patient zero

American  

[pey-shuhnt zeer-oh] / ˈpeɪ ʃənt ˈzɪər oʊ /

noun

1. Pathology.  the first known carrier of infection in an outbreak.

   Public health officials are tracing all contacts of infected patients, trying to work their way back to find patient zero.

2. the person or thing that is believed to be the point of origin for any spreading effect, status, or event, especially if negative.

   One rowdy new student was patient zero for all kinds of classroom chaos and problem behaviors.

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Etymology

Origin of patient zero

First recorded in 1985–90

Example Sentences

I could not identify the patient zero of the cheese-pull phenomenon, but it was around this time that Chili’s became inescapable on TikTok—everyone stretching cheese as far as they could while praising the Triple Dipper.

From Slate

Patient zero for this ad experiment appears to be X user @FearedBuck, who started as a Milwaukee Bucks fan account but later pivoted to posting Kick clips full time.

From Slate

At the New Yorker, Susan Glasser offers this description of Trump’s recent speech in Rome, Georgia, noting how he embodies and projects malignant normality as a type of patient zero and the main character in a twisted politics reality TV show that he is making up as he goes along:

From Salon

McConaughey appears to be patient zero for testing the theory while living in the middle of the United States.

From Los Angeles Times

Since re-emerging into the public eye in 2014, she has regularly spoken out publicly against cyberbullying, calling herself "patient zero" of the internet trend.

From BBC