How much damage does a tapeworm do to the human body?

Less than you'd think

Also in this week's column:

How much damage does a tapeworm do to the human body?

Asked by George Gomez of Concord, California, USA

Tapeworms produce surprisingly few physical problems for the human body in infected individuals. But it is still to be avoided.

In The Odd Body 3 (2007), it is pointed out that the subject of tapeworms is an often-asked Odd Body Question even though tapeworm infestation is less of a problem in modern industrial societies as the quality of our food is higher. Thank the inventor of the refrigerator for much of this.

Tapeworms come into the body via contaminated food. Many organisms live on and in the human body. A tapeworm can easily survive and thrive indefinitely inside us. A tapeworm in a human can range in length from 1/250 of an inch (.0063 cm) to an incredible 50 feet (15.23 meters)!

Tapeworms have no digestive tract so they must eat food already digested by another animal. That is precisely what they do as a parasite inside our intestines. Tapeworms absorb nutrients directly across their skin (cuticle). They also reproduce inside us. There are many species of tapeworms, not all can infest humans.

Tapeworms are simple in design, but ruthless in action. They consist of two organs. The first organ (scolex) anchors the beastie to the wall of the intestine with suckers and hooks. The second organ (proglottid) is really a series of organs that grow out from the scolex with each having full reproductive capability. Proglottids form a chain of varying length. The last segment of the chain eventually breaks off and is passed out with feces.

Tapeworms resist being destroyed by the body's immune system or digestive juices. Tapeworms cause health problems around the world and can even kill since they rob us of nutrients, block our intestines, and take up space in organs that stop them from functioning normally. A tapeworm cyst can settle in the brain, eye, liver, and elsewhere.

Although little is known about the origins of tapeworms in humans, it is well known that some tapeworms live in both animals and humans. Some tapeworms have such a complex life that they are required to live first in an herbivore (such as a cow) and then in a carnivore (such as a human) where it only then can reproduce [Source: Arnold, J. (2001) Scientific sleuths track the origins of tapeworms in humans. ARS U.S. Department of Agriculture, 23 October, p. 1.]

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

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