Hello and welcome to the History of Japan podcast, episode 469, The Vaccinators, Part 1.

I imagine that these days, when you hear the word smallpox, you don't have much of a

reaction, if you have one at all. The last known natural infection of smallpox was in

1977, and in 1980, the World Health Organization declared

it to have been eradicated, the only disease we have ever managed to accomplish that with.

But that's a relatively recent accomplishment.

For much of human history, smallpox, a common name for infections of variola virus, was an absolute terror.

It's been with us for basically all of human history.

The disease is thought to have first jumped from rats to humans over 10,000 years ago,

and we have evidence of infections as far back as Egyptian mummies from the 1500s BCE.

There are several different strains of variola virus which I will not bother you with the names of.

The disease's mortality rate varies a great deal based on the strain.

The most common form, ordinary smallpox, it's called, was around

30%. Less common were haemorrhagic strains, which were almost always fatal. Regardless

of the precise strain, the fact that smallpox can be transmitted via aerial droplets from an

infected person meant it could spread very quickly, making outbreaks

very difficult to contain.

The best estimates from the WHO suggest that in the century before smallpox was eradicated,

this transmissibility made it an enormous killer.

Smallpox was probably responsible for about half a billion deaths in the span of those 100 years.

In addition to the usual symptoms associated with any sort of viral infection, fever, chills, aches, all that good stuff,

smallpox is most readily identifiable by the skin rashes it causes.

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