Incubation; 2-5 days
Droplet spread – from nasopharynx of case or carrier.
- 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.
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.
[image from Illnois Department of Public Health, courtesy of US Centers for Disease Prevention and Control]
Culture from throat or nasal swabs (toxin studies must be performed)
**do not delay treatment to wait for diagnosis