Giardia duodenalis (G. lamblia; G. intestinalis) - PowerPoint PPT Presentation

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Giardia duodenalis (G. lamblia; G. intestinalis)

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Giardia duodenalis (G. lamblia; G. intestinalis) Giardiasis. Most distinctive of the flagellates. Has both a trophozoite and cyst stage. Giardia duodenalis ... – PowerPoint PPT presentation

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Title: Giardia duodenalis (G. lamblia; G. intestinalis)


1
Giardia duodenalis (G. lamblia G. intestinalis)
  • Giardiasis.
  • Most distinctive of the flagellates.
  • Has both a trophozoite and cyst stage.

2
Giardia duodenalis Trophozoite
Trophozoites are binucleated (looks like a face).
12-15 µm.  
3
Giardia duodenalis Trophozoite
Trophozoites are binucleated (looks like a face).
12-15 µm. Ventral surface bears
adhesive disk to adhere to surface of intestinal
cell.  
4
Giardia duodenalis Trophozoite
Trophozoites are binucleated (looks like a face).
12-15 µm. Ventral surface bears
adhesive disk to adhere to surface of intestinal
cell. 8 flagella (2 anterior, 2 posterior, 2
ventral, and 2 caudal) - all arise from
kinetosome.  
5
Giardia duodenalis Trophozoite
Trophozoites are binucleated (looks like a face).
12-15 µm. Ventral surface bears
adhesive disk to adhere to surface of intestinal
cell. 8 flagella (2 anterior, 2 posterior, 2
ventral, and 2 caudal) - all arise from
kinetosome. Median bodies occur behind adhesive
disk - function is unknown.  
6
Giardia duodenalis Trophozoite
Light microscope photos of trophozoites
7
Giardia duodenalis
  • Lives in the upper part of the small intestine
    (duodenum, jejunum, and upper ileum).
  • Here the trophozoites attach to the epithelial
    cells.

8
Giardia duodenalis Trophozoite
ventral
dorsal
Scanning EM view of trophozoite surface showing
the adhesive disk.
9
  • Feeds on mucous that forms in response to
    irritation.

10
  • Feeds on mucous that forms in response to
    irritation.
  • Also absorbs vitamins and amino acids.

11
  • Feeds on mucous that forms in response to
    irritation.
  • Also absorbs vitamins and amino acids.
  • Interferes with absorption in host especially
    lipids.

12
  • Feeds on mucous that forms in response to
    irritation.
  • Also absorbs vitamins and amino acids.
  • Interferes with absorption in host especially
    lipids.
  • Giardia can also interfere with vitamin/nutrient
    absorption.
  • Vitamin A? vision
  • Vitamin D? rickets Both of these are due to long
    standing infections.

13
Cyst of Giardia duodenalis
The cyst forms as trophozoites become dehydrated
when they pass through the large intestine.

14
Cyst of Giardia duodenalis
  • The cyst forms as trophozoites become dehydrated
    when they pass through the large intestine.
  • Morphology
  • ovoid in shape 8-12 µm long x 7-10 µm wide
  • thin cyst wall.
  • Four nuclei present, often concentrated at on
    end.
  • Flagella shorten and are retracted within cyst.
  • Axonemes provide internal support.

15
Cyst of Giardia duodenalis
Cyst may remain viable in the
external environment (usually water) for many
months.
16
Cyst of Giardia duodenalis
Cyst may remain viable in the
external environment (usually water) for many
months. -14 billion cysts can be passed in 1
stool sample -Moderate infections 300 million
cysts.
17
Cyst of Giardia duodenalis
18
Symptoms
  • Range from none? abdominal discomfort causing
    acute or chronic diarrhea and other GI signs.
  • Gray, greasy, voluminous malodorous diarrhea!
  • Flatulence.

19
Giardia duodenalis
  • Giardia trophs are attracted to bile salts so
    sometimes you can get infections in bile ducts
    and gall bladder, causing jaundice and colic.
  • This is irritating but not life threatening
    infection like E. histolytica.

20
Pathogenesis and Pathology
  • Nutrient malabsorption and physical blockage and
    damage to microvilli.
  • Trophs attach to small intestine? cause damage
    (mechanical and toxins).

21
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22
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24
Giardia trophozoite
Trophozoite attaches to surface of epithelial
cells with its adhesive disk.
25
Pathogenesis and Pathology
  • 1) Fat/CHO digestion decreases and causes
    maldigestion.

26
Pathogenesis and Pathology
  • 1) Fat/CHO digestion decreases and causes
    maldigestion.
  • 2) Absorption decreases due to villus blunting
    causing malabsorption.

