Corynebacterium diphtheria, a gram positive rod. Incubation period 1-5 days. Produces fibrinous pseudomembrane on pharyngeal mucosa and exotoxin causes clinical effects.

Respiratory droplet spread. Mainly present in developing countries due to less vaccine availability.

Insidious onset: Fever, tachycardia, coryzal symptoms 

Respiratory (commonest): Slow onset fever, sore throat (pseudomembranous 

pharyngitis), nausea, vomiting, dysphagia, 

Cutaneous: Painful ulceration with offensive smell, may be superinfected with 

staphylococci or streptococci.

Conservative: Bed rest

Medical: Diphtheria antitoxin, antibiotics, early tracheostomy and ventilation if 

signs of tracheal obstruction or respiratory muscle paralysis.

Overall mortality 5-10%, myocarditis – 50% mortality.

Laryngeal obstruction, myocarditis, neuropathy.