Page 468 - Review of Medical Microbiology and Immunology ( PDFDrive )

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CHAPTER 54 Cestodes

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FIGURE 54–5
Taenia solium. Life cycle including cysticercosis stage. Center and left side of figure describes the cycle of T. solium within
the human and the pig similar to Figure 54–1. Note, however, that there are now blue arrows between the egg at the bottom that go up the left
side of the figure to the person at the top right. In cysticercosis, humans are infected when they ingest the eggs of T. solium in food contami-
nated with human feces. The eggs differentiate into cysticerci primarily in brain, eyes, and skin. (Source: Dr. Alexander J. da Silva and Melanie Moser,
Centers for Disease Control and Prevention.)

The life cycle of T. saginata is shown in Figure 54–1.
Humans are infected by eating raw or undercooked beef
the definitive hosts and cattle the intermediate hosts.
Unlike T. solium, T. saginata does not cause cysticercosis
containing larvae (cysticerci). In the small intestine, the completed when the cysticerci are ingested. Humans are
in humans.
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larvae attach to the gut wall and take about 3 months to
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grow into adult worms measuring up to 10 m (Figure 54–7).
Pathogenesis & Epidemiology
The gravid proglottids detach, are passed in the feces, and
are eaten by cattle. The embryos (oncospheres) emerge
in the small intestine. The epidemiology of taeniasis caused
from the eggs in the cow’s intestine and burrow into a
blood vessel, where they are carried to skeletal muscle. In
by T. saginata is related to the access of cattle to human
feces and to the consumption of raw or undercooked beef.
the muscle, they develop into cysticerci. The cycle is

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