The Agent

Human sparganosis may occur following ingestion of species of Cyclops that are infected with the procercoid larva of various pseudophyllidean tapeworms of the species Spirometra.1,45 The procercoid penetrates the intestinal wall and migrates to various sites, including subcutaneous tissues, the central nervous system, and muscle, where they develop to second-stage larvae or plerocercoids. This condition is called sparganosis. Ingestion, either deliberately or accidentally, of infected uncooked flesh of an amphibian, reptile, bird, or mammal harboring plerocercoid larvae may also be a source of infection. All the spargana are morphologically indistinguishable. Since these worms cannot mature in humans, they migrate into the tissues and remain as plerocercoid larvae. However, in the few instances in which the larvae were allowed to complete their life cycle in dogs or cats, they were identified as members of the genus Spirometra. In some cases in the United States, they were identified as S. mansoni. Molecular approaches have been applied to this parasite that may aid in the diagnosis of this infection.46