The world is swarming with deadly pandemics, epidemics, diseases, and the history of humanity can certainly attest to this fact. There have been many instances spanning our existence of historic epidemics that threatened humanity. While we are typically alarmed by more modern diseases and viruses such as AIDS or influenza, many scary health epidemics have been known to resurface over time. These illnesses that almost wiped out humans seem like something that could only happen in the distant past, but be warned: if we're not careful, future diseases could threaten to end humanity as we know it.