|The Black Death|
Estimates vary for the number of people killed by the Black Death that ravaged Europe from 1347 to 1351. But the number was certainly in the tens of millions; it is thought that as much as half of the entire European population at the time may have died.
Around 800 years before the Black Death hit Europe another plague swept through what was then the Eastern Roman, or Byzantine, Empire. Known as the Plague of Justinian. Again, estimates of the number of deaths vary, but they were likely also in the tens of millions, with one contemporary account estimating that as many as 100 million people may have died.
David Wagner, professor at Northern Arizona University in Flagstaff and the lead author of a new scientific paper says.
“In my mind, pretty much all plague [Y. pestis] strains around the world are capable of causing human disease, and if conditions were right, would probably be capable of causing these large pandemics again," But Wagner also stated he doesn’t think that there’s much of a chance of that happening. “What’s changed is not the organism. What’s changed is humans and the human condition,” he says. “Hygiene has improved immensely … you don’t just have rats all over the place like you might have had during the time of the major pandemics.” We also have antibiotics. “Plague is highly susceptible to simple modern antibiotics,”
So while the Black Death should probably not keep you up at night it is something that the world needs to keep an eye on.