Malaria

Question 1

Define Malaria

Answer 1

Infection with protozoan Plasmodium (Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae).

Question 2

Aetiology of Malaria

Answer 2

Infection by Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae, with Plasmodium Falciparum being the most common but also most serious

Transmission by the bite of a female Anopheles mosquito. The protozoa infect RBCs and grow intracellularly

Question 3

What are the risk factors for Malaria

Answer 3

Travel to endemic areas
Lack of appropriate chemoprophylaxis
Absence of insecticide-treated bed net in an endemic area
Settled migrants returning from travel to an endemic area

Question 4

Risk factors for a severe infection with malaria

Answer 4

Severe infection risk factors:
Low host immunity 
Pregnancy 
Age <5 years
Immunocompromise 
Older age

Question 5

Epidemiology of Malaria

Answer 5

Innate immunity in certain populations (sickle cell trait, G6PD Deficiency, pyruvate kinase deficiency, thalassaemia)
Endemic in tropics (Sub-Saharan Africa, Southeast Asia, Oceania and Amazon basin of South America)
92% of all cases are in the African region
Pregnant women and children under 5 are the most susceptible

Question 6

Symptoms of Malaria

Answer 6

Typical patient: Feverish traveller (incubation up to a 1 year, usually 1-2 weeks)

Fever
Flu-like symptoms
Severe sweating
Shivering
Cold/rigors 
Peak temperature may coincide with rupture of intra-erythrocytic schizonts
	○ Every 48 hours - P. falciprum
	○ Every 72 hours - P. malariae

Cerebral malaria: Headache, disorientation, coma

Question 7

What is malaria caused by plasmodium falciparum characterised by

Answer 7

Cerebral involvement,
Severe anaemia
Renal failure
Hypoglycaemia
Pulmonary oedema
DIC/bleeding
Hypovolaemia
Acidosis
Hyper parasitaemia

Question 8

Signs of Malaria on examiantion

Answer 8

Pyrexia
Rigors
Anaemia
Hepatosplenomegaly

Question 9

Investigations for Malaria

Answer 9

Thick/thin blood film: intra-erythrocytic ring-formed parasites (Must be negative for 3 days to exclude malaria, Giemsa-stained, >2% in P. falciparum is SEVERE)

Urinalysis: protein +, haematuria , urobilinogen and conjugate bilirubin
throat swab: typically -ve, exclude influenza

FBC: thrombocytopenia, anaemia, variable WCC
U+Es: normal or mildly impaired, renal failure may be present if severe
HIV: may be positive (risk factor)
Blood cultures: typically no abnormal growth, exclude other infections
ICT test: detects histidine protein 2 only found in P. falciparum