3. The Black Death
Bubonic Plague would be responsible again during an outbreak from 1346 to 1353, this time claiming the lives of an estimated 75 million, possibly as many as 200 million as it cut a path of destruction across three continents, Europe, Africa and Asia, where the outbreak was believed to have originated.
The plague was likely spread by fleas living on rats that boarded ships which were sailed to ports across the world.
4. The Third Cholera Pandemic
Of the seven cholera pandemics, the third outbreak from 1852 to 1860 was generally considered the most deadly as it took 1 million people with it. The previous pandemics, like this one, originated from India spreading from the Ganges River Delta before making its way across Asia, Europe, North America and Africa.
British physician John Snow, while working in a poor area of London, tracked cases of cholera and eventually succeeded in identifying contaminated water as the means of transmission for the disease.