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CHAPTER 10 The Cestodes
Six-hooked onconosphere
A
Contains 5-30 eggs
Size range of each egg: 30-60 m in diameter
B
FIGURE 10-12 A, Dipylidium caninum egg packet. B, Dipylidium caninum egg packet. (B from Bowman DD: Georgis’
parasitology for veterinarians, ed 9, St. Louis, 2009, Saunders.)
TABLE 10-7
Parameter
Description
Number of eggs in
5-30
enclosed packet
Diameter range per egg 30-60 µm
Individual egg features Six-hooked oncosphere
Proglottids. The mature and gravid proglottids
of D. caninum resemble pumpkin seeds in
shape (see Table 10-8). Each mature segment
contains two sets of both male and female reproductive
organs. Following self-fertilization, the
resulting gravid proglottid is full of eggs enclosed
in an embryonic membrane (Fig. 10-13).
Laboratory Diagnosis
D. caninum diagnosis is based on the recovery
of the characteristic egg packets or gravid
proglottids in stool samples. The presence of a
single egg in a stool sample may occur, but is
extremely rare.
Life Cycle Notes
Dipylidium caninum Egg
Packet: Typical
Characteristics at a Glance
As the common name implies, D. caninum is
primarily a parasite of dogs and cats. However,
humans may become accidentally infected on
TABLE 10-8
Parameter
Scolex
Number of suckers
Rostellum
Hooks
Gravid Proglottid
Shape
Appearance
Embryonic membrane
FIGURE 10-13 Dipylidium caninum proglottid.
Dipylidium caninum Adult:
Typical Characteristics at
a Glance
Description
Four
Present; club-shaped, with
one to seven circlets of
spines
Absent
Pumpkin seed
Full of eggs in enclosed
embryonic membrane