protozoan and helminth parasite

Question 1

what is parasitism

Answer 1

the parasite benefits at the expense of the host

Question 2

what are obligate parasites

Answer 2

spend at least part of their life cycle in parasitic relationship

Question 3

what are facultative parasites

Answer 3

free living but can become parasitic if enter a suitable host

Question 4

what is a definitive host

Answer 4

where the parasite reaches sexual maturity

Question 5

what is a intermediate host

Answer 5

host required for parasite development but no sexual development takes place

Question 6

what is an incidental host

Answer 6

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

Question 7

what is a paratenic host

Answer 7

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

Question 8

what are helminths

Answer 8

parasitic worms

Question 9

what are the 3 main groups of helminths

Answer 9

nematodes
cestodes
trematodes

Question 10

what are nematodes

Answer 10

roundworms

Question 11

what are cestodes

Answer 11

tapeworms

Question 12

what are trematodes

Answer 12

flukes

Question 13

what is the most common helminthic infection

Answer 13

whipworm

Question 14

how does whipworm infect a host

Answer 14

eggs ingested from environment and sexual reproduction occurs in mammalian host

Question 15

how do whipworms act once in host

Answer 15

larvae emerge in duodenum + females and males mate

Question 16

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

Answer 16

cause diarrhea, intestinal bleeding, iron deficiency and rectal prolapse

Question 17

what can filarial worms cause

Answer 17

can cause river blindness

Question 18

what is taeniasis

Answer 18

adult worms found in the gut

Question 19

how may cysticercrosis develop

Answer 19

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

Question 21

How can infecting hosts be a challenge for protozoal parasites

Answer 21

May involve migration and parasite motility to transport around host

Question 22

What challenges may protozoal parasites encounter

Answer 22

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

Question 23

What is a sporozoite

Answer 23

Injected into the human host when mosquito feeds

Question 24

What is a gametocyte

Answer 24

Sexual stages that form in the human

Question 25

What is an Ookinete

Answer 25

Formed from macrogametocyte and microgametocyte

Question 26

How is toxoplasmosis caused

Answer 26

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

Question 27

How can humans be infected by toxoplasma gondii infection

Answer 27

Contamination by cat faeces Eating infected meat

Question 28

How is the African trypanosomiasis transmitted

Answer 28

By the tsetse fly (definitive host)

Question 29

How do African trypanosomiasis replicate

Answer 29

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

Question 30

How can parasites evade host immune response

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

What do apicomplexan parasites use to invade host cells

Answer 33

Gliding motility

Question 34

Where is gliding motility used during parasite invasion

Answer 34

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

Question 35

What must intracellular parasites avoid to escape immune detection

Answer 35

Evade host cell killing mechanism Prevent host cell apoptosis

Question 36

How is pfEMP1 encoded

Answer 36

Encoded by around 60 members of the var gene family

Question 37

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

Answer 37

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

Question 38

What coat can shield parasites

Answer 38

Variant surface glycoprotein coat (VSG)

Question 39

What are characteristics of the N-terminal of the VSG

Answer 39

Antigenic diversity Highly variable sequence Forms similar structure

Question 40

What are characteristics of the C-terminal of the VSG

Answer 40

Surface packing Conserved region Anchored into plasma membrane

Question 41

How many VSG can be activated at a time

Answer 41

One one promoter is active at a time

Question 42

What are the 4 mechanisms of switching between different VSGs

Answer 42

Gene conversion Segmental gene conversion Telomere exchange Transcriptional switch

Question 43

How does a parasite infect a new host

Answer 43

Parasite must stop proliferating and differentiate into transmission-competent form

Question 44

What does a slender form of a parasite allow for

Answer 44

Proliferation

Question 45

What does a stumpy form of a parasite allow for

Answer 45

Transmission