Smallpox

Key Points

There are no known cases of smallpox in the world at this time.
The potential release of smallpox by terrorists is a possibility and warrants resuming a phasedvaccination program in the United States.
The vaccine is safe for the vast majority of the population. Individuals for whom a vaccination is not recommended (pregnant women, those with suppressed immunity and certain skin conditions such as eczema) will be identified. Individuals having members of their household with those conditions should not be vaccinated as well, or remain away from household members for three-weeks following the vaccination.
In this phased approach, healthcare workers are first vaccinated, as they are most likely to initially treat a smallpox patient. Those less likely to be exposed will receive the vaccination later.

General Information

Someone infected with smallpox will become very sick before they are likely to become contagious and would therefore be unlikely to spread the disease to the public in general.

If someone is exposed to smallpox and receives the vaccine within four days, their risk of developing the disease is greatly reduced.

Smallpox is believed to have originated thousands of years ago; it is a disease affecting only humans.

Epidemics of this devastating disease swept across continents killing large populations and literally changing the course of history. Thirty percent of those infected died and the survivors were left with scars and often blinded.

In 1796, Edward Jenner discovered inoculation with cowpox virus could protect against smallpox.

Currently, there is no evidence of smallpox transmission anywhere in the world.

The last natural case of smallpox in the United States occurred in 1949
The last natural case of smallpox in the world occurred in Somalia in 1977.
Vaccinations in the United States for the general public ended in 1972 and in 1990 for the military.
In 1980, the World Health Organization (WHO) declared the global eradication of smallpox and recommended that all countries cease vaccination.
The WHO recommended all labs throughout the world destroy their stocks of the virus or transfer them to one of two WHO reference laboratories in the former Soviet Union or the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.
Until recently, the only people indicated for the vaccination were researchers, scientists and medical professionals directly involved with the smallpox virus or other closely related viruses.

Progression of smallpox

Incubation Not contagious	Incubation period is 7-17 days (usually 12-14) from exposure to first symptoms. Patient feels fine and is not contagious at this stage.
Initial Symptoms (Prodrome) (Duration: 2 to 4 days) Sometimes contagious*	The first symptoms of smallpox include fever, malaise, head and body aches, and sometimes vomiting. The fever is usually high, in the range of 101 to 104 degrees Fahrenheit. At this time, people are usually too sick to carry on their normal activities. This is called the prodrome phase and may last for 2 to 4 days.
Early Rash (Duration: about 4 days) Most contagious	A rash emerges first as small red spots on the tongue and in the mouth. These spots develop into sores that break open and spread large amounts of the virus into the mouth and throat. At this time, the person becomes contagious. Around the time the sores in the mouth break 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 the rash spreads to all parts of the body within 24 hours. As the rash appears, the fever usually falls and the person may start to feel better. By the third day of the rash, the rash becomes raised bumps. By the fourth day, the bumps fill with a thick, opaque fluid and often have a depression in the center that looks like a bellybutton. (This is a major distinguishing characteristic of smallpox.) Fever often will rise again at this time and remain high until scabs form over the bumps.
Pustular Rash (Duration: about 5 days) Contagious	The bumps become pustules - sharply-raised, usually round and firm to the touch as if there's a small round object under the skin. People often say the bumps feel like BB pellets embedded in the skin.
Pustules and Scabs (Duration: about 5 days) Contagious	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.
Resolving Scabs (Duration: about 6 days) Contagious	The scabs begin to fall off, leavi ng marks on the skin that eventually become pitted scars. Most scabs will have fallen off three weeks after the rash appears. The person is contagious to others until all of the scabs have fallen off.
Scabs resolved Not contagious	Scabs have fallen off. Person is no longer contagious.

* Smallpox may be contagious during the prodrome phase, but is most infectious during the first 7 to 10 days following rash onset.

Terms

Bifurcated needle - a small, two-pronged needle holding a drop of vaccine used to prick the skin and administer the vaccine.

Vaccinia immune globulin - a treatment used to treat severe side effects of the vaccination. It is made from the plasma of people who've recently been vaccinated.

Ring vaccination - the procedure of isolating infected patients and vaccinating those in close contact