It’s that thing that’s going around

We’ve had three up/down weather cycles in the last ten days (25-35 degree temperature differences in the daytime highs), and that almost always gives me laryngitis.  This time was no exception.  The laryngitis wasn’t bad–one crummy day and then a come-back–but it was followed by something evil that took me downhill for three days.  This is the fourth day and I think I bottomed out yesterday, because I feel a little better today.  I assume that in 7-10 days, I’ll be fine.  Sooner would be good.

Question:  When you get sick in the winter, why does everyone blame it on “that thing that’s going around”?  Does “that thing” ever “go around” in other seasons?