What is smallpox?

Smallpox is a contagious and sometimes fatal disease caused by the variola virus which is characterized by a distinctive progressive skin rash.

In 1980, the disease was declared eradicated following worldwide vaccination programs. However, in the aftermath of the events of September and October, 2001, the United States government is taking precautions to be ready to deal with a bioterrorist attack using smallpox as a weapon.

As a result of these efforts the Centers for Disease Control and Prevention (CDC) developed a detailed nationwide smallpox response plan designed to quickly vaccinate people and contain a smallpox outbreak.

How is smallpox spread?

Smallpox normally is spread in the air by tiny droplets from the mouth or nose of infected persons. Generally, direct face-to-face contact is required to spread smallpox from one person to another. It can also be spread by direct contact with skin eruptions, bodily fluids or contaminated objects such as bedding or clothing.

Indirect spread is less common. Rarely, smallpox has been spread by virus carried in the air in enclosed buildings and trains. Smallpox is not known to be transmitted by insects or animals.

What are the symptoms of smallpox?

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 that crust, scab, and fall off after about three weeks, leaving a pitted scar.

If someone comes in contact with smallpox, how long does it take to show symptoms?

After exposure, it takes between seven and 17 days for symptoms of smallpox to appear (average incubation time is 12 to 14 days).

During this time, the infected person feels fine and is not contagious. A person with smallpox is sometimes contagious with onset of fever, but the person becomes most contagious with the onset of rash. At this stage the infected person is usually very sick and not able to move around in the community.

The infected person is contagious until the last smallpox scab falls off.

The Smallpox Disease Chart webpage details smallpox symptoms.

If I am concerned about a smallpox attack, can I go to my doctor and get the smallpox vaccine?

At this time, the smallpox vaccine is not available for members of the general public. In the event of a smallpox outbreak, however, there is enough smallpox vaccine to vaccinate everyone who would need it.

Visit the Smallpox Vaccine webpage to learn more.

For information about the smallpox vaccine and heart disease, visit the Smallpox and Heart Disease webpage.

Is smallpox fatal?

The majority of patients with smallpox recover, but death may occur in up to 30 percent of naturally-acquired cases. Many smallpox survivors have permanent scars over large areas of their body, especially their face. Some are left blind.

Is there a treatment for smallpox?

There are no medicines available to treat smallpox once the lesions begin to develop. Antiviral medicines are sometimes useful at preventing the development of smallpox if they are given to a person immediately after exposure to the disease.

Supportive care (e.g., intravenous fluids, medicine to control fever or pain and antibiotics for any secondary bacterial infections that may occur) is the primary therapy available.

How serious is the smallpox threat?

The deliberate release of smallpox as an epidemic disease is now regarded as a possibility, and the United States is taking precautions to deal with this possibility.

Smallpox is classified as a Category A agent by the CDC. Category A agents are believed to pose the greatest potential threat for adverse public health impact and have a moderate to high potential for large-scale dissemination.

Where can I get more information?

Additional information about smallpox can be found on the Centers for Disease Control and Prevention’s website at www.cdc.gov.