Figure 4.

Possible plague spreading pattern from port to inland in Europe, AD1347–1760. Plagues were carried from other permanent plague focus to major trade ports in Europe. The contagion will go further to the hinterland by major trade routes or navigable river connecting the major trade ports. By transporting through the major trade route, the contagion will eventually focus at major trade node, resulting in the formation of plague hotspot in historical Europe. The pathway from major trade route to plague hotspot would also pass through local trade route. Certain amount of contagion would enter nearby navigable rivers from major trade route or major trade node. The navigable rivers would further carry the contagion inland and create sporadic cases all over the European continent.