Smallpox is a contagious viral illness caused by the variola virus. The virus can spread from an infected person through the air when there is fairly prolonged (1-3 hours) direct contact. It can also spread via body fluids, either by direct contact with fluids from an infected person or by touching objects that have been contaminated by infected body fluids. The last documented case of smallpox disease occurred in 1977. However, smallpox is still considered a possible biological threat.
An infected person usually begins to experience symptoms 12 to 14 days after exposure. Smallpox disease results in a fever and viral-like symptoms, followed by a rash that progresses from papules to pustules. Eventually the pustules form scabs and the scabs fall off. People with smallpox can spread the virus to others beginning when their fever is 101°F until all their scabs fall off.
There is no proven cure for smallpox. Historically, death has occurred in about 30% of cases. Giving smallpox vaccine soon after exposure to the virus can help to reduce the effects of smallpox disease. Vaccine given within 3 days after exposure can help prevent death. Vaccine given within 7 days after exposure can result in a less severe (modified-type) smallpox illness.
There is only one smallpox vaccine available in the United States. It is a live, attenuated vaccine made from vaccinia virus. Vaccinia virus is closely related to variola virus, which is the virus that causes smallpox. Immunity against vaccinia virus also provides protection against variola virus. It is administered using a bifurcated needle that is jabbed into the surface of the skin.
To reduce the chance of spreading the vaccine virus to other body parts or other people, please follow these recommendations:
The Department of Defense reported its first case of inflammation in or around the heart (myopericarditis) after smallpox vaccination in early February 2003. As of January 2008, DoD has identified 161 cases of acute myocarditis and/or pericarditis among 1.4M smallpox vaccinees, with symptoms appearing 7 to 19 days after vaccination. These people had clinical conditions that varied from mild to moderate; the condition was severe in two cases.
Most cases occurred among those receiving smallpox vaccinations for the first time. Most cases occurred among men.
The health of our people is foremost in our priorities. These cases were followed carefully to evaluate their recovery, at 27 hospitals in 21 states and several countries overseas. Detailed follow-up cardiac testing is available in 46 cases: all had normal electrocardiograms (EKGs), echocardiograms ("echos") and normal treadmill test results. Based on our data and European experience, we have reason to believe these people should recover and remain well.