Cysticercosis: The Ides of March

Unlike the tiny adult tapeworms of Echinococcus, tapeworms that belong to the genus Taenia are the archetype of what we think of as tapeworms. Human infections are associated with three species, Taenia solium, T. saginata and the more recently discovered T. asiatica. These are huge parasites, for which the name tapeworm was first used to describe them. The adult stage of Taeniid tapeworms live in the human small intestines with their scolex embedded in the mucosal wall of the intestine (Fig. 3.1). The main body of the tapeworm, known as the strobila, is flat and broad like a measuring tape and it can extend to 25 m (80 feet) long, and lives floating in the nutrient rich broth of the host intestinal lumen where it shares its food. This type of infection by the adult tapeworm is called taeniasis, and it seldom causes anything more life threatening than bowel irritation and discomfort. However, since sections of the strobila are occasionally passed out in the stool, still visibly moving and undulating, this must be disturbing to the carrier to say the least, and these large parasites must have been easily observed and known by our early ancestors (Fig. 3.2).