Studying Smallpox: A Brief History of the Killer

While Americans are concerned about anthrax, some experts say that a greater danger would be if highly contagious smallpox was released. With limited doses of smallpox vaccine stockpiled, researchers are now studying whether a diluted version could multiply the existing supply of the vaccine.

Dr. Sharon Frey of the St. Louis University School of Medicine is the lead investigator for the study. She spoke with the Early Show about the study--why it is so important, what exactly smallpox is, why we don't have enough vaccine, and how big a health threat smallpox is.

The Virus

Smallpox is caused by variola, one of the largest and most complex of viruses. Once one of the most feared diseases, smallpox has been eliminated by the use of vaccines. In the 20th century alone, it killed up to 500 million people.

Brief History

The origin of smallpox is unknown, but it has left a trail of misery.

10,000 BC: First known outbreaks of smallpox occur among agricultural settlements in northeastern Africa.
1796: Edward Jenner injects a boy with the first smallpox vaccination, made from a dairy maid's cowpox lesion.
1800-1801: Vaccination, usually among infants, spreads throughout Europe, North America, and Russia.
Late 1800s to early 1900s: Despite widespread infant vaccination, epidemics continue to occur.
1949: Last US case is reported in Texas.
Early 1950s: Smallpox is eliminated in Europe, North America, and Central America.
1972: The United States ends its requirement for routine vaccination.
1980: Declared eradicated worldwide.
1999: The United States decides to keep its smallpox stock, reversing earlier decision. Later, World Health Organization delays decision.

Vaccines

The World Health Organization declared in 1980 that smallpox had been eradicated and recommended that countries halt vaccinations. Despite federal precautions, many say the US health system is ill equipped to manage the fallout from a large-scale bioterrorist attack.

Smallpox is given a high priority because it has no cure, and about 30% of its victims do not survive the painful, disfiguring disease.

Only 6 million to 7 million doses of vaccine remain, although a fresh batch of 40 million doses is expected next summer.

How the Disease Progresses

Incubation: The virus enters the body through the mouth or nose. Once inside the cells, it uses the cells' own materials to replicate itself. The virus travels from the respiratory tract to regional lymph nodes and then spreads to other lymphatic organs (spleen, bone marrow, and so on) and to small blood vessels in the skin.
First symptoms: At the end of the incubation period, the patient experiences high fever, headache, backache, abdominal pain, and in some cases delirium.
The rash: A rah appears first on the tongue and roof of the mouth and then on the face, hands, and forearms. The rash spreads to the arms, legs, and trunk.

Unlike in the case of chickenpox, the spots on the trunk are more scattered, and all skin lesions are in the same stage of development at a given moment.

The rash quickly progresses from flat spots to small blisters and eventually to pustules. If the patient recovers, the rash forms scabs and later scars.

Death: About a third of the victims die, mainly as a result of bleeding, cardiovascular collapse, and secondary infections.

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