Question

The Schick test is used to determine susceptibility to:

• A. Measles
• B. Polio
• C. Diptheria
• D. Typhoid

Answer 1

The Correct Option is C

The Schick test is a historical skin test that was used to determine an individual's susceptibility to diphtheria, a serious bacterial infection caused by Corynebacterium diphtheriae. Although not commonly used today due to widespread vaccination against diphtheria, understanding the test is crucial for historical and pathological insight.

Explanation:

• Mechanism of the Schick Test: The test involves injecting a small amount of diphtheria toxin into the skin. If the person lacks immunity, they will react to the toxin, causing inflammation at the site of injection. Conversely, if the person is immune, either due to previous infection or vaccination, there will be no significant skin reaction as the immune system neutralizes the toxin.
• Process:
  1. A small dose of diphtheria toxin is injected intradermally, typically on the forearm.
  2. A control injection of inactivated toxin is also administered on the other arm as a comparison.
  3. The test site is observed over 24 to 48 hours for a reaction.
  4. A positive reaction (redness and swelling) indicates susceptibility, while no significant reaction suggests immunity.

Examination of Options:

• Measles: Immunity to measles is determined through antibody testing or vaccination history, not the Schick test.
• Polio: For polio, an oral polio vaccine (OPV) or inactivated polio vaccine (IPV) is used, and there is no Schick-like test for susceptibility.
• Diphtheria (Correct Answer): The Schick test is directly related to testing for susceptibility to diphtheria.
• Typhoid: Typhoid susceptibility is not determined by the Schick test. Vaccination and water sanitation are primary prevention methods.

Conclusion: The correct answer is Diphtheria, as the Schick test was specifically designed to identify individuals susceptible to diphtheria by testing their immune response to the diphtheria toxin.