Diphtheria

**Definition:** A disease commonly of the respiratory system, caused by an infection of the gram-positive bacteria Corynebacterium diphtheriae. This disease is characterised by sore throat, fever, and a pseudomembrane on the tonsils, pharynx, or nasal cavity. Transmission is by inhalation of infected respiratory secretions, or direct cutaneous contact. Confirmation is by identification of Corynebacterium diphtheriae from a throat swab or infected tissue, and by clinical signs.

**Long definition:** Localized infection of mucous membranes or skin caused by toxigenic strains of Corynebacterium diphtheriae; it is characterized by the presence of a pseudomembrane at the site of infection; diphtheria toxin, produced by C. diphtheriae, can cause myocarditis, polyneuritis, and other systemic toxic effects.