[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 3 The Amebas
TABLE 3-10
choice for identifying E. nana trophozoites and
cysts is stool examination.
Epidemiology
E. nana is found primarily in warm, moist regions
of the world, as well as other areas in which poor
hygiene and substandard sanitary conditions
exist. Food or drink contaminated with E. nana
infective cysts serve as the major sources of parasite
transmission.
Clinical Symptoms
E. nana infections are usually asymptomatic.
Treatment
E. nana is considered a nonpathogen. Treatment
is generally not indicated.
Prevention and Control
Endolimax nana Cyst:
Typical Characteristics at
a Glance
Parameter
Description
Size range 4-12 µm
Shape
Spherical, ovoid, ellipsoid
Number of nuclei One to four; four most
common
Karyosome
Large, blotlike, usually
central
Peripheral chromatin Absent
Cytoplasm
Granular and vacuolated
Cytoplasmic inclusions Chromatin granules
Nondescript small mass
Diffuse glycogen mass in
young cysts
As with other intestinal amebas, protection of
food and drink from flies and cockroaches is
essential to halt the spread of E. nana infections.
In addition, good sanitation and personal hygiene
practices are also crucial preventive measures.
Quick Quiz! 3-15
The appearance of an E. nana karyosome is usually
which of the following? (Objective 3-9A)
A. Granular
B. Large and round
C. Small and round
D. Blotlike
Quick Quiz! 3-16
Which of the following statements is true regarding
E. nana? (Objectives 3-2 and 3-7)
A. E. nana is found primarily in cold regions of the
world.
B. E. nana is prevalent in areas in which poor hygiene
and substandard sanitary conditions exist.
C. E. nana is considered as a human pathogen, so
treatment is mandatory.
D. Humans can obtain protection from E. nana via
vaccination.
Iodamoeba bütschlii
(eye-o’doh-mee’buh/bootch’lee-eye)
Common associated disease or condition names:
None (considered as a nonpathogen).
Morphology
Trophozoites. The trophozoites of Iodamoeba
bütschlii average 12 to 18 µm but may vary from
8 to 22 µm in size (Fig. 3-16; Table 3-11). These
trophozoites characteristically exhibit progressive,
sluggish motility. The single nucleus consists
of a large, usually central karyosome surrounded
by refractive achromatic granules, which are
often not distinct, even when the trophozoite is
permanently stained. Peripheral chromatin is
absent. The coarsely granular and vacuolated
cytoplasm may contain bacteria, yeast cells, or
other debris.
Cysts. I. bütschlii cysts typically measure 8 to
12 µm in size. Some cysts may be as small as