paciente zero
paciente inicial → ασθενής μηδέν, πρωτογενές κρούσμα, περίπτωση δείκτης
The index case, sometimes colloquially referred to as patient zero, is the first documented patient in the onset of an epidemiological investigation, or more generally, the first case of a condition or syndrome (not necessarily contagious) 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 study in the literature, as did Phineas Gage, the first known person to exhibit a definitive personality change as a result of a brain injury.
https://en.wikipedia.org/wiki/Index_casear: المريض رقم صفر; de: Indexpatient; en: index case; es: caso índice; fa: بیمار صفر; fr: patient zéro; it: paziente zero; ja: インデックス・ケース; pt: paciente zero; ru: нулевой пациент; sv: indexfall; zh: 指示病例