Page 130 - Medical Parasitology_ A Textbook ( PDFDrive )

Cyclophyllidean Tapeworms 123

Habitat
The adult worms of both T. saginata and T. solium live in the small intestine of
human.

Morphology
The adult T. saginata is dorsoventrally flattened and segmented, measuring 5–10 m
in length. The scolex of T. saginata is about 1–2 mm in diameter, bearing 4 suckers
for attachment. The scolex has no rostellum or hooklets (Fig. 11.4a). The neck is
long and narrow. The strobila consists of 1000–2000 proglottids. They are hermaph-
rodites. The gravid segments are about 20 mm long and 5 mm broad and each gravid
segment has 15–30 lateral uterine branches (Fig. 11.4b). The gravid segments break
away and are expelled singly out through the host’s anus. The gravid segment can
be seen moving actively.
Eggs of T. solium and T. saginata are identical. They are brown and spherical,
measuring 31–43 μm in diameter. The shell is radially striated (Fig. 11.5). The
embryo (oncosphere) has 6 hooklets.
Cysticercus bovis is the larva of T. saginata. The larva is the infective stage to
humans. It is ovoid, milky white opalescent fluid filled vesicle measuring about
5 mm × 10 mm in diameter and contains a single invaginated scolex (bladder worm).
The cysticerci are found in the muscles of infected cattle. They can be seen grossly
as white dots in the infected beef (measly beef). Cysticercus bovis infection is not
reported in humans.
The adult T. solium is dorsoventrally flattened and segmented, measuring 2–3 m
in length. The scolex of T. solium is about 1 mm in diameter, bearing 4 suckers for
attachment. The scolex has rostellum and hooklets (Fig. 11.6a). The neck is short.

a b

Fig. 11.4 Taenia saginata. (a) Scolex, (b) Gravid proglottid