Positive Schick’s test indicates that person is –
Wait, the Schick test involves injecting a small amount of diphtheria toxin into the skin. If the person has antibodies, there's no reaction. If there's a reaction, they're susceptible. So a positive result means they're not immune. But the question is phrased as "positive Schick's test indicates that person is..." So the options should be something like susceptible, immune, carrier, etc.
Looking at the correct answer, the user didn't provide options, but the correct answer is probably "susceptible to diphtheria." Let me confirm. The Schick test: positive means the person doesn't have enough antibodies, so they're susceptible. Negative means they are immune. So the correct answer would be the option stating susceptibility.
Now, the other options might be about immunity, carrier status, or hypersensitivity. Let's think. A carrier might have the bacteria but not show symptoms. The Schick test doesn't determine carrier status; that's a different test. So if an option says carrier, that's incorrect.
Another possible wrong option could be hypersensitivity. But the Schick test isn't about allergies; it's about immunity. So a positive Schick test is about lack of immunity, not an allergic reaction.
Clinical pearl here is that the Schick test is used to assess immunity to diphtheria, important in epidemiological studies or vaccination programs. It's not commonly used now due to widespread vaccination.
Wait, the user's correct answer is missing the letter and text. But in the example, the user provided a placeholder. I need to make sure the correct answer is properly formatted. Since the correct answer is "susceptible to diphtheria," the options should include that. The other options would be incorrect if they suggest immunity, carrier, or hypersensitivity.
So in the explanation, the core concept is the Schick test's role in diphtheria immunity. The correct answer is positive meaning susceptibility. The wrong options would be immunity (negative test), carrier status (requires culture), or hypersensitivity (not related). The clinical pearl is the test's purpose and its current usage.
**Core Concept**
The Schick test assesses susceptibility to *Corynebacterium diphtheriae* by measuring the presence of diphtheria antitoxin antibodies. A positive result indicates insufficient immunity, while a negative result confirms prior immunity via vaccination or natural infection.
**Why the Correct Answer is Right**
A positive Schick test occurs when a small dose of diphtheria toxin injected intradermally causes a local inflammatory reaction. This reaction signifies the absence of protective antitoxin antibodies in the patient’s serum, making them susceptible to diphtheria. The test exploits the body’s immune response to neutralize the toxin; a lack of neutralizing antibodies leads to visible skin changes (erythema, induration) within 48 hours.
**Why Each Wrong Option is Incorrect**
**Option A:** Claims