Malaria

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How the diagnosis is reached

Fever in someone back from sub-Saharan Africa is malaria until three blood films say otherwise, and nothing else in the history is allowed to distract from that until it is excluded. Prophylaxis abandoned after a week and no bed net removes the only two things that might have protected her. The blood count then points hard in one direction: thrombocytopenia is among the most consistent findings in malaria, and a low platelet count with fever and recent travel is close to a rule of thumb. The anaemia, raised bilirubin and raised LDH are haemolysis, red cells rupturing as parasites complete their cycle, and the palpable spleen is the organ clearing the debris. The rest of the panel exists to remove the conditions that look identical: a negative dengue antigen, sterile cultures, negative typhoid serology and a clean chest film and urine. The film is diagnostic, and it also grades severity, which is what decides the route of treatment. Falciparum shows fine ring forms and readily infects a red cell more than once, and a parasitaemia of 8% is far above the 2% that defines severe disease. She has three more severity markers besides: hypoglycaemia, a lactate above 2, and a creatinine that is climbing. That combination is what makes this intravenous artesunate rather than tablets. Artesunate clears parasites faster than quinine and carries a clear mortality advantage over it, so quinine survives only as a fallback where artesunate is unavailable. It runs until she can reliably swallow, after which a full oral artemisinin-combination course finishes the job, since artesunate alone does not eliminate the infection. Glucose is rechecked repeatedly, because the disease and quinine both cause hypoglycaemia and hers is already 3.4 mmol/L. She also needs warning about delayed post-artesunate haemolysis, which appears one to three weeks later and needs a follow-up blood count.

Key clinical clues

• Cyclical fever in a traveller returning from sub-Saharan Africa
• Prophylaxis stopped after one week, with no bed net used
• Thrombocytopenia alongside haemolytic anaemia, jaundice and splenomegaly
• Negative dengue, typhoid and cultures, removing the closest mimics
• Ring forms with multiply-infected cells and a parasitaemia of 8%, well into severe disease

The case in full

1

Presenting complaint

Patient history

A 31-year-old woman has had four days of high fever with shaking chills, headache and aching limbs. The fever spikes and then settles rather than staying up, and she feels wrung out between episodes.

2

Travel history

Patient history

She returned ten days ago from three weeks in rural Nigeria visiting family. She took antimalarial tablets for the first week but stopped when they upset her stomach, and she slept without a net.

3

Examination and observations

Physical examination

She looks unwell and mildly jaundiced. The spleen is palpable two finger-breadths below the costal margin. There is no rash, no neck stiffness and nothing focal in the chest or abdomen.

Measurements

Parameter	Value	Reference
Temperature	39.4 °CRef 36.1–37.5	36.1–37.5
Heart rate	118 bpmRef 60–100	60–100
Blood pressure	104/64 mmHg	–
Respiratory rate	24 /minRef 12–20	12–20
Glasgow Coma Scale	15Ref 15	15

4

Blood tests

Laboratory results

Bloods are sent on arrival.

Measurements

Parameter	Value	Reference
Haemoglobin	96 g/LRef 115–165	115–165
Platelets	48 ×10⁹/LRef 150–400	150–400
White cell count	6.2 ×10⁹/LRef 4.0–11.0	4.0–11.0
Bilirubin	58 µmol/LRef <21	<21
LDH	480 U/LRef <250	<250
Creatinine	118 µmol/LRef 45–90	45–90
Glucose	3.4 mmol/LRef 3.9–7.8	3.9–7.8
Lactate	3.8 mmol/LRef <2.0	<2.0

5

Ruling out the mimics

Laboratory results

The other causes of fever in a returning traveller are screened for.

Measurements

Parameter	Value	Reference
Dengue NS1 antigen	NegativeRef Negative	Negative
Blood cultures	No growth at 48 hRef No growth	No growth
Typhoid serology	NegativeRef Negative	Negative
Urinalysis	NormalRef Normal	Normal
Chest radiograph	ClearRef Clear	Clear

6

Blood film

Pathology

Thick and thin films are prepared and examined under oil immersion. The thin film is shown below. The parasitaemia is reported at 8% of red cells.