Frequently Asked Questions About Smallpox
What is smallpox?
Smallpox is a viral infection that causes a fever and a rash all over the body. A successful vaccination program has eliminated the naturally occurring disease in the entire world. However, smallpox has received recent attention as a potential weapon of biological terrorism. Smallpox is a deadly disease, but nearly 60% of infected people do survive.
Should I get a smallpox vaccination?
In the United States, routine vaccination against smallpox ended in 1972 and is not currently available. The Center for Disease Control and Prevention (the "CDC") maintains an emergency supply of vaccine. Use of the vaccine within four days following exposure to smallpox can reduce sickness and risk of death. Plans are underway to manufacture more smallpox vaccine.
How is smallpox spread?
Smallpox is spread from one person to another by face-to-face contact. A person with smallpox is most likely to spread smallpox to others during the first week of the illness but can continue to spread the disease until the smallpox rash heals and all the scabs fall off. Bed linen and clothes can spread the disease and special cleaning of these is necessary to prevent spreading the infection.
If a person has been vaccinated in the past, will they be immune?
Routine vaccination against smallpox ended in 1972. It is not known how long the protection against smallpox infection lasts. It is likely, but not certain, that prior vaccination will provide at least partial protection.
How does smallpox start? What does it look like?
A person infected with smallpox will first develop a fever to 101° F, tiredness, headache, backache, and maybe abdominal pain. After three to four days the rash appears. Most of the rash is on the face, lower arms and legs, and is less on the back and abdomen. The rash first appears as elevated bumps on the skin (papules), which change into small fluid filled blisters (vesicles), which then fill with pus (pustules), and then scab over. From beginning of illness to healing takes about 3 to 4 weeks. On any one part of the body (face, arm, leg, chest, or back) the rash is all the same type; that is, the rash appears either as papules, vesicles, pustules, or scabs.
What can be confused with smallpox?
The rash of chickenpox can be confused with smallpox, but there are a number of features that help distinguish between the two. Chickenpox is a disease mainly of children, and unlike smallpox, children with chickenpox do not have high fever, extreme tiredness, headache, backache, or abdominal pain. Adults with chickenpox may develop a fever, tiredness, and muscle aching. The rash is mostly on the chest and back, or found in equal amounts on the chest and back, face and extremities. Like smallpox, the rash of chickenpox changes from papules and vesicles to pustules and scabs, but with two important differences. First, the rash changes from papules to scabs in a day or two, rather than three or four weeks as seen with smallpox. Second, in chickenpox, papules, vesicles, pustules and scabs can appear together on any one part of the body (face, chest, back, extremities), rather than all looking the same; that is, all papules, vesicles, pustules or scabs as in smallpox.
Search this point-of-care decision support tool today. A free benefit of ACP membership.
Have questions about the new ABIM MOC Program?
One Click to Confidence - Free to members
ACP Smart Medicine is a new, online clinical decision support tool specifically for internal medicine. Get rapid point-of-care access to evidence-based clinical recommendations and guidelines. Plus, users can easily earn CME credit. Learn more