[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 3 The Amebas
51
Quick Quiz! 3-5
E. histolytica infection is traditionally diagnosed by
finding which of the following? (Objective 3-8)
A. Adult and egg forms of the parasite in a suspected
stool sample
B. Trophozoites and/or cysts in a suspected stool
sample
C. Larvae in a suspected CSF sample
D. Adult form of the parasite in suspected tissue
samples
Cytoplasm
Central
karyosome
Even peripheral
chromatin
Pseudopod
Quick Quiz! 3-6
The infective stage of E. histolytica is which of the
following? (Objective 3-5)
A. Trophozoite
B. Cyst
Quick Quiz! 3-7
Which of the following factors is not responsible for
the asymptomatic carrier state of a patient infected
with E. histolytica? (Objective 3-7A)
A. Low virulence strain
B. Low inoculation into host
C. Intact patient’s immune system
D. Patient’s blood type
Quick Quiz! 3-8
Which of the following prevention measures can
control the spread of E. histolytica? (Objective 3-7C)
A. Drinking tap water
B. Using human feces as fertilizer
C. Boiling water or treat with iodine crystals
D. Practicing unsafe sex
Size range: 5-15 m
Average size: 8-12 m
FIGURE 3-7 Entamoeba hartmanni trophozoite.
Entamoeba hartmanni
(en’tuh-mee’buh/hart-man’nee)
Common associated disease or condition names:
Intestinal amebiasis, amebic colitis, amebic dysentery,
extraintestinal amebiasis.
Morphology
Size accounts for the major difference between
the trophozoites and cysts of Entamoeba hartmanni
and Entamoeba histolytica.
Trophozoites. The typical E. hartmanni trophozoite
measures a mere 8 to 12 µm, with a size
range of 5 to 15 µm (Fig. 3-7; Table 3-3). Fingershaped
pseudopods exhibiting nonprogressive
motility are standard. Trophozoites contain one
nucleus that is not typically visible in unstained
preparations. The peripheral chromatin is usually
present as evenly distributed granules and often
has a beaded appearance. The karyosome may
be centrally or eccentrically located. Nuclear
structure variations identical to those described
in the discussion of E. histolytica may occur. The
finely granular cytoplasm of E. hartmanni may
contain bacteria. Unlike that of E. histolytica, the