Malaria

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

Definition

Malaria is a life-threatening disease caused by Plasmodium parasites, which are transmitted to people through the bites of infected female Anopheles mosquitoes.

Aetiology

Malaria is caused by infection with Plasmodium parasites. There are five species that commonly infect humans:

• Plasmodium falciparum: The most severe and deadly form of malaria.
• Plasmodium vivax: Causes relapsing malaria.
• Plasmodium ovale: Similar to P. vivax, causes relapsing malaria.
• Plasmodium malariae: Causes long-lasting but less severe malaria.
• Plasmodium knowlesi: A zoonotic species that can cause malaria in humans.

Pathophysiology

The pathophysiology of malaria involves:

• The bite of an infected Anopheles mosquito introduces Plasmodium sporozoites into the bloodstream.
• The sporozoites travel to the liver, where they mature and multiply.
• The liver cells release merozoites, which infect red blood cells (RBCs).
• The parasites multiply within the RBCs, causing them to burst and release more merozoites to infect other RBCs.
• This cycle of RBC infection and destruction leads to the clinical manifestations of malaria, including fever, anaemia, and organ damage.

Risk Factors

• Living in or travelling to endemic areas
• Lack of access to mosquito prevention measures (e.g., insecticide-treated bed nets, indoor residual spraying)
• Young children and pregnant women
• Immunocompromised individuals
• Previous lack of exposure (no immunity)

Signs and Symptoms

The signs and symptoms of malaria include:

• High fever and chills
• Headache
• Muscle and joint pain
• Nausea and vomiting
• Diarrhoea
• Fatigue and weakness
• Jaundice (yellowing of the skin and eyes)
• Splenomegaly (enlarged spleen)

Investigations

Specific investigations to diagnose malaria include:

• Microscopic examination: Blood smear microscopy to detect Plasmodium parasites in red blood cells.
• Rapid diagnostic tests (RDTs): To detect specific malaria antigens in the blood.
• Polymerase Chain Reaction (PCR): To detect and identify Plasmodium DNA in blood samples (used for confirmation and species identification).
• Serology: Detection of antibodies against Plasmodium (not typically used for acute diagnosis).

Management

Primary Care Management

• Antimalarial medications: Choice of medication depends on the Plasmodium species and drug resistance patterns. Common treatments include artemisinin-based combination therapies (ACTs) for P. falciparum and chloroquine for P. vivax, P. ovale, and P. malariae.
• Supportive care: Ensuring adequate hydration, rest, and management of symptoms such as fever and pain with antipyretics and analgesics (e.g., paracetamol).
• Prevention: Advising on measures to prevent mosquito bites, such as using insect repellent, wearing protective clothing, and sleeping under insecticide-treated bed nets.

Specialist Management

• Hospitalisation: For severe cases or patients with significant comorbidities. This may include intravenous antimalarial medications, fluid management, and intensive care support.
• Management of complications: Treating severe manifestations such as cerebral malaria, acute respiratory distress syndrome (ARDS), and renal failure.
• Public health measures: Reporting cases to public health authorities to monitor and prevent outbreaks, and implementing malaria control programmes.

References

1. NHS (2024) Malaria. Available at: https://www.nhs.uk/conditions/malaria/ (Accessed: 24 June 2024).
2. Centers for Disease Control and Prevention (2024) Malaria. Available at: https://www.cdc.gov/malaria/index.html (Accessed: 24 June 2024).
3. World Health Organization (2024) Malaria. Available at: https://www.who.int/news-room/fact-sheets/detail/malaria (Accessed: 24 June 2024).
4. British Medical Journal (2024) Malaria: clinical features, diagnosis, and management. Available at: https://www.bmj.com/content/350/bmj.h2732 (Accessed: 24 June 2024).

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