Definition, Diagnostic Criteria & Classification

Question	Answer
1. Detail the World Health Organization (WHO 2022) criteria for Severe / Complicated Malaria.	In a patient with Plasmodium falciparum (or P. vivax) asexual parasitemia, Severe Malaria is defined by the presence of at least one of the following: 1) Impaired Consciousness: Blantyre Coma Score $<3$ (in children $<5$y) or Glasgow Coma Scale $<11$. 2) Prostration: Inability to sit unassisted (or inability to drink/breastfeed in infants). 3) Multiple Convulsions: $\ge 2$ generalized seizures within 24 hours. 4) Acidosis: Base deficit $>8\text{ mEq/L}$, serum bicarbonate $<15\text{ mmol/L}$, or venous plasma lactate $>5.0\text{ mmol/L}$ (clinically manifests as deep, labored acidotic breathing / "respiratory distress"). 5) Hypoglycemia: Blood glucose $<40\text{ mg/dL}$ ($<2.2\text{ mmol/L}$). 6) Severe Malarial Anemia: Hemoglobin $<5.0\text{ g/dL}$ or Hematocrit $<15\%$ with parasitemia $>10,000/\mu\text{L}$. 7) Acute Kidney Injury: Serum creatinine $>3.0\text{ mg/dL}$ ($>265\mu\text{mol/L}$) or blood urea $>20\text{ mmol/L}$. 8) Jaundice: Serum total bilirubin $>3.0\text{ mg/dL}$ with parasitemia $>100,000/\mu\text{L}$. 9) Pulmonary Edema: Radiologically confirmed or arterial oxygen saturation $<92\%$ on room air with tachypnea. 10) Significant Bleeding: Spontaneous mucosal bleeding, epistaxis, or DIC. 11) Shock ("Algid Malaria"): Systolic BP $<70\text{ mmHg}$ (or cold clammy peripheries, CRT $>3$s). 12) Hyperparasitemia: Parasitemia $>10\%$ of circulating erythrocytes (or $>400,000/\mu\text{L}$).
2. Define Cerebral Malaria and describe the Blantyre Coma Scale.	- Definition: Unarousable coma persisting for $>1\text{ hour}$ after termination of a seizure (or correction of hypoglycemia), in the presence of P. falciparum parasitemia, with exclusion of other causes of encephalopathy (e.g., bacterial meningitis, viral encephalitis). - Blantyre Coma Scale (Total 0 to 5; Score $\le 2$ defines coma): - Eye Movement (0-1): Follows looks/faces = 1; Fails to follow = 0. - Best Motor Response (0-2): Localizes painful stimulus = 2; Withdraws limb from pain = 1; Non-specific or no response = 0. - Best Verbal Response (0-2): Cries appropriately with pain / speaks = 2; Moan or abnormal cry = 1; Inappropriate / absent = 0.
3. What are the characteristic Fundoscopic findings in Cerebral Malaria?	Malarial Retinopathy: Unique clinical sign present in up to $60-70\%$ of pediatric cerebral malaria; highly specific ($>90\%$) to distinguish true cerebral malaria from other encephalopathies with incidental bystander parasitemia: 1) Retinal Whitening: Patchy opacification around the fovea and macula sparing the foveal center. 2) Vessel Changes: Orange or white discoloration of retinal capillaries and venules. 3) Retinal Hemorrhages: Flame-shaped or white-centered (Roth-like) hemorrhages. 4) Papilledema: Sign of severe intracranial hypertension.
4. What are the diagnostic modalities for Malaria and their limitations?	1) Light Microscopy (Thick & Thin Blood Smear): Gold standard. - Thick Smear: Highly sensitive (detects down to $5-10\text{ parasites}/\mu\text{L}$). - Thin Smear: Identifies species morphology (falciparum, vivax, malariae, ovale) and quantifies % parasitemia. 2) Rapid Diagnostic Tests (RDTs): - HRP-2 (Histidine-Rich Protein 2): Specific for P. falciparum. Remains positive for $2-4\text{ weeks}$ after parasite clearance (cannot be used to monitor cure). False negatives can occur with pfhrp2/3 gene deletions. - pLDH (Plasmodium Lactate Dehydrogenase): Identifies vivax or pan-malaria; disappears within 48h of parasite death (tracks cure).
5. VIVA TRAP: Can a patient have severe Cerebral Malaria with a completely negative peripheral blood smear?	YES. In severe P. falciparum malaria, mature trophozoites and schizonts sequester completely inside deep microvascular capillary beds of the brain and viscera via cytoadherence. Only young ring-forms circulate freely. If the synchronized parasitic cycle is currently in the sequestration phase, peripheral blood may show scant or even zero detectable parasites! If clinical suspicion is high, repeat thick smears every 6 to 8 hours over 24-48 hours!

