The disease normally breaks out 2 to 5 days after infection. Damage is done by the toxin. The disease usually affects the tonsils, pharynx, larynx and occasionally the skin. Symptoms range from a moderately sore throat to toxic life-threatening diphtheria of the larynx or of the lower and upper respiratory tracts. This occurs because the disease results in the formation of a membrane in the throat that may get so big it completely blocks the larynx, causing death by suffocation.
Untreated patients are infectious for up to four weeks.
Unless immunized, children and adults may be infected repeatedly with the disease. The most effective method of epidemic control is mass immunization of the entire population. The most effective method of prevention is immunization in early childhood, often followed by booster doses at school entry. It is transmitted through direct contact with discharges from respiratory mucous membranes of infected persons carried in the air. The bacteria invade the nose and throat, the trachea, and the bronchial tubes of the lungs, causing symptoms in about a week.