Model explains bubonic plague’s persistence

After bubonic plague reached Europe in the 14th century, major cities such as Venice enacted strict quarantines intended to keep out infected, shipborne rats. The cities would remain free of the disease for a time, but every decade or so, the plague returned. People have presumed that infected rats had sneaked back into town.

Challenging that assumption, computer modeling of how bubonic plague spreads from rats to people now suggests that the disease never went away.