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MII > protozoan and helminth parasite > Flashcards

protozoan and helminth parasite Flashcards

1
Q

what is parasitism

A

the parasite benefits at the expense of the host

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2
Q

what are obligate parasites

A

spend at least part of their life cycle in parasitic relationship

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3
Q

what are facultative parasites

A

free living but can become parasitic if enter a suitable host

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4
Q

what is a definitive host

A

where the parasite reaches sexual maturity

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5
Q

what is a intermediate host

A

host required for parasite development but no sexual development takes place

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6
Q

what is an incidental host

A

a host that can be infected but does not play a role in lifecycle

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7
Q

what is a paratenic host

A

no development takes place but parasite remains alive and infective to another host

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8
Q

what are helminths

A

parasitic worms

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9
Q

what are the 3 main groups of helminths

A

nematodes
cestodes
trematodes

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10
Q

what are nematodes

A

roundworms

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11
Q

what are cestodes

A

tapeworms

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12
Q

what are trematodes

A

flukes

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13
Q

what is the most common helminthic infection

A

whipworm

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14
Q

how does whipworm infect a host

A

eggs ingested from environment and sexual reproduction occurs in mammalian host

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15
Q

how do whipworms act once in host

A

larvae emerge in duodenum + females and males mate

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16
Q

what are the effects of the helminth (nematode) trichuris dysentery syndrome

A

cause diarrhea, intestinal bleeding, iron deficiency and rectal prolapse

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17
Q

what can filarial worms cause

A

can cause river blindness

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18
Q

what is taeniasis

A

adult worms found in the gut

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19
Q

how may cysticercrosis develop

A

after indigestion of eggs from environment and become larvae to penetrate intestinal wall

20
Q
A
21
Q

How can infecting hosts be a challenge for protozoal parasites

A

May involve migration and parasite motility to transport around host

22
Q

What challenges may protozoal parasites encounter

A

Undergoing transmission
Gaining nutrients - having to adapt to different environments
Avoid being killed by host
Maintain balance between proliferation and forming long term infection

23
Q

What is a sporozoite

A

Injected into the human host when mosquito feeds

24
Q

What is a gametocyte

A

Sexual stages that form in the human

25
Q

What is an Ookinete

A

Formed from macrogametocyte and microgametocyte

26
Q

How is toxoplasmosis caused

A

By opportunistic infections, blurred vision caused by severe inflammation of retina

27
Q

How can humans be infected by toxoplasma gondii infection

A

Contamination by cat faeces
Eating infected meat

28
Q

How is the African trypanosomiasis transmitted

A

By the tsetse fly (definitive host)

29
Q

How do African trypanosomiasis replicate

A

T. Brucei proliferates extracellularly in the host bloodstream and moves into CNS later into the infection

30
Q

How can parasites evade host immune response

A

Hide in host cells
Live free in the bloodstream
Live in protected sites (e.g gut, brain)

31
Q

What are the advantages of a parasite living within a red blood cell

A

Gain nutrients from host cell
Shielded from host immune system
Host cells (erythrocytes) are readily available and are accessible to mosquito vector
Transmission is v efficient

32
Q

What are the disadvantages of a parasite living within a red blood cell

A

Remodelling of cell membrane by parasite causes inc. cell rigidity
Parasite must convert terminally-differentiated erythrocytes into cells with nutrient uptake system
Infected erythrocytes may be detected and removed by spleen

33
Q

What do apicomplexan parasites use to invade host cells

A

Gliding motility

34
Q

Where is gliding motility used during parasite invasion

A

Used by motile stages of lifecycle to migrate to host cell and propel themselves into host cell

35
Q

What must intracellular parasites avoid to escape immune detection

A

Evade host cell killing mechanism
Prevent host cell apoptosis

36
Q

How is pfEMP1 encoded

A

Encoded by around 60 members of the var gene family

37
Q

How does PfEMP1 play a role in a parasite evading immune detection

A

A role in antigenic variation encoding var genes to allow about 60 different versions per individual parasite genome

38
Q

What coat can shield parasites

A

Variant surface glycoprotein coat (VSG)

39
Q

What are characteristics of the N-terminal of the VSG

A

Antigenic diversity
Highly variable sequence
Forms similar structure

40
Q

What are characteristics of the C-terminal of the VSG

A

Surface packing
Conserved region
Anchored into plasma membrane

41
Q

How many VSG can be activated at a time

A

One one promoter is active at a time

42
Q

What are the 4 mechanisms of switching between different VSGs

A

Gene conversion
Segmental gene conversion
Telomere exchange
Transcriptional switch

43
Q

How does a parasite infect a new host

A

Parasite must stop proliferating and differentiate into transmission-competent form

44
Q

What does a slender form of a parasite allow for

A

Proliferation

45
Q

What does a stumpy form of a parasite allow for

A

Transmission

MII (21 decks)

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