in streams. Once the parasite has entered the body and begun to produce eggs, it uses the hosts’ immune system (granulomas) for transportation of eggs into the gut. The eggs stimulate formation of granuloma around them. The granulomas, consisting of motile cells, carry the eggs to the intestinal lumen. When in the lumen, granuloma cells disperse leaving the eggs to be excreted within feces. Unfortunately, about two-thirds of eggs are not excreted, instead they build up in the gut. Chronic infection can lead to characteristic Symmer’s fibrosis (also known as “clay pipe stem” fibroses, these occur due to intrahepatic portal vein calcification which assume the shape of a clay pipe in cross section). S. japonicum is the most pathogenic of the schistosoma species because it produces up to 3,000 eggs per day, ten times greater than that of S. mansoni.

As a chronic disease, S. japonicum can lead to Katayama fever, liver fibrosis, liver cirrhosis, liver portal hypertension, splenomegaly, and ascites. Some eggs may pass the liver and enter lungs, nervous system and other organs where they can adversely affect the health of the infected individual.

https://en.wikipedia.org/wiki/Schistosoma_japonicum

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