During the late 1800s, a diphtheria epidemic killed thousands of children in western Europe and the United States and spurred research into ways of controlling the disease. Diphtheria is a contagious disease caused by a bacterium.
Diphtheria is spread through respiratory droplets in infected individuals. The droplets are scattered and passed to other people through sneezing and coughing. The bacteria go to the mucous membranes of the throat and secrete (release) a potent toxin (poison) which causes tissue destruction and the formation of a gray membrane (a thin covering) in the upper respiratory tract. This membrane can loosen and cause the patient to suffocate (die from lack of oxygen). The toxin may also spread via the blood and damage tissues elsewhere in the body.
Finding the Test
During the epidemic, a tremendous effort was launched to find effective treatments and immunizations for the disease. One of the first findings was the diphtheria test. The test was developed by Bela Schick (1877-1967), a Hungarian pediatrician (children's doctor) who specialized in childhood diseases. The Schick test, as it was called, was based on the toxin-antitoxin research of German bacteriologist Emil von Behring (1854-1917). Behring's research revealed that the body will naturally develop its own protection from bacteria. These protective antitoxins or antibodies can neutralize (offset) the invading substances.
How the Test Works
The Schick test works by injecting a small amount of specially-prepared diphtheria toxin beneath the skin. If the person is susceptible to the disease, a red swollen rash appears around the injection area. A vaccine may then be used to protect the person from diphtheria.
The vaccine is a serum (a clear fluid) containing diphtheria toxoids. Toxoids are toxins from the disease that have been inactivated so they can't do any damage. The toxoid stimulates the production of diphtheria antibodies in the body to ward off the disease.
Used with the diphtheria vaccine, Schick's test dramatically reduced the occurrence of diphtheria worldwide. Until the 1920s, there were 150,000 to 200,000 cases of diphtheria in the United States each year. The number dropped to less than ten cases per year by the 1970s. Other scientists using Schick's approach developed similar tests for other diseases. These diseases included measles, tuberculosis, pertussis, gonorrhea, and syphilis. The tests have saved thousands of lives.