Most animals, including humans, can be infested with parasitic worms that derive all their nutrients from their hosts. Most of these worms live in the intestines for at least part of their life cycle. In many cases, worm infestations are long-term diseases that produce few symptoms in their early stages.
Various types of the family of worms known as roundworms can infest humans. Most affect only people in the developing world. However, some roundworms, such as threadworm, commonly affect people in developed countries. The first five articles in this section describe several types of roundworm infestation: threadworm infestation, toxocariasis, ascariasis, hookworm infestation, and tropical worm infestations, such as filariasis.
Infestations in humans that are caused by other types of worms known as flatworms, which include tapeworms and flukes, are covered in the last three articles on schistosomiasis, tapeworm infestation, and hydatid disease.
It is possible to acquire a tropical worm infestation abroad but not to experience symptoms until some months later. If you become ill after visiting the tropics, you should visit a doctor familiar with tropical diseases.
For more information on the structure of worms
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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