Paper II — 2018 July (Supplementary) (2010 Scheme)

Paper II

2018 July (Supplementary) (2010 Scheme) · 40 marks · 120 min

Question

Laboratory diagnosis of falciparum malaria and its complications

Q35 marksShort Essays

Laboratory diagnosis of Plasmodium falciparum malaria:

Peripheral blood smear microscopy — gold standard; thick smear for screening, thin smear for species identification/parasitaemia quantification (Giemsa stain). P. falciparum is identified by delicate ring forms (often with double chromatin dots, multiple rings per cell), absence of larger trophozoite/schizont stages in peripheral blood (sequestered in deep vessels), and characteristic crescent/banana-shaped gametocytes.
Rapid diagnostic tests (RDTs) — detecting P. falciparum-specific histidine-rich protein-2 (HRP-2) antigen.
QBC method — fluorescence-based concentration technique.
PCR — highly sensitive/specific, detects low-level/mixed infections.

Complications of falciparum malaria (driven largely by cytoadherence/sequestration of parasitized RBCs, via PfEMP1, to vascular endothelium):

Cerebral malaria — altered consciousness, seizures, coma, from sequestration in cerebral microvasculature.
Severe anaemia — from haemolysis of parasitized and non-parasitized RBCs, and marrow suppression.
Acute kidney injury — including “blackwater fever” (massive intravascular haemolysis with haemoglobinuria).
Hypoglycaemia — from parasite glucose consumption and impaired hepatic gluconeogenesis.
Pulmonary complications — acute respiratory distress syndrome (ARDS).
Placental malaria — in pregnancy, causing low birth weight, and severe maternal disease.
Disseminated Intravascular Coagulation (DIC) and circulatory collapse/shock in severe disease.
Splenic rupture (rare, more with other species but can occur).