Threadworms (Enterobius vermicularis) in the villi of the gut

Threadworms (coloured green), also known as pinworms, are tiny parasitic worms that hatch eggs and infect the large intestine of humans. Two villi (finger-like projections) in the gut are shown here (coloured brown). Threadworms are the most common type of worm infection in the UK, and are particularly common in young children, infecting up to half of all children under the age of 10. Eggs that are swallowed hatch in the small intestine and then make their way to the large intestine. They are spread from person-to-person as a result of poor hygiene. If one member of a household is infected, there is a high risk that other members will also be infected. Horizontal field width is 100 micrometres.