Consider your words carefully.
Patient O
In 1981, the Center for Disease Control (CDC) began documenting the human immunodeficiency virus, or HIV. Researchers identified a group of about 40 men who seemed to be connected. One of these men, Gaëtan Dugas, was referred to as “Patient O”—that’s O as in Oscar. To the researchers, the Patient O designation indicated that Dugas lived outside of California. Unfortunately, that appellation was misinterpreted.
Misunderstanding
In epidemiology, the term “Patient 0” (zero) refers to the first carrier of a disease. During an outbreak, researchers may search for Patient 0 to track and contain the spread of an epidemic.
When Dugas was cited as Patient O, readers mistakenly interpreted the O as a zero. As a result, Dugas was publicly excoriated as the cause of the HIV crisis. This misunderstanding persisted for decades.
“What is the worst way this could be misinterpreted?”
Exoneration (Finally)

Fresh research examined samples of Dugas’s blood. The samples had degraded over time. The lab used a new technique dubbed “RNA jackhammering” to extract genetic information. The research showed no evidence that Dugas was the primary carrier who brought HIV to the US. Rather, his strain of HIV was consistent with other contemporary strains.
Gaëtan Dugas was not Patient 0.
There’s a Lesson Here
Clearly, the authors of the original research did not intend to implicate Dugas or stir up the public against him during his final years. The authors just created a convention to track their research. Unfortunately, that innocent decision had horrendous results that lasted for years.
Editing is important. One of the most important facets of editing is to consider your readers’ perspective. Whenever you’re editing, ask yourself, “What is the worst way this could be misinterpreted?”
Misunderstandings are inevitable. Writers must do everything possible to mitigate the likelihood and fallout of miscommunication.