Malaria

Question 1

Definition

Answer 1

Infection with protozoan Plasmodium

Question 2

Types of plasmodium

Answer 2

FIVE types of Plasmodium:

o Plasmodium falciparum - MOST SERIOUS
o Plasmodium vivax
o Plasmodium ovale
o Plasmodium malariae
o Plasmodium knowlesi

Question 3

Aetiology

Answer 3

• Transmitted by the bite of the female Anopheles mosquito

* The protozoa grow in red blood cells

Question 4

Life cycle

Answer 4

o Injection of sporozoites into the blood stream by mosquito
o Invasion and replication in hepatocytes
o Parasites reinvade the blood and enter red blood cells
o They replicate within red blood cells and develop ring forms
o Red blood cells rupture and release merozoites, which reinfect other red blood cells
o Gametocytes are taken up when another mosquito feeds, and develop into
sporozoites in the gut of the mosquito
o They then move to the salivary gland of the mosquito to be transmitted with the next bite

Question 5

Innate immunity

Answer 5

Some populations have innate immunity to malaria:

o Sickle cell trait
o G6PD deficiency
o Pyruvate kinase deficiency
o Thalassemia

Question 6

Epidemiology

Answer 6

• Endemic in the tropics

* 250 million people worldwide

Question 7

Presenting symptoms

Answer 7

• Feverish traveller (incubation period can be up to 1 year)

• Symptoms are CYCLICAL:
o High fever
o Flu-like symptoms
o Severe sweating
o Shivering cold/rigors

• NOTE: the interval between cycles of symptoms are slightly different in different types
of malaria

Question 8

Cerebral symptoms

Answer 8

o Headache
o Disorientation
o Coma

Question 9

Signs on physical examination

Answer 9

• Pyrexia
• Anaemia (haemolytic)
• Hepatosplenomegaly

Question 10

Investigations

Answer 10

• Thick/Thin Blood Films
o Thick for quantifying
o Thin for identifying type of malaria

• Bloods
o FBC - haemolytic picture
o U&Es
o LFTs
o ABG

• Urinalysis -check for blood or protein