Malaria: Diagnosis and Treatment of Falciparum and Vivax

Malaria is a parasitic infection spread by the bite of infected female Anopheles mosquitoes. Plasmodium falciparum causes most severe disease and deaths. In Pakistan, both P. vivax (the majority of cases) and P. falciparum occur. Any fever in a person who lives in, or has travelled to, a malaria area must be tested for malaria.

Species

• P. falciparum — can rapidly become severe and fatal.
• P. vivax and P. ovale — form dormant liver stages (hypnozoites) that cause relapses weeks or months later.
• P. malariae — can persist at low levels for years; associated with nephrotic syndrome.
• P. knowlesi — seen in Southeast Asia; can be severe.

Clinical features

Common symptoms:

• fever, often with chills and rigors
• headache
• muscle aches
• fatigue
• nausea and vomiting
• sometimes diarrhoea or cough

The classic cyclical fever pattern is often absent. Signs may include anaemia, jaundice and an enlarged spleen and liver.

Features of severe malaria

• Impaired consciousness or seizures (cerebral malaria).
• Prostration.
• Respiratory distress or pulmonary oedema.
• Shock.
• Severe anaemia.
• Hypoglycaemia.
• Acidosis.
• Acute kidney injury.
• Jaundice.
• Abnormal bleeding.
• High parasitaemia (for example more than 10% in some definitions; thresholds vary).

Diagnosis

• Microscopy of thick and thin blood films — the reference standard. The thick film detects parasites; the thin film identifies the species and measures parasitaemia.
• Rapid diagnostic tests (RDTs) detecting parasite antigens.
• If the first test is negative but malaria is suspected, repeat it (in the UK, three sets over 48–72 hours).
• Other tests:
  • full blood count (anaemia, low platelets)
  • glucose
  • kidney and liver function
  • lactate

Treatment (follow WHO and national guidelines)

• Uncomplicated P. falciparum: an artemisinin-based combination therapy (ACT), for example artemether–lumefantrine.
• Severe malaria (any species): IV artesunate is the treatment of choice. Follow it with a full course of an ACT once the patient can take tablets. Also manage hypoglycaemia, fluids, seizures and organ support.
• P. vivax and P. ovale: chloroquine (where the parasite is still sensitive) or an ACT, plus primaquine or tafenoquine to kill the liver hypnozoites and prevent relapse. Test for G6PD deficiency first, because these drugs can cause haemolysis. Primaquine is avoided in pregnancy.

Prevention

• Insecticide-treated bed nets and indoor residual spraying.
• Repellents and protective clothing.
• Chemoprophylaxis for travellers, according to destination.
• Malaria vaccines (RTS,S and R21) are recommended by WHO for children in endemic areas, mainly in Africa.

Exam pearls

• Fever after travel to a malaria area is malaria until proven otherwise.
• Severe malaria needs IV artesunate. Check glucose often, because hypoglycaemia is common, especially with quinine.
• Always check G6PD before primaquine.

For tropical medicine, see the infectious diseases chapter of the Medicine Companion. See also Dengue Fever and Typhoid Fever.

Test yourself

5 exam-style single-best-answer questions. Choose your answer, then tap “Show answer”.

1. Treatment of choice for severe malaria:

   1. Oral chloroquine
   2. Paracetamol
   3. IV artesunate
   4. Primaquine
   5. Doxycycline alone
   Show answer

   Answer: C. IV artesunate
   IV artesunate reduces mortality compared with quinine in severe malaria.

2. Which species form dormant liver stages that cause relapse?

   1. P. knowlesi
   2. P. malariae
   3. P. vivax and P. ovale
   4. All species
   5. P. falciparum
   Show answer

   Answer: C. P. vivax and P. ovale
   Hypnozoites of P. vivax and P. ovale cause relapses and need primaquine or tafenoquine.

3. Before giving primaquine, which test is needed?

   1. Liver biopsy
   2. Chest X-ray
   3. HbA1c
   4. Blood culture
   5. G6PD level
   Show answer

   Answer: E. G6PD level
   Primaquine can cause severe haemolysis in G6PD deficiency.

4. What does the thin blood film add to the thick film?

   1. Identifies the species and measures parasitaemia
   2. Detects antibodies
   3. Detects parasites more sensitively
   4. Measures haemoglobin
   5. Nothing
   Show answer

   Answer: A. Identifies the species and measures parasitaemia
   Thick films detect parasites; thin films identify species and quantify parasitaemia.

5. First-line treatment for uncomplicated falciparum malaria:

   1. Artemisinin-based combination therapy
   2. Chloroquine
   3. Amoxicillin
   4. Primaquine alone
   5. Quinine alone
   Show answer

   Answer: A. Artemisinin-based combination therapy
   ACTs such as artemether–lumefantrine are first-line.

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Disclaimer

For education and exam preparation only. This is not medical advice and must not be used to diagnose or treat patients. Always follow current clinical guidelines and the advice of qualified senior colleagues.