First: mechanical damage. Entamoeba trophozoites can destroy intestinal mucosa and degrade intestinal villi in intestinal tissue.
Second: contact dissolution. The lectin of amoeba can adsorb and dissolve intestinal mucosal cells and release ions to rupture them.
Third: enterotoxin.
In a word, jam-like stool is caused by intestinal tissue destroyed by amoeba, which releases a lot of cell fluid. The stool is thin and jam-colored, and blood cells are mixed in it.