An infection by the plerocercoid, or sparganum, of certain species of the genus Spirometra. Members of this genus have a life cycle much like that of Diphyllobothrium latum. The adult normally occurs in the intestine of dogs and cats, the procercoid in copepods, and the plerocercoid in the musculature of frogs, snakes, or aquatic mammals, but not in fish. The whitish, unsegmented plerocercoid usually is an inch or so in length, but may reach a length of a foot or more. Humans may become infected accidentally by drinking water with infected copepods or by eating hosts containing plerocercoids. Since humans are not suitable hosts for the adult stage, the plerocercoids leave the gut and enter the musculature, body cavities, or other sites and remain as plerocercoids. In Eastern countries, freshly opened frogs are sometimes used as poultices on sores, particularly around the eyes, and if plerocercoids are present, they may invade the human tissues. Human sparganosis is rare in North America.