Your next patient has had fever, sweats and headache for 5 days after returning from abroad. Here's how the falciparum malaria case unfolds and what to pick up on the way.

This falciparum malaria case is easy to miss if you skim the travel story or accept a single negative film. Your patient reports fever, sweats and headache for five days after returning from abroad. They returned from West Africa two weeks ago, have swinging fevers with rigors, took prophylaxis erratically and used no bed nets, are jaundiced with dark urine, and have a tender, mildly enlarged spleen, though not drowsy or confused. This page walks through how the case presents, what to pick up in the history, the tests, and the teaching points: any fever in a traveller returning from a malarial area is malaria until proven otherwise, diagnosis rests on thick and thin blood films with or without a rapid antigen test, a single negative film does not exclude malaria so repeat, and speciation matters because P. falciparum can deteriorate rapidly.

How the case presents

Your next patient has had fever, sweats and headache for 5 days after returning from abroad. In their own words: "Fever, sweats and headache for a few days after returning from abroad."

Observations on arrival:

Observation	On arrival
Heart rate	112 beats per minute
Blood pressure	118/72 mmHg
Respiratory rate	20 breaths per minute
Oxygen saturation	97%
Temperature	39.5 °C

What to pick up in the history

These are the findings the case is built around. Each one moves you towards or away from falciparum malaria, and the scorecard checks whether you found it.

Returned from West Africa two weeks ago: travel to an endemic area makes malaria the diagnosis until blood films prove otherwise.
Five days of swinging fevers with rigors and sweats: swinging fever with rigors in a returning traveller is the classic malarial pattern.
Took prophylaxis erratically and used no bed nets: poor prophylaxis and no bite avoidance greatly increase the likelihood of malaria.
Jaundiced and passing dark urine: jaundice with dark urine indicates haemolysis and marks severe falciparum disease.
Not drowsy or confused at present: absence of impaired consciousness argues against cerebral malaria but needs repeated checking.
Tender, mildly enlarged spleen: splenomegaly supports malaria over most other causes of fever in a returning traveller.
Reduced urine output and feeling steadily worse.

Red flags you must not miss

The case marks these as must-elicit. They only come out if you ask.

Returned from West Africa two weeks ago.
Five days of swinging fevers with rigors and sweats.
Took prophylaxis erratically and used no bed nets.
Jaundiced and passing dark urine.
Not drowsy or confused at present.

Investigations and what they showed

Blood film for parasites: Thick and thin films show P. falciparum ring forms (small rings, sometimes multiple per cell/appliqué forms); the thin film speciates and the count gives the parasitaemia. Repeat up to three times if the first is negative. Why it helps: the gold-standard diagnostic test, thick films detect parasites, thin films speciate and quantify; a single negative film does not exclude malaria, so repeat over 24 to 48 hours.
Full blood count: Thrombocytopenia is common; anaemia from haemolysis; the white count is often normal. Why it helps: thrombocytopenia and anaemia support malaria and help gauge severity; a falling Hb reflects haemolysis.
Bilirubin: Raised (unconjugated) from haemolysis, contributing to the jaundice. Why it helps: reflects the haemolysis and severity of falciparum malaria.
Urea and electrolytes: May show acute kidney injury (a severity criterion).
Lactate: Raised lactate indicates severe disease.
Ultrasound abdomen: Splenomegaly (often with mild hepatomegaly), a uniformly enlarged spleen; no focal collection. Why it helps: splenomegaly is common in acute malaria and supports the diagnosis; ultrasound is quick and at the bedside, and it also flags the enlarged spleen's risk of rupture.
Inspect the sclera: Both sclerae are distinctly yellow in a young adult man, clear scleral icterus against an otherwise unremarkable face.
Inspect the urine: A specimen pot of deep tea-brown urine, uniformly dark and clear rather than cloudy. Why it helps: dark urine here is haemoglobinuria from intravascular haemolysis, 'blackwater fever'. It is another severity criterion and warns of acute kidney injury, so it demands urine dipstick, renal function and early senior involvement.
Inspect the conjunctiva: The lower palpebral conjunctivae are pale and washed-out rather than the normal deep pink, with a yellow tinge at the fornix.
Inspect the abdomen: Slight fullness in the left upper quadrant below the costal margin, moving down with inspiration, a mildly enlarged, tender spleen. Why it helps: splenomegaly supports malaria over most other travellers' fevers (and raises typhoid and visceral leishmaniasis in the differential). It also matters practically, an acutely enlarged spleen can rupture, so handle gently and avoid deep palpation.
Inspect the patient's level of alertness and demeanour: Exhausted and flat, lying still with his eyes closed and rousing slowly, but orientated and answering appropriately when he does. 5°C. Why it helps: reassess it repeatedly; deterioration can be over hours.

