The Schick test, invented between 1910 and 1911 is a test used to determine whether or not a person is susceptible to diphtheria. It was named after its inventor, Béla Schick (1877–1967), a Hungarian-born American pediatrician.
The test is a simple procedure. A small amount (0.1 ml) of diluted (1/50 MLD) 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.
- Schick B (1913). "Die Diphtherictoxin-Hautreaktion del Menschen als Vorprobe der prophylaktischen Diphtherie-heilseruminjection". Münchener medizinische Wochenschrift 60: 2608–2610.
- Barile MF, Kolb RW, Pittman M (September 1971). "United States standard diphtheria toxin for the Schick text and the erythema potency assay for the Schick text dose". Infect. Immun. 4 (3): 295–306. PMC 416303. PMID 4949493.
- Taber's Cyclopedic Medical Dictionary, 20th Ed. (2005).