Malaria

Question 1

Outline the lifecycle of Malaria

Answer 1

• Female anopheles mosquito delivers sporozoites into the blood
• Merozoites release invasion proteins that bind to RBC receptors
• Parasitovorous vacuole absorbs parasite into cell
• Perforin-like-proteins lyse RBC membrane, causing egress of new merozoites.
• Gametogenesis occurs in mosquito when taken up

Question 2

How does sickle cell anaemia protect from Malaria?

Answer 2

• HbAS decreases the habitability inside RBCs, especially under low oxygen tension
• Decreased endothelial adherence due to reduced parasite protein expression
• Increased removal of RBCs by spleen clears the parasite more than normal

Question 3

What host protein does P. Vivax require in order to invade human red cells?

Answer 3

Duffy antigen receptor for chemokines (DARC)

Question 4

How does the disruption of the cytoskeletal network associated with HbS and HbC deter the pathogenesis of Malaria?

Answer 4

Parasites rely on host-derived cytoskeletal proteins to traffic essential parasite proteins to the RBC membrane.

Question 5

What blood group systems offer malarial protection?

Answer 5

ABO, Duffy, S-sU

Question 6

How may HbAS assist in malarial immunity?

Answer 6

Prolonged subclinical/mild parasitaemia is often seen in children with HbAS infected with P. falciparum. This provides the host with sufficient opportunity to develo[ humoral immunity against the infection.