Severe Malaria Flashcards

1
Q

what is severe malaria, what causes it

A

Severe Malaria = a metabolic disease problem caused by sequestration of RBCs leading to acidosis of blood, impaired oxygenation of tissues and tissue hypoxia.

sequestration of infected erythrocytes in the brain and other vital organs in association with high parasite burden is the most important feature of severe malaria pathogenesis - Sahu 2021

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2
Q

what causes acidosis

A

-sequestration: microvascular obstruction leads to tissue hypoxia and a switch from aerobic to anaerobic glycolysis with build-up of lactic acid (Possemier et al., 2021 PLoS Pathogens)
- increased levels of lactic acid = metabolic acidosis
- acidosis causes coma/impaired consciousness, respiratory distress and organ failure
- if pH of blood falls below 7 = death
- acidosis is therefore the most accurate prognosis factor to predict fatal outcome

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3
Q

Why does P. Falciparum Sequester?

A
  • when RBCs become infected, they change shape and become rigid through remodelling of the cell membrane by the parasite
  • the spleen removes rigid red cells (usually old/damage cells)
  • sequestration protects P. Falciparum from being removed by the spleen
  • the low oxygen environment in post-capillary venules is also beneficial to parasite growth
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4
Q

How can variations in clinical disease be caused by sequestration?

A

variations in clinical disease can be caused by WHERE the parasites cause RBC sequestration - brain epithelium

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5
Q

Cerebral malaria

A
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6
Q

how does malaria cause brain swelling and what happens?

A
  • MRI studies in endemic regions show that sequestration of RBCs can lead to swelling in the brain
  • fluid-filled spaces in the brain disappear due to swelling of brain tissue
  • the brain expands down into the neck, squashing the brain stem
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7
Q

how does sequestration contribute to anaemia

A

sequestration causes hypoxia

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8
Q
A
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