[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 3 The Amebas
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areas in which specific and accurate diagnoses
have been made. The ingestion of infected cysts
present in contaminated food or water accounts
for the transmission of E. hartmanni. The means
whereby food and water become contaminated
are similar to those of E. histolytica.
Clinical Symptoms
Infections with E. hartmanni are typically
asymptomatic.
Quick Quiz! 3-10
Which of the following is true regarding E. hartmanni?
(Objectives 3-2, 3-4, 3-5, and 3-7)
A. The organism is found worldwide.
B. It is generally considered a pathogen and treatment
is indicated.
C. It is an extraintestinal ameba.
D. The life cycle requires one morphologic form, the
trophozoite.
Treatment
Although some questions exist regarding the
pathogenicity (the ability to produces infectious
disease) of E. hartmanni, it is generally considered
a nonpathogen and treatment is usually not
indicated.
Prevention and Control
Good sanitation and personal hygiene practices,
as well as protection of food from flies and cockroaches,
will help prevent the spread of E.
hartmanni.
Notes of Interest and New Trends
Entamoeba hartmanni was at one time designated
as “small race” E. histolytica because
of the many similarities between the two
organisms.
Serologic differences between E. hartmanni
and E. histolytica have been described.
Quick Quiz! 3-9
A main difference between the trophozoites of E.
hartmanni and E. histolytica is which of the following?
(Objective 3-11A)
A. Trophozoites of E. histolytica are smaller in size.
B. Presence of pseudopods
C. Trophozoites of E. hartmanni do not contain
ingested red blood cells.
D. Nuclear structure and peripheral chromatin
Entamoeba coli
(en’tuh-mee’buh/ko’lye)
Common associated disease or condition names:
Intestinal amebiasis, amebic colitis, amebic dysentery,
extraintestinal amebiasis.
Morphology
Trophozoites. The trophozoites of Entamoeba
coli typically measure between 18 and 27 µm
(Figs. 3-9 and 3-10; Table 3-5). Some trophozoites
may be as small as 12 µm, whereas others
may be as large as 55 µm. The tropho zoite is
equipped with blunt pseudopods and exhibits
sluggish, nonprogressive motility. The single
TABLE 3-5
Entamoeba coli Trophozoite:
Typical Characteristics at
a Glance
Parameter
Description
Size range 12-55 µm
Motility
Nonprogressive, blunt
pseudopods
Number of nuclei One
Karyosome
Large, irregular shape,
eccentric
Peripheral chromatin Unevenly distributed
Cytoplasm
Coarse and granulated
Cytoplasmic inclusions Vacuoles containing bacteria
often visible