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Protozoal Microorganisms as Intestinal Parasites 45

Source: Centers for Disease Control and Prevention (CDC) General FEATURE
MICROSCOPIC DIAGNOSTIC

Flagellate
Classification
Trichomonas vaginalis
Organism
Specimen Required Urine, vaginal and
prostatic secretions
Stage
Trophozoites most
easily distinguishable
FIGURE 3-7 Trichomonas vaginalis stained with Size 8–23 μm in length and
Giemsa dye 5–12 μm in width
Shape Pear-shaped
specimen will yield a pear-shaped cell with an axostyle, trophozoite
a centrally located line extending throughout the length Motility Nondirectional but
of the organism (Figure 3-7). One nucleus is generally sometimes vigorous
visible at the anterior end, and the organism is generally in fresh specimens
5 to 19 μm. This is also within the range of white blood Nucleus(i) 1, somewhat centrally
cells, so it is easy to miss a T. vaginalis infection when the located
specimen is more than a few minutes old and where white Cytoplasm Evenly distributed
cells are also present. Another important group of patho- chromatin with
genic flagellates are those found chiefly in the blood and granules near axostyle
tissues, and will be discussed in a later section. Other Features Prominent axostyle
with 4–6 flagella and
undulating membrane
Symptoms
The infected individual may suffer itching, burning, T. vaginalis
and considerable irritation of the surrounding tissues of Trophozoite
the vaginal mucosa, and in some cases produce a foul-
smelling and yellowish discharge with lesions. Men may
be asymptomatic or suffer from prostate and upper uro-
genital tenderness and even swelling.

Life Cycle
The trophozoite stage, again the only one found in in-
fections with T. vaginalis, is motile and somewhat easy
to distinguish in urine samples and in vaginal secretions.
However, they can be confused with white blood cells,
especially if the organisms are sluggish due to temperature,
light, and other adverse environmental conditions. Due Delmar/Cengage Learning
to the difficulty of maintaining viability of Trichomonas
organisms for microscopic examination and perhaps cul-
ture, a routine universal transport medium may be indi-
cated, and a number of these are available commercially.
Fifty percent of infected women are asymptomatic even