Categorization
Parasitic worms belong to four groups: monogeneans, cestodes (tapeworms), nematodes (roundworms), and trematodes (flukes). The following table shows the principal morphological distinctions for each of these helminth families:
| Cestodes (tapeworms) | Trematodes (flukes) | Nematodes (roundworms) | |
|---|---|---|---|
| Shape | Segmented plane | Unsegmented plane | Cylindrical |
| Body cavity | No | No | Present |
| Body covering | Tegument | Tegument | Cuticle |
| Digestive tube | No | Ends in cecum | Ends in anus |
| Sex | Hermaphroditic | Hermaphroditic, except schistosomes which are dioecious | Dioecious |
| Attachment organs | Sucker or bothridia, and rostellum with hooks | Oral sucker and ventral sucker or acetabulum | Lips, teeth, filariform extremities, and dentary plates |
| Example diseases in humans | Tapeworm infection | Schistosomiasis, swimmer's itch | Ascariasis, dracunculiasis, elephantiasis, enterobiasis (pinworm), filariasis, hookworm, onchocerciasis, trichinosis, trichuriasis (whipworm) |
Note: ringworm (dermatophytosis) is actually caused by various fungi and not by a parasitic worm.
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