Flagellates-mastigophora

• Phylum protozoa, Subphylum Mastigophora

• 2 groups

  1. Intestinal flagellates

  2. Atrial flagellates

• Movement of flagellates

  • presence of whiplike structures known as flagella in trophozoite form

• Life Cycle

  • Otrophozoite

    • similar to amebic trophozoites but with no known cyst stages; trophozoites are more resistant

    • appear to survive in the outside environment

  • Cysts

  • Encystation and Excystation

• Location

  • small intestine

  • cecum

  • colon

  • duodenum (Giardia intestinalis)

Giardia intestinalis

• Cercomonas intestinalis

• Giardia duodenalis

• 1681

  • observed by Anthony van Leeuwenhoek

• 1859

  • Vilem Lambl observed in stool of children with diarrhea

  • Gr. Giard Czechslovakian scientist

• 1915

  • Stiles coined the term Giardia lamblia

• multiplies by binary fission

DS

• stool

MORPHOLOGY

TROPHOZOITE

• 8-20 microns length; 5-16 microns width (10-15 microns long)

• pear or teardrop-shaped

• broad anterior end tapers off at the posterior end

• Motility

  • falling leaf

• bilaterally symmetrical

• Nuclei

  • two ovoid to spherical

  • Karyosome

    • large, centrally located

  • best detected on permanently stained specimen

• 2 Axonemes

  • supports trophozoites as an axostyle— inner portions of the flagella

  • Median bodies

    • 2 slightly curved rodlike structures

    • sit on the axonemes posterior to the nuclei

• Flagella

  • difficult to detect

  • 4 pairs

    • 1 pair anterior end

    • 1 pair posterior end

    • 2 pairs laterally; axonemes extending

• Sucking disc

  • 50%-70% of the ventral surface

  • serves as nourishment point of entry

    • attaching to the intestinal villi of the infected human

• 

CYST

• 8-17microns long; 6-10 microns wide (10-12 microns)

• cyst wall

  • colorless and smooth

  • prominent and distinct from the interior of the organism

• Ovoid

• Nuclei

  • Immature cyst

    • two

  • Mature cyst

    • four

  • Karyosomes

    • Central

• Cytoplasm

  • retracted from cell wall

• Median bodies/parabasal

  • immature

    • two

  • mature

    • four

• Interior flagellar structures

  • twice as many in mature cyst compared with immature

• 

Life Cycle

• ingestion

  • infected cyst enter stomach

• digestive juices (gastric acid)

  • stimulate cysts to excyst in duodenum

• trophozoites in duodenum

  • becomes established and multiply every 8hrs.

    • longitudinal binary fission

  • feed

    • attaching sucking discs to the muscosa of the duodenum

    • may also infect common bile duct and gallbladder

• Changes

  • result in unacceptable environment for multiplication stimulate encystation

    • trophozoites migrate to the large bowel

• cysts

  • enter the outside environment via feces

  • remain viable for 3 months in water

Giardiasis

• infection in small intestine

• spreads through contact with infected people

Signs and Symptoms

• Diarrhea

• Gas

• Greasy stools that tend to float

• Stomach or abdominal cramps

• Upset stomach/nausea

• Dehydration (loss of fluids)

Treatment

• accdng. to CDC

  • metronidazole

  • tinidazole

  • nitazoxanide

• accdng. to FDA

  • metronidazole (not approved; carcinogenic in rats and mice)

  • tinidazole (approved; carcinogenic in rats and mice)

  • nitazoxanide

Lab Diagnosis

• examine multiple samples

  • stool

  • duodenal contents by aspiration

    • ETEROTEST (string test)

  • upper small intestine (jejunum)

• Concentration methods

• Giardia western immunoblotting

• Trichrome stain

• Antigen detection tests by enzyme immunoassay

• Wet mount

• Direct fluorescent antibody (DFA)

• Rapid immunochromatographic cartridge assays

Prevention and Control

• practice good hygiene

• avoid water that may be contaminated

• avoid eating food that may be contaminated

• prevent contact and contamination with feces during sex

Chilomastix mesnili

• found more frequently in warm climates

• occur commensally in the intestine of various vertebrate

MORPHOLOGY

TROPHOZOITES

• 8-15 microns

• pear-shaped

• Motility

  • stiff

  • rotary

  • directional

• Nuclei

  • one

  • Karyosome

    • small central or eccentric

• Flagella

  • four

    • 3 extending from anterior end

    • 1 posteriorly from cytostome region

• prominent cytosome

  • 1/3 to ½ body length

• spiral groove

CYST

• 7-10 microns long; 2-7 microns width; 5-10 microns length

• Nucleus

  • one

  • karyosome

    • large central

• well-defined cytostome

  • w/ accompanying fibrils

  • found one side of the nucleus

• 

Epidemiology

• cosmopolitan in its distribution

• warm climates

• greatest risk reduction:

  • personal hygiene & poor sanitary

• transmission

  • hand to mouth

Diantamoeba fragilis

MORPHOLOGY

TROPHOZOITE

• 5-18 microns

• irregularly round

• Motility

  • progressive

  • broad hyaline pseudopodia

• Nuclei

  • two

  • each consisting clumps of four to eight chromatin granules

• Cytoplasm

  • bacteria-filled vacuoles common

  

Epidemiology

• true MOT remains unknown

• distributed in cosmopolitan areas

• rarely collected and difficult to identify

IS

• Trophozoite

MOT

• via eggs of E. vermicularis or A. lumbricoides

• fecal-oral

HABITAT

• mucosal crypts of large intestine of man

symptomatic

• mucus diarrhea

• flatulence

• fatigue

• low-grade eosinophilia

• pruritus

Lab Diagnosis

• examination of fresh saline smear of stool

• staining with iron hematoxylin is preferable

• Conventional and real-time polymerase chain reaction (RT-PCR) methods

Treatment

• iodoquinol

• tetracycline (let)

• paromomycin (humatin)

Prevention and Control

• maintain personal and public sanitary conditions

• avoidance of unprotected homosexual practices

Trichomonas hominis

• non-pathogenic although it has been associated with diarrheic stools

• most commonly found flagellate next to G. lamblia and D. fragilis

MORPHOLOGY

TROPHOZOITE

• 7-20 microns long; 5-18 microns wide

• pear-shaped

• Motility

  • nervous, jerky

• Nuclei

  • one

  • karyosome

    • small central

• Fllagella

  • three to five anterior

  • one posterior extending from the posterior end of the undulating membrane

• axostyle

  • extends beyond the posterior end of the body

• full body length undulating membrane

• conical cytosome cleft (shepherd’s crook)

  • anterior region ventrally located opposite the undulating membrane

Lab Diagnosis

• stool examination

• flagellates

  • move very quickly in a jerky non-directional manner

  • hard to stain

• axostyle and undulating membrane are diagnostic

• axostyle

  • can be seen on a stained preparation

Life Cycle

• trophozoites are shed in feces

• fecal-oral route

• resides in large intestine

MOT

• ingestion of trophozoites

• contaminated milk as one of the infectious causes

• patients suffering from achlorydria act as shield of T. hominis trophozoites upon entry

• fecal-oral

Trichomonas tenax

HABITAT

• oral cavity

IS

• use of contaminated dishes/utensils

IH

• man

MORPHOLOGY

TROPHOZOITE

• 5-14 microns long

• oval, pear-shaped

• Nuclei

  • one

  • ovoid nucleus

  • vesicular region filled with chromatin granules

• Flagella

  • five

    • all anteriorly

    • four anteriorly

    • one to posterior

• undulating membrane extending two thirds of body length with accompanying costa

• thick axostyle curves around nucleus

  • extends beyond body length

• small anterior cytosome

  • opposite undulating membrane

• 

Lab Diagnosis

• examination of tonsillar crypts and pyorrheal pockets (mouth scrapings)

• tartar bet. teeth and gingival margin of the gums

  • primary areas of the mouth that may harbor this

• samples ay be cultured

Life Cycle

Trichomonas vaginalis

MORPHOLOGY

TROPHOZOITE

• up to 30 microns long

• ovoid, round or pear-shaped

• Nuclei

  • one

  • ovoid

  • nondescript

• Flagella

  • all originating anteriorly

    • three to five anteriorly

    • one to posterior

• undulating membrane extending half of body length

• prominent axostyle

  • often curves around nucleus

  • granules may be seen along

• 

Lab Diagnosis

• DNA-based assay

  • Affirm VPII (BD Diagnostics, Sparks, MD)

  • sensitivity and specificity is greater than standard methods

• InPouch TV (Bio Med Diagnostics, White Cry, OR) culture system

  • vaginal swabs from women

  • urethral swabs from men and semen sediment

  • requires incubation time up to 3 days

Life Cycle

• mucosal surface of the vagina

• growing trophozoites

  • multiply by longitudinal binary fission

  • feed on local bacteria and leukocytes

  • thrive on alkine or slightly acidic pH

• prostate gland region and epithelium of the urethra

  • unknown details

Epidemiology

• worldwide

• primary MOT

  • sexual intercourse

• may migrate from mother’s birth canal and infect unborn child

• rare transmission

  • via contaminated toilet articles or underclothing

  • sharing of douche supplies and communal bathing

• trophozoites are known to survive

  • in urine, wet sponges, and on damp towels

    • several hours

  • in water

    • up to 40 minutes

Asymptomatic

• most frequently occur in men

Persistent Urethritis

• symptomatic men

  • enlarged tender prostate, dysuria, nocturia, epididymitis

  • patients often release a thin white urethral discharge

    • contains trophozoites

Persistent Vaginitis

• foul-smelling

• greenish-yellow liquid vaginal discharge

• after incubation period of 4-28 days

• burning, itching, ad chafing

• Red punctate lesions

• urethral involvement, dysuria, and increased frequency of urination

• cystitis

  • less commonly observed but may occur

Infant infections

• recovered from infants suffering from

  • respiratory infection

  • conjunctivitis

Treatment

• metronidazole

• treatment of all sexual partners is recommended

Prevention and Control

• avoidance of unprotected sex

• prompt diagnosis and treatment of asymptomatic men is essential

Retortamonas intestinalis

MORPHOLOGY

TROPHOZOITES

• 3-7 microns long; 5-6 microns wide

• ovoid

• Motility

  • jerky

• Nuclei

  • one

  • karyosome

    • small central

  • ring of chromatin granules may be on the nuclear membrane

• Fllagella

  • two; anterior

• cytosome

  • extending halfway down body length

    • w/ well defined fibril border

  • opposite the nucleus in the anterior end

• 

CYST

• 3-9 microns long; up to 5 microns wide

• lemon-shaped, pear-shaped

• Nucleus

  • one

  • located anterior canal central region

  • central karyosome

  • may be surrounded by a delicate ring of chromatin granules

• two fused fibrils

  • resembling a bird’s beak in the anterior nuclear region

  • only visible in stained preps

• 

Lab Diagnosis

• best sample

  • stool

  • stained prep

• difficulty of identification bc of small size

• cyst and trophozoite in stool

Epidemiology

• warm and temperate climates

• MOT

  • ingestion of infected cyst

• conditions to contract

  • poor sanitation and hygiene

Enteromonas hominis