The infection also causes the lymph glands and tissue on both sides of the neck to swell to an unusually large size. Some people can be infected but not appear ill. They can also spread the infection. Symptoms usually appear 2 to 4 days after infection. Diagnosis is by physician examination and throat culture.
Diphtheria is most common in areas where people live in crowded conditions with poor sanitation.
Persons, especially children, who are not immunized or who did not receive adequate immunization are most at risk. This poison can spread through the body and cause serious, often life-threatening complications. The diphtheria toxin can damage the heart muscles and cause heart failure or paralyze the breathing muscles. The membrane that forms over the tonsils can also move deeper into the throat and block the airway. Diphtheria is a medical emergency.