patients zero

Noun

patient zero (plural patient zeros or patient zeroes or patients zero)

1. The initial patient in the population of an epidemiological investigation.
   • When epidemiologists trace the evolution of a disease, they look for the first individual known to have contracted it, who is given the inglorious label "Patient Zero". For example, the official Patient Zero for the AIDS epidemic was a South African man who died in 1959 (though it is suspected that...2005, John De Graaf, David Wann, Thomas H. Naylor, Redefining Progress, Affluenza: the all-consuming epidemic, 2nd illustrated edition, Berrett-Koehler Publishers, →ISBN, page 128

   Synonyms:

   index patient

2. (figuratively, informal) The source or origin of something.
   • Danny Boyle, patient zero of the zombie revival, reviews The Walking Dead.2013 April 20, “Populist: Items of interest this week”, in Alan Rusbridger, editor, The Guardian, London: Guardian News & Media, →ISSN, →OCLC, archived from the original on 10 Oct 2014