[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 10 The Cestodes
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In addition, tropical and subtropical climates
worldwide are known to harbor this parasite.
Persons residing in close quarters, such as in
institutional settings, as well as children attending
preschool or at day care centers, are at a
particularly high risk of contracting H. nana. In
addition to infective eggs generated by contaminated
human feces, stool from contaminated
rodents may also serve as a source of infection.
Clinical Symptoms
Asymptomatic. Light infections with H. nana
typically remain asymptomatic.
Hymenolepiasis: Dwarf Tapeworm Disease.
Persons with heavy H. nana infections often
develop gastrointestinal symptoms, such as
abdominal pain, anorexia, diarrhea, dizziness,
and headache.
Treatment
Praziquantel is considered to be the treatment of
choice for infections with H. nana. Niclosamide
is also known to be an effective alternative medication;
however, it is not yet readily available in
the United States.
Prevention and Control
Proper personal hygiene and sanitation practices
are crucial to preventing the spread of H. nana.
Controlling transport host populations and avoidance
of contact with potentially infected rodent
feces are also prevention and control measures
aimed at halting the spread of the parasite.
Quick Quiz! 10-10
A primary differential feature between an H. nana
egg and H. diminuta egg is which of the following?
(Objective 10-9)
A. A flattened side for H. diminuta egg
B. A thick shell for H. nana egg
C. Polar filaments in H. nana egg
D. Radial striations in H. diminuta egg
Quick Quiz! 10-11
The characteristic of the life cycle of H. nana that
differentiates it from the other cestodes is which of
the following? (Objective 10-9)
A. Lack of an intermediate host.
B. Infective larval stage.
C. Need for external environment
D. Larval passage through the lungs
Quick Quiz! 10-12
Which of the following does not apply to H. nana?
(Objectives 10-3, 10-6, 10-7A, 10-7B)
A. Dwarf tapeworm
B. Steatorrhea
C. Proper hygiene and sanitation procedures
D. Praziquantel therapy
Dipylidium caninum
(dip” i-lid’e-um/kain-i’num
ˇ )
Common names: Dog or cat tapeworm, pumpkin
seed tapeworm.
Common associated disease and condition
names: Dipylidiasis, dog or cat tapeworm disease.
Morphology
Egg Packets. The average Dipylidium caninum
egg may range in diameter from 30 to
60 µm (Fig. 10-12; Table 10-7). It consists of the
typical six-hooked oncosphere. Unlike the eggs
of the other cestodes discussed thus far, which
appear individually, those of D. caninum form
membrane-enclosed packets; each packet may
contain 5 to 30 eggs.
Scolices. The D. caninum scolex is equipped
with four suckers and a club-shaped armed
rostellum (Table 10-8). Rather than containing
hooks, like some cestodes discussed earlier, D.
caninum contains one to six or seven circlets of
spines that reside on the rostellum.