THE DEADLIEST VIRUSES STILL IN EXISTENCE

It doesn't matter how tough you are, how well you eat, how often you exercise, or how often you tell people that you're vegan, a virus doesn't discriminate. It sees everyone as a viable host, and that's what makes an outbreak so terrifying.

For example, one of the most devastating outbreaks in recent history — and by recent, we just mean within the last few hundred years — was the Spanish flu. It hit on the eve of World War I, was incubated in the unsanitary conditions of the front lines, and was spread all over the world by soldiers returning home in what should have been a happy occasion. According to the BBC, somewhere between 50 and 100 million people died during the Spanish flu outbreak, and that's unfathomable — especially considering the entirety of World War I had claimed around 20 million lives. 

In other words, viruses are no joke, and while no one is coming down with that particular strain of flu any more, there are plenty of ultra-deadly viruses still out there. Seriously, the world is crawling with terrifying diseases, some of which are relatively new and some of which have been around for a while. Whether they're spread by bats, dogs, or people, these are the deadliest viruses still in existence.