A recent email from Susan demonstrates the how quickly an interconnected globe becomes personal. A student at my nieces school near Cleveland was on the plane with the infected Ebola nurse from Dallas. Suddenly a infectious disease across the ocean is one degree from me (only if all the degrees aligned - contact of my niece with a student and then contact with me an my niece).
The simulation in the Washington Post article show the reason in black squares why this disease has people concerned:
Naturally, I couldn't resist researching the mathematics of disease. The key variable is the basic reproductive ratio, . The rate of increase of the disease over a generation. For measles this ratio is 12-18; for flu 2-6; for Ebola - the guess is 1.5 - 2.
So the good news is Ebola travels slowly - unless you travel by air!