During a malaria surveillance study in a teaching hospital in West Bengal, blood smears from 500 confirmed malaria patients were examined. The most common site of parasite sequestration in severe Plasmodium falciparum malaria is which of the following?

Explanation

## Sequestration in Severe P. falciparum Malaria **Key Point:** Cerebral microvasculature is the most common and clinically significant site of parasite sequestration in severe P. falciparum malaria, leading to cerebral malaria — the most frequent cause of mortality in severe malaria. ## Pathophysiology of Sequestration **High-Yield:** P. falciparum-infected RBCs express PfEMP1 (P. falciparum erythrocyte membrane protein 1) on their surface, which binds to endothelial receptors (CD36, ICAM-1, CSA) in the microvasculature. This causes: - Cytoadherence and rosetting - Obstruction of microvascular flow - Local inflammation and blood–brain barrier disruption - Sequestration away from the splenic circulation (immune evasion) ## Organ-Specific Sequestration Patterns | Organ | Frequency of Sequestration | Clinical Consequence | Severity | | --- | --- | --- | --- | | **Brain (cerebral)** | Most common | Cerebral malaria, seizures, coma, death | Highest mortality (15–20%) | | **Lungs (pulmonary)** | Common | ARDS, pulmonary edema | High mortality (10–15%) | | **Kidneys (renal)** | Moderate | Acute kidney injury, renal failure | Moderate–high mortality | | **Liver (hepatic)** | Less common | Hepatomegaly, jaundice | Lower mortality | **Clinical Pearl:** Cerebral malaria is defined as: - Unrousable coma (Glasgow Coma Scale ≤2 on a scale of 15) - P. falciparum parasitaemia (any density) - Absence of other causes of coma - Mortality 15–20% even with treatment; 50% if untreated ## Why Cerebral Sequestration Is Most Common 1. **High endothelial receptor density:** Brain endothelium expresses abundant CD36 and ICAM-1 2. **Immune evasion:** Sequestration in brain avoids splenic clearance 3. **Vascular permeability:** Brain microvasculature is uniquely vulnerable to inflammatory mediators (TNF-α, IL-1, IL-6) 4. **Clinical impact:** Cerebral involvement is the leading cause of death in severe malaria **Mnemonic:** **CRASH** — Cerebral, Renal, ARDS, Severe anaemia, Hypoglycaemia (complications of severe P. falciparum malaria). Cerebral is listed first because it is the most common severe manifestation. [cite:Harrison 21e Ch 219]