Diphtheria

The incubation period—the time from exposure to the bacteria to the first symptoms—is one to seven days. The first symptoms of diphtheria are fatigue, a low-grade fever, and a sore throat. As the disease progresses, the throat swells, sometimes so much that the patient has noticeable neck swelling. The bacteria infect the throat first before spreading to the larynx (voice box) and trachea (windpipe). At the site of infection, the throat is red and sore. In reaction to the infection, the throat tissues release a discharge containing fibrous material and immune cells. This discharge covers the throat tissues and appears as a grayish, membrane-like material. The throat and trachea continue to swell; if not relieved, the swelling may obstruct the airway, leading to death by suffocation.

Sometimes diphtheria bacteria infect the skin first. When this type of infection occurs, skin lesions appear. For reasons that are not clear, the diphtheria characterized by infection is more contagious than the disease characterized by respiratory infection. The skin-type of diphtheria is more common in tropical and sub-tropical countries.