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Taxonomy of Helminths

Medically important Helminths

Medically important Protozoa

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Helminth Taxonomy

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Medically Important Parasitic Diseases - Lifecycles

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   Medically important Helminths    
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There is no real consensus on the taxonomy of the helminths, differing textbooks showing different  groupings, particularly with the nematodes. The term 'Helminth' itself contains a number of phyla, many of which are completely unrelated (for example the Annelids are much more closely related to the Arthropods than the Platyhelminths, and the Nematodes appear to be even more distantly related). However, for convenience sake the term is still used to describe four groups with superficial similarities, the phyla Annelida (Trematodes), Platyhelminths (Digeneans and Cestodes), Nematoda and Acanthocephala. A fifth group, the phylum Pentastomida (the Tongue worms) are not usually included here, but a very brief description of them is given at the end of this page, as some older authorities do include them with the helminths. The following taxonomy of the Helminths is that generally used, and is shown with particular reference to the schistosomes. The two most important phyla in terms of parasites infecting man are the Platyhelminths, and the Nematodes.

For more information of the true phylogenetic relationship between these organisms, see the University of Arizona's 'Tree of Life' pages, or the University of California Museum of Paleontology Phylogeny Pages.

Click on the species name to see an image.

Phylum Plathyhelminthes (the flatworms) Phylum Nematoda (the roundworms)
  • Class Aphasmida (=Enoplea)
    • Order Dioctophymatida
      • Family Dioctophymatidae
        • Dioctophyme renale
      • Family Eustrongylidae
        • Eustrongylides tubifex
    • Order Trichurida
      • Family Capillaridae
        • Capillaria hepatica
        • Capillaria philippinensis
      • Family Trichinellidae
        • Trichinella spiralis (trichinosis, trichinellosis)
      • Family Trichuridae
        • Trichuris spp. (whipworms)
  • Class Rhabditae
    • Order Rhabditidae
        • Strongyloides stercoralis
    • Order Strongylida
      • Family Ancylostomidae
        • Ancylostoma spp. (hookworms)
        • Necator americanus (hookworms)
        • Placoconus (= Arthrocephalus) sp.
      • Family Angiostrongylidae
        • Angiostrongylus cantonensis
      • Family Trichostongyloidae
        • Cooperia spp.
        • Haemonchus spp.
        • Nematodirus spp.
        • Obeliscoides cuniculi
        • Ostertagia spp.
        • Trichostongylus spp.
    • Order Ascaridida
        • Ascaris spp. (human and pig roundworms)
        • Toxocara canis (canine roundworms)
        • Baylisascaris procyonis
        • Anisakis spp.
    • Order Oxyurida
        • Enterobius vermicularis (pinworms)
        • Cosmocerella sp.
    • Order Spirurida
      • Suborder Spirurina
        • Family Onchocercidae
          • Brugia malayi (brugian filariasis, elephantiasis)
          • Dirofilaria immitis (canine heartworm)
          • Loa loa (African eye worm)
          • Onchocerca volvulus (onchocerciasis, river blindness)
          • Wuchereria bancrofti (bancroftian filariasis, elephantiasis)
        • Family Rhabdochonidae
          • Spinitectus sp.
      • Suborder Camallanina
        • Family Camallanidae
          • Camallanus oxycephalus
        • Family Dracunculidae
          • Dracunculus medinensis (guinea worm, fiery serpent)
          • Philometra cylindracea
Phylum Acanthocephala (the thorny-headed worms)
  • Class Archiacanthocephala
        • Macrocanthorhynchus hirudinaceus
        • Moniliformis sp.
  • Class Palaeacanthocephala
    • Order Echinorhynchida
        • Leptorhynchoides sp.
        • Pomphorhynchus sp.
        • Echinorhynchus sp.
    • Order Polymorphida
        • Plagiorhynchus sp.
        • Polymorphus minutus
Phylum Annelida (the true segmented worms)
  • Class Hirudinea (leeches)
    • Order Rhynchobdellida
      • Family Glossiphoniidae
        • Placobdella sp.