[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 12 Artifacts and Confusers
LOOKING BACK
Artifacts and confusers are defined as microscopic
forms that resemble parasites but are not parasites.
Therefore, it is important to screen all specimens
carefully and take all features of suspicious microscopic
forms seen into consideration before deciding
on their final identity. One artifact in particular,
Charcot-Leyden crystals, is of importance and
should be reported when seen because they are
indicative of an immune response that may or may
not be caused by a parasitic infection. Especially
careful screening should be completed before deciding
that these specimens have no parasites present.
The most common artifacts are visually summarized
and distinguished from true parasites at
the end of this chapter in the three comparison
drawings—protozoan look-alikes, malarial lookalikes,
and helminth look-alikes.
TEST YOUR KNOWLEDGE!
c
b
FIGURE 12-17 Giemsa stain, 1000×. Plasmodium faciparum
ring form (a) and schizont (b) and stain precipitate (c).
Quick Quiz! 12-7
Which of these characteristics distinguish(es) stain
precipitate from malarial parasites? (Objective 12-1)
A. Color
B. Size
C. Shape
D. More than one: ___________ (specify)
12-1. Match the following artifacts or confusers
(column A) with the appropriate parasite
(column B). (Objective 12-1)
a
Column A
___ A. Yeast
___ B. Vegetable cells
___ C. Macrophages
___ D. Clumped
platelets
___ E. Vegetable spirals
___ F. White blood
cells
___ G. Pollen grains
Column B
1. Taenia spp. eggs
2. Malarial
parasites
3. Entamoeba
histolytica cysts
4. Helminth
larvae
5. Entamoeba
histolytica
trophozoites
6. Helminth eggs
7. Entamoeba
hartmanni cysts
12-2. When examining a sputum specimen, you
notice the presence of diamond shaped crystals.
What are these crystals called? Which
clinical condition should be suspected when
these crystals are observed? (Objective 11-2)
12-3. When examining a specimen for parasites,
it appears that there are helminth larvae
present. However, it is difficult to discern
whether they are helminth larvae or a confuser,
such as plant hair. Which of the following
findings substantiates that it is
plant hair? (Objective 12-1)
A. Presence of head or tail region
B. Buccal cavity
C. Nondescript internal structure
D. Intestine
12-4. When examining a specimen, you think
that you have identified amebic trophozoites;
however, the structures also look
similar to epithelial cells. Describe how to
differentiate the possible parasites from
epithelial cells. (Objective 12-1)
12-5. Which of the following confusers may
cause difficulties when identifying E. hartmanni
or E. nana? (Objective 12-1)
A. Epithelial cells
B. Plant material
C. Vegetable cells
D. Starch cells
12-6. List the artifacts or confusers that may be
confused with malarial parasites. (Objective
12-1)