FAR EASTERN UNIVERSITY
INSTITUTE OF HEALTH SCIENCES AND NURSING
MEDICAL TECHNOLOGY
Flagellates
Lecture
Subkingdom:
Phylum:
Subphylum:
Class:
Protozoa
Sarcomastigophora
Mastigophora
Zoomastigophora
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Intestinal and Atrial
Pathogenic and nonpathogenic
Flagella- structure for locomotion
Trophozoites and cysts( not all flagellates have) are the morphologic forms
General characteristics are almost similar to amoebas
No known cystic stage = trophozoites are more resistant
With cystic stage – undergoes encystation and excystation
Stool is the sample required for diagnosis
Diagnostic stage: cysts and trophozoite
Infective stage: dependent on the parasite
Nuclei present and positioning of nuclear structures are helpful in differentiating
Structures like undulating membrane(fin-like structure on the outer edge) and axostyle
(rodlike support structure)
 Saline, iodine wet preps, permanent stains aid in identification
Pathogenesis
 Recovered from diarrheic patients
 G. intestinalis, the only intestinal pathogenic flagellate
 Atrial flagellates may cause mouth and genital tract symptoms
I.
Giardia lamblia
 Giardiasis, traveler’s diarrhea
 1859 by Dr. F. Lambl, introduced as Cercomonas intestinalis
 Giardia intestinalis – Giardia lamblia, Giardia duodenale
Trophozoite form
 Pear, teardrop-shape, bilaterally symmetrical w/ Falling leaf
motility
 Axostyle is made up of 2 axonemes
 Median bodies sit on the axonemes
 Typical trophs have 4 pairs of flagella
 G. lamblia have a sucking disc making up 50-75% of its ventral surface
 Old man with whiskers, cartoon character, monkey’s face, old man with eyeglasses
Cystic form
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 Colorless, smooth cyst wall
 Retracted cytoplasm = clearing zone, achieved through formalin preservation
 4 nuclei, 4 median bodies seen in iodine wet prep/permanent stains
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Diagnostic specimen of choice: Stool, multiple samples = cysts and trophs
Duodenal aspirations, SI biopsies are also collected.
String test/ Enterotest, RT-PCR
EIA, ELISA, Direct fluorescence, Giardia Western immunoblotting
Life Cycle
1. Giardia cysts can contaminate food, water, and surfaces, and
they can cause giardiasis when swallowed in this infective
stage of their life cycle. Infection occurs when a person
swallows Giardia cysts from contaminated water, food,
hands, surfaces, or objects.
2. When Giardia cysts are swallowed, they pass through the
mouth, esophagus, and stomach into the small intestine
where each cyst releases two trophozoites through a process
called excystation. The Giardia trophozoites then feed off
and absorb nutrients from the infected person.
3. Giardia trophozoites multiply by splitting in two in a process
called longitudinal binary fission, remaining in the small
intestine where they can be free or attached to the inside
lining of the small intestine.
4. The Giardia trophozoites then move toward the colon and
transform back into cyst form through a process called
encystation. The Giardia cyst is the stage found most
commonly in stool.
5. Both Giardia cysts and trophozoites can be found in the stool of someone who has giardiasis and
may be observed microscopically to diagnose giardiasis. Giardia cysts are immediately infectious
when passed in the stool or shortly afterward, and the cysts can survive several months in cold
water or soil.
Epidemiology
 Worldwide in streams, lakes, other water sources
 Most common intestinal parasite especially among children
 Cysts are resistant to routine chlorination
 Transmitted through eating contaminated fruits and vegetables
 Oral-anal sexual practices, fecal-oral route
 Higher risks: Day care center kids, poor sanitary households, drinking
contaminated water in endemic areas, unprotected sex esp in
homosexual men.
 Reservoir hosts: Beavers, muskrats, water voles, domestic sheep, cattle,
and dogs and can transmit it directly to humans.
