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Protozoal Microorganisms as Intestinal Parasites 67

amoeba that inhabits the mouth and is found particularly drinking from equipment contaminated by an individual
in periodontal disease and in smokers. Entamoeba gingi- with an E. gingivitis infection.
valis is a protozoan that is renowned as the first amoeba
in humans to be described by investigators. It is found Laboratory Diagnosis
only in the mouth between the gingival pockets and near
the base of the teeth. Entamoeba gingivalis is found in A cyst form has not been identified at this point, and
transmission is believed to occur directly from one per-
95 percent of people with periodontitis (gingivitis or
inflammatory gum disease) and in 50 percent of people son to another by kissing and sharing drinking containers
and dining table utensils and dishes. Only the trophozo-
with healthy gums.
ite form is the sole form observed, and the parasite ranges
from 10 to 20 μm in diameter. Entamoeba gingivalis pro-
Morphology tozoa have pseudopodia that allow them to move quickly,
as a characteristic typically found in the trophozoite stage.
A cyst form has not been identified, and transmission is
believed to occur directly from one person to another by A round (spheroid) nucleus will be from 2 to 4 μm in
diameter and will contain a small central endosome. An
kissing and sharing drinking containers and dining table
utensils and dishes. Only the trophozoite form is observed endosome is a lumen (opening) found in the cytoplasm
that serves to differentiate between waste products that
and the organisms range from 10 to 20 μm in diameter.
Entamoeba gingivalis protozoa have pseudopodia that are transported into lysosomes for destruction and those
materials that can be metabolized by the organism. There
allow them to move quickly, particularly because they are
found only in the trophozoite stage. A round (spheroid) are numerous food vacuoles and cellular materials, blood
cells, bacteria, and other organic materials that may have
nucleus will be from 2 to 4 μm in diameter and will con-
tain a small central endosome. Numerous food vacuoles been ingested by the organism. A variety of permanent
stains are used, such as crystal violet.
are present and cellular materials, blood cells, bacteria,
and perhaps other miscellaneous organic materials may
have been ingested by the organism. Treatment and Prevention
Treatment where symptoms exist is based on good oral care
Symptoms and judicious choices of those whom one kisses. Those at
risk or those who have gingivitis should consult with a peri-
Most hosts of this organism will be asymptomatic.
odontist (dentist with a specialty practice in diseases of the
In some cases severe periodontal conditions, includ- gums and mouth tissues) where deep cleaning around the
ing inflammation and pyorrhea (purulent discharge in
roots of the teeth is performed on a regular basis.
periodontal disease) of the gums, iares present. Serious
effects of gum disease may lead to loosened teeth accom-
panied by bleeding, which may eventually lead to loss of COCCIDIA OF THE HUMAN
teeth if not successfully treated. In addition, periodontal INTESTINE
disease is known to lead to cardiac problems.
Several species of sporozoans have recently been found
to inhabit the human intestine and that of other mam-
Life Cycle mals. Two of the most prevalent organisms from the sub-
phylum Sporozoa are presented in Table 3-7.
Reproduction for E. gingivitis is the same as for other
amoeboid organisms, through bilateral fission (splitting
into two or more parts).
CRYPTOSPORIDIUM PARVUM
Disease Transmission Coccidia are classified as members of the subphylum
Sporozoa and are nonmotile and obligate intracellular
Transmission has been linked to kissing people with parasites that have complex life cycles of both sexual and
serious gingivitis, smoking that causes constant and asexual states that occur in definitive and intermediate
persistent inflammation of the gums, and eating and hosts, in that order. Coccidia are found in a number of