Cestodea | Host of Adult Worm | Name of Metacestode (Intermediate) Stage | Measurements of Metacestode | Principal Intermediate Hosts | Site of Metacestode |
---|---|---|---|---|---|
Taenia saginata | Humans only | Cysticercus “beef measles” | 9 × 5 mm | Cattle | Skeletal and cardiac muscle |
Taenia solium | Humans only | Cysticercus “pork measles” | 6–10 × 5–10 mm | Pigs, rarely dogs (humans may be both definitive and aberrant intermediate hosts) | Skeletal and cardiac muscle, occasionally nervous system |
Diphyllobothrium spp | Humans, 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 sensu lato | Dogs, wolves, foxes, and several other wild carnivores | Hydatid cyst | Diameter 50–100 mm, sometimes ≥150 mm | Sheep, cattle, pigs, horses, moose, deer, occasionally humans | Commonly in liver and lungs, occasionally in other organs and tissues |
Echinococcus multilocularis | Canids and domestic cats | Alveolar hydatid cyst | Variable | Field mice, voles, lemmings, sometimes domestic mammals and humans | Usually liver, various other organs and tissues |
a Human infections with the metacestodes of Taenia crassiceps, Taenia 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. |