9. Malaria

Question 1

What is the causative agent of malaria? What are the different species of this?

Answer 1

Protozoal parasite: Plasmodium

• P. falciparum
• P. vivax
• P. ovale
• P. malariae
• P. knowlesii

Question 2

Which Plasmodium species most commonly cause malaria and which is most lethal?

Answer 2

• 75% cases = P. falciparum (90% cases Africa) - highest mortality (10-20%)
• other cases mostly P. vivax or P. ovale (90% cases India)

Question 3

How is Plasmodium transmitted?

Answer 3

• Vector = pregnant female Anopheles mosquito

- (no person-to-person spread)

Question 4

What is the incubation period in malaria?

Answer 4

• minimum 6 days
• P. falciparum: up to 6 mths
• P. vivax/ovale: up to 1 yr+

Question 5

What are the symptoms of malaria?

Answer 5

Often non-specific

1. headache
2. chills/sweating (cycle every 3rd/4th day)
3. dry cough
4. fatigue and muscular/back pain
5. nausea and vomiting

Question 6

What are the signs of malaria?

Answer 6

Often few signs

1. fever
2. +/- splenomegaly

Question 7

What parasite load if required to cause severe falciparum malaria?

Answer 7

> 2%

Question 8

What are the features of severe malaria in adults?

Answer 8

1. impaired consciousness or seizures
2. renal impairment: oligouria or high creatinine
3. metabolic acidosis (pH <7.3), hypoglycaemia (<2.2mmol/l)
4. pulmonary oedema or ARDS
5. anaemia (haemoglobin <80g/L) and haemoglobinuria (withough G6PD deficiency)
6. spontaneous bleeding/DIC
7. shock (BP <90/60 mmHg)
8. parasitaemia >10%

Question 9

Which groups of people are more likely to develop severe malaria?

Answer 9

immunocompromised, e.g. pregnant, children, elderly

Question 10

Which investigations are performed in suspected malaria cases?

Answer 10

1. malaria parasite screen (thick and thin film +/- rapid antigen test) x3
2. FBC and coagulation tests
3. U and Es and LFTs
4. glucose
5. head CT if CNS symptoms
6. CXR (for pulmonary oedema/ARDS)

Question 11

How should P. falciparum malaria be treated?

Answer 11

1. IV artesunate (7 days)

if not available:
2. IV quinine + PO doxycycline (monitor blood glucose)

Question 12

How should P. vivax/ovale malaria be treated? Why?

Answer 12

chloroquine + primaquine

primaquine treats hypnozoite (dormant liver) stage of P. vivax - required to prevent recurrence of infection

Question 13

What blood tests needs to be performed before primaquine treatment?

Answer 13

G6PD screen to ensure no G6PD deficiency - primaquine can cause acute haemolytic episodes in this condition

Question 14

Does previous malaria infection confer immunity?

Answer 14

Regular infection (in endemic areas) allows development of protection against severe disease but this immunity is soon lost after leaving endemic area

Question 15

How is malaria prevented?

Answer 15

Assess risk - knowledge of at risk areas

Bite prevention - repellent, nets, adequate clothing

Chemoprophylaxis - starts before and continues after return