Diphtheria spreads through respiratory droplets (such as those produced by a cough or sneeze) of an infected person or someone who carries the bacteria but has no symptoms. Diphtheria can also be spread by contaminated objects or foods (such as contaminated milk). Symptoms usually occur 2 to 5 days after you have come in contact with the bacteria. The bacteria most commonly infects the nose and throat. The throat infection causes a gray-to-black, tough, fiber-like covering, which can block the airways. In some cases, diphtheria may first infect the skin, producing skin lesions. Once infected, dangerous substances produced by the bacteria can spread through your bloodstream to other organs, such as the heart, and cause significant damage. The most common complication is inflammation of the heart muscle (myocarditis). The nervous system is also frequently and severely affected, and may result in temporary paralysis. Diphtheria may be mild or severe. Some people may not have symptoms. In others, the disease can slowly get worse. Because of widespread and routine childhood DPT immunizations, diphtheria it is now rare in many parts of the world. There are fewer than 5 cases of diphtheria a year in the United States. Risk factors include crowded environments, poor hygiene, and lack of immunization. | 
General Pediatrics
