Signs and Symptoms

This stage can last anywhere from 7 to 19 days (although the average length is 10 to 14 days).

Contagious? No

The incubation period is the length of time the virus is in a person’s body before they look or feel sick. During this period, a person usually has no symptoms and may feel fine.

This stage lasts anywhere from 2 to 4 days.

Contagious? Sometimes. Smallpox may be contagious during this phase, but is most contagious during the next 2 stages (early rash and pustular rash and scabs).

The first symptoms include:

• High fever
• Head and body aches
• Sometimes vomiting

At this time, people are usually too sick to carry on their normal activities.

By the fourth day, the skin sores fill with a thick, opaque fluid and often have a dent in the center.

This stage lasts about 4 days.

Contagious? Yes. At this time, the person is most contagious.

A rash starts as small red spots on the tongue and in the mouth. These spots change into sores that break open and spread large amounts of the virus into the mouth and throat. The person continues to have a fever.

Once the sores in the mouth start breaking down, a rash appears on the skin, starting on the face and spreading to the arms and legs, and then to the hands and feet. Usually, it spreads to all parts of the body within 24 hours. As this rash appears, the fever begins to decline, and the person may start to feel better.

By the fourth day, the skin sores fill with a thick, opaque fluid and often have a dent in the center.

Once the skin sores fill with fluid, the fever may rise again and remain high until scabs form over the bumps.

By day 6 of the rash, the sores become pustules.

This stage lasts about 10 days.

Contagious? Yes

The sores become pustules (sharply raised, usually round and firm to the touch, like peas under the skin).

After about 5 days, the pustules begin to form a crust and then scab.

By the end of the second week after the rash appears, most of the sores have scabbed over.

By the end of the second week after the rash appears, most of the sores have scabbed over.

This stage lasts about 6 days.

Contagious? Yes

The scabs begin to fall off, leaving marks on the skin.

Three weeks after the rash appears, most scabs will have fallen off.

Contagious? No.

Four weeks after the rash appears, all scabs should have fallen off. Once all scabs have fallen off, the person is no longer contagious.