Ubiquitous - Lyrics - Index Case

The index case, primary case, or patient zero is the initial patient in the population of an epidemiological investigation, or more generally, the first case of a condition or syndrome to be described in the medical literature, whether or not the patient is thought to be the first person affected. An index case will sometimes achieve the status of a "classic" case in the literature, as did Phineas Gage. ...