Smallpox is an acute, contagious, and sometimes fatal disease caused by the variola virus, and marked by fever and a distinctive progressive skin rash. Prolonged face-to-face contact is required to spread smallpox from one person to another. Smallpox also can be spread through direct contact with infected bodily fluids or contaminated objects such as bedding or clothing.
The symptoms of smallpox begin with high fever, head and body aches, and sometimes vomiting. A rash follows that spreads and progresses to raised bumps and pus-filled blisters that crust, scab, and fall off after about three weeks, leaving a pitted scar. The majority of patients with smallpox recover, but death may occur in up to 30% of cases. In 1980, the disease was declared eradicated following worldwide vaccination programs. Smallpox can be prevented through use of the smallpox vaccine. Please see the vaccine information statement (VIS) below.
Smallpox is classified as a Category A agent by the Centers for Disease Control and Prevention. Category A agents are believed to pose the greatest potential threat for adverse public health impact and, broad-based public health preparedness efforts are necessary.