Merck Manual

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Cestodes of Public Health Importance

Cestodes of Public Health Importance

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.