Diphtheria

Since most children in the United States are vaccinated against diphtheria, the domestic incidence of the disease is very low. When diphtheria does occur, it tends to strike adults, because fewer adults than children have been immunized against the disease. In developing countries, where less than 10% of the children are vaccinated against diphtheria, about one million deaths are caused each year by this disease. Diphtheria is highly contagious. The disease is prevalent in densely-populated areas, especially during the winter months when more people crowd together indoors. Transmission of the bacteria occurs when an infected person sneezes or coughs and a susceptible person breathes in the saliva or mucus droplets form the air.