Cestodea | Host of Adult Worm | Name of Metacestode (Intermediate) Stage | Measurements of Metacestode | Principal Intermediate Hosts | Site of Metacestode |
---|---|---|---|---|---|
Taenia saginata | People only | Cysticercus “beef measles” | 9 × 5 mm | Cattle | Skeletal and cardiac muscle |
Taenia solium | People only | Cysticercus “pork measles” | 6–10 × 5–10 mm | Pigs, rarely dogs (people may be both definitive and intermediate hosts) | Skeletal and cardiac muscle, occasionally nervous system |
Diphyllobothrium spp | People, dogs, cats, and other fish-eating mammals | Procercoid in copepod, plerocercoid in fish | 2–25 × 2.5 mm for plerocercoid | Copepod, then fish | Mesenteric tissues, testes, ovary, muscles of fish |
Echinococcus granulosus | Dogs, wolves, foxes, and several other wild carnivores | Hydatid cyst | Diameter 50–100 mm, sometimes ≥150 mm | Sheep, cattle, pigs, horses, moose, deer; occasionally people | Commonly in liver and lungs, occasionally in other organs and tissues |
Echinococcus multilocularis | Canids and domestic cats | Alveolar hydatid cyst | Variable, penetrates like neoplastic tissue | Field mice, voles, lemmings, sometimes domestic mammals and people | Usually liver, various other organs and tissues |
a Human infections with the metacestodes of Taenia crassiceps, T multiceps, Mesocestoides spp, and other cestodes not listed here occur rarely. Children occasionally become infected with adult Dipylidium caninum, which appears to have no medical significance but important aesthetic aspects. |