Smallpox
Smallpox, the most universally feared disease, killed nearly three hundred million people in the twentieth century alone. This is three times more than all the wars in the twentieth century combined. This virus does not infect animals, and it is limited to humans. Its course starts as an acute disease that produces distinct skin lesions, then afterwards leaves distinctive pock marks on the face of the survivor. Then after a ten to fourteen day incubation period in which the infected can still remain active, headache, fever and weakness suddenly occur. …
