Malaria

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Malaria is a mosquito borne infectious disease caused by Plasmodium species, leading to cyclical fever, haemolysis, and multi organ complications if untreated.

Aetiology

  • Caused by protozoan parasites of the Plasmodium genus.
  • Five main species: P. falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi.
  • Transmitted via bites from infected female Anopheles mosquitoes.

Pathophysiology

  • Parasites enter the bloodstream, infect hepatocytes, and mature into merozoites.
  • Merozoites infect red blood cells, leading to haemolysis and cyclic fever episodes.
  • Severe malaria (primarily P. falciparum) can cause microvascular obstruction and multi organ failure.

Risk Factors

  • Travel to or residence in endemic areas (sub-Saharan Africa, South Asia, South America).
  • Lack of prophylactic antimalarial medication.
  • Pregnancy (higher risk of severe disease).
  • Young children and immunocompromised individuals.

Signs and Symptoms

  • Uncomplicated malaria:
    • Fever with chills and sweats (cyclical pattern).
    • Headache, myalgia, and malaise.
    • Gastrointestinal symptoms: nausea, vomiting, diarrhoea.
  • Severe malaria (P. falciparum):
    • Cerebral malaria: altered consciousness, seizures.
    • Severe anaemia (haemolysis).
    • Acute kidney injury.
    • Hypoglycaemia and metabolic acidosis.
    • Shock and multi-organ failure.

Investigations

  • Blood films (thick and thin): gold standard for parasite identification.
  • Rapid diagnostic tests (RDTs): detect Plasmodium antigens.
  • Full blood count (FBC): anaemia, thrombocytopenia.
  • Urea and electrolytes (U&E): assess kidney function.
  • Liver function tests (LFTs): raised bilirubin, transaminitis.
  • Blood glucose: to check for hypoglycaemia.

Management

1. Uncomplicated Malaria:

  • First line: oral artemisinin-based combination therapy (ACT).
  • Alternative: chloroquine (only if P. vivax or P. ovale and no resistance).
  • Primaquine for radical cure in P. vivax and P. ovale to prevent relapse.

2. Severe Malaria:

  • IV artesunate (first line).
  • Supportive care: fluid resuscitation, blood transfusion if needed.
  • Monitor for complications: renal failure, acidosis, cerebral involvement.

3. Prevention:

  • Use of prophylactic antimalarials (e.g., atovaquone-proguanil, doxycycline, mefloquine) when travelling to endemic areas.
  • Insect bite prevention: mosquito nets, insect repellent, protective clothing.
  • Vector control: elimination of standing water sources.

4. Referral:

  • Infectious diseases: for severe or drug-resistant malaria.
  • Intensive care: for cerebral malaria or multi-organ failure.
  • Travel medicine: for pre travel advice and prophylaxis.
Infectious DiseasemypanotesMalaria