Koplik spots are seen in?

Koplik's Spots: They are pathognomonic of measles. Their presence establishes the diagnosis of measles. These are bluish grey specks on grain substance on a red base which usually appear on the buccal mucosa opposite the second molar. They appear at the end of the prodrome, just before the appearance of the rash. Koplik's spots usually appear after 2 days of illness and last for 24-48 hours. May also appear on the mucous membrane of the conjunctiva and the vagina.