claimed 60 million lives "Smallpox: Conquered Killer" claimed 60 million lives smallpox Smallpox: Conquered Killer smallpox smallpox National Geographic: Smallpox – conquered killer "Smallpox: Conquered Killer" smallpox smallpox "Smallpox: Conquered Killer" "Smawwpox: Conqwered Kiwwer" "Smallpox: Conquered Killer" "Smallpox: Conquered Killer" http://science.nationalgeographic.com... 300-500 million people in the 20th century National Geographic: Smallpox – conquered killer