Case 41: Headache and fever in a traveller from PNG

Question 1

What is the appearance of a thick blood film in p. falciparum infection?

Answer 1

Red blood cells are lysed, leaving only white cells visible.

Large numbers of trophozoites seen.

Question 2

What is the appearance of a thin blood film in p. falciparum infection?

Answer 2

Multiple parasites seen inside RBCs - trophozoites

Question 3

What is p. vivax treated with?

Answer 3

Primaquin

Question 4

What are the symptoms consistent with p. falciparum?

Answer 4

Fever

Arthralgia

Weakness

Anaemia

Hypoglycaemia

Question 5

How is p. falciparum infection contracted?

Answer 5

Mosquito injects sporozoites, which infect liver, mature into merozoites, release of merozoits causes disease

Question 6

What is the treatment for p. falciparum infection?

Answer 6

Artemisinin combination therapy (ART)

Question 7

What is parasite load associated with?

Answer 7

Seriousness of infection

Lysis of RBCs and resultant inflammatory response is more serious.

Infected RBCs express adhesion molecules and cause clogging of microvasculature, leading to cerebral malaria and organ damage

Question 8

What other infections would have been considered when collecting blood for serological testing?

Answer 8

Scrub typhus (Rickettsia-like bacteria)

Japanese encephalitis

Chikangunya

Dengue

Typhoid

Question 9

Which stage of the plasmodium lifecycle infects humans?

Answer 9

Sporozoites

Question 10

Which stage of the plasmodium lifecycle is seen in samples taken from patients?

Answer 10

Trophozoite

Gametocyte

Schizont

Merozoites

Question 11

Which stage of the plasmodium lifecycle makes the patient sick?

Answer 11

Merozoites