- Confirm parasitemia and choose the species from microscopy, rapid diagnostic test (RDT), or polymerase chain reaction (PCR). If the species is uncertain, choose "Unknown or mixed"; it applies the most sensitive threshold of each criterion so a severe case is not missed.
- Tick any clinical feature present and enter the laboratory values you have. Leave a field blank if it was not measured; the tool reports only the criteria it can evaluate.
- For adults, enter the Glasgow Coma Scale (GCS) and an acidosis measure (base deficit preferred, then bicarbonate, then respiratory rate) to obtain the CAM score.
- Press Calculate. All computation runs in your browser; nothing is transmitted.
Any single WHO criterion defines severe malaria and calls for parenteral artesunate. The CAM score helps triage the level of care; it never downgrades the need for artesunate.
When to Use
Use at admission and at each reassessment for any patient with a positive malaria film or RDT, particularly those with fever and kidney injury after exposure in southern Palawan forest or foothill areas, or after travel to a malaria-endemic country.
Appropriate population
WHO criteria: adults and children with confirmed malaria. CAM score: adults (16 years or older in the derivation cohort) with severe malaria in low-transmission Asian settings, which matches the Philippine context.
Limitations
The WHO definition was built for research and epidemiology and requires the absence of another explanation for each finding. The CAM score was not validated in children or in high-transmission African settings, and it was derived when many patients received quinine. Neither tool replaces bedside judgment, and neither addresses co-infection with bacterial sepsis, leptospirosis, or scrub typhus.
Pearls & Pitfalls
A low CAM score does not mean a safe kidney
In the derivation and validation cohorts, about four in five patients who died despite a CAM score below 2 had renal failure, died late (median about 108 hours after admission), and mostly had not received dialysis. A low score supports general-ward care only if creatinine and urine output are measured serially and dialysis is reachable.
The WHO renal threshold is late
Creatinine above 3 mg/dL (265 µmol/L) is specific but misses early injury. Stage acute kidney injury (AKI) by Kidney Disease: Improving Global Outcomes (KDIGO) criteria in parallel, and treat a rising creatinine as a warning even below the WHO threshold.
P. knowlesi looks benign on the film
P. knowlesi replicates every 24 hours and is often misread as P. malariae. Its hyperparasitemia threshold is a density above 100,000/µL rather than a percentage, and its jaundice criterion uses a density above 20,000/µL.
Severe Malaria Criteria and CAM Score
Clinical features
Laboratory values
WHO criteria met
CAM score (adults)
Next Steps
- Any WHO criterion met: give intravenous (or intramuscular) artesunate now for at least 24 hours, then a full 3-day artemisinin-based combination therapy (ACT). No renal dose adjustment is needed, including during dialysis.
- Renal criterion met or creatinine rising: involve nephrology early, avoid liberal fluids, monitor urine output hourly, and plan kidney replacement therapy (KRT); blood-based therapy outperformed peritoneal dialysis in an infection-associated AKI trial.
- CAM score 2 or more: high-dependency or intensive care where available. Below 2: ward care is reasonable only with serial creatinine and access to dialysis.
- Check hemoglobin during the month after artesunate (post-artesunate delayed hemolysis), and glucose every 4 hours in unconscious patients.
Evidence & Formula
WHO severe malaria criteria (any one, without another explanation)
| Criterion | Threshold | Species notes |
|---|---|---|
| Impaired consciousness | GCS below 11 (adult); Blantyre below 3 (child) | All species |
| Prostration | Cannot sit, stand, or walk unaided | All species |
| Multiple convulsions | More than 2 in 24 hours | All species |
| Acidosis | Base deficit above 8 mmol/L, or bicarbonate below 15 mmol/L, or lactate ≥5 mmol/L | All species |
| Hypoglycemia | Glucose below 40 mg/dL (2.2 mmol/L) | All species |
| Severe malarial anemia | Hb ≤5 g/dL (child under 12) or below 7 g/dL (adult) with density above 10,000/µL | P. vivax: no density threshold |
| Renal impairment | Creatinine above 3 mg/dL (265 µmol/L) or urea above 20 mmol/L (blood urea nitrogen above 56 mg/dL) | All species |
| Jaundice | Bilirubin above 3 mg/dL (50 µmol/L) with density above 100,000/µL | P. knowlesi: density above 20,000/µL; P. vivax: no density threshold |
| Pulmonary edema | Radiologic, or SpO₂ below 92% on room air with respiratory rate above 30/min | All species |
| Significant bleeding | Recurrent or prolonged bleeding; hematemesis; melena | All species |
| Shock | Compensated: capillary refill ≥3 s or temperature gradient; decompensated: systolic BP below 80 mmHg (adult) or 70 mmHg (child) | All species |
| Hyperparasitemia | P. falciparum parasitemia above 10% | P. knowlesi: density above 100,000/µL; P. vivax: not applicable |
Coma Acidosis Malaria (CAM) score
| Component | 0 points | 1 point | 2 points |
|---|---|---|---|
| GCS | 15 | 11–14 | ≤10 |
| Base deficit, mmol/L (CAM) | ≤2 | above 2 and below 10 | ≥10 |
| Bicarbonate, mmol/L (BCAM) | ≥24 | 15 to below 24 | below 15 |
| Respiratory rate, /min (RCAM) | below 20 | 20–39 | ≥40 |
The CAM score (0–4) was derived from 868 adults in the South East Asian Quinine Artesunate Malaria Trial (SEAQUAMAT) and validated in Bangladesh (n = 188) and Vietnam (n = 292). Area under the curve was 0.81 at derivation and 0.74 in the Vietnamese validation. A score below 2 predicted survival with a positive predictive value of about 96% at derivation and 94–95% in the two validation cohorts. The bicarbonate version (BCAM) performed almost as well; the respiratory-rate version (RCAM) was clearly weaker (positive predictive value about 92%) and should be used only when no blood gas or bicarbonate is available.
