Clinical Features of Diphtheria

Key points

  • Respiratory and cutaneous diphtheria are the most common disease presentations.
  • Respiratory diphtheria can lead to severe complications including myocarditis, neuropathy, airway obstruction, and death.
  • Diphtheria has clinical features that can be confused with other infections.
Child with cervical swelling, referred to as bull neck, which is a symptom of diphtheria.

Disease presentation

Diphtheria can involve almost any mucous membrane. Clinically, diphtheria can be classified into type of manifestation, depending on the disease site.

Respiratory sites most commonly include:

  • Pharyngeal and tonsillar diphtheria
  • Laryngeal diphtheria
  • Nasal diphtheria

Cutaneous infections can also occur.

Common symptoms

Respiratory diphtheria

Respiratory diphtheria has a gradual onset and is characterized by:

  • Mild fever
  • Sore throat
  • Difficulty swallowing
  • Malaise
  • Loss of appetite
  • Hoarseness (if the larynx is involved)

The hallmark of respiratory diphtheria is a pseudomembrane that appears within 2–3 days of illness. It appears over the mucous lining of the tonsils, pharynx, larynx, or nares and can extend into the trachea.

A lesion on the leg caused by cutaneous diphtheria.
A lesion on the leg caused by cutaneous diphtheria.

Cutaneous diphtheria

Cutaneous diphtheria may present as a scaling rash or ulcers with clearly demarcated edges and membrane. These skin infections are slow to heal.

Complications

Respiratory diphtheria

Most complications, including death, are attributable to the toxin's effects.

Complications include:

  • Myocarditis
  • Neuritis
  • Respiratory insufficiency due to airway obstruction

Myocarditis and neuritis are the most frequent complications. Respiratory insufficiency due to airway obstruction is more common in infants.

Risk of death

The overall case-fatality rate for diphtheria is 5–10%. People younger than 5 years and older than 40 years of age experience higher death rates (up to 20%).

Cutaneous diphtheria

The systemic complications from cutaneous diphtheria appear to be less than from other sites.

Similar diseases

Infection with other pathogens could result in similar clinical presentation as diphtheria, including:

  • Group A Streptococcus
  • Staphylococcus aureus
  • Candida albicans
  • Epstein-Barr
  • Cytomegalovirus
  • Adenovirus
  • Herpes

Other Corynebacterium species

Two other Corynebacterium species (C. ulcerans and C. pseudotuberculosis) may produce diphtheria toxin; both are zoonotic.

Toxin-producing C. ulcerans may cause disease indistinguishable from that caused by toxin-producing C. diphtheriae. However, person-to-person spread hasn't been documented.

Toxin-producing C. pseudotuberculosis can cause lymphadenitis in humans.

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Content Source:
National Center for Immunization and Respiratory Diseases (NCIRD); Division of Bacterial Diseases