Diphtheria is an acute disease caused by toxin-producing strains of Corynebacterium diphtheriae (in some cases also by Corynebacterium ulcerans) bacteria, that is known to colonise mucous membranes.

Following infection, after a usually short incubation period (2–5 days), the release of the cytotoxin may produce characteristic lesions on the affected mucous membranes (tonsils, pharynx, larynx, nose) or wounds. Obstruction of the airway may follow.

The toxin, once absorbed, reaches other organs and can cause myocarditis, paralytic symptoms and nephritis. In non-vaccinated individuals, and especially if proper treatment is delayed, death can occur in up to 10% of clinical cases despite antibiotics and the use of anti-sera, Diphtheria is transmitted mainly by direct projection (droplet spread). It is preventable by vaccination.

Read more about diphtheria in the factsheet for general public.