index case
n.— «A man whom doctors call the “index case”—the first patient they knew about—got sick in December 2006 and was hospitalized at the Mayo Clinic for about two weeks.» —“A Medical Mystery Unfolds in Minnesota” by Denise Grady in Austin, Minnesota New York Times Feb. 5, 2008. (source: Double-Tongued Dictionary)
Further reading
Amid court-ordered busing in the 1970s, a middle-school teacher tried to distract her nervous students on the first day of class with this strange assignment: find a monarch caterpillar. The result? A memorable lesson in the miracle of metamorphosis...
Unwrap the name of a candy bar, and you just might find a story inside. For instance, one chewy treat found in many a checkout lane is named after a family’s beloved horse. And: 50 years ago in the United States, some Latino elementary...