Bioterrorism

Smallpox

What is smallpox?

Smallpox is a highly infectious viral disease caused by the variola virus. Smallpox was common prior to and during the nineteenth century, but in 1977 the disease was eliminated from the world. In 1980, the World Health Organization (WHO) declared smallpox extinct and recommended that all countries cease vaccination. However, the virus is still maintained at laboratories at the Centers for Disease Control and Prevention (CDC) in the United States and at the Institute of Virus Preparations in Moscow, Russia.

Smallpox had been used as a biological weapon (an infectious agent or toxic chemical that is intended to cause mass destruction) as early as the French and Indian Wars in the 1700s. Deliberate reintroduction of smallpox as a biological weapon is still a threat, especially since declining financial support for Russian laboratories has increased the risk of the existing expertise and equipment falling into the wrong hands.

What are the symptoms of smallpox?

The incubation period for smallpox is between seven and 17 days following exposure, with the average being 12 days. The following are the most common symptoms of smallpox. However, each individual may experience symptoms differently. Symptoms may include:

initial symptoms:
- high fever
- fatigue
- head and back aches
a distinct rash that presents with the following characteristics, most often, two to three days after exposure:
- a rash starts with flat, red lesions, usually on the face, arms, and legs
- lesions become pus-filled and start to crust over early in the second week
- scabs form which then separate and fall off after three to four weeks

The symptoms of smallpox may resemble other medical conditions or problems. Always consult a physician for a diagnosis.

How is smallpox transmitted?

Smallpox can be spread from person to person through infected saliva droplets. A person is most infectious (contagious) during the first week of the illness. Risk of transmission remains until scabs have fallen off.

Treatment for smallpox:

Specific treatment for smallpox will be determined by your physician based on:

your age, overall health, and medical history
extent of the condition
your tolerance for specific medications, procedures, or therapies
expectations for the course of the condition
your opinion or preference

Most patients with smallpox recover. However, about 30 percent of smallpox cases are fatal. The smallpox vaccine, even when given four days after exposure, can lessen or even prevent illness. If a person does become ill, treatment may include supportive therapy such as intravenous fluids, fever and pain control, and antibiotics for secondary bacterial infections. Research is ongoing to evaluate new antiviral agents as treatment for smallpox.

About the smallpox vaccine:

Routine vaccinations against smallpox ended in 1972. However, the vaccine still exists and, when given during early symptoms of smallpox, can lessen the severity of the illness. Immunity among people vaccinated before 1972 is uncertain. The United States keeps an emergency supply of smallpox vaccine. Always consult your physician for more information.

This page was last updated on: May 23, 2006.

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