Structure: Worms

Worms are complex organisms that range in size from microscopic to several metres long. There are two types, flatworms and roundworms, that are adapted to infest humans. Adult worms or immature larvae infest various parts of the body, including the intestines and blood vessels.

Female roundworm

Roundworms have long, cylindrical bodies with a tough covering. Eggs laid by the female are excreted in the faeces of infected people.


Most common in the tropics, flukes are flat and leaf-shaped or elongated parasitic flatworms.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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