[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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APPENDIX D Answers to Test Your Knowledge (Review Questions)
Beyond this, the life cycle in a male host
is unknown.
4-6. Enteromonas hominis cysts are oval in
shape, with a predominant cell wall. The
cysts may be binucleated or quadrinucleated.
The nuclei show central karyosomes
but do not have peripheral chromatin.
4-7. Trophozoite and cyst stages: Giardia
intestinalis, Chilomastix mesnili, Enteromonas
hominis, Retortamonas intestinalis;
trophozoite stage only: Dientamoeba
fragilis, Trichomonas hominis, Trichomonas
tenax, Trichomonas vaginalis; cyst
stage only—not applicable.
4-8. Giardia intestinalis, Dientamoeba fragilis.
4-9. A. Axoneme—intracellular portion of
the flagellum.
B. Axostyle—rodlike support structure
found in some flagellates.
C. Costa—rodlike structure located at
the base of the undulating membrane.
It is located between the undulating
membrane and the body of some flagellates,
connecting the two structures.
It may also aid in supporting the
undulating membrane.
D. Cytosome—rudimentary mouth.
E. Median bodies—comma-shaped structures
located in the posterior end of
Giardia intestinalis trophozoites and
cysts; believed to be associated with
energy and metabolism or with supporting
the organism’s posterior end.
Their exact function is unclear.
F. Undulating membrane—finlike structure
connected to the outer edge of
some flagellates; aids in the organism’s
locomotion, moving in a wavelike
pattern.
4-10. Dientamoeba fragilis can be difficult to
diagnose for two primary reasons. First,
D. fragilis sheds irregularly and so may
not be present in all stool samples of an
infected individual. The parasite resides in
deeper mucosal crypts in the large intestine
and may shed sporadically as a result.
Second, D. fragilis can be difficult to
identify in stained stool preparations. The
parasite can stain very lightly and also has
few distinguishing features, so it easily
blends into the background material on a
stained slide. Therefore, multiple stool
samples collected over several days may
be necessary to diagnose D. fragilis.
4-11. Giardia intestinalis, Chilomastix mesnili,
Enteromonas hominis, Retortamonas
intestinalis.
4-12. Chilomastix mesnili, Trichomonas hominis,
Enteromonas hominis, Retortamonas
intestinalis, Trichomonas tenax.
Note: there is considerable controversy
over the pathogenicity of Dientamoeba
fragilis.
4-13. Trichomonas tenax.
CHAPTER 5
5-1. A. 4
B. 5
C. 2
D. 1
E. 3
5-2. C
5-3. D
5-4. E
5-5. B
5-6. B
5-7. A
5-8. C
5-9. B
5-10. D
5-11. A
5-12. Belize, Guatemala, the Yucatan Peninsula,
the Amazon River Basin, Venezuela,
Brazil, the Venezuelan Andes.
5-13. Enlargement of the postcervical lymph
nodes commonly seen in infections with
Trypanosoma brucei gambiense and
occasionally in Trypanosoma brucei
rhodesiense infections.
5-14. Cattle, sheep, wild game animals.
5-15. Complement fixation (CF), direct agglutination
(DAT), and indirect immunofluorescence
(IIF).