Clinical Symptoms
 Only known pathogenic intestinal flagellate
 Asymptomatic carrier
 Mild diarrhea, abdominal cramps, anorexia, flatulence to tenderness of epigastric region,
steatorrhea, and malabsorption syndrome.
 Fat soluble vitamin deficiencies, hypoproteinemia with hypogammaglobulinemia, folic acid
deficiencies, and structural changes in intestinal villi
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 Incubation period: 10-36 days.
 Px with intestinal diverticuli or an IgA deficiency are susceptible to reoccurring infections.
 Hypogammaglobulinemia may predispose to Giardia and achlorhydria.
Treatment
 CDC:
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 FDA:
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Metronidazole
Tinidazole
Nitazoxanide
Tinidazole
Nitazoxanide
Prevention and Control
 Proper water treatment
 Good personal hygiene
 Proper cleaning and cooking of food
 Avoidance of unprotected oral-anal sex
 Portable water purification systems
II.
Chilomastix mesnili
 Nonpathogenic
Trophozoite form
 Pear-shaped, stiff rotary motility in a directional manner(
corkscrew motility)
 Have 4 flagella, 3 of it seldom stain extends upto anterior
end.
 Has a rudimentary mouth called cytostome
Cystic form
 Lemon-shaped, clear hyaline knob for cysts
Diagnosis
 Diagnostic stage:
Freshly passed liquid stool = Trophs
Formed stool = Cysts
 Iodine wet preparation demonstrates organisms features clearly
 Infections are asymptomatic
Epidemiology
 Cosmopolitan in warm climates.
 Poor sanitary conditions and personal hygiene
Mode of transmission
 Hand-to-mouth contamination/contaminated food/drink with infective cyst
III.
Dientamoeba fragilis
 Initially classified as an ameba because of pseudopodia.
 Amoeboflagellate
Trophozoite form
 Irregular and roundish in shape, motility is seen on freshly passed stool by broad hyaline
pseudopodia
 Stain of choice: Iron hematoxylin
 No known cyst stage
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 Diagnostic identification of D. fragilis is through the exhibition of Hakansson phenomenon when
the parasite is mounted in water preparations.
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Method of choice for diagnosis: Stool examination
Unknown mode of transmission
Unproven theory for MOT is: transmission with the eggs of E. vermicularis and A. lumbricoides
D. fragilis were identified in patients infected with E. vermicularis in a several studies
At risk demographics include: children, homosexual men, semicommunal groups, and
institutionalized people.
Clinical Manifestations:
 Mode of transmission: fecal-oral, oral-anal routes, person-toperson routes
 Infected patients may experience diarrhea and abdominal pain,
may also include bloody or mucoid stools, flatulence, nausea, or
vomiting, weight loss, and fatigue.
 Some patients experience diarrhea alternating with constipation,
low grade eosinophilia, and pruritus.
Treatment:
• Iodoquinol is the treatment of choice for such infections
• Tetracycline is the acceptable alternative
• Paromomycin (Humatin) is another alternative if both aforementioned treatments are inappropriate.
Prevention and control
• Maintaining personal hygiene and sanitary public conditions aid in preventing in this infection;
avoidance of unprotected homosexual practices also helps minimize infections.
IV.
Trichomonas hominis
 Pear-shaped with jerky motility with the assistance of full-body length undulating membrane.
 Equipped with a costa, rod-like structure at the undulating
membrane base.
 The troph is supported by an axostyle that extends beyond
the posterior of the body.
 Cone-shaped cytostome cleft may also be present
 Troph has 3-5 flagella and no known cystic stage
 Stool examination is the method of choice for T. hominis
recovery
Epidemiology
 Found worldwide in cosmopolitan warm and temperate climates
 Children in warm climates are at a higher risk of contracting infection
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 MOT: Ingestion of trophozoites, contaminated milk may be suspected to harbor the parasite,
fecal-oral transmission may also occur
 With patients suffering from achlorhydria, the contaminated milk may shield the parasite when
it is ingested
 Treatment is not indicated because T. hominis is nonpathogenic.
V.