27
Pathogenesis and Pathology
  • 1) Fat/CHO digestion decreases and causes
    maldigestion.
  • 2) Absorption decreases due to villus blunting
    causing malabsorption.
  • 3) Malabsorption and maldigestion causes
    diarrhea.

28
Pathogenesis and Pathology
  • 4) Physical damage clubbing of villi decreases
    villus-to-crypt ratio brush borders of cells are
    irregular.

29
Epidemiology
  • Get infected by ingesting cysts through
    contaminated water.

30
Epidemiology
  • Get infected by ingesting cysts through
    contaminated water.
  • Most common intestinal flagellate of people.

31
Epidemiology
  • Get infected by ingesting cysts through
    contaminated water.
  • Most common intestinal flagellate of people.
  • World wide distribution prevalence ranges from
    2.4-67.5.

32
Epidemiology
  • Get infected by ingesting cysts through
    contaminated water.
  • Most common intestinal flagellate of people.
  • World wide distribution prevalence ranges from
    2.4-67.5.
  • Reservoir hosts can play a significant role.

33
Reservoir Hosts
Transmission from animals to humans is
controversial dependent on strain or type
involved.
34
Human Infections
  • There are hot spots Vacations and Travels?
    Camping.

35
Human Infections
  • There are hot spots Vacations and Travels?
    Camping.
  • Colorado ski resorts are notorious for outbreaks?
    drinking from Mountain Springs, washing
    utensils/drinking water that is not treated.

36
Human Infections
  • There are hot spots Vacations and Travels?
    Camping.
  • Colorado ski resorts are notorious for outbreaks?
    drinking from Mountain Springs, washing
    utensils/drinking water that is not treated.
  • Day care centers.

37
Diagnosis
  • Trophs in diarrheic feces cysts in formed feces.
  • At least 3 exams (one every other day) before
    judge negative.
  • ELISA tests detect soluble antigen.

38
Treatment and Prognosis
  • Drug of choice is Flagyl.
  • Giardia thrives in people? not necessarily hard
    to treat, but keeping those who were infected
    from becoming reinfected.

39
Blood and Tissue Flagellates Phylum Euglenoidea
  • Known as Hemoflagellates or Kinetoplastids.
  • Some have forms that live in the alimentary canal
    of insects such as flies, bugs, etc.

40
Adaptation to Parasitism
  • Most parasites came from free-living forms.

41
Adaptation to Parasitism
  • Most parasites came from free-living forms.
  • They became parasites when hosts ingested them
    and they survived the process.

42
Adaptation to Parasitism
  • Most parasites came from free-living forms.
  • They became parasites when hosts ingested them
    and they survived the process.
  • They were then selected for and adapted to
    colonize hosts.

43
Adaptation to Parasitism
  • This is not the case for blood and tissue
    flagellates.

44
Adaptation to Parasitism
  • This is not the case for blood and tissue
    flagellates.
  • Because most insect species have flagellates that
    live within them and these share characters with
    human blood and tissue flagellates.

45
Adaptation to Parasitism
  • This is not the case for blood and tissue
    flagellates.
  • Because most insect species have flagellates that
    live within them and these share characters with
    human blood and tissue flagellates.
  • Therefore biting insects probably gave these
    parasites to us!

46
Blood and Tissue Flagellate Anatomy and Life
Stages
  • There are seven ontogenetic stages, but not all
    species have all seven.
  • These stages are continuous.

47
Life-cycle stages of trypanosomatidae. A.
promastigote b. ophistomastigote c.
epimastigote d. trypomastigote e.
choanomastigote f. amastigote g. paramastigote
K. kinetoplast N. nucleus F. flagellum.
48
  • You will be responsible for 4 of them.
  • Remember not all 4 stages will be found in each
    species life cycle.

49
Promastigote
anterior
Flagellum Kinetosome Kinetoplast Nucleus
posterior
50
Epimastigote
anterior
Undulating membrane
posterior
51
Trypomastigote
anterior
posterior
52
Amastigote
anterior
Flagellum Kinetosome Kinetoplast Nucleus
posterior
These are intracellular, stages that occur within
cells.
53
Leishmaniasis
  • Infection with Leishmania spp.
  • Disease of the Reticulo-Endothelial Cells.

54
Leishmaniasis
  • Infection with Leishmania spp.
  • Disease of the Reticulo-Endothelial Cells.
  • Reticulo-Endothelial System- is diffuse in the
    body and made up of all phagocytes except for
    leucocytes.

55
Leishmaniasis
  • Infection with Leishmania spp.
  • Disease of the Reticulo-Endothelial Cells.
  • Reticulo-Endothelial System- is diffuse in the
    body and made up of all phagocytes except for
    leucocytes.
  • Macrophage is a standard reticulo-endothelial
    cell.
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