Swine flu, smallpox, bird flu, plague, HIV. These are among the most frightening and uncontrollable means that Earth is using to kill all of us. Sometimes our medicines and countermeasures ward off disease. Other times, microbes get the upper hand, infecting and killing millions of people in a matter of years in what's called a pandemic, a disease that infects people across a huge geographical area.
The Black Death was one of the most infamous pandemics in history. In 1347, it spread from China to Europe via trade ships. Dying sailors were stricken with the black boils that gave the disease its awful name. Caused by an airborne bacteria, it spread at a breakneck pace around the world, and it hit Europe harder than anywhere else.
By some estimates, the bacteria wiped out around 200 million in just a couple of years. Lower estimates are still staggering, at roughly 75 million. There are estimates that indicate that 60 percent of London's the population was killed by the Black Death.
The Black Death is simply one example of a pandemic. There have been others, like the 1918 Spanish Flu that killed around 200,000, or the HIV outbreak, which is ongoing and has killed perhaps 25 million people. It's further proof that the smallest enemies are sometimes the worst.