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Recently it was widely reported in the media about the results of new genetic testing of early HIV samples. The reports showed two major flaws against the usefulness of identifying a Patient Zero in that outbreak:

  1. the man described in the 1980s as Patient Zero in the AIDS outbreak was in fact not the source of the outbreak, but a typical case several genetic steps removed from a putative first case in the US. As a result the notion is "both ethically and scientifically challenged".

  2. The notation used in the actual samples in that original case were marked "Patient O" with an Oh, not "Patient 0 (Zero)". 'O' for "outside California. It was a typo or an accidental misreading to call the case Patient Zero.

Looking at wikipedia we can see that most uses of the term seem to refer to the AIDS case. I've also seen the term used in zombie movies, but this may not be a reliable source for medical terminology. Is or was the concept of a patient zero ever used in medicine or epidemiology or virology, or was the concept created out of whole cloth via a mistaken translation by non-medical observers?

1 Answer 1


You are indeed correct! The origins and first usage of the word "patient-zero" was actually a total misinterpretation that was caught on quickly by the media, and has since been perpetuated henceforth. The phrase was coined in the early 1980's in reference to Gaëtan Dugas, who was erroneously identified as the cause of the AIDS outbreak. Your sources are correct in that new scientific evidence has since demonstrated that he didn't spread HIV, but the damage has been done, and his reputation has been tarnished.

The "Patient Zero" reference has since been used in reference to Ebola, Avian Flu, Swine Flu, and Typhoid (this one retroactively). The more medically correct term is index-case.

Here are excerpts from a CNN article indicating the etymology of the "Patient Zero" and the usage of index cases: http://www.cnn.com/2016/11/08/health/patient-zero-history-super-spreaders/index.html

When a researcher's scrawling of the letter O was misinterpreted as a zero in reference to a HIV patient in the early 1980s, the provocative term "patient zero" was born.

"Patient zero" is still frequently used to describe index cases -- the first documented cases of a disease observed or reported to health officials.

Here is another CNN article explaining the misinterpretation of the "patient O" and the clearance of Gaëtan Dugas as the cause for the AIDS outbreak: http://www.cnn.com/2016/10/27/health/hiv-gaetan-dugas-patient-zero/index.html

Dugas was placed near the center of this cluster, and the researchers identified him as patient O, an abbreviation to indicate that he resided outside California. However, the letter O was misinterpreted as a zero in the scientific literature. Once the media and the public noticed the name, the damage was done.

Here is a list of other alleged "patient-zeros" or "index cases": http://www.cnn.com/2016/11/08/health/gallery/patient-zero-cases-history/index.html

  • So are you saying that the concept of a first infection in an outbreak was used by medical practitioners, but it just went by a different name ("index case" instead of "patient zero")? The CNN article you've referenced mentions the press's confusion about the term "patient zero", but does not clarify whether they misread a typo because it looked like an existing concept, or whether they made up the concept entirely.
    – ziggurism
    Dec 4, 2016 at 2:53

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