Malaria

Question 1

Burden of disease

Answer 1

The most important tropical parasitic infection

>2 million episodes (2010)

>600,000 deaths (2010)

86% deaths in children <5

Question 2

Intensity of transmission

Answer 2

Low, moderate, high

Hypoendemic, mesoendemic, hyperendemic, holoendemic

More intense transmission > more immunity and less severe disease (with increasing age)

Question 3

Uncomplicated malaria: clinical features

Answer 3

fever

malaise

headache

myalgia

GI sx

Anaemia

Question 4

Severe malaria: features

Answer 4

Cerebral malaria

Anaemia

Acidosis

Hypoglycaemia

Question 5

Malaria in pregnancy

Answer 5

Risk factor for severe disease

IUGR

Death

Anaemia

Intermittent Presumptive Therapy IPT

Question 6

Malaria diagnosis

Answer 6

1. Peripheral blood slide for presence of parasite

Thin film: monolayer of red cells (ID species and parasitaemia)

Thick film: haemolysed red cells (if inf present)

2. Detection of parasite antigen

Test-strip

RDT

Question 7

Uncomplicated malaria: treatment

Answer 7

Artemisinin-Combination Therapy (ACT) e.g.

Artemether-Lumefantrine (Coartem)

Quinine (imported malaria in travellers)

Question 8

Classes of antimalarial drugs

Answer 8

Artemisinin derivatives

• chinese herb Artemisia

active against all stages of their parasite life-cycle

Quinoline derivatives e.g

• Quinine
• Chloroquine (CQ)
• Amodiaquine (AQ)
• Mefloquine (Lariam)
• Lumefantrine

Primaquine

Anti-folate combinations

Antibiotics

• Doxy, Azithro
• Clindamycin

Atovaquone

• • proguanil (Malarone)

Question 9

Sporozoite

Answer 9

Injected into human by mosquito

approx 50, liver

can’t see it

Question 10

Merozoites

Answer 10

approx 30K

Question 11

Trophozoite

Answer 11

RBC + parasite

For diagnosis

(asexual erythrocytic cycle)

Question 12

Schizonts

Answer 12

Mature form of trophocyte - likely to rupture (and increase parasitaemic x 16)

Vivax x 8

falciparum x 16

Question 13

Sequestration

Answer 13

Binding of schizonts to capillaries… Excess of schizonts suggests high parasite biomass

Only falciparum

Question 14

Gametocyte

Answer 14

trophozpoite can become schizont or gametocyte

Wants to meet another gametocyte in mosquito midgut

M/F

can’t replicate in human

drugs don’t work on gametocyte (?ethics of treating to improve someone else’s health)

Question 15

Hypnozoite

Answer 15

Sleeping form of…

Only vivax / ovale

24 / 48 hours

Question 16

Relapse vs. Recrudescence

Answer 16

Relapse

Sleeping hypozoites return (vivax/ovale)

Recrudescence

comes back ? undertreated

Answer 17