Pathophysiology & Complications

Question	Answer
6. Detail the molecular mechanisms of Cytoadherence, Sequestration, and Rosetting.	- Cytoadherence: P. falciparum expresses variable surface antigen PfEMP-1 (Plasmodium falciparum Erythrocyte Membrane Protein 1) encoded by var genes on the surface of infected red blood cells (knob structures). - Endothelial Ligand Binding: PfEMP-1 binds specific microvascular receptors: - CD36: General microvascular adherence. - ICAM-1: Upregulated in cerebral microvessels by TNF-$\alpha$. - EPCR (Endothelial Protein C Receptor): Critical receptor mediating blood-brain barrier breakdown, loss of endothelial integrity, and severe cerebral malaria. - Rosetting: Adherence of infected RBCs to uninfected RBCs, forming large obstructive cell clumps. - Consequence: Microvascular mechanical obstruction, tissue ischemia, localized lactate accumulation, and blood-brain barrier disruption with cerebral edema.
7. What are the mechanisms of Severe Malarial Anemia?	Multitiered pathogenesis: 1) Direct Parasite Lysis: Obligatory rupture of erythrocytes at schizont maturation every 48 hours. 2) Immune-Mediated Clearance: Spleen recognizes and destroys both infected RBCs and uninfected bystander RBCs coated with complement and immune complexes. 3) Dyserythropoiesis & Bone Marrow Suppression: High levels of TNF-$\alpha$ and hemozoin inhibit erythropoietin response and iron incorporation into reticulocytes. 4) Post-Artesunate Delayed Hemolysis (PADH): Occurs 1-3 weeks after therapy (see Viva Trap).
8. Explain why Hypoglycemia is common and dangerous in pediatric severe malaria.	- Causes: 1) High metabolic consumption of glucose by massive parasite biomass. 2) Impaired hepatic gluconeogenesis due to lactic acidosis and TNF-$\alpha$. 3) Historically aggravated by Quinine-induced pancreatic $\beta$-cell hyperinsulinemia. - Presentation: Hypoglycemia can mimic or worsen cerebral malaria (seizures, coma, sweating, hypothermia). - Mandatory Rule: Check bedside blood glucose immediately on arrival and every 4 hours; administer $5\text{ mL/kg}$ of 10% Dextrose IV bolus for glucose $<40\text{ mg/dL}$.

Guidelines & Management Protocols (WHO 2022 Guidelines)

Question	Answer
9. Detail the first-line antimalarial regimen for Severe Malaria.	- Drug of Choice: Intravenous Artesunate (reduces mortality by $22.5\%$ compared to quinine [AQUAMAT trial]). - Dosage: - Children $<20\text{ kg}$: $3.0\text{ mg/kg/dose}$ IV. - Children $\ge 20\text{ kg}$ and adults: $2.4\text{ mg/kg/dose}$ IV. - Schedule: Administered at 0 hours, 12 hours, and 24 hours, then once daily thereafter. - Duration: Minimum of 3 full parenteral doses (first 24 hours). As soon as the child can swallow and tolerate oral feeds, switch to a full 3-day course of oral Artemisinin-based Combination Therapy (ACT) (e.g., Artemether-Lumefantrine).
10. Outline the supportive intensive care management of Cerebral Malaria.	1) Airway & Breathing: Lateral position, clear airway; elective endotracheal intubation if GCS $<8$ or frequent recurrent seizures. 2) Seizure Control: Immediate IV Midazolam ($0.15\text{ mg/kg}$) or Lorazepam ($0.1\text{ mg/kg}$); Levetiracetam or Fosphenytoin for refractory seizures. (Avoid prophylactic phenobarbital as it increases mortality). 3) Fluid Management: Strict Maintenance Only (Restrictive Fluid Strategy). Overhydration rapidly precipitates fatal non-cardiogenic pulmonary edema and brain edema! Maintain euvolemia using isotonic crystalloids. 4) Blood Transfusion: Transfuse Packed RBCs ($10\text{ mL/kg}$) promptly if $\text{Hb} < 5.0\text{ g/dL}$ (or $<7\text{ g/dL}$ in the presence of respiratory distress/shock).
11. What is the role of Corticosteroids or Mannitol in Cerebral Malaria?	- Corticosteroids (Dexamethasone): STRONGLY CONTRAINDICATED. Randomized trials demonstrated that dexamethasone prolonged coma duration, increased pneumonia and GI bleeding, and had NO mortality benefit! - Mannitol / Osmotic Agents: Not routinely recommended; clinical trials failed to show improvement in neurological outcomes or mortality.

VIVA TRAPs & Counter-Questions

Question	Answer
12. VIVA TRAP: What is "Post-Artesunate Delayed Hemolysis" (PADH)?	- Definition: A severe episode of Coombs-negative hemolytic anemia occurring 1 to 3 weeks following successful artesunate treatment of severe hyperparasitemic malaria. - Mechanism: Artesunate kills intraerythrocytic parasites rapidly. The spleen removes the dead parasite from the RBC without destroying the cell ("pitting"). These "once-parasitized pitted erythrocytes" return to circulation but have a shortened lifespan and undergo accelerated splenic destruction weeks later. - Clinical Pearl: All children treated with IV artesunate for severe malaria must have hemoglobin monitored weekly for 4 weeks post-discharge!
13. VIVA TRAP: A 4-year-old child with severe vivax malaria presents with Hb 4.2 g/dL and hemoglobinuria. Can P. vivax cause severe complicated malaria?	YES, DEFINITELY. Historically considered "benign", Plasmodium vivax is now universally recognized by WHO to cause severe life-threatening malaria, including severe anemia, acute respiratory distress syndrome (ARDS), splenic rupture, shock, and acute renal failure. Treatment for severe vivax malaria is identical to severe falciparum: IV Artesunate!
14. Counter-Question Chain: "When do you initiate Primaquine in a child with P. falciparum vs P. vivax malaria?"	- *For P. falciparum:* A single gametocytocidal dose of Primaquine $0.25\text{ mg/kg}$ orally on Day 1 to prevent transmission of drug-resistant parasites (G6PD testing not required for single low dose). - *For P. vivax:* Radical cure to eradicate dormant hypnozoites in the liver: Primaquine $0.5\text{ mg/kg/day}$ orally for 14 days administered AFTER checking G6PD status! If G6PD deficient, give $0.75\text{ mg/kg}$ once weekly for 8 weeks under close monitoring.