WHO Severe Malaria Criteria
Applies the WHO severe malaria criteria: any one of twelve features in confirmed falciparum parasitemia is severe malaria.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Age group
- Adult
- Parasitemia, percent of parasitized red cells
- 15
- Impaired consciousness
- Yes
- Acidosis
- Yes
Result: 3 features, severe falciparum malaria, including hyperparasitemia at 15%
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What the result means
- Any one feature
- Severe falciparum malaria. One is enough; this is a list of defining features, not a score, so the count above one adds nothing to the definition.
- The twelve
- Impaired consciousness, prostration, more than two convulsions in 24 hours, acidosis, hypoglycemia, severe malarial anemia, renal impairment.
- The twelve, continued
- Jaundice, pulmonary edema, significant bleeding, shock, and parasitemia above 10 percent of red cells.
- The parasite count
- Does not grade severity, except as the hyperparasitemia feature itself. Sequestered parasites are not on the film, so a low count does not exclude severe malaria.
- Anemia and jaundice
- Each is defined together with a parasite density. The hemoglobin or the bilirubin on its own does not meet either feature.
- By age
- Consciousness, severe anemia and hypotension all use different thresholds in children under 12 years than in adults.
What you enter
- Age group
- Parasitemia, percent of parasitized red cells
- Impaired consciousness (GCS below 11 in adults, Blantyre below 3 in children)
- Prostration (unable to sit, stand or walk unassisted)
- More than two convulsions in 24 hours
- Acidosis (base deficit above 8 mEq/L, bicarbonate below 15 mmol/L, or lactate at or above 5 mmol/L)
- Hypoglycemia (glucose below 40 mg/dL)
- Severe malarial anemia (with a parasite count above 10,000 per microliter)
The other 5 fields
- Renal impairment (creatinine above 3 mg/dL or urea above 20 mmol/L)
- Jaundice (bilirubin above 3 mg/dL with a parasite count above 100,000 per microliter)
- Pulmonary edema (radiologic, or saturation below 92 percent on room air with a rate above 30)
- Significant bleeding
- Shock (capillary refill at or above 3 seconds, or hypotension for age)
How this is calculated
World Health Organization. WHO Guidelines for Malaria. Geneva: World Health Organization; 2023. Severe malaria definition, carried forward from Severe malaria. Trop Med Int Health. 2014;19(Suppl 1):7-131. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.