5.0 Parasitology

Question 1

Define ectoparasite:

Answer 1

Lives externally on host

Question 2

Define endoparasite:

Answer 2

Lives internally on host

Question 3

Define host:

Answer 3

Organism that provides food/habitat to parasite (to its own detriment)

Question 4

Define vector:

Answer 4

Organism responsible for transmission of disease causing organism

Question 5

Define definitive host:

Answer 5

Host in which parasite sexual maturity and reproduction occurs

Question 6

Define intermediate host:

Answer 6

Host in which parasite asexual reproduction occurs

Question 7

Define direct life cycle:

Answer 7

Involves only a single host species

Question 8

Define indirect life cycle:

Answer 8

Involves 2 or more host species

Question 9

Define zoonosis:

Answer 9

Disease that mainly infects animals but may be passed to humans

Question 10

What are the different types of helminths:

Answer 10

<b>1) Nematodes</b><br></br><b>2) Platyhelminths</b><br></br>a) Trematodes<br></br>b) Cestodes

Question 11

Common features of nematodes:

Answer 11

<b>Round worm</b><br></br>Cylindrical<br></br>Radial symmetry<br></br>Separate sexes<br></br>Non-cellular outer cuticle (exoskeleton)

Question 12

What are the different types of protozoa:

Answer 12

<b>1) Kinetoplastida</b><br></br><b>2) Apicomplexa</b>

Question 13

What are the 5 plasmodium species that cause human malaria?

Answer 13

1) P. falciparum<br></br>2) P. vivax<br></br>3) P. ovale<br></br>4) P. malariae<br></br>5) P. knowlesi

Question 14

What is the infective state of plasmodium?

Answer 14

Sporozoites

Question 15

Where in the human does plasmodium differentiation and amplification occur?

Answer 15

In the hepatocytes

Question 16

Brief stages of plasmodium life cycle:

Answer 16

Sporozoites infect human → hepatocytes<br></br>Differentiation and amplification in hepatocytes<br></br>Rupture of hepatocytes → merozoite release<br></br>Merozoite invade RBCs<br></br>In RBCs: Merozyte → rings → trophozoites → schizonts<br></br>Rupture → release of more merozoites to invade new RBCs

Question 17

Clinical manifestations of malaria:

Answer 17

Fever<br></br>Headache<br></br>Anaemia<br></br>Splenomegaly <br></br>RBC sequestration (P. falciparum)<br></br>Hypoglycaemia<br></br>Glomerulonephritis

Question 18

Mechanism of p.falcuparum induced sequestration:

Answer 18

Modifies RBC to express parasitic proteins on surface → endothelial cell adhesion → sequestration<br></br><br></br>RBC expresses <b>PfEMP-1</b><br></br>Endothelial cell receptors =<br></br>1) ICAM-1<br></br>2) CD-36<br></br>3) VCAM-1<br></br>4) CSA (high in placenta)

Question 19

How does sequestration lead to symptoms in malaria?

Answer 19

1) Blockage of vessels<br></br>2) Cytokine release (GPI causes TNF alpha + IL-1 release)<br></br>3) Disruption of blood-brain barrier<br></br>4) Severe anaemia due to destruction of RBCs (uninfected RBCs are also destructed)

Question 20

What conditions offer natural immunity to malaria?

Answer 20

1) Sickle cell Hb<br></br>2) Thalassemias<br></br>3) Glucose-6-phosphate dehydrogenase deficiency<br></br>4) HLA-B53

Question 21

What three schistosoma spp. cause disease in humans?

Answer 21

1) Schistosoma mansoni<br></br>2) Schistosoma japonicum<br></br>3) Schistosoma haematobium

Question 22

Where are the adult worms of the following located?<br></br>1) Schistosoma mansoni<br></br>2) Schistosoma japonicum<br></br>3) Schistosoma haematobium

Answer 22

All located in blood vessels around<br></br>1) Schistosoma mansoni <b>gut</b><br></br>2) Schistosoma japonicum <b>gut</b><br></br>3) Schistosoma haematobium <b>bladder</b>

Question 23

What can be used to treat schistosomiasis?

Answer 23

Praziquantel