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Microbiology > Parasitology Exam 3: Hemoflagellates > Flashcards

Parasitology Exam 3: Hemoflagellates Flashcards

1
Q

What are the 2 genera of hemoflagellates that infect humans?

A

Leishmania spp.
Trypanosoma spp.

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2
Q

Kinetoplast

A

A network of circular DNA inside a large mitochondrion found in hemoflagellates

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3
Q

What are the 4 morphological stages of hemoflagellates?

A

Amastigote
Promastigote
Epimastigote
Trypomastigote
**Not successive, no pattern, any form is capable of developing into another form

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4
Q

Describe amastigotes

A

Usually develop in vertebrate host cells
Ovoid, single prominent nucleus, very short flagellum projecting barely beyond the cell surface

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5
Q

Describe promastigotes

A

Occurs only in the insect vector
More elongated than amastigote
Long flagellum and 2 mitochondrial branches

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6
Q

Describe epimastigotes

A

Kinetoplast-basal body complex situated more anteriorly than in promastigotes, but remains anterior to the nucleus
Has an undulating membrane

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7
Q

Describe trypomastigotes

A

Polymorphic
Long and slender or stumpy
Undulating membrane is much larger and prominent

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8
Q

What is a hemoflagellate?

A

Flagellate protozoans found in the blood of humans

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9
Q

What are the causative organisms of African Trypanosomiasis? What is the vector?

A

Vector: Tsetse fly (Glossina spp.)

Trypanosoma brucei gambiense –> West African

Trypanosoma brucei rhodesiense (East African)

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10
Q

What are the natural reservoir hosts of Trypanosoma?

A

Game animals like bushbuck and cattle

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11
Q

What is unique about African Trypanosomes?

A

They can change the antigens on the membrane of their trypomastigote every 5-7 days, allowing them to evade host’s immune response
Sustained high IgM levels

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12
Q

What is the infective stage of Trypanosomiasis?

A

Injection of trypomastigotes by tsetse fly

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13
Q

What is the diagnostic stage of Trypanosomiasis?

A

Trypomastigotes in blood

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14
Q

What does T. brucei gambiense cause? What are the symptoms/pathogenesis?

A

West African Sleeping Sickness
Stage 1 - no CNS involvement
Stage 2 - organisms invade CNS, progressive meningoencephalitis

Lymphadenopathy, hepatomegaly and/or splenomegaly

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15
Q

Somnolence

A

State of drowsiness (symptoms of Sleeping Sickness, stage 2)

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16
Q

What does T. brucei rhodesiense cause? What are the symptoms/pathogenesis?

A

East African Sleeping Sickness
More rapid, fulminating disease

Myocarditis

Death before extensive CNS involvement

17
Q

General morphology of African Trypomastigotes

A

Kinetoplast located at posterior end, stains red
Undulating membrane and flagellum arise from the kinetoplast

18
Q

What is another name for American Trypanosomiasis?

A

Chaga’s Disease

19
Q

What is the causative organism of American Trypanosomiasis/Chagas Disease?

A

Trypanosoma cruzi

20
Q

What is the vector of Chagas disease?

A

Reduviid bug/kissing bug/triatomid bug

21
Q

How is Chagas disease transmitted?

A

Reduviid bug bites you, poops, scratch the bite, and the feces gets into your tissue/bloodstream

Can also be transmitted via blood transfusion or organ transplantation

22
Q

Describe the life cycle of Chagas Disease

A
  1. Trypomastigotes ingested by reduviid bug during blood meal
  2. Transform into epimastigotes
  3. More tryptomastigotes
  4. Bug defecates while biting human
  5. Human scratches bite
  6. Trypomastigotes travel in blood
  7. Amastigotes multiply in cell and released into blood with trypomastigotes
23
Q

What are the vectors for African and for American trypanosomiasis?

A

African - Tsetse fly
American - Kissing bug

24
Q

What is a specific feature of American trypomastigotes (chagas)

A

C or U shaped!!

25
Q

Pathogenesis of Chagas disease

A

Acute Symptoms:
Myocarditis, death from myocardial insufficiency or cardiac arrest

Chronic symptoms:
Megacolon
Cardiac changes (enlargement of heart, conduction changes)

26
Q

Routine method for diagnosis of Trypanosomiasis

A

Thick and thin blood films

27
Q

What is Xenodiagnosis?

A

Used to detect light infections like chronic infections

28
Q

Differentiate between T. cruzi and T. brucei trypomastigote morphology

A

T. cruzi is C or U shaped

29
Q

What species cause Leishmaniasis?

A

L. donovani
L. braziliensis

30
Q

What disease is 2nd in mortality and 4th in morbidity among all tropical diseases?

A

Leishmaniasis

31
Q

What is the vector of Leishmaniasis?

A

Sandfly

32
Q

What are the 2 distinct phases of Leishmaniasis life cycle and where are they seen?

A

Amastigote - seen in humans
Promastigote - seen in insects

33
Q

What are the infective/diagnostic stages of Leishmaniasis?

A

Infective: Sandfly introduces PROMASTIGOTES into skin

Diagnostic: Detection of AMASTIGOTES in tissues

34
Q

What is CL? MCL?

A

Cutaneous Leishmaniasis
Mucocutaneous Leishmaniasis
- First sign is a lesion at the bite site, secondary lesions develop
Similar presentations

35
Q

What is VL?

A

Visceral Leishmaniasis, AKA Kala-azar

Enlarged liver and spleen, swollen lymph nodes

36
Q

What is diffuse leishmaniasis?

A

Nodular disease that results in high parasitemia due to an inappropriate antibody response of the patient

37
Q

What are the characteristics of severe VL (kala-azar)

A

Characteristic hypergammaglobulinemia of both IgG and IgM

Microbiology (24 decks)

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