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1. What is smallpox?

Smallpox is caused by the variola virus.

2. When was the last case of smallpox reported in the United States?

Smallpox infection was eliminated from the world in 1977.

3. What is the incubation period for smallpox?

The incubation period is seven to 17 days following exposure.

4. What are the symptoms of smallpox?

Initial symptoms of smallpox include high fever, fatigue, and head and back aches. A characteristic rash, most prominent on the face, arms, and legs, follows in two to three days. The rash starts with flat red lesions that evolve at the same rate. Lesions become pus-filled and begin to crust early in the second week. Scabs develop and then separate and fall off after three to four weeks. The majority of patients with smallpox recover, but death occurs in up to 30% of cases.

5. How is smallpox spread?

Smallpox is spread from one person to another by infected saliva droplets that expose a susceptible person having face-to-face contact with the ill person. Persons with smallpox are most infectious during the first week of illness, because that is when the largest amount of virus is present in saliva. However, some risk of transmission lasts until all scabs have fallen off.

6. Is a smallpox vaccine available?

The United States currently has an emergency supply of smallpox vaccine.

7. Is there a treatment for smallpox?

There is no proven treatment for smallpox, but research to evaluate new antiviral agents is ongoing. Patients with smallpox can benefit from supportive therapy and antibiotics for any secondary bacterial infections that occur.