[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

A P P E N D I X
B
Answers to Case Studies:
Under the Microscope
CHAPTER 1
Case Study 1-1: Under the Microscope
1. A parasite is an organism that gains it nourishment
from and lives in or on another
organism.
2. Joe most likely came into contact with parasites
during his mission trip to Haiti. Increased population
density, poor sanitation, marginal water
sources, poor public health practices, and environmental
changes are all factors that might
have contributed to Joe’s current condition.
3. Other populations at risk for contracting parasite
infections include the following: (1) individuals
in underdeveloped areas/countries;
(2) refugees; (3) immigrants; (4) visitors from
foreign countries; (5) immunocompromised
individuals; (6) individuals living in close quarters;
and (7) children attending day care centers.
4. The most likely additional symptoms of individuals
with intestinal parasitic infections are
fever and chills.
5. The key components of a traditional O&P
study include direct macroscopic and microscopic
examination and microscopic examination
of the sample following a fecal debris
removal process.
CHAPTER 2
Case Study 2-1: Under the Microscope
1. The most common procedure performed in
the area of parasitology is the examination of
a stool specimen for O&P. Based on the
patient’s history and symptoms, it is also
advisable for the technologist to recommend
that the physician order a stool screen for
Giardia and Cryptosporidium.
2. Because parasites are often shed intermittently,
it is recommended that three specimens
be collected within 10 days. Because the
patient will need to transport the specimens
to the laboratory, the specimens should be
collected in vials containing fixatives.
3. A macroscopic examination can be performed
to detect the presence of gross abnormalities
and determine the consistency and color of
the sample. However, if the specimen is submitted
in a fixative, this step would be eliminated.
The microscopic examination of the
stool would include a direct wet preparation,
concentrated wet preparation, and permanently
stained smear. Again, if the specimen is
received in fixative, the direct wet preparation
can be eliminated.
4. Stool screening methods that detect antigen in
the patient’s specimen are commercially available
for a limited number of parasites. Because
the patient’s symptoms are consistent with
those of Giardia and Cryptosporidium infection,
it is recommended that testing begin
using this protocol. These tests are highly
sensitive and specific and not as technically
demanding as the O&P examination. If the
result of this test is negative, a complete O&P
examination is recommended.
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