Diseases That Threaten Humanity

Published: Dec 17, 2013, 3:16 PM EST weather.com

An American policeman wearing a mask to protect himself from the outbreak of Spanish flu following World War I, ca. 1918. (Topical Press Agency/Getty Images)

While it's impossible to calculate the odds of a disease wiping out humanity (Are they better or worse than an asteroid hitting earth? What about a robot uprising?), this staple subject of both page and screen contains a kernel of truth. There are diseases out there in the world that pose a substantial risk to humankind. There are diseases that have attacked us already, killing millions upon millions. What follows are five diseases that, given the perfect, deadly mutation and the right push could lay siege to humanity.

And at the the end of this list there's a kind of bonus: a disease that once would have been listed here, which ravaged humankind, killing upwards of 300 million people in the 20th century alone. But decades ago humanity struck back, eradicating it from the face of the earth.


It's believed that flu pandemics have occurred throughout human history, when especially nasty strains of influenza virus spread globally. The deadliest of these waves that we know about was the 1918 "Spanish" flu outbreak that according to flu.gov infected between 20 and 40 percent of the worldwide population and killed approximately 50 million people. With its high mutation rate and ability to spread easily, the flu virus remains a constant risk to humanity. Just as recently as 2009, the H1N1 strain of flu is believed to have killed hundreds of thousands of people. 

While the flu shot is not perfect - this year's version was less effective for the elderly for reasons that are unclear - the CDC recommends that everyone over the age of six months old get a flu shot.

The slideshow above shows photos from some notable outbreaks of the flu.

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