Diphtheria is a serious infection caused by strains of the bacteria called
Corynebacterium diphtheriae
which makes a toxin. The toxin attaches itself most commonly to tissues in the respiratory system and causes disease by killing healthy tissue.
Typical symptoms of the infection include a sore throat, fever, swollen neck glands and weakness. Within 2–3 days from infection, the dead tissue forms a thick, grey coating that can cover tissues in the nose, tonsils and throat, making it hard to breathe and swallow. More rarely, the toxin gets into the blood stream and causes damage to the heart, kidneys and nerves.
Diphtheria bacteria spread from person to person, usually through respiratory droplets, like from coughing or sneezing. People can also get sick from touching infected open sores or ulcers. Those at increased risk of getting sick include household contacts, those exposed to secretions from the patient and those with frequent and close contact with the infected person.