5.0 Parasitology Flashcards
Define ectoparasite:
Lives externally on host
Define endoparasite:
Lives internally on host
Define host:
Organism that provides food/habitat to parasite (to its own detriment)
Define vector:
Organism responsible for transmission of disease causing organism
Define definitive host:
Host in which parasite sexual maturity and reproduction occurs
Define intermediate host:
Host in which parasite asexual reproduction occurs
Define direct life cycle:
Involves only a single host species
Define indirect life cycle:
Involves 2 or more host species
Define zoonosis:
Disease that mainly infects animals but may be passed to humans
What are the different types of helminths:
<b>1) Nematodes</b><br></br><b>2) Platyhelminths</b><br></br>a) Trematodes<br></br>b) Cestodes
Common features of nematodes:
<b>Round worm</b><br></br>Cylindrical<br></br>Radial symmetry<br></br>Separate sexes<br></br>Non-cellular outer cuticle (exoskeleton)
What are the different types of protozoa:
<b>1) Kinetoplastida</b><br></br><b>2) Apicomplexa</b>
What are the 5 plasmodium species that cause human malaria?
1) P. falciparum<br></br>2) P. vivax<br></br>3) P. ovale<br></br>4) P. malariae<br></br>5) P. knowlesi
What is the infective state of plasmodium?
Sporozoites
Where in the human does plasmodium differentiation and amplification occur?
In the hepatocytes
Brief stages of plasmodium life cycle:
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
Clinical manifestations of malaria:
Fever<br></br>Headache<br></br>Anaemia<br></br>Splenomegaly <br></br>RBC sequestration (P. falciparum)<br></br>Hypoglycaemia<br></br>Glomerulonephritis
Mechanism of p.falcuparum induced sequestration:
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)
How does sequestration lead to symptoms in malaria?
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)
What conditions offer natural immunity to malaria?
1) Sickle cell Hb<br></br>2) Thalassemias<br></br>3) Glucose-6-phosphate dehydrogenase deficiency<br></br>4) HLA-B53
What three schistosoma spp. cause disease in humans?
1) Schistosoma mansoni<br></br>2) Schistosoma japonicum<br></br>3) Schistosoma haematobium
Where are the adult worms of the following located?<br></br>1) Schistosoma mansoni<br></br>2) Schistosoma japonicum<br></br>3) Schistosoma haematobium
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>
What can be used to treat schistosomiasis?
Praziquantel