Enteromonas hominis
Trophozoite form:
 Oval in shape and exhibits jerky motility.
 May also been in a form of half-circle, flattened on one side.
 4 flagella present in the anterior end
 Posterior end may come together to resemble a small tail structure.
 Binucleated cyst form of this parasite is more common, with the nucleus
appearing on opposite ends; quadrinucleated cyst may also be present.
Cystic form:
 Cysts are protected by a well-defined cell wall
 The size range of this parasite overlaps with Endolimax nana
 Stool examination is the method of choice in recovery of this parasite, but difficult to identify
due to small size.
 Primary cause of contraction is the ingestion of infected cysts.
 Treatment is not indicated since this is nonpathogenic.
VI.
Retortamonas intestinalis
 Ovoid shape with jerky motility as a trophoizoite
 Fine delicate ring of chromatin granules may be visible on the nuclear
membrane.
 Lemon to pear-shaped cyst
 Two fused fibrils resembling a bird’s beak appearance
 Stained stool appearance is the best sample to examine
 Existence has been documented in warm and temperate climates
 MOT: Ingestion of infected cysts
 Psych hospitals and crowded conditions residences have reported to
contract this parasite
VII.
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Trichomonas tenax
Trophozoite is described as being oval to pear-shaped
T. tenax trophozoite is equipped with five flagella
An undulating membrane that extends two thirds of the body length
A small anterior cytostome is located next to the axostyle, opposite
the undulating membrane.
No known cystic stage
T. tenax trophozoites survive in the body as mouth scavengers
Smallest Trichomonas
T. tenax trophozoite is mouth scrapings.
Microscopic examination of tonsillar crypts and pyorrheal pockets
Tartar between the teeth and gingival margin of the gums are the primary areas of the mouth that
may also potentially harbor this organism.
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 MOT: the use of contaminated dishes and utensils, as well as introducing droplet contamination
through kissing
VIII.
Trichomonas vaginalis
 Persistent urethritis, persistent vaginitis, infant Trichomonas vaginalis
infection are most common associated with this parasite.
 ovoid, round, or pearlike in shape with rapid jerky motility
 accomplished with the aid of the organism’s 4-6 flagella
 No known cystic stage
 T. vaginalis trophozoites reside on the mucosal surface of the vagina
in infected women.
 The growing trophozoites multiply by
longitudinal binary fission and feed on local
bacteria and leukocytes.
 trophozoites thrive in a slightly alkaline or slightly acidic pH
 the prostate gland region and the epithelium of the urethra is the most
common site as for males
 MOT: sexual intercourse may also migrate through a mother’s birth canal
and infect the unborn child.
 T. vaginalis is known to be transferred via contaminated toilet articles or
underclothing.
 Sharing of douche supplies, as well as communal bathing, are also
potential routes of infection.
 Persistent or recurring urethritis is the condition that symptomatic men experience as a result of a T.
vaginalis infection
 Involvement of seminal vesicles, higher parts of the urogenital tract, and prostate may occur in
severe cases of infection.
 Release a thin, white urethral discharge that contains the T. vaginalis trophozoites.
 Persistent vaginitis, found in infected women, is characterized by a
 Foul smelling, greenish-yellow liquid vaginal discharge after an incubation period of 4 to 28 days.
 Burning, itching, and chafing may also be present.
 Red punctate lesions may be present upon examining the vaginal mucosa of infected women.
 Urethral involvement, dysuria, and increased frequency of urination are among the most commonly
experienced symptoms. Cystitis is less commonly observed but may occur.
 T. vaginalis has been recovered from infants suffering from both respiratory infection and
conjunctivitis.
 T. vaginalis trophozoites migrating from an infected mother to the infant through the birth canal
and/ or during vaginal delivery.
 T. vaginalis infections is the avoidance of unprotected sex. In addition, the prompt diagnosis and
treatment of asymptomatic men is also essential.
 There is evidence to suggest a connection between
 T. vaginalis infections and cervical carcinoma.
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