Smallpox used to be one of the world’s deadliest illnesses.
The disease has existed for thousands of years, causing fevers, rashes, and death in 30% of cases, according to the World Health Organisation. There’s no treatment for the disease, but there have been vaccines to prevent it since 1796.
Even so, smallpox remained a huge problem through the 1900s, eventually being eradicated in the late 1970s. Now, the virus exists in two labs: one in the US and the other in Russia.
Here’s what the spread of smallpox looked like in the 20th century, including when eradication efforts began in the 1950s. The size of the circles represents how many cases there were that year in a particular geographic area. By 1980, the disease had been eradicated.
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