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Diphtheria
Background
Overview
Definition
Diphtheria is a potentially fatal infection caused by toxin-producing strains of Corynebacterium diphtheriae, and occasionally by toxigenic Corynebacterium ulcerans and Corynebacterium pseudotuberculosis strains, causing upper respiratory tract or cutaneous disease.
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Pathophysiology
The pathophysiology of diphtheria involves the production of an exotoxin by the pathogen, which inhibits protein synthesis and causes cell death. This leads to the formation of a pseudomembrane in the throat, a characteristic feature of the disease. However, atypical cases without pseudomembrane formation have been reported.
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Epidemiology
There were 16,611 reported cases of diphtheria globally in 2018. The last confirmed case of respiratory diphtheria in the US was in 2003, and there were 4 reported cases of cutaneous diphtheria between 2015 and 2018.
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Risk factors
Risk factors for diphtheria include lack of immunization or partial immunization, as well as living in crowded or unsanitary conditions.
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Disease course
Clinically, diphtheria presents as an acute upper respiratory tract infection. Symptoms include sore throat, fever, and difficulty breathing due to airway obstruction caused by the pseudomembrane. Cutaneous presentations include scaly rash and skin ulcers.
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Prognosis and risk of recurrence
The prognosis of diphtheria is generally good with prompt treatment, which includes the administration of diphtheria antitoxin and antimicrobial therapy. However, severe cases can lead to complications such as myocarditis and neuropathy, which are associated with increased fatality risk.
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Guidelines
Key sources
The following summarized guidelines for the evaluation and management of diphtheria are prepared by our editorial team based on guidelines from the World Health Organization (WHO 2024), the Center for Disease Control (CDC 2020,2018), and the American College of Obstetricians and Gynecologists (ACOG 2017).
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Diagnostic investigations
Medical management
Antibiotic therapy: as per WHO 2024 guidelines, administer macrolide antibiotics (azithromycin, erythromycin) over penicillin antibiotics in patients with suspected or confirmed diphtheria.
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Diphtheria antitoxin
Preventative measures
Vaccination, children, up to 6 years
As per CDC 2020 guidelines:
Administer a series of three tetanus and diphtheria toxoid-containing vaccines, including at least one tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis dose in children aged 7-18 years who have never been vaccinated against pertussis, tetanus, or diphtheria. Administer vaccination series preferably according to the following schedule: one dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, followed by one dose of either Td or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis ≥ 4 weeks afterward, and one dose of either Td or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis 6-12 months later.
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Administer a single dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, preferably as the first dose in the catch-up series, in children aged 7-18 years who are not fully immunized against tetanus and diphtheria. Administer either Td or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis if additional tetanus toxoid-containing doses are required. Do not restart the vaccination series in children with incomplete diphtheria toxoid, tetanus toxoid, and acellular pertussis history, regardless of the time that has elapsed between doses.
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Vaccination (children, 7-18 years)
Vaccination (adults)
Vaccination (pregnant individuals)
Vaccination (wound management)