Malaria

Question 1

Which pathogen causes malaria?

Answer 1

Eukaryotic single-celled parasite of the genus plasmodium.

Question 2

Which malaria parasite is this describing?

1. Incubation 12 days
2. No dormant stage
3. Found in: Africa, India, SE Asia, Indonesia, Oceania, Central America, Middle East.

Answer 2

P. falciparum

Question 3

Which malaria parasite is this describing?

1. Incubation 14 days
2. Dormant liver stage
3. Found in: South Asia, South and Central America, Africa, Middle East.

Answer 3

P. virax

Question 4

Which malaria parasite is this describing?

1. Incubation 30 days
2. No Dormant stage
3. Found in: Africa, South and Central America, SE Asia.

Answer 4

P. malariae

Question 5

What is the life cycle of malaria?

Answer 5

1. Plasmodium (sporozoite) spill into blood from mosquito, asexual reproduction in liver.
2. Mature to merozoites, liver cell ruptures to release them.
3. Infect RBCs - asexual reproduction again, also sexual production to form gametocytes.
4. RCs rupture - cause symptoms and release gametocytes (taken up by next mosquito)
5. Mature and fuse to form zygote, then forms oocyst which ruptures, releasing sporozoites.

Question 6

What are the clinical features of uncomplicated malaria?

Answer 6

Headache, body and joint pains, rigors, anorexia, abdominal pain, diarrhoea, N&V, splenomegaly, jaundice.

Question 7

What are the clinical features of severe malaria?

Answer 7

1. Impaired consciousness, seizures, AKI, shock, BG <2.2mmol/L, pulmonary oedema, Hb <80g/L, DIC, pH <7.3, parasitaemia.

Question 8

What is the aetiology of severe anaemia?

Answer 8

Cytoadherence of P. falciparum in particular which causes microvascular obstruction and multi-organ failure.

Question 9

How is malaria diagnosed?

Answer 9

1. Giemsa stained thick blood smear - localises parasites in RBCs
2. Giemsa stained thin blood smear - identifies plasmodium species
3. Rapid diagnostic testing (direct specific parasite antigens) - requires drop of blood
4. FBC - anaemia, thrombocytopenia, high creatinine and urea, DIC, hypoglycaemia, lactic acidosis, haemoglobinuria.

Question 10

What is the prophylactic management for malaria?

Answer 10

1. Vector control - eliminate stagnant water, long-lasting insecticidal nets, indoor spraying.
2. Chemoprophylaxis - insect repellent (20-50% DEET)

Question 11

What is the management for uncomplicated falciparum malaria?

Answer 11

1. Artemisinin-based combination therapy - take with high fat food
2. If failed, non-ACT treatment (quinine + doxycycline)
3. Chloroquine not for pregnancy

Question 12

What is the management for severe malaria?

Answer 12

1. IV artesunate (artemisinin derivative)
2. Correct fluid and electrolyte abnormalities
3. Give thiamine and treat hypoglycaemia