I recently began a Daily Comment about the growing threat of viral epidemics with one of modern medicine’s more famous quotes. “In 1967, William H. Stewart, the Surgeon General, travelled to the White House to deliver one of the most encouraging messages ever spoken by an American public-health official,’’ I wrote. Then I continued with the quote, “ ‘It’s time to close the books on infectious diseases, declare the war against pestilence won, and shift national resources to such chronic problems as cancer and heart disease,’ Stewart said.”

Stewart’s stupendously short-sighted comment was a perfect opening for my piece, which was about the risks posed by research into the genetics of deadly viruses. And the fears caused by infectious diseases are hardly theoretical. While scourges such as measles, polio, typhus, and even smallpox no longer posed a serious threat in the West by 1967, globalization has brought new viruses into wide exposure, some of them as dangerous as some that we have previously seen. SARS, MERS, Ebola, and bird flu, to name just a few, all have the potential to kill millions (as H.I.V. has already done).

I liked Stewart’s quote so much that I had used it before—once, several years ago, in a piece for this magazine about Nathan Wolfe, a scientist who travels the world hunting for deadly viruses. Stewart’s quote also appeared in a piece that I wrote more than twenty years ago, when I worked at the New York Times. It was part of a series on the resurgence of tuberculosis in the United States. I was hardly alone in pointing to the foolishness of the Surgeon General. The quote has been used dozens of times by journalists, scientists, and public-policy officials. That’s easy to understand. One rarely sees a better example of that kind of inept thinking. There was just one problem.

Stewart never said it.

Although I should have known this, I only became aware of it the other day when my friend, the distinguished science writer Carl Zimmer, sent me a note about my column, but added a link from a recent study:*

I liked your piece on disease. I thought you’d be interested in this paper which shows that that disease-is-over quote is an urban legend. It was brought to my attention only after I used it in print.

Best,

C

I was skeptical, and not just because it suggested that I was wrong. I have made much bigger mistakes, and no doubt will make more. I try not to make errors; we all do. But preventing errors altogether, though a laudable goal, is not possible. So we publish corrections and append them to pieces where we make mistakes, and then we move on.

But I could not get over the fact that this anecdote had been published so often in so many significant places. How could it have been wrong? I have since checked, and the views expressed in the quote were held by many infectious-disease experts at the time. It was a great moment in that community. Still, optimism is not blindness.

That is precisely why this error seems worthy of a special note (self-flagellation?), because it has been used so often and so prominently that it illustrates a critical point about the way information spreads these days. Once a “fact” or a quote is widely distributed, particularly across a group of well-regarded publications, it moves like a virus. Ubiquitous, unpredictable, and seemingly impossible to eradicate.

And yet the study, titled “On the exoneration of Dr William H. Stewart: debunking an urban legend” and published almost two years ago in the journal I__nfectious Diseases of Poverty, leaves no doubts. The authors combed through major medical databases, hundreds of news sources, and congressional records.

“This spectacularly erroneous quote has been cited innumerable times to underscore ongoing public health problems caused by antibiotic-resistant and emerging infections,’’ the authors wrote. “The quote was referred to in Dr. Stewart’s obituary, published in a leading medical journal in July of 2008. The persistent relevance of this quote to modern society is underscored by its citation in a 2009 Wall Street Journal article about the recent H1N1 influenza outbreak, and in an article regarding the deadly shiga-toxin producing E. coli 0104:H4 outbreak in Germany and Europe in 2011.”

It gets worse. “After many years of searching, only one source has been identified which contains a primary reference to Dr. Stewart’s quote,’’ the authors wrote. “The reference is to a speech given by Dr. Stewart at the 65th Annual Meeting of the Association of State and Territorial Health Officers in 1967. However, a review of the actual contents of the speech revealed that it contains nothing even remotely resembling the alleged quote. To the contrary, Dr. Stewart actually said in that speech, ‘Warning flags are still flying in the communicable disease field. . . . While we are engaged in taking on new duties . . . we cannot and must not lose sight of our traditional program responsibilities [emphasis added].’ ”

I used to buy the line that today’s newspaper will be used to wrap fish tonight and will be forgotten tomorrow. If that was ever true, it clearly is no longer. Once a fact, an assertion, a quote, or a meme has been launched into cyberspace, it will orbit there forever. Unless somebody shoots it down.

I regret the repeated error, of course. More than that, though, I hope that the next time a journalist reaches for this handy example of myopia among our public-health leaders, he or she latches onto a foolish statement that somebody actually made. Sadly, there are plenty to go around.

*Clarification: This post has been updated to qualify when the author learned of the quote.