Caused by the bacterium Corynebacterium diphtheriae, diphtheria is an infection the signs and symptoms of which may vary from mild to severe. They usually start two to five days after exposure. Symptoms often come on fairly gradually, beginning with a sore throat and fever. Although popularly considered a disease of the past, widespread infection in South East Asia has brought the condition in sharp focus, as did a poster on the subject displayed at the IBMS Biomedical Science Congress last year.
In severe cases, a grey or white patch develops in the throat, which can block the airway and create a barking cough as in croup. The neck may swell in part due to enlarged lymph nodes. A form of diphtheria that involves the skin, eyes, or genitals also exists.
Complications may include myocarditis, inflammation of nerves, kidney problems, and bleeding problems due to low platelet numbers. Myocarditis may result in an abnormal heart rate and inflammation of the nerves may result in paralysis.