Clinical Scenario:
A 9-year-old boy is brought to the emergency department with a 5-day history of intermittent high-grade fever with chills and vomiting. During the last 12 hours, he has become lethargic with cold extremities. On examination, he is confused, pulse is 156/min, blood pressure 68/40 mmHg, capillary refill time is 5 seconds, and the extremities are cold and clammy. Mild icterus and splenomegaly are present. Despite receiving 40 mL/kg of isotonic saline, his hypotension persists.
Laboratory investigations reveal:
- Hemoglobin: 8.4 g/dL
- Hematocrit: 25%
- Platelet count: 52 × 10⁹/L
- Serum lactate: 5.9 mmol/L
- Blood glucose: 94 mg/dL
- CRP: 10 mg/L
What is the most likely diagnosis?
A. Algid malaria
B. Dengue shock syndrome
C. Septic shock
D. Toxic shock syndrome
E. Viral myocarditis
Correct answer & Explanation:
Correct Answer: A. Algid malaria
Explanation: Malaria/ Algid malaria/ shock differentials
This child has shock associated with fever, but several features favor algid malaria rather than dengue shock syndrome or bacterial sepsis.
The key clues are:
- Intermittent fever with chills
- Splenomegaly
- Mild jaundice
- Anemia with a low hematocrit (25%)
- Thrombocytopenia
- Persistent hypotension despite fluid resuscitation
The low hematocrit is particularly important. In algid malaria, extensive intravascular hemolysis results in anemia and a reduced hematocrit. In contrast, dengue shock syndrome is characterized by hemoconcentration, and the hematocrit is typically elevated due to plasma leakage.
Why the other options are incorrect
B. Dengue shock syndrome
DSS commonly presents with thrombocytopenia and shock, but hematocrit is usually elevated because of plasma leakage. A hematocrit of 25% argues strongly against dengue shock syndrome.
C. Septic shock
Septic shock remains an important differential diagnosis, but fever with chills, splenomegaly, jaundice, anemia, thrombocytopenia, and a low hematocrit are more suggestive of severe malaria.
D. Toxic shock syndrome
Typically presents with diffuse erythematous rash, mucosal hyperemia, and multiorgan involvement, which are absent in this patient.
E. Viral myocarditis
May cause cardiogenic shock but is usually associated with signs of myocardial dysfunction (gallop rhythm, hepatomegaly, cardiomegaly, reduced ejection fraction) rather than anemia, jaundice, and splenomegaly.
Learning Point
A useful examination pearl is:
| Feature | Algid malaria | Dengue shock syndrome |
|---|---|---|
| Hematocrit | ↓ Low/Normal | ↑ High |
| Hemoglobin | ↓ Low | Usually normal initially |
| Platelets | ↓ | ↓↓ |
| Jaundice | Common | Uncommon |
| Splenomegaly | Common | Rare |
| Shock | Refractory, distributive | Due to plasma leakage |
This subtle use of hematocrit makes the question much stronger and forces candidates to distinguish algid malaria from dengue shock syndrome, a classic postgraduate examination challenge.
