Smallpox is a contagious disease caused by the variola virus. The variola virus is the causative agent of smallpox. It can infect humans due to its ability to bypass the human’s immune responses and complement activation. Smallpox gets its name from pus-filled blisters that form during the illness. It was one of the world’s most devastating diseases known to humanity. Smallpox was responsible for an estimated 300-500 million deaths during the 20th century.
Symptoms of smallpox include: fever, headache, fatigue, vomiting, and severe pain in the back. Eventually symptoms would go away but, a rash would appear. The rash would begin on the face then spread to the hands, forearms, and the main point of the body.