History of Diphtheria
Diphtheria: The Plague Among Children
Diphtheria once was a major cause of illness and death among children. The United States recorded 206,000 cases of diphtheria in 1921, resulting in 15,520 deaths. Diphtheria death rates range from about 20% for those under age five and over age 40, to 5-10% for those aged 5-40 years. Death rates were likely higher before the 20th century. Diphtheria was the third leading cause of death in children in England and Wales in the 1930s.
Since the introduction of effective immunization, starting in the 1920s, diphtheria rates have dropped dramatically in the United States and other countries that vaccinate widely. Between 2004 and 2008, no cases of diphtheria were recorded in the United States. However, the disease continues to play a role globally. In 2007, 4,190 cases of diphtheria were reported, which is likely an underestimate of the actual number of cases.
Transmission and Symptoms
Diphtheria is transmitted from person to person, usually via respiratory droplets. The infection is caused by bacteria called Corynebacterium diphtheriae. An infected person, unless treated with antibiotics, is infectious for two to three weeks. Symptoms include sore throat, loss of appetite, and fever. The most notable feature of diphtheria infection, however, is the formation of a thick gray substance called a pseudomembrane over the nasal tissues, tonsils, larynx, and/or pharynx.
The pseudomembrane is formed from waste products and proteins caused by the toxin secreted by the bacteria. The pseudomembrane sticks to tissues and may obstruct breathing. The toxin itself may travel to the heart, muscle, kidneys, and liver, where it may temporarily or permanently damage these organs.
Complications from diphtheria may include myocarditis (damage to the heart muscle), neuritis (inflammation of nerves, which may contribute to nerve damage, paralysis, respiratory failure, and pneumonia), airway obstruction, and ear infection.
Diphtheria treatment today involves use of antibiotics to kill the diphtheria bacteria plus antitoxin to neutralize the toxins secreted by the bacteria. Diphtheria patients are usually kept in isolation until they are no longer capable of infecting others, usually about 48 hours after antibiotic treatment begins.
The current U.S. childhood immunization schedule for diphtheria includes five diphtheria toxoid immunizations before age six years, plus one booster dose for adolescents. (A toxoid is a toxin modified to invoke an antibody response, but not capable of causing disease.) All diphtheria immunizations for children are given in a single injection combined with tetanus toxoid and pertussis vaccine (known as DTP or DTaP). Adults receive diphtheria toxoid in combination with a tetanus toxoid booster, which is recommended every ten years. The adult product can protect against tetanus and diphtheria (a vaccine known as Td) or all three diseases (a vaccine known as Tdap).
 Epidemiology and Prevention of Vaccine-Preventable Diseases, 11th Edition (The Pink Book). National Immunization Program, Centers for Disease Control and Prevention. http://www.cdc.gov/vaccines/Pubs/pinkbook/downloads/dip.pdf. Accessed 12/16/2009.