Intestinal Flagellates 3e3n4f

INTESTINAL FLAGELLATES Common intestinal flagellates Giardia lamblia , Chilomastrix mesneli , Trichomonas hominis, Deintamoeba fragilis Occasionally encountered intestinal flagellates Enteromonas hominis, Retortamonas intestinalis = no evidence that any of this organism can cause disease except G. lamblia and D. fragilis = Pathogenic Trichomonads: 1. Trichomonas vaginalis - found in the urogenital tract 2. Trichomonas tenax - commensal found in the mouth Giardia lamblia • a protozoan flagellate considered as one of the more common cause of infectious diarrhea throughout the world • Synonym: Cercomonas intestinalis Megastoma enterica • Geog. Dist: Worldwide (tropical and subtropical region) • Disease: Giardiasis, Lambliasis, Traveler’s diarrhea

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Morphology: exhibit the trophozoite and cyst stages -

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Trophozoite: found in diarrheic stool pear or pyriform shaped rounded anteriorly and pointed posteriorly bilaterally symmetrical size 9-20um L X 5 - 15um W sucking disc occupying 1/2 - 3/4 of the ventral surface (used for attachment of organism) axoneme (axostyle) found at the anterior end terminating posteriorly 4 pairs of lateral flagella, 2 ventral and 2 caudal (enhance erratic jerky motion) or falling leaf movement 2 pairs of blepharoplast: 1 pair at anterior end 1 pair at caudal end 2 oval-shaped nuclei with large central karyosome on each side near the anterior end 2 deeply stained (parabasal bodies) found posterior to the sucking disc

Life Cycle: Ingestion of viable cyst (infective stage) → cyst undergo excystation in duodenum → becomes a trophozoit → colonize mucosa of duodenum → Reproduce by binary fission → encystations in the large intestine → cyst in feces Epidemiology: Giardiasis • most prevalent disease in areas with poor environmental sanitation and personal hygiene

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one of the most common cause of travelers and epidemic diarrhea considered to be a major cause of diarrheal outbreak from contaminated water supplies transmitted by fecal-oral route foods and drinks may be a source of infection all age group are affected, but attack rate is more common in children (90%) than adult

Pathologenesis: • disease may be asymptomatic or may manifest as a self-limiting acute onset of diarrhea associated with nausea, anorexia and crampy abdominal pain

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diarrheic stool is non-bloody, foul smelling and steatorrheic (fatty stool) containing large amount of fats and mucus → Malabsorption syndrome

Lab. Diag: 1. Stool examination (unstained preparation) • demonst. pear-shaped body with progressive falling leaf motility - trophozoite 2. Intestinal biopsy • shortening and blunting of intestinal villi due to mucosal invasion of the organism 3. String test (Entero test); Fecal antigen test 4. Serological – ELISA, Immunofluorescence test Treatment: Metronidazole (Flagyl) - DOC 40mg TID for 7 days Prevention and Control: • proper disposal of human excreta to prevent contamination of water supply • protect food from contamination (from infected food handlers and flies)

Cystic stage: = ovoidal/ellipsoidal – shaped = thick wall and doubly contour = size 8-12um L X 7 - 10um W = contains 2-4 nuclei located at one end = axoneme, parabasal bodies and other remnant organelles of the trophozoite are also found inside the cyst • Habitat: duodenum and jejunum

Dientamoeba fragilis Geog. Dist: Cosmopolitan Morphology: • only trophozoite stage known • very small with an ave. size of 5-12um dia. • nuclear membrane without peripheral chromatin • majority are binucleated (2 nuclei) with large central karyosome composed of 4-8 chromatin granules arranged symmetrically • motility non-progressive and very active in a freshly ed stools

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cytoplasm finely granular and vacuolated with ingested bacteria and other debris

Epidemiology: • habitat: mucosal crypt of large intestine • oral transmission not established • commonly associated with ova of E. vermicularis • infective stage Trophozoite Pathogenesis and Symptomatology:

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pathogenicity disputed does not invade tissue but causes superficial irritation of the intestinal mucosa resulting in excess secretion of mucus, hypermotility of bowel and diarrhea abdominal ternderness and pain are also present anal pruritus has been observed all manifestation are referred to as Dientamoebiasis or Hakanssons syndrome

Cyst: • found in formed or semi-formed stools • pear/lemon-shaped rounded anteriorly with anterior hyaline knob/nipple-like protuberance (very prominent) • measures 7 – 10um L X 4.5 – 6um W • cyst wall thicker at the anterior end • rudimentary cytostome with prominent cytostomal fibrils curving posteriorly around the cytostome which resembles a “shepherd crook” • single spherical nucleus with central karyosome

Diagnosis: Direct fecal smear of diarrheic stool stained with iron-hematoxylin Treatment: Iodoquinol Tetracycline (alternate drug) Prevention: Same with amoebiasis NON – PATHOGENIC FLAGELLATES Chilomastix mesnili Synonym: Cercomonas intestinalis Macrostoma mesnili Geog. Dist: Worldwide (more prevalent in warm than in) cool climate Morphology: exhibit both trophozoite and cyst stage Trophozoite: • found in diarrheic or liquid stools • assymetrically pear-shaped/elongate rounded flattened anterior end and pointed posterior end measures 6 – 20um L X 3-10u W • body marked externally by a spiral groove across the ventral surface (diagnostic feature) • cytoplasm finely granular and vacuolated • cytostome large, cleft-like and occupies the anterior half of the body • single nucleus with minute central or eccenteric karyosome

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3 pairs of blepharoplast near the anterior pole of nucleus from where the flagellae arises 2 short anterior flagella and 1 short posterior flagellum lying near the cytostome motility is progressive and boring spiral forward movement no undulating membrane and axostyle

Pathogenesis and Epidemiology: • considered as normal inhabitant of cecal region of the large intestine (harmless parasite) • transmission thru ingestion of cyst in food or drinks contaminated with human feces • prevalence rate in the Phil. is less than 1% Lab. Dx: Stool examination diarrheic stool – trophozoite formed stool – cyst semi-formed – both Treatment: None Prevention: Good sanitation and personal hygiene reduce incidence of infection Trichomonas hominis Synonym: Cercomonas hominis Trichomonas confusa Geog. Dist: = Worldwide; most common intestinal flagellates found in humans; has little evidence of pathogenicity for human Morphology: • exhibit trophozoite stage only • pear-shaped, rounded anterior and pointed posteriorly • size 7-15um L X 3-4um W • cytostome at ventral side near the ant. end of the body

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single nucleus with small central karyosome near the anterior end close to the margin of the anterior flagella chromatin granules unevenly distributed cytoplasm finely granular and vacuolated blepheroplast lying between the nucleus and anterior end of the body giving rise to the flagella, axostyle and undulating membrane 4 anterior flagella (serves for propulsion) and recurrent flagellum that runs to the posterior end and forms the outer edge of the undulating membrane axostyle (slender rod) extend through the body from anterior to the posterior end and protrudes as a sharp pointed tail (diagnostic) undulating membrane at the dorsal surface of the body and impart the rotatory motion of the organism (jerky non-directional)

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2 blepharoplast adjacent to the nucleus which gives rise to 3 anterior flagella w/c enhance jerky forward movement and 1 posterior flagellum no cytostome entire cytoplasm vacuolated and contains numerous bacteria elongate-ovoidal shaped 6-8um W X 5um L cyst wall well-defined contains 1-4 nuclei usually 2 lying at opposite end resembles E. nana cyst

Pathogenesis and Epidemiology: • parasites is a commensal in the cecal region of the large intestine • no proof provided of its pathogenicity • infection is the result of ingestion of cyst from contaminated food and drink Pathogenesis and Epidemiology:  evidence of pathogenicity insufficient, however organism is always associated with diarrhea

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acquired through ingestion of food and drinks contaminated with the trophozoite

Lab. Diag.: Stool Examination • demonstration of trophozoite from diarrheic stool (jerky, non-directional movement of the undulating) membrane and protrusion of the axostyle

Lab. Diag.: Demonstration of characteristic trophozoite and cyst by stool exam Treatment: = None (no therapy indicated) Prevention: Good personal and community hygiene Retortamonas intestinalis Synonym: Waskia intestinalis Embadomonas intestinalis

Rx: No indication for specific treatment

Geog. Dist.: China, Malaysia, Philippines, Egypt, Brazil, USA and probably cosmopolitan in warm climates = harmless commensal of the intestine of man

Prevention: 1. Improvement of community sanitation 2. Personal hygiene

Morphology: exhibit both trophozoite and cyst stage

Enteromonas hominis Synonym: Trichomonas intestinalis Geog. Dist: Worldwide; more widely distributed throughout tropical areas and temperate region Morphology: exhibit both stages: Trophozoite and Cyst Trophozoite: • pear/oval shaped with one side flattened • measures 4-10uL X 3-6u W (small flagellate) • single nucleus near the anterior end of the body with central karyosome

Trophozoite: • pear/oval shaped attenuated posteriorly • size from 4 – 10um L X 3-4um W • nucleus, single and large at the anterior end with central karyosome • lateral to the nucleus is a pair of blepharoplast giving rise to 2 flagella (1 long anterior and 1 short) posterior flagellum • cytoplasm finely granular and vacuolated • prominent cleft-like cytostome at the anterior end of the body about half of the length of the organism

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cyst Cyst: • • • • •

pear/pyriform shaped cyst wall thick and doubly contoured measures 4-7um L X 5um W contain a single large nucleus with central karyosome 2 fibrils extending from the nuclear region to the attenuated end giving a characteristic bird beak fibrillar arrangement (diagnostic)

Pathogenesis and Epidemiology: • no evidence of its pathogenicity • commonly discovered in diarrheic stool • transmission is from hand to mouth thru contaminated food or drinks Diagnosis: Direct microscopy of fresh stool specimen Treatment: None (no indication for treatment parasite is commensal) Prevention: Good personal and community hygiene Trichomonas vaginalis • a urogenital flagellate • closely related to T. hominis • differ from T. hominis by having a short undulating membrane that extend about half of the distance to the posterior end • produce a cell detaching factor that causes detachment and sloughing of vaginal epithelial cell Morphology: • exhibit the trophozoite stage only • pear-shaped, measures 8-30um L X 3-17um W • single, elongated nucleus with large central karyosome • 4 anterior flagella & 1 posterior flagellum which forms the free margin of the undulating membrane (no free flagellum beyond the undulating membrane) • axostyle slender and project posteriorly • parabasal body well-defined • small cytostome at anterior end • cytoplasm contains large amount of siderophil granules • motility jerky, non-directional

Pathogenesis and Epidemiology: Disease: Trichomoniasis • one of the most common sexually transmitted infection seen in women worldwide • acquired sexually, direct with infected person, contaminated toilet seats, age through an infected birth canal • often asymptomatic but frequency of symptomatic disease is highest among sexually active women in their 30’s and lowest in post menopausal women

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habitat: vagina and urethra (female), prostate, seminal vesicle and urethra (male)

Clinical Manifestation: (Female) • profuse watery to creamy foul smelling greenish vaginal discharge acd. with burning and itching sensation • vaginal mucosa and cervix diffusely hyperemic with bright red punctate lesion (strawberry cervix) • urinary frequency and dysuria are common symptoms (Male) • usually asymptomatic • about 10% of infected men have urethritis with thin urethral discharge • prostate enlarged and tender associated with inflammation of the epididymis Lab. Diag.: 1. Direct microscopy of wet mount preparation = demonstrate the pear-shaped trophozoite in typical jerky motion 2. Culture (Feinberg – Whittington or Modified Diamond’s med.) 3. Serological - DOT - blot DNA hybridization assay (more effective than microscopic exam) PCR Rx: Metronidazole for both partners to prevent re-infection = restoration of the normal acid pH of vagina = periodic vaginal douches Prevention: • good personal hygiene • detection and treatment of infected males • condom limits transmission • no prophylactic drug or vaccine available Trichomonas tenax Synonym: Trichomonas buccalis Trichomonas elongata Geog. Dist.: Worldwide

Morphology: exhibits trophozoite stage only Trophozoite: • pear/pyriform-shaped • size 5-12um L (smaller & slender than T. vaginalis) • single nucleus with few chromatin granules • possesses 4 anterior flagella of equal length and 5th flagellum runs along the margin of the undulating membrane (resp. jerky rapid motility)

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presence of costa with the same length as the undulating membrane a single blepharoplast parabasal apparatus lies near the nucleus thick axostyle protrudes beyond the posterior end cytoplasm is delicately granular

Pathogenesis and Epidemiology: • considered as harmless commensal of the human mouth feeding on microorganisms and cellular debris • most abundant between the teeth and gums, tooth cavities, pyorrheal pockets and tonsillar crypt. • can also be found in the trachea and lungs • MOT: through kissing, use of utensil during eating or drinking water (parasite can live for several) hours in drinking water Lab. Diagnosis: Direct microscopy Treatment: None (no specific treatment) = directed to the underlying condition if any Prevention: Good oral hygiene (eliminate/decrease infection)