[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

APPENDIX D Answers to Test Your Knowledge (Review Questions)
345
for the laboratory to provide education
to medical providers about the purpose
and usefulness of assays.
2-12. Parasites that reside in the small intestine
can be difficult to detect from a stool
specimen. Duodenal material is an alternative
sample that will allow detection of
parasites such as Giardia intestinalis,
Cryptosporidium spp., Isospora belli,
and Strongyloides stercoralis.
2-13. B
2-14. Thick films are prepared by placing drops
of blood onto a microscope slide and
spreading them in a circular fashion to
the size of a dime or nickel. The slide is
then air-dried and, prior to staining, the
cells are ruptured by placing the slide
into buffered water. An advantage is
increased recovery of malaria because of
the concentration of cells. A disadvantage
is that is difficult to identify species
because of poor morphology.
Thin films are prepared by placing a
drop of blood toward the end of a microscope
slide and then using the edge of
another slide to spread the blood cells
into a thin layer. On staining, the red
blood cells are left intact for observation
of intracellular malaria parasites. An
advantage is the speciation of the malaria.
A disadvantage is that is difficult to detect
because the cells are not concentrated.
2-15. Entamoeba histolytica, Trichomonas
vaginalis, Leishmania spp., Trypanosoma
cruzi, Toxoplasma gondii.
2-16. A. 2
B. 5
C. 6
D. 3
E. 1
F. 4
2-17. Xenodiagnosis is a diagnostic tool that
uses a reduviid bug to diagnose patients
with Chagas’ disease (Trypanosoma
cruzi). An uninfected bug is allowed to
feed on a patient. The insect is later
tested to determine whether the parasite
was transmitted from the patient to the
insect.
2-18. In most cases, immunologic tests are used
in parasitology as an adjunct to diagnosis.
In some cases, when the infection is
difficult to diagnose by demonstrating
the diagnostic stage, or the technique is
too invasive, more immunology testing
may be necessary. See Table 2-8 for
examples of antigen tests and antibody
tests.
2-19. The reporting of parasitology results is a
critical component of the postanalytic
phase of laboratory testing. It is important
to spell out the genus and species. In
this situation, reporting E. coli instead of
Entamoeba coli would confuse the physician
because of the confusion with the
bacteria Escherichia coli.
2-20. Quality assurance in parasitology must
include the following:
Procedure manuals
Reagents and solutions
Controls
Calibration of centrifuges and ocular
micrometer
Recording of temperatures
Action plans for out of control results
References
Proficiency testing of personnel
CHAPTER 3
3-1. A. 4
B. 8
C. 3
D. 1
E. 2
F. 7
G. 5
H. 6
3-2. C
3-3. Cysts.
3-4. Entamoeba histolytica, intestinal; Entamoeba
hartmanni, intestinal; Entamoeba
coli, intestinal; Entamoeba
polecki, intestinal; Endolimax nana,