Noun
The smallpox.
Source: Webster's dictionaryEdward Jenner had also discovered vaccination using cowpox ( Vaccinia ) to give cross-immunity to smallpox in 1796, and by Pasteur's time this had generally replaced the use of actual smallpox ( Variola ) material in inoculation. Source: Internet
Smallpox (Variola major and Variola minor) began to spread in Mesoamerica immediately after the arrival of Europeans. Source: Internet