Contents
Organism
Cornynebacterium diptheriae
Incubation; 2-5 days
Transmission
Droplet spread – from nasopharynx of case or carrier.
Epidemiology
- Death rate is 10%(higher in children under 5 and adults over 40).
- Immunity (natural/vaccine-induced) does not prevent carriage.
- Up to 5% healthy population in endemic areas test positive from pharyngeal cultures.
- Largely been eradicated in the developed countries through vaccination programmes.
Pathogenesis
Organism usually infects the epithelium of the skin and the mucosa of the upper respiratory tract (classically tonsils and pharynx)
- Inflammation of tissues
- Bacteria secrete exotoxin which interferes with cell protein synthesis (resulting in tissue necrosis) and call interfere with local neurological supply of palate and hypopharynx (paralysis)
- Build-up of inflammatory cells, necrotic epithelial cells, and bacteria debris – form the characteristic adherent grey/black, tough, fibre-like covering (pseudomembrane).
- Inflammation, pseudomembrane formation and paralysis can combine to result in airway obstruction
- Systemic spread of the toxin in the bloodstream – can injure the kidneys, heart, and brain.
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[image from Illnois Department of Public Health, courtesy of US Centers for Disease Prevention and Control]
Diagnosis
Culture from throat or nasal swabs (toxin studies must be performed)
**do not delay treatment to wait for diagnosis
Treatment
Penicillin/erythromycin
Isolation
Cardiac monitor