Diphtheria is an acute, infectious bacterial disease, now uncommon, caused by the bacterium Corynebacterium diptheriae. which often enters through the upper respiratory tract.
Symptoms include fever, malaise, and sore throat, with a characteristic "pseudomembrane" on the throat or pharynx; also, the lymph nodes may enlarge. The larynx, if involved, leads to a hoarse voice, breathlessness, and stridor; this may progress to respiratory obstruction requiring tracheotomy. The bacteria produce toxins which can damage nerves and heart muscle; cardiac failure and abnormal rhythm, or paralysis or palate, eye movement, and peripheral neuritis may follow.
Early treatment with antitoxin and use of antibiotics are important. Protection is given by vaccination.