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Infectious Diseases

Diphtheria

An acute bacterial infection caused by toxin-producing Corynebacterium diphtheriae, primarily affecting the nasopharynx and causing systemic effects via exotoxin. Spread by droplets. Incubation 2-7 days.

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Referral and warning signs

When to refer

IMMEDIATE URGENT REFERRAL to Hospital (H/RR) for ALL suspected cases of diphtheria, for administration of antitoxin, antibiotics, and airway monitoring.

Red flags

  • Presence of greyish pseudomembrane.
  • Stridor or signs of airway compromise.
  • Extensive neck swelling ('bull neck').
  • Signs of myocarditis (tachycardia out of proportion to fever, gallop rhythm, heart failure).
  • Neurological signs (e.g., palatal palsy).

Signs and symptoms

  • Sore throat, dysphagia.
  • Low-grade fever.
  • Characteristic: Formation of a tough, greyish, adherent pseudomembrane on tonsils, pharynx, larynx, or nasal passages. Attempting to remove it causes bleeding.
  • Cervical lymphadenopathy ('bull neck' appearance in severe cases).
  • Nasal discharge (may be bloody).
  • Hoarseness, stridor, potential airway obstruction if larynx involved.
  • Systemic Toxin Effects (Later):
  • - Myocarditis (cardiac dysfunction, heart failure, arrhythmias) - usually 1-2 weeks after onset.
  • - Neuropathies (palatal paralysis, oculomotor palsies, peripheral neuropathy) - weeks to months later.
  • - Renal failure (acute tubular necrosis).

Risk factors

  • Lack of immunization (DPT/Pentavalent vaccine).
  • Living in endemic areas or outbreak settings.
  • Overcrowding.
  • Poor socioeconomic conditions.

Diagnosis

Clinical assessment

Diagnosis based primarily on clinical presentation: sore throat + adherent grey pseudomembrane in pharynx/tonsils +/- bull neck or signs of toxicity.

Investigations

  • Throat Swab Culture: Obtain swab from beneath edge of membrane for specific culture (requires special medium - tell lab diphtheria suspected).
  • Gram stain may show Gram-positive bacilli.
  • Toxin detection tests (Elek test) - specialized labs.
  • ECG (monitor for myocarditis).

Diagnostic criteria

Clinical diagnosis based on characteristic pseudomembrane. Confirmation by culture.

Management

Non-pharmacological management

  • Urgent Hospital Admission.
  • Strict Isolation: Droplet and contact precautions until cultures negative.
  • Airway Management: Close monitoring for obstruction. Intubation/tracheostomy may be needed if laryngeal involvement/severe swelling.
  • Bed rest.
  • Supportive care (fluids, nutrition).

Pharmacological treatment

  • Antitoxin (DAT - Diphtheria Antitoxin): CRITICAL and URGENT. Neutralizes circulating toxin (does not affect bound toxin). Give as soon as diphtheria clinically suspected, DO NOT wait for culture results. Requires sensitivity testing first. Dose varies based on severity and location (pharyngeal, laryngeal, extensive) - refer to specific protocols. (LOC: H/RR)
  • Antibiotics (Eradicate bacteria, stop toxin production, prevent spread):
  • - First line: Procaine Benzylpenicillin 1.2 MU IM daily (Adult); 50,000 IU/kg IM daily (Child) until patient can swallow.
  • - Then switch to Phenoxymethylpenicillin (Penicillin V) 250-500mg PO Q6H (Adult); 12.5mg/kg PO Q6H (Child <6y: 125mg Q6H) to complete a 14-DAY TOTAL course. (LOC: H)
  • - Alternative (Penicillin allergy): Erythromycin 500mg IV/PO Q6H for 14 days (Child: 50mg/kg/day divided Q6H). (LOC: H)
  • Management of Complications: Treatment for myocarditis/heart failure, respiratory support, management of neuropathy.
  • Contacts Management:
  • - Monitor close contacts for 7 days.
  • - Throat swab for culture.
  • - Prophylactic Antibiotics: Single dose Benzathine Penicillin G IM (Adult/Child >10y: 1.2 MU; Child <10y: 0.6 MU) OR Erythromycin PO for 7-10 days.
  • - Immunization: Check status, give booster if last dose >1 year ago, complete schedule if needed.

Monitoring

Monitor airway, cardiac function (ECG), neurological status. Repeat throat swabs after treatment to confirm clearance.

Complications

  • Airway obstruction.
  • Myocarditis, Heart failure, Arrhythmias.
  • Neuropathies (paralysis).
  • Acute renal failure.
  • Secondary bacterial infections.
  • Death.

Prevention

  • Routine childhood immunization with Diphtheria-containing vaccine (DPT/Pentavalent/Td).
  • Booster doses (Td) for adolescents/adults.
  • Early diagnosis and treatment of cases.
  • Isolation of cases.
  • Management of contacts (monitoring, prophylaxis, immunization).

Patient education

  • Explanation of the seriousness of the infection.
  • Need for hospitalization, isolation, antitoxin, and antibiotics.
  • Importance of completing full antibiotic course.
  • Need for contact tracing and management.
  • Importance of vaccination for prevention.

Uganda-specific notes

Diphtheria is rare due to vaccination but can occur in unimmunized individuals/communities. High index of suspicion needed if characteristic membrane seen. Antitoxin availability is critical but likely limited to specific centres. Prompt referral essential.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 2, Section 2.1.3

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 18 (Immunization)

For learning and professional reference. Use current local guidance and clinical judgement.

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