A scarring and often deadly illness passed from person to person that is caused by the smallpox virus.

Smallpox is a serious viral illness that can cause scarring and death. Smallpox was wiped out worldwide by 1980. It no longer lives in the natural world. But researchers have kept samples of the virus in labs for study.

Symptoms of smallpox show up about 7 to 19 days after a person has contact with the virus. Symptoms include fever, tiredness and muscle aches. Then flat spots appear on the body. They become blisters before they scab and fall off, and they can leave scars.

Antiviral medicines might treat smallpox, but they haven't been tested in people with the condition. A vaccine can prevent it. But most people don't get the vaccine because the risk of getting smallpox is so low.