Imaging findings

X-ray chest: Clear lungs here; would look for ARDS/pulmonary oedema in severe malaria or an alternative infective focus.
CT abdomen and pelvis: Splenic infarction, sharply demarcated peripheral wedge-shaped non-enhancing areas within an enlarged spleen.

Why the diagnosis is falciparum malaria

The decisive diagnosis is falciparum malaria, a febrile returning traveller from an endemic area (West Africa) with swinging fevers, rigors, sweats, headache, myalgia, jaundice and splenomegaly, and erratic prophylaxis. any fever in someone back from a malarial area is malaria until excluded. The diagnosis rests on thick and thin blood films (with a rapid antigen test as an adjunct), speciating to P. falciparum and quantifying parasitaemia; a single negative film does not exclude it, repeat up to three times over 24 to 48 hours.

Falciparum malaria at a glance

What it is

Falciparum malaria is an infection with Plasmodium falciparum, a single-celled parasite spread by the bite of an infected female Anopheles mosquito. Of the five malaria species that infect humans, it is the one that causes almost all the world's malaria deaths, because it can multiply to very high levels in the blood and cause organ damage within a day or two of the first symptoms.

Pathogenesis

The parasite invades red blood cells and multiplies inside them, causing the cells to rupture in synchronised waves, which drives the cyclical fevers. Falciparum-infected red cells also become sticky and stick to the walls of small blood vessels in the brain, kidneys, lungs and placenta, blocking flow and starving those organs of oxygen, the mechanism behind cerebral malaria, acute kidney injury and respiratory distress.

Who it affects

Anyone bitten by an infected mosquito in an endemic area, overwhelmingly sub-Saharan Africa, South and Southeast Asia, and parts of South America. Travellers who skip or stop antimalarial prophylaxis, migrants returning to visit family in an endemic country without re-taking precautions, and young children and pregnant women in endemic areas carry the highest risk of severe disease.

How serious it is

Falciparum malaria causes roughly 600,000 deaths worldwide each year and can kill within 24 to 48 hours of the first symptom if severe features develop.

Causes and risk factors

Infection follows a bite from an infected Anopheles mosquito, almost always in or shortly after travel to an endemic region. People without a spleen, and those with no prior immunity, are at particular risk.

Investigations and lab tests

Thick and thin blood films are the diagnostic standard: the thick film is more sensitive for detecting parasites, and the thin film identifies the species and quantifies the percentage of red cells infected (parasitaemia). A rapid antigen test can support the diagnosis but does not replace films. Supporting labs typically show thrombocytopenia, haemolytic anaemia, and raised bilirubin and LDH from red cell breakdown, plus blood glucose, lactate and renal function to assess severity.

At a glance: Diagnose: thick and thin blood films, repeated if negative. Speciate and quantify: thin film parasitaemia. Assess severity: glucose, lactate, renal function, consciousness level.

Teaching points

Any fever in a traveller returning from a malarial area is malaria until proven otherwise, always take a detailed travel and prophylaxis history.
Diagnosis rests on thick and thin blood films (± rapid antigen test); thick films detect, thin films speciate and quantify parasitaemia.
A single negative film does not exclude malaria, repeat up to three times over 24 to 48 hours.
P. falciparum is the lethal species and can deteriorate rapidly, speciation matters.
Assess severity: impaired consciousness/seizures (cerebral malaria), hypoglycaemia, acidosis/high lactate, renal failure, ARDS, shock, bleeding, haemoglobinuria and high parasitaemia.
Common labs: thrombocytopenia, haemolytic anaemia and raised bilirubin/LDH.
Consider and empirically cover concurrent bacterial sepsis/typhoid in the unwell febrile traveller.
For relapsing species (vivax/ovale), add primaquine to clear liver hypnozoites after checking G6PD, not required for falciparum.

Practise a similar case

Reading this case is one thing, but under a bit of pressure it’s easy to miss a key thread, like erratic prophylaxis and no bed nets after a return from West Africa. Try another acute medicine history and see how it feels when you have to decide what to ask next in real time.

Here's one from the same specialty, with the diagnosis left for you to find. Your next patient is 19 with a fever and a bad headache since yesterday. Take this patient's history in Diagnosica. It's free to start, no card needed.

Falciparum malaria case presentation: history, findings and tests