World Health Organization gets ready for 'Disease X'

By Susan Scutti, CNN

Updated 1627 GMT (0027 HKT) March 12, 2018

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There were 216,000 global cases of leprosy, an ancient and disfiguring disease, in 2013.
Photos: 10 diseases you thought were gone
There were 216,000 global cases of leprosy, an ancient and disfiguring disease, in 2013.
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In the 19th century, scarlet fever was a common killer in Europe. In 2016, nearly 20,000 cases were reported in the United Kingdom -- the biggest increase in 50 years.<br /><br />Scarlet fever is just one disease that many have forgotten but that is by no means gone, despite our best efforts to eliminate it.
Photos: 10 diseases you thought were gone
In the 19th century, scarlet fever was a common killer in Europe. In 2016, nearly 20,000 cases were reported in the United Kingdom -- the biggest increase in 50 years.

Scarlet fever is just one disease that many have forgotten but that is by no means gone, despite our best efforts to eliminate it.
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Though it's often thought of as a medieval disease, the World Health Organization reports 1,000 to 3,000 global cases of plague every year. The US averages seven new human cases a year, <a href="https://www.cdc.gov/plague/maps/index.html" target="_blank">mostly in the Southwest</a>. Pictured, a patient with gangrene and necrosis, caused by plague.<br />
Photos: 10 diseases you thought were gone
Though it's often thought of as a medieval disease, the World Health Organization reports 1,000 to 3,000 global cases of plague every year. The US averages seven new human cases a year, mostly in the Southwest. Pictured, a patient with gangrene and necrosis, caused by plague.