Other Flagellates

1
Other Flagellates
2
Retortamonadida and Diplomonadida Orders

• Lack mitochondria and dictysosomes
• Possess a recurrent flagellum in cytostomal
  groove
• Occupy anoxic (low O2 concentration in tissue)
  environments
• Life cycle
• Trophozoite in cecum colon ? cyst in feces ?
  ingested ? trophozoite in cecum colon

3
Retortamonadidae

• 2 species found in humans
• Chilomastix mesnili non-pathogenic
• Infects 3.5 of population in USA
• Found in the cecum and colon of humans, chimps,
  orangutans, monkeys and pigs
• Transmitted by the ingestion of cysts fecal
  contamination of drinking H2O
• Retortamonas intestinalis
• Similar to C mesnili
• Found in the cecum and large intestine of
  monkeys, chimps and human
• Probably a harmless commensal

4
C mesnili (Troph)

• Stool smear
• Pyriform shape with variable size, single
  nucleus, and presence of cytostomal groove (C),
  visible when the focus is changed slightly
  (arrow)
• Three anteriorly directed flagella (F), and one
  flagellum that is recurved into the cytostomal
  groove

5
C mesnilicysts

• Stool smear
• Lemon shaped with a single nucleus and cap at
  one end (C).
• Axonemes and the cytostomal groove often can be
  seen within the cyst

6
Diplomonadida Order

• Family Hexamitidae
• Have 2 equal sized nuclei
• Giardia species have no mitochondria
• Thought to be the divergence point between
  prokaryotes and eukaryotes
• Very widespread, infects all nations and across
  all socioeconomic groups

7
Giardia Species

• G. lamblii human
• Live in warm climates
• Kids are susceptible
• Most common flagellate in human GI tract
• G. muris mammals
• G. ardea and G. psittaci birds
• G. ugilis - amphibians

8
Giardia lamblii

• Trophozoites have a flattened shape
• Has an adhesive disc that is used to adhere to
  the intestinal wall
• Has 2 ventral flagella and 3 other pairs
• Median bodies behind the adhesive disc with
  unknown function
• No golgi, mitochondria, lysosome or SER
• 2 nuclei

9
G. LambliaTroph

• Stool smear
• Flagella (which number 8) are not visible in
  these photographs, although axonemes (A) can be
  seen in the cytoplasm of some cells as dark lines

10
G. Lamblia Cysts

• Stool smear
• Oval shape, smooth cyst wall, axonemes (A), and
  four nuclei, usually not all of which are visible
  in one focal plane
• Cytoplasm often is retracted from the cyst wall
  in fixed specimens, leaving a clear space

11
Life Cycle

• Trophozoite in all parts of the small intestine ?
  cyst in stools ? ingested ? trophozoite in small
  intestine
• Divide by binary fission starting with the
  nucleus, locomotor apparatus, sucking disc and
  then the cytoplasm
• Encystment occurs as the trophs move into the
  stool and it starts to dehydrate
• Young cysts have 2 nuclei as they age, they
  divide and end up with 4 nuclei the cyst also
  gets 2 sucking discs and locamotor apparatus so
  when injested, it can complete dividing and grow
  flagella

12
Pathogenesis, Diagnosis and Treatment

• Some hosts are more susceptible than others
• See an increase in mucus production in stool,
  diarrhea, dehydration, intestinal pain,
  flatulence and weight loss
• No blood and not fatal
• Diagnosis is made by seeing the troph or cyst in
  the stool
• Treatment is with quinaacrine or metronidozole
  (Flagyl) and the entire family should be treated,
  highly contagious

13
Order Trichomonadida

• Several species that are very similar to one
  another
• Anterior tuft of flagella, stout median rod
  (axostyle) and undulating membrane
• Found in the intestines and the reproductive
  tracts in vertebrates and invertebrates
• One group only in termintes
• Most do not form cysts

14
Human Trichomonads

• Trichomomas tenax
• Trichomomas vaginalis
• Pentatrichomomas hominis (formerly Trichomomas
  hominis)

15
T. tenax

• World wide distribution
• Found only in the oral cavity
• 4 anterior flagella with the 5 curving back along
  the margin of the undulating membrane but not in
  it
• Acessory filament courses in the indulating
  membrane
• Costa rod like structure with complex
  cross-striations arise in the kinetosome
  complex
• Used to distinguish Trichomonads from the rest
• Axostyle sheet of microtubules that extends
  from the kinetosome area posteriorly
• Transmission by kissing or common use of eating
  and drinking utensils
• Trophs divide by binary fission

16
T. vaginalis

• Larger, single nucleus, shorter undulating
  membrane (U), four anterior flagella (F), and
  axostyle (A)
• Transmission is direct
• Usually via sexual intercourse but also by
  sharing washcloths
• Vagina, urethra, prostate, seminal vesicles
• Symptoms range from none to a painful discharge
  (leukorrhea) in females and prostatitis in males
• Division by longitudinal fission
• Treat with metronidozole (Flagyl)
• Partners should be treated