[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 11 The Trematodes
271
infection have been successfully treated with
dichlorophenol (bithionol). Triclabendazole is
more effective but is not available in the United
States.
Prevention and Control
Prevention of future potential infections with F.
buski and F. hepatica may be accomplished by
exercising proper human fecal disposal and sanitation
practices, particularly in areas in which
animal reservoir hosts reside, controlling the
snail population, and avoiding the human consumption
of raw water plants or contaminated
water.
Quick Quiz! 11-4
Fasciolopsis buski infects which organ in humans?
(Objective 11-5)
A. Bile ducts
B. Liver
C. Colon
D. Small intestine
Quick Quiz! 11-5
The determination of Fasciolopsis versus Fasciola can
only be accomplished in the laboratory by the recovery
of which of the following? (Objective 11-5)
A. Eggs
B. Larvae
C. Adults
D. Sporocysts
Quick Quiz! 11-6
The eggs of Fasciolopsis and Fasciola possess a caplike
structure from which their contents are released
under the appropriate conditions; this is called a (an):
(Objective 11-1)
A. Operculum
B. Shoulder
C. Coracidium
D. Digenea
TABLE 11-2
Parameter Description
Average size 30 by 15 µm
Egg contents Developed miracidium
Operculum Present
Other features Presence of distinct shoulders and
presence of small knob
opposite operculum
Clonorchis sinensis
(klo-nor’kis/si-nen’sis)
Common name: Chinese liver fluke.
Common associated disease and condition
names: Clonorchiasis.
Morphology
Eggs. The typical Clonorchis sinensis egg
measures 30 by 15 µm (Fig. 11-5; Table 11-2).
The developed miracidium takes up the interior
of the egg. The egg is equipped with a distinct
operculum opposite a small knob. A thick rim is
strategically located around the operculum and
is referred to as shoulders.
Adults. The average adult C. sinensis measures
2 by 0.5 cm (Fig. 11-6). Each end of the
adult worm is narrower than the midportion of
the body.
Laboratory Diagnosis
Diagnosis of C. sinensis is accomplished by
recovery of the characteristic eggs from stool
specimens or duodenal aspirates. The Enterotest
(see Chapter 2) may also be performed. The
rarely encountered adult worms are only seen
when removed during a surgery or autopsy
procedure.
Life Cycle Notes
Clonorchis sinensis Egg:
Typical Characteristics at
a Glance
Human C. sinensis infection occurs following the
ingestion of undercooked fish contaminated with