The parasite that's doing the damage is a flatworm, a trematode called Hepatodirus hominis.
If a flatworm be cut in two, the front piece grows out a new tail, the hind piece a new head, and two perfect worms result.
Such is seen in the life history of the liver fluke, a flatworm which kills sheep, and in the tapeworm.
flatworm flat·worm (flāt'wûrm')
Any of various worms of the phylum Platyhelminthes, including the parasitic tapeworms and flukes, characteristically having a soft, flat, bilaterally symmetrical body and no body cavity. Also called platyhelminth.
Any of various parasitic and nonparasitic worms of the phylum Platyhelminthes, characteristically having a soft, flat, bilaterally symmetrical body. Flatworms lack a coelom (body cavity), respiratory system, and circulatory system, but are the most primitive invertebrates to have a brain. The evolutionary history of flatworms is uncertain, but they share some basic characteristics with rotifers, nematodes, and a few other invertebrate phyla. Cestodes (tapeworms), planarians, and trematodes (flukes) are flatworms.