Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 11.04.2021

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Roundworms or threadworms; spindle-shaped, unsegmented, a few mm to about 1 m long, separately sexual parasites. Development proceeds from the egg through 4 larval stages to the adult worm. Some species require an intermediate host for their development.

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The worm class of nematodes contains about 30,000 species of which many have human pathological significance (see classification). The classification of nematodes into:

  • Nematodes with intestinal manifestation
  • and
  • nematodes with extraintestinal manifestation

is fluid. However, for diagnostic purposes, it is significant to assign - intestinal infestation/tissue infestation of crucial importance (stool examination, blood examination, histology).

Classification according to clinical criteria:

Intestinal nematodes:

  • Enterobius vermicularis (pinworm: causative agent of oxyuriasis)
  • Ascaris lumbricoides (roundworm: causative agent of ascaridiasis)
  • Trichuris trichiuria (whipworm: causative agent of trichuriosis)
  • Ancylostoma duodenale (hookworm: causative agent of ancylostomiasis)
  • Trichinella spiralis (trichinae).

Filariae (causative agent of lymphatic filiarosis):

  • Wucheria bancrofti a. Brugia species (causative agent of lymphatic filiarosis)
  • Loa Loa (causative agent of loiasis)
  • Onchocerca volvulus (causative agent of onchocerciasis = river blindness)
  • Dracunculus medinensis (medina worm: causative agent of dracunculosis).


Ankylomstomatidae (hookworms)

Ascarididae (flushing worms)

  • Ascaris lumbricoides (roundworm: large roundworms up to 40cm long, causative agent of ascaridiasis; affects about 1 billion people)
  • Anisakis simplex (causative agent of anisakiasis = herring worm disease)
  • Toxocara canis (roundworms of dogs; larva migrans visceralis syndrome)
  • Toxcara cati (roundworms of cats; larva migrans visceralis syndrome)

Filariidae (nematodes, causative agent of lymphatic filiarosis)

Spiruridae (nematodes whose development requires an intermediate host, often small crustaceans of the genus Cyclops)

Oxyuridae (pinworms)

  • Enterobius vermicularis (pinworm: causative agent of oxyuriasis; about 1 billion people are affected)

Rhabdititae (dwarf pinworms; about 80 million people are infected)

  • Strongyloides stercoralis (dwarf threadworms: strongyloidosis, causative agent of larva migrans cutanea syndrome)
  • Strongyloides fuelleborni (Dwarf threadworms: causative agent of Larva migrans cutanea syndrome)

Trichinella (causative agent of trichinosis)



Please ask your physician for a reliable diagnosis. This website is only meant as a reference.


Last updated on: 11.04.2021