Infection 2: Malaria

Question 1

Name 4 malarial species that infect humans

Answer 1

P falciparum 
p vivax 
P ovale 
P malarie
p knowlesi

Question 2

Name an important malaria control intervention used in sub-Saharan Africa

Answer 2

Insecticide treated mosquito nets

Question 3

What diagnostic test would you request?

Answer 3

1. Giemsa-Stained Blood Film
2. RDTs
3. thick and thin film

Blood film: take blood sample, drop of blood on a slide, dry, fix with alcohol, dry, treat with Giemsa stain to stain parasites, dry then look at through a microscope. Can then identify species, no. of parasites.

Question 4

What is the parasitemia cut off for severe malaria?

Answer 4

Parasitaemia >2%  
or
Parasitaemia <2% plus…
either schizonts reported on blood film 
or complications

Question 5

What is the first-line treatment for severe malaria?

Answer 5

IV ARTESUNATE

Question 6

What are the problems with RDTs?

Answer 6

1. They are less sensitive by 10 – 100x than microscopy
2. Detect parasite antigen rather than live parasite
   may therefore be positive in patients who have been recently treated (up to 2 weeks) or come from a malaria endemic area and have a low level of asymptomatic parasitaemia
3. Not possible to determine the % parasitaemia or stage of parasite

Question 7

Outline the pathogenesis of malarial anaemia?

Answer 7

[1] Haemolysis of iRBC

[2] Haemolysis of uRBC

[3] Bone Marrow Suppression (dyserythropoiesis)

Question 8

Describe the life cycle of plasmodium

Answer 8

Infective sporozoites
Liver cells (Schizonts)
Merozoites
RBC
a. Tropoozites > schizonts>merozoites (symptoms)

Question 9

What is the mechanism of action of artesunate?

Answer 9

Acts in earlier stage

Question 10

Describe the type of fever in P. falciparum

Answer 10

Malignant tertian

irregular without rhythm

Question 11

Describe the type of fever in P. vivax

Answer 11

Benign tertian

Every 48 hours

Question 12

Describe the type of fever in P. ovale

Answer 12

tertian

Question 13

Describe the type of fever in P. malarie

Answer 13

Quartan

Every 72 hours

Question 14

Describe the type of fever in P. knowlesi

Answer 14

Quotidian