Fever and Confusion in a Returning Traveler With a Negative Malaria Test
A 38-year-old man presents with a 4-day history of fever up to 39.2°C, rigors, headache, myalgia and one episode of confusion reported by his wife. He returned 6 days ago from 3 weeks in Nigeria, including 5 days in a rural area of Ogun State, and took no malaria chemoprophylaxis. He has no rash, neck stiffness or focal neurology. Temperature is 38.9°C, pulse 112/min, BP 104/62 mmHg, respiratory rate 24/min and SpO2 96% on air. He is alert but slow to answer. Hemoglobin is 11.6 g/dL, platelets 58 × 10⁹/L, white cells 7.2 × 10⁹/L, creatinine 1.5 mg/dL (baseline unknown), total bilirubin 2.4 mg/dL, lactate 3.1 mmol/L and glucose 5.8 mmol/L. A malaria rapid diagnostic test performed in triage is negative; thick and thin films have been sent but results will take 2 hours. Blood cultures are pending.
1. What are your immediate actions, and would you start antimalarial treatment before the blood film result?
Read the worked answer
This is suspected severe malaria until proven otherwise, and treatment should not wait for the film. He has a compatible exposure history, fever, confusion, jaundice, acute kidney injury and thrombocytopenia - features that place him in the severe category. Start IV artesunate 2.4 mg/kg at 0, 12 and 24 hours, then daily, after drawing blood cultures and baseline samples. If artesunate is unavailable, use intramuscular artemether or IV quinine with glucose monitoring. Admit to a high-dependency area, check glucose frequently, monitor urine output and lactate, and give isotonic fluids cautiously.
The negative rapid diagnostic test does not exclude malaria: HRP2 deletions, low parasitemia and non-falciparum species can all produce false negatives. A single negative test has poor negative predictive value in a febrile traveler from an endemic area. If bacterial sepsis or meningitis remains plausible, add empiric ceftriaxone after cultures, but do not let that delay the antimalarial.
2. How do the laboratory results influence your assessment of severity, and how should the films be followed up?
Read the worked answer
Confusion is the most important severity marker and raises concern for cerebral malaria, although hypoglycemia and bacterial infection must be excluded. Bilirubin 2.4 mg/dL indicates jaundice; creatinine 1.5 mg/dL indicates renal impairment; platelets 58 × 10⁹/L reflect malaria-associated consumption. Lactate 3.1 mmol/L is abnormal but not in the highest-risk range; a rising lactate or falling glucose would be ominous. Hemoglobin 11.6 g/dL is not yet severe anemia.
Thick and thin films should be repeated every 8–12 hours for at least three sets if the first is negative, because parasitemia fluctuates and may be low with partial immunity. If all films are negative but the clinical picture remains consistent and no alternative diagnosis emerges, treat for malaria anyway after discussion with infectious diseases. If an alternative diagnosis is confirmed - for example positive blood cultures or positive dengue testing - narrow therapy accordingly.
3. What alternative diagnoses would you consider, and what findings would change your management?
Read the worked answer
The differential includes dengue, typhoid, rickettsial infection, leptospirosis, bacterial sepsis and viral encephalitis. Dengue typically causes thrombocytopenia and hemoconcentration but often presents after a longer incubation and with a different exposure pattern; a positive NS1 or IgM would shift attention but would not exclude malaria. Typhoid may cause fever and abdominal symptoms with relative bradycardia. Rickettsial disease may show a rash or eschar, which he lacks.
Findings that would change management include a positive blood culture (narrow antibiotics), a positive dengue test with warning signs (fluids and monitoring), or a clear alternative source such as pneumonia or meningitis. A falling glucose, rising lactate, oliguria or worsening consciousness should prompt escalation and consideration of transfer to intensive care. Avoid quinine where possible because of hypoglycemia and cardiac effects, and continue to monitor glucose and renal function during artesunate therapy.