Diphtheria (dif-THEER-e-uh) is a serious bacterial infection usually affecting the mucous membranes of your nose and throat. Diphtheria typically causes a sore throat, fever, swollen glands and weakness. But the hallmark sign is a sheet of thick, gray material covering the back of your throat, which can block your airway, causing you to struggle for breath.
Diphtheria is extremely rare in the United States and other developed countries, thanks to widespread vaccination against the disease.
Medications are available to treat diphtheria. However, in advanced stages, diphtheria can damage your heart, kidneys and nervous system. Even with treatment, diphtheria can be deadly — up to 3 percent of people who get diphtheria die of it. The rate is higher for children under 15.