malaria

Question 1

prevelence of malaria

Answer 1

300-500 million cases per year
1-2 million deaths per year
confined to tropical and sub tropical zones

Question 2

mosquito

Answer 2

anopheles

Question 3

plasmodium

Answer 3

protozoan parasite 
single celled eukaryote 
replicates intracellularly 
infects red blood cells 
sexual stages in the mosquito - gametocyte - sporozoites

Question 4

plasmodium faciparum

Answer 4

main cause of death - most severe

chemotherapy can rid from blood

Question 5

P. vivax and P . ovale

Answer 5

vivax = most common, less severe

some parasite remains dormant in liver cells, can reactivate

Question 6

sporozoites

Answer 6

parasite injected into the blood by mosquito - extracellular stage
pre-erythrocytic stage
entire surface covered with CSP

Question 7

CSP

Answer 7

antigen on entire surface of sporozoites
highly antigenic, middle of protein made up of 40X repeats
but highly variable - serves as a decoy antigen to select for specific clonality

Question 8

liver cell stage

Answer 8

parasite shows LDA-1 antigen and CSP antigen

divide into meozoites

Question 9

merozoites

Answer 9

blood and
erythrocyte stage
elicit antibody response
MSP-1 serves as a decoy antigen

Question 10

Trophozoites

Answer 10

in red blood cell
intracellular but express antigens on red blood cell - express pfEMP-1 involved in cytoadherence to endothelial cells on capillary - red blood cells attach so they arent removed by the spleen
EXTREMELY variable between species, strain, stage
varies within a clonal strain
part of a gene family, 59 var genes, only 1 gene encode protein

Question 11

pathology

Answer 11

recurrent fever 
parasite observed in blood smear 
enlarged spleen 
anaemia 
TNF induction - inflammation, tissue damage 
celebral malaria 
glomerulonephritis with P. malariae

Question 12

cerebral malaria

Answer 12

main cause of death
accumulation of parasitized red blood cells in the capillaries of brain due to pfEMP attachment
block blood flow, starve brain of oxygen.
upregulation of TNF receptor - more tissue damage

Question 13

natural resistence

Answer 13

children with continuous exposure show resistance to P. vivax
population in west Africa missing Duffy antigen, merozoites use as receptor to invade RBC

Question 14

resistance to P. Falciprium

Answer 14

unfavourable conditions in RBC - cant grow
sickle cell anamia
release more free heme - heme activates antioxidant production, prevents oxidative damage

Question 15

south east asia resistance

Answer 15

ovalocytosis - cytoskeletal differences prevents invasion

Question 16

glucose-6-dehydrogenase deficiency

Answer 16

permits reactive oxygen species

Question 17

dendritic cell

Answer 17

ingest RBC with parasite 
presents proteins to CD4 
produce TNFa 
secrete IL-12 to induce NK cells
secrete IFN-y for macrophage killing and T cell activation
fever induced by cytokine production

Question 18

fever

Answer 18

inhibits parasite growth - fast growth would be fatal to host - allows passage of parasite
TNF-a regulates parasite growth