Schick test
Encyclopedia
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
. It was named after its inventor, Béla Schick
Béla Schick
Béla Schick , was a Hungarian-born American pediatrician. He is the founder of the Schick test. Was born in Balatonboglár, Hungary, and brought up in Graz, Austria, where he attended medical school. In 1902 he joined the Medicine Faculty of the University of Viennawhere he remained until 1923...
(1877–1967), a Hungarian-born American pediatrician.
The test is a simple procedure. A small amount (0.1 ml) of diluted (1/50 MLD
Minimum lethal dose
Minimum lethal dose is the least amount of drug that can produce death in a given animal species under controlled conditions.For the concept Median Lethal Dose , see Median lethal dose....
) diphtheria toxin is injected intradermally into the arm of the person. If a person does not have enough antibodies to fight it off, the skin around the injection will become red and swollen, indicating a positive result. This swelling disappears after a few days. If the person has an immunity, then little or no swelling and redness will occur, indicating a negative result.
Results can be interpreted as:
- Positive: when the test results in a wheal of 5–10 mm diameter
- Pseudo-positive: when there is only a red colored inflammation and it disappears rapidly
- Negative reaction:
- pseudo negative reaction:
The test was created when immunizing agents were scarce and not very safe, however as newer and safer toxoids were made available there was no more requirement for susceptibility tests.