Worm disease

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As worm disease or helminthiasis is known diseases caused by parasitic worms are triggered. Depending on the type of infestation, a distinction can be made as to whether the host is an intermediate host or a final host .

Most of the people important worms are among the flatworms - with classes tapeworms (Cestoda) and flukes (Trematoda) - or to nematodes (Nematoda), which are also called roundworms because of their circular cross-section. As a collective term for worms, filaria belong to the families Filariidae and Onchecercidae . The scratch worms (Acanthocephala) are / were partially classified here, but should represent a separate tribe .

The schistosomiasis is of schistosomes caused the biologically a genus represent the flukes. Tongue worms (pentastomida) are worm-like endoparasites which, as a biological class , are assigned to crustaceans and cause porocephalosis , but can still be dealt with in worm diseases.

Phases of infection

Prepatent infection: worm infection begins with the ingestion or penetration of infectious worm stages into an organism. The worms then develop in the host organism.

Patent Infection: This phase begins when the invaders have completed development into adult, egg-laying worms and their reproductive products appear in the host's excretions.

Worm diseases

The diseases caused are identified by the respective worm species or group that caused it.

The most important worm diseases:

Worm infections are treated with antihelminthics . Praziquantel is best for tapeworms and schistosomes, and mebendazole for roundworms .

Pathogenic species

Only the higher-level taxa of the parasitic worms are highlighted here, for a general overview see Human Parasites .



Genera and species

Selected species

Roundworms (nematodes)

Enterobius vermicularis (pinworm)

The pinworm is a white non-invasive worm about 1 cm long that occurs worldwide. It feeds on the food pulp in the intestine, at night the females crawl outside to lay their eggs on the anal skin, which causes severe itching. Otherwise there will be no symptoms of infection . If you look closely, you can see the small worms on the droppings. As a result of the itching and scratching, the eggs are distributed to the surrounding area and reabsorbed into the mouth via the fingers. To establish the diagnosis, a sample of the eggs is taken from the anal skin with a slide. The patient's surroundings and bed linen must be disinfected and contact persons examined.

Trichuris trichuria (whipworm)

The whipworm gets its name from its long, thin tail, with which it is stuck in the intestinal lining. It acts as a food competitor, and if it is heavily infested, it can cause abdominal pain. It lays its eggs in the intestinal mucosa and the hatching larvae develop into adult worms on the spot. Excreted eggs can be ingested by the nearest humans with the food.

Ascaris lumbricoides (roundworm)

The roundworm is the most common worm in the world. Its reproduction cycle is similar to that of the whipworm. However, the larvae of the roundworm penetrate the intestinal wall and reach the lungs via the bloodstream. There they break through the wall of the alveoli and are coughed up via the windpipe into the throat and then swallowed back into the intestine via the esophagus and stomach. The roundworm thus shows its relationship to various tropical worms, the larvae of which can be absorbed through the skin and then reach their actual food source in the intestine by the same route.

Ancylostoma duodenale and Necator americanus , Strongyloides stercoralis

The larvae of these worms can penetrate the skin after prolonged contact time (at least 20 minutes), for example when walking barefoot over a cesspool . Their further reproduction cycle then corresponds to that of the roundworm. The finished worm lays eggs in the intestine, from which larvae hatch in the intestine and are then excreted. In dwarf threadworms, some larvae penetrate the host's intestinal wall again to go through the cycle again (auto-infection).

Trichinella spiralis (Trichinella)

This worm produces larvae in the intestine that penetrate the intestinal wall, spread through the blood and form cysts (very firm capsules that feed on connective tissue cells) in the muscles so that they can be absorbed by the nearest living being. The reproduction cycle is thus similar to that of the pork tapeworm .

One can also become infected by eating infected meat, which has become rare these days through meat inspection.

Tapeworms (cestodes)

In the case of tapeworms , a distinction is made between the ultimate host, which carries the worms in the intestine, and the intermediate host. The intermediate host ingests the larvae through contaminated food, they penetrate the intestinal wall and settle in the muscles as fins , which are to be eaten by the final host (a predator). Since humans are normally not eaten, they can only be considered as false intermediate hosts.

Humans are the final hosts of pork tapeworm ( Taenia solium ) and beef tapeworm ( T. saginata ). The fish tapeworm (Diphyllobothrium latum) has now largely been eradicated. The worm forms a commensal with humans in the intestine . Tapeworms are much longer than roundworms, the patient finds their fallen proglottids (tapeworm limbs) in the stool.

The situation is different with dog tapeworms ( Echinococcus granulosus ) and fox tapeworms ( E. multilocolaris ), where humans are false intermediate hosts . The Finns are usually deposited in the liver, but can also affect other organs and cause discomfort there. The dog tapeworm can be surgically removed, the fins of the fox tapeworm are more difficult to define in terms of their growth and, if left untreated, lead to death in the long run.


Schistosomiasis or schistosomiasis occurs primarily in waters in Africa, but also in the Near and Far East. The causative agents of the disease are the pair of leeches , flukes of the genus Schistosoma.

Roundworms (filaria)

Filaria are only a few millimeters long. Onchocerca volvulus and Loa loa live under the skin. The females give birth to microfilariae, which are transferred to the skin of the nearest host through an insect bite . They can lead to blindness. Wuchereria bancrofti and Brugia malayi live in lymphatic vessels . Over time, this leads to inflammation, which can lead to lymphatic congestion and the clinical picture of elephantiasis . In adaptation to the flight time of the respective vectors , the microfilariae of Loa loa v. a. during the day, those of Wuchereria bancrofti can be detected in the blood, especially at night.

See also

Individual evidence

  1. Hans-Adolf Oelkers: Pharmacological basics of the treatment of worm diseases. 3rd edition, Leipzig 1950 (= contributions to drug therapy. Volume 4).