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10 nm

Flagellates

The Mastigophora, or flagellates, contain specialized locomotor organelles called flagella; long, thin cytoplasmic extensions that may vary in number and position depending on the species. Different genera may live in the intestinal tract, the bloodstream, or various tissues. Detection of the blood- and tissue-dwelling flagellates is discussed in the previous section.

Four common species of flagellates are found in the intestinal tract: Giardia lamblia, Dientamoeba fragilis, Chibmastvcmesnili, and Pentatrichomonas hominis (Figures 49-29 to 49-36) (see Tables 49-15 and 49-16). Several other smaller flagellates, such as Enteromonas hominis and Retortamonas intestinalis (see Figure 49-29), are rarely seen, and none of the flagellates in the intestinal tract, except for G. lamblia and D. fragilis, is considered pathogenic. D. fragilis has been associated with diarrhea, nausea, vomiting, and other nonspecific intestinal complaints. Trichomonas vaginalis is pathogenic but occurs in the urogenital tract. Trichomonas tenax is occasionally found in the mouth and may be associated with poor oral hygiene.

G. lamblia is probably the most common protozoan organism found in persons within the United States and causes symptoms ranging from mild diarrhea, flatulence, and vague abdominal pains to acute, severe diarrhea to steatorrhea and a typical malabsorption syndrome. Various documented waterborne and food*, borne outbreaks have occurred during the past several years, and various animals may serve as reserved animal hosts for G. lamblia. A number of immuno-1 assays are now commercially available for the detection of antigen or organisms in clinical specimen? (see Table 49-10).

Most flagellate trophozoites are pear shaped and have different numbers and arrangements of flagella. The sucking disk and axonemes of Giardia, the cyto-stome and spiral groove of Chilomastix, and the undulating membrane of Trichomonas are all distinctive criteria for identification (see Figures 49-29 to 49-33).

Dientamoeba has no known cyst stage and the trophozoite has one or two nuclei, which have no peripheral chromatin and which have four to eig J chromatin granules in a central mass. This organises varies tremendously in size and shape and may contain ingested bacteria and other debris; it will be overlook^ unless the permanent stained smear is performed as a routine part of the O&P examination (see Figures 49-3^

14 15 16

Figure 49-24 l to 5, Trophozoites of Endolimaxnana. 6 to 10, Cysts of J?, nana, II to 13, Trophozoites of iodamoeba bulschlii, 14 to 16, Cysts of I. butschlii. (From Garcia LS: Diagnostic medical parasitology, ed 5, Washington, DC, 2007, ASM Press.)

14 15 16

Figure 49-24 l to 5, Trophozoites of Endolimaxnana. 6 to 10, Cysts of J?, nana, II to 13, Trophozoites of iodamoeba bulschlii, 14 to 16, Cysts of I. butschlii. (From Garcia LS: Diagnostic medical parasitology, ed 5, Washington, DC, 2007, ASM Press.)

to 49-36). Symptoms include intermittent diarrhea, abdominal pain, nausea, anorexia, malaise, fatigue, poor weight gain, and unexplained eosinophilia.

Ciliates

The class Ciliata, or ciliates, contains spedes that move by means of cilia, short extensions of cytoplasm that cover the surface of the organism. This group contains only one organism that infects humans: Balantidium coli infects the intestinal tract and may produce severe symptoms. Balantidium coli is the largest protozoan and the only cUiate that infects humans (Figures 49-37 and 49-38) (see Table 49-17). The Trophozoites have a rapid, rotatory, boring motion and the surface is covered with short cilia. The cytoplasm contains both a large, bean-shaped macronucleus and a smaller, round micronudeus that is often difficult to see. Although this infection is uncommon within the United States, the organisms can be seen in profi-dency testing specimens.

Coccidia

Members of the dass Sporozoa are found in the blood and other tissues and have a complex life cyde that involves both sexual and asexual generations. The four spedes of Plasmodium, the cause of malaria, are found in

10 nm

Figure 49-25 A to C, Trophozoites of Endolimax nana. D and E, Cysts of E. nana.

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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