It has been
theorized by
William H. McNeill in
Plagues and Peoples that the
silk road, the overland route from
The East, that brought the
Black Death to
Europe.
He speculates that it was Venice, the hinge of Europe, (and the title of one of his books), that radiated this disease throughout the western world.
In this, he illuminates the role transportation always has, and more importantly, still plays today in the spread of disease. Jets can bring ebola fever, or some other highly contagious disease to North America in a matter of scant hours.
Rather than religion, or ignorance that brings us disease, it is technology and intelligence.