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.
The parasite that's doing the damage is a flatworm, a trematode called Hepatodirus hominis.
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')
n.
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.