Cause of schisto. It's the worm that causes shistosomiasis. The lucky male and female worm live in your blood vessels near the bladder or liver "in copulo" (a state of perpetual copulation), the smaller male worm living in the larger female's "gynecophoric canal." because of all this prolific sexual activity, the female then releases millions of eggs per day, which are the cause of the disease.
A Trematode disease. Schistosomiasis is a disease cause by one of several types of this worm that lives with its mate in a state of eternal copulation in the veins draining from the intestine or urinary bladder. The disease is not due to the procreating adults but rather our immune reaction to the eggs that wind up in the liver causing cirrhosis or in the urinary bladder causing blood in the urine or scarred bladder.