Amid all the bleak forecasts about Swine Flu, it’s timely (and far less worrying) to reflect once more on the role epidemics play in marketing.

This subject, was first popularized in Malcolm Gladwell’s The Tipping Point, a book which like its subject, has spawned a thousand virulent mutations. 

My friend Lisa Flattery recently alerted me to a superbly documented example of a social epidemic, in an article by Chris Wilson in Slate. 

Wilson polled his readers on when they first encountered a “25 Things” note on Facebook.  If you’re on Facebook, you can’t have escaped this phenomenon at the beginning of the year.  It’s a sort of mini-profile made through a list of personal idiosyncrasies.  It seemed to explode over a couple of weeks and then disappear altogether.  Wilson wanted to find out why. 

He notes that “’25 Things’ wasn’t always ‘25 Things’”.  It stated as a chain letter called “16 Random Things You Know About Me”.  Similar lists had appeared on Friendster, My Space and other sites.  Wilson continues:

“Like any disease, “Random Things” was mutating in hopes of finding a strain uniquely suited to its host.  In this case, the right number was vital to its survival:  The more people who are tagged, the more likely the note is to spread.”  The list eventually stabilized at “25 Things”.  It then spread rapidly, starting on January 20^th and fizzling out towards the end of the month.

I think that there are three big lessons from this case for marketers.

Firstly, it shows the importance of recency.  There’s a graph in the article that shows the date that users first wrote their own notes, after being tagged by someone else.  17 percent of people did it the same day, the median is three days and there is a sharp decay from there.  Lauren Ancel Meyers, a specialist in infectious diseases at the University of Texas, likens this to radioactive decay.  We’ve seen this elsewhere.  If credit card holders don’t activate within 90 days of receiving the card, they won’t activate at all.

Second is the importance of mutation.  “25 Things” would never have taken off at all if it hadn’t been allowed to find it’s most successful form.  In a world of ‘open source marketing’, customers have to be allowed to ‘play’ with brands and reinvent them to their own ends.

Thirdly, fads are fads.  They do mutate, but when successful, they quickly run out of people to infect.  As Wilson says:  “All in all, Facebook infections look remarkably similar to human ones.  And like organisms, the odds do seem stacked against all but the fittest of memes”. 

Hopefully, swine flu will turn out to be a fad too.