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Protozoal Microorganisms as Intestinal Parasites 47

Life Cycle of which are transmitted by the fecal-oral route through
ingestion of food or water contaminated with cyst forms
T. tenax is considered a commensal, living harmless in the of flagellates. T. hominis and Chilomastix mesnili, which
mouth, particularly those with pyorrhea (pus- associated are the two flagellates that are encountered most fre-
inflammation) and those with poor oral hygiene, espe- quently, are used as comparison for the more pathogenic
cially in smokers. The trophozoite stage of T. tenax is organisms. The flagellates belong to the Magistophora
simple as are the other trichomonads. Reproduction is and possess more than one flagellum. Beating these fla-
by simple longitudinal binary fission. gella enable them to move. Unlike amoebae, flagellates
can swim which enables them to invade tissues quickly
Disease Transmission and to find environments more conducive to survival.
Flagellates may be found in the reproductive tract, ali-
The mode or modes for transmission has not been firmly mentary canal, tissue sites, and also the blood stream.
established. It is theorized that exchange of oral secre-
tions by oral to oral contact such as in kissing is a possi- Morphology
ble route for infection. Contaminated dishes and perhaps
contaminated food may be another possible means for Both T. hominis and C. mesnili are found as trophozo-
the organism to become introduced to the oral tissues. ites only, although this point is somewhat argumental.
Both are found in the intestine and are excreted in the
Laboratory Diagnosis feces, but are often missed during microscopic exami-
nation. The C. mesnili parasite is also found widely in
The diagnosis of infection by T. tenax is accomplished chimpanzees, orangutans, monkeys, and pigs. Although
by direct observation of motile trophozoites in wet preps, transmission occurs chiefly through eating and drinking,
hanging drop suspensions, and surgically obtained gum areas where monkeys and other simians are common,
scrapings. The disease is often accompanied with other provides a ready source for infection of humans and is
pathogenic bacteria as opportunistic organisms when possibly directly transferred between the species.
dental hygiene is poor or absent. The organism may also T. hominis is identified in a similar method as that
be cultured in the same manner used for T. vaginalis, for T. vaginalis. T. hominis trophozoites are seldom
but this is not a common practice. identified microscopically in the urine except in fecally
contaminated specimens. The axostyle and an oval
Treatment and Prevention nucleus are similar to that of the T. vaginalis organism.
It too has an undulating membrane attached along the
This parasite is generally considered to be a nonpatho- length of the costa or ribs of the organism, and contains
genic organism. Therefore, no medication is generally four flagella as a feature common with that of the patho-
prescribed for the condition. Treatment includes deep genic T. vaginalis and is attached to the anterior portion
dental cleaning by periodontal specialists and oral pro- of the organism.
phylaxis (preventive measures) on a regular basis.
Symptoms
DIFFERENTIATING THE
This organism, known as T. hominis, is found particu-
ORGANISM(S) TRICHOMONAS larly in warm climates and most often an asymptomatic
HOMINIS AND CHILOMASTIX condition is common with this infection. The organism
MESNILI may cause diarrhea even though it is considered to be
nonpathogenic.
It is absolutely necessary to differentiate between
T. hominis and C. mesnili. For this reason, these two Life Cycle
organisms will be discussed together in this section in
order to provide a convenient comparison. A wide variety T. hominis, like the other trichomonads, reproduce
of protozoa inhabit the intestinal tract of humans, most simply by longitudinal binary fission. These active