Diphtheria

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

Definition

Diphtheria is a serious bacterial infection caused by Corynebacterium diphtheriae. It primarily affects the mucous membranes of the throat and nose and can lead to severe respiratory difficulties and other complications.

Aetiology

Diphtheria is caused by the bacterium Corynebacterium diphtheriae, which produces a potent toxin that can cause widespread damage in the body. Transmission occurs through:

• Respiratory droplets from coughing or sneezing
• Direct contact with infected skin lesions
• Contact with contaminated objects or surfaces

Pathophysiology

The pathophysiology of diphtheria involves:

• The bacteria colonise the mucous membranes of the throat and nose.
• They produce a toxin that inhibits protein synthesis in cells, leading to cell death.
• The toxin can spread through the bloodstream to other organs, causing systemic effects such as myocarditis and neuritis.
• The local infection in the throat leads to the formation of a thick, grey pseudomembrane, which can obstruct the airway.

Risk Factors

• Lack of vaccination against diphtheria
• Living in or travelling to areas with poor vaccination coverage
• Close contact with an infected person
• Overcrowded living conditions
• Compromised immune system

Signs and Symptoms

The signs and symptoms of diphtheria include:

• Sore throat and hoarseness
• Difficulty swallowing
• Thick, grey membrane covering the throat and tonsils
• Swollen glands (lymph nodes) in the neck
• Fever and chills
• Weakness and fatigue
• Difficulty breathing or rapid breathing

Investigations

Specific investigations to diagnose diphtheria include:

• Throat swab: To culture and identify Corynebacterium diphtheriae.
• Toxin assay: To detect diphtheria toxin in clinical specimens.
• Full blood count (FBC): To check for elevated white blood cell count and other markers of infection.
• Electrocardiogram (ECG): To assess for myocarditis.
• Chest X-ray: To evaluate for respiratory complications.

Management

Primary Care Management

• Immediate referral: Suspected cases should be referred urgently to secondary care for further evaluation and management.
• Isolation: To prevent the spread of the infection to others.
• Initial supportive care: Ensuring stabilisation of the patient while arranging urgent transfer to hospital.

Specialist Management

• Antitoxin: Administration of diphtheria antitoxin to neutralise the toxin and prevent further damage.
• Antibiotics: Intravenous antibiotics such as penicillin or erythromycin to eradicate the bacteria.
• Respiratory support: Mechanical ventilation if there is airway obstruction or respiratory failure.
• Surgical intervention: Possible tracheostomy to secure the airway if necessary.
• Monitoring for complications: Continuous monitoring for complications such as myocarditis, neuritis, and renal failure.
• Public health measures: Reporting cases to public health authorities to monitor and prevent outbreaks, and ensuring contacts are traced and managed appropriately.

References

1. NHS (2024) Diphtheria. Available at: https://www.nhs.uk/conditions/diphtheria/ (Accessed: 24 June 2024).
2. Centers for Disease Control and Prevention (2024) Diphtheria. Available at: https://www.cdc.gov/diphtheria/index.html (Accessed: 24 June 2024).
3. World Health Organization (2024) Diphtheria. Available at: https://www.who.int/health-topics/diphtheria (Accessed: 24 June 2024).
4. British Medical Journal (2024) Diphtheria: clinical features, diagnosis, and management. Available at: https://www.bmj.com/content/350/bmj.h2017 (Accessed: 24 June 2024).

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