[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 11 The Trematodes
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dysfunction may result in persons severely
infected over a long period of time.
Treatment
The treatment for C. sinensis infection is praziquantel
or albendazole.
Prevention and Control
Prevention and control measures for halting the
spread of C. sinensis include practicing proper
sanitation procedures, especially in regard to
fecal disposal by the human and reservoir host
(dogs and cats) and avoiding the ingestion of
raw, undercooked, or freshly pickled freshwater
fish and shrimp.
Quick Quiz! 11-7
The number of Clonorchis cases has tripled in which
country because of aquaculture? (Objective 11-2)
A. Japan
B. Vietnam
C. China
D. Korea
Quick Quiz! 11-8
What procedures must be done to recover the adult
form of Clonorchis sinensis? (Objective 11-8)
A. Direct examination of stool and after autopsy
B. Direct and concentration examinations of stool
C. Following surgery and after autopsy
D. Following surgery and duodenal aspiration
Quick Quiz! 11-9
Which of the following is a recommended prevention
and control strategy designed to halt the spread of
Clonorchis? (Objective 11-7B)
A. Consuming raw, pickled, freshwater fish
B. Protecting food from flies
C. Avoidance of swimming in fresh water
D. Proper human and reservoir host fecal disposal
Heterophyes heterophyes
(het-ur-off’ee-eez/het”ur-off’ee-eez)
Common name: Heterophid fluke.
Common associated disease and condition
names: Heterophyiasis.
Metagonimus yokogawai
(met’uh-gon’imus/yo-ko-gah-wah’eye)
Common name: Heterophid fluke.
Common associated disease and condition
names: Metagonimiasis.
Morphology
Eggs. The eggs of Heterophyes heterophyes
and Metagonimus yokogawai are basically indistinguishable
and may be easily confused with
those of C. sinensis (Table 11-3; see Fig. 11-5).
These eggs measure approximately the same as
C. sinensis, 30 by 15 µm. There are only two
somewhat discrete differences among the eggs of
H. heterophyes and M. yokogawai versus those
of C. sinensis. First, although the Heterophyes
and Metagonimus eggs have shoulders, they are
less distinct than those of Clonorchis. Second,
the eggs of Heterophyes and Metagonimus may
lack the small terminal knob found on those of
Clonorchis.
TABLE 11-3
Heterophyes heterophyes
and Metagonimus
yokogawai Egg:
Typical Characteristics
at a Glance*
Parameter Description
Average size 30 by 15 µm
Egg contents Developing miracidium
Operculum Present
Shoulders
Present but discrete
Small knob May be absent
Shell thickness Heterophyes, thick; Metagonimus,
thin
*These eggs may be confused easily with those of Clonorchis
sinensis.