Koplik’s spots occur in which phase of measles –
**Core Concept**
Koplik's spots are a characteristic clinical feature of measles, representing an early sign of the disease. They are small, white, or bluish spots that appear on the buccal mucosa, typically before the onset of the rash.
**Why the Correct Answer is Right**
Koplik's spots occur during the prodromal phase of measles, which is the initial phase of the illness before the appearance of the rash. This phase is characterized by a range of symptoms, including fever, cough, runny nose, and conjunctivitis. The presence of Koplik's spots is a key diagnostic feature of measles during this phase, and they are often used as an early indicator of the disease.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Koplik's spots are not typically associated with the rash phase of measles, which occurs later in the course of the disease.
**Option B:** This option is incorrect because Koplik's spots are not a feature of the recovery phase of measles, which occurs after the rash has resolved.
**Option C:** This option is incorrect because Koplik's spots are not a feature of the incubation period of measles, which is the time between exposure to the virus and the onset of symptoms.
**Clinical Pearl / High-Yield Fact**
Koplik's spots are a distinctive clinical feature of measles that can aid in early diagnosis. They are often described as "grains of salt" or "cottage cheese-like" lesions on the buccal mucosa.
**Correct Answer: C. Prodromal phase.