[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 8 The Nematodes
195
Undeveloped
unicellular embryo
Hyaline plug
at each pole
Smooth shell
surface
A
Average length: 50-55 m
B
Average width: 25 m
FIGURE 8-4 A, Trichuris trichiura egg. B, Trichuris trichiura egg. (B from Mahon CR, Lehman DC, Manuselis G: Textbook
of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)
TABLE 8-3
Parameter Description
Size 50-55 by 25 µm
Shape
Barrel, football; hyaline polar plug
at each end
Embryo
Unicellular; undeveloped
Shell
Smooth; yellow-brown color
because of bile contact
Trichuris trichiura
(trick-yoo’ris/trick”ee-yoo’ruh)
Common name: Whipworm.
Common associated disease and condition
names: Trichuriasis, whipworm infection.
Morphology
Trichuris trichiura Egg:
Typical Characteristics at
a Glanee
Eggs. The average barrel-shaped (also considered
by some to be football-shaped) Trichuris
trichiura egg measures 50 to 55 µm by 25 µm
(Fig. 8-4; Table 8-3). The undeveloped unicellular
embryo is surrounded by a smooth shell that
retains a yellow-brown color from its contact
with host bile. A prominent hyaline polar plug is
visible at each end.
Adults. The typical adult whipworm measures
2.5 to 5 cm in length (Table 8-4). The
anterior end of the adult appears colorless and
TABLE 8-4
Parameter
Size
Anterior end
Posterior end
contains a slender esophagus. The posterior end
assumes a pinkish-gray color, consisting of the
intestine and reproductive systems. The adult
male (Fig. 8-5) is usually smaller than the adult
female. In addition to a digestive system, intestinal
tract, and reproductive organs, the male possesses
an easily recognizable curled tail. The
posterior end of the adult T. trichiura is large and
resembles that of a whip handle. The anterior
end is much smaller and looks like the whip
itself. It is these two morphologic features that
are the basis for the name whipworm.
Laboratory Diagnosis
Trichuris trichiura Adults:
Typical Characteristics at
a Glance
Description
2.5-5 cm long; males usually
smaller than females
Colorless; resembles a whip
handle; contains a slender
esophagus
Pinkish-gray; resembles whip
itself; contains digestive and
reproductive systems; males
possess prominent curled tail
The specimen of choice for the recovery of T.
trichiura eggs is stool. These eggs are particularly