[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 10 The Cestodes
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from both rat droppings and from intermediate
host insects is critical to prevent consumption of
contaminated food. Finally, thorough inspection
of all potentially contaminated foodstuffs prior
to human consumption is necessary to prevent
transmission of the parasite to unsuspecting
humans.
Quick Quiz! 10-7
Which of the following is characteristic of an H.
diminuta egg? (Objective 10-10A)
A. Spherical, with radial striations
B. Ellipsoid, with terminal polar plugs
C. Oval, with thin shell and polar filaments
D. Oval, with polar thickenings and no filaments
Quick Quiz! 10-9
Prevention and control measures against H. diminuta
include all except which of the following? (Objective
10-7B)
A. Vaccination program
B. Effective rodent control
C. Inspection of food prior to consumption
D. Protection of food from rodents
Hymenolepis nana
(high”men-ol’e-pis/nay’nuh)
Common name: Dwarf tapeworm.
Common associated disease and condition
names: Hymenolepiasis, dwarf tapeworm disease.
Morphology
Quick Quiz! 10-8
The infective stage of H. diminuta for humans is
which of the following? (Objective 10-5)
A. Rhabditiform larva
B. Cysticeroid larva
C. Embryonated egg
D. Encysted form
Eggs. The somewhat roundish to oval egg
of Hymenolepis nana typically measures 45 by
38 µm in size (Fig. 10-10; Table 10-5). The centrally
located hexacanth embryo is equipped
with the standard three pairs of hooklets. A shell
complete with polar thickenings protects the
embryo. Numerous polar filaments originate
from the polar thickenings, which, in addition
to size, help distinguish it from the egg of
Filaments emerge from
polar thickenings
Colorless embryophore
(shell)
Three pairs
of hooklets
Hexacanth embryo
B
A
Average size: 45 m by 38 m
FIGURE 10-10 A, Hymenolepis nana egg. B, Hymenolepis nana egg, 400×. (B from Mahon CR, Lehman DC,
Manuselis G: Textbook of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)