EPIDEMICS

Dinner on the Norsk vessel Vesterhalen

Those glasses of wine were >$10

What is an epidemic, you ask?  Well, most would agree that it is a sudden upsurge in some natural phenomenon – usually a disease.  Take the Black Death, for instance.  It arose suddenly, spread like lightning, and killed half of Eurasia.  Several times, in fact.  The Black Death is what we geologists might term the type locality of epidemics.  Zika might qualify as this sort of epidemic, but for the fact that it is spread by a fat, lazy little toad of a mosquito that is averse to travel.  To contract Zika you have to go to the mosquito, not vice versa.  So, don’t be stupid.

There is another type of epidemic which I will term a “media epidemic.”  Take earthquakes, for example.  The frequency and severity of earthquakes vary over the short term, of course, but the average over periods of years is reasonably constant.  As far as I know there are no long-term trends.  However, the media will leap on any significant seismic event – and then pay unwarranted attention to other such events, wherever they occur and regardless of how insignificant they may be.  The result is to give the false impression that the earth is about to shake itself into a bunch of little pieces!  Once, a long time ago, I was stuck in a mountain hut with three young men in the grip of such a media epidemic; they were sure that we were entering the End of Days.  Being young and foolish I tried to talk them out of it.  When my party left the next morning I believe they were praying for my soul.

Well, the Ingwalls have alerted me to another kind of epidemic – an epidemic of over-diagnosis.    It is only human to celebrate the appearance of a tool or technique that makes your life’s work simpler to accomplish – and to use the hell out of it.  Such it is with all these new imaging gadgets:  ultrasound, MRI, CT, etc.  These and other modalities may allow you to detect more “anomalies”, cancers, for instance, than previously, but they don’t say much at all about their “penetrance” (likelihood to cause trouble.)  This is illustrated by the recent history of thyroid cancer.  In many countries diagnosis of thyroid cancer suddenly has increased many-fold, leading to a proportional increase in the number of surgeries.  However, pathology shows that many (most?) of these surgeries were unnecessary – the “cancer” involved was never going anywhere.  What to do?  How about the old standby, watch and wait?

In passing, it should be easy to distinguish a diagnostic epidemic from a real one.  Just examine the death statistics.   

http://www.nytimes.com/2016/08/23/health/got-a-thyroid-tumor-most-should-be-left-alone.html?smprod=nytcore-ipad&smid=nytcore-ipad-share&_r=0