The DPT vaccine is one type of preventive medicine called immunization (to make things resistant to disease). The vaccine causes the body to form protective antibodies (disease-fighting proteins) against three serious diseases: diphtheria, pertussis (whooping cough), and tetanus (lockjaw). DPT is given in the form of an inoculation (shot or injection) in three separate doses about two months apart, with a "booster" shot one year after the primary series of inoculations is completed.
In the United States the DPT vaccine is usually given to babies during their first year of life because diphtheria and whooping cough tend to strike young children, are highly contagious, and can be fatal. A second booster shot is given at age four to six. Tetanus, or lockjaw, is an often-fatal disease that can strike persons of any age, but it can be prevented through immunization and supplementary booster injections every five to ten years.
Immunization is the best way to fight these and many other diseases. Many states in the United States have passed laws that say children cannot be enrolled in schools or day care centers unless they have been immunized against diphtheria, whooping cough, and tetanus. They must also have been immunized against polio and measles, mumps, and rubella (German measles). The polio vaccine is given orally (by mouth), and the measles, mumps, and rubelia (MMR) vaccine is combined into a series of injections, like the DPT vaccine.
Diphtheria is a disease of the respiratory system caused by the bacterium "Corynebacterium diphtheriae." It mostly affects children and causes grayish white or yellowish mucous (slimy) coatings to form in the passages of the nose and throat. These "false membranes" can block the air passages, and surgery may be necessary to help the patient breathe. Bacteria enter the body through the mouth and nose and multiply, giving off a powerful toxin (poison). This toxin can damage the kidneys, heart, and central nervous system, leading to death.
Diphtheria is spread from person to person by coughing and sneezing and is more common among poor populations living in crowded conditions. In the late 1800s, before the development of a diphtheria antitoxin (a medicine to counteract the effects of the toxin), diphtheria killed thousands of people—especially children—in Europe and the United States.
German physician Emil von Behring (1854-1917) and Japanese scientist Shibasaburo Kitasato (1852-1931) were the first researchers to develop an antitoxin vaccine against diphtheria in about 1890. German microbiologist Paul Ehrlich (1854-1915) developed standard dosages for the antitoxin. In 1891 pathologist Anna Wessels Williams found a stronger strain of diphtheria antitoxin. In 1894 French bacteriologist Pierre Roux (1853-1933) developed a diphtheria antitoxin serum that he used to successfully treat more than 300 cases of the disease.
In 1913 Hungarian scientist and pediatrician Bela Schick (1877-1967) introduced the Schick test, which tells whether or not a person can get diphtheria if exposed to it. In the test a small amount of diphtheria toxin is injected under the skin. If a red, swollen rash develops, the person is susceptible to diphtheria and should be immunized.
Whooping cough, or pertussis, is a very contagious respiratory disease that causes patients to cough violently. After a series of coughs, the patient draws a deep breath that makes a whooping sound. Whooping cough is mainly a childhood disease and can be fatal, especially to infants.
Although whooping cough had been identified for at least a thousand years, it was not named until 1675 by English doctor Thomas Sydenham (1624-1689). Belgian scientists Jules Bordet and Octave Gengou discovered the bacillus that causes whooping cough in 1906. They developed a vaccine against the disease, but it did not work very well and whooping cough continued to infect thousands of children every year in the United States alone. It was through the work of three female scientists—Dr. Pearl Kendrick, Dr. Grace Eldering, and Dr. Margaret Pitman—that a potent whooping cough vaccine was developed in the first half of the twentieth century. Dr. Kendrick continued to make sure that the whooping cough vaccine being given all over the world was strong enough to prevent the disease. The vaccine is now given with diphtheria and tetanus vaccines to infants worldwide.
Tetanus is a serious infectious disease of the nervous system that causes severe contraction of the muscles. It is also known as lockjaw because spasms of the cheek muscles (tetany) make it nearly impossible to open the jaws. The muscle spasms caused by tetanus can spread to other muscles in the body, eventually making breathing difficult and resulting in death.
Tetanus is caused by a bacterium called Clostridium tetani that lives in soil and gets into the body through deep puncture wounds, burns, or crushing wounds in which there is much tissue damage. The tetanus bacilli multiply, releasing exotoxin (a poison) into the surrounding tissues. About 60 percent of the cases of tetanus are fatal, but immunization is an effective tool in the prevention of tetanus.
Behring and Kitasato also produced an antitoxin for tetanus. Behring later developed a toxin-antitoxin vaccine against tetanus. In 1893 Roux found a way to improve the procedures for using antitoxin serum to prevent as well as treat tetanus.
Today's tetanus vaccine is a toxoid (a form of tetanus toxin chemically treated so that it is nontoxic) that stimulates the growth of antibodies to the disease. In addition to the DPT vaccine series and booster shots, a person who suffers a dangerous wound that could be contaminated by the tetanus bacterium is often given two tetanus inoculations at the time of the injury. One is called tetanus immunoglobulin (Hypertet), which gives immediate immunity (by means of preformed antibodies already produced in a laboratory). The other is called tetanus toxoid, which stimulates the body's own defense system to make tetanus antibodies in about two weeks.