: a person identified as the first to become infected with an illness or disease in an outbreak
The quest to find patient zero, the first person to contract the new virus, has revealed the first known case occurred in Wuhan …—Susan Dunlevy
especially: a person documented as being the first known case of a communicable disease in a particular population or region
Stay out of hospital emergency rooms unless you are severely ill or injured. For now, it's the likeliest place to catch coronavirus. Anyone unknowingly suffering from coronavirus is likely to go there. That's what "patient zero" in Italy did. —Betsy McCaughey
The 26-year-old nurse contracted Ebola after volunteering to care for U.S. 'patient zero' Thomas Eric Duncan, who tragically died on October 10 from the deadly disease. —Ashley Collman et al.
Recent Examples on the WebThe patient zero for the latest outbreak of the Ebola virus is believed to have been a person in a remote, mountainous area in southern Guinea, a country with just one doctor per 10,000 people.—Jessica Hatcher, Foreign Affairs, 28 Apr. 2014 The major concern with these coronavirus clusters is that the patient zero spreads the illness beyond their household and inner circle and into the community.—Selena Randhawa, refinery29.com, 20 Oct. 2020 For instance: Where is Huang Yanling, a lab employee widely rumored to be patient zero?—Michael Brendan Dougherty, National Review, 7 Mar. 2023 Emile was patient zero in the worst Ebola outbreak the world has ever seen.—Caroline Chen, ProPublica, 27 Feb. 2023
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'patient zero.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.