Color enhanced transmission electron micrograph (TEM) of Corynebacterium diphtheria bacterium that are found in the human throat and are the causative agent of diphtheria. Diphtheria is an acute bacterial infection of the throat (larynx, pharynx, tonsils), once common but now rare due to immunization and improved hygiene. Toxins produced by diphtheria bacteria destroy mucous membranes lining the throat, giving them a gray, veil-like appearance, and causing the swelling of underlying tissues. Toxins can also damage the nervous system and affect the heart. Symptoms include fever, headache, sore throat, and swollen glands in neck. followed by obstructed breathing, irregular pulse, vomiting, and difficulty swallowing or focusing. Treatment of infection usually involves penicillin. A vaccine exists to prevent diphtheria. 3,750x at 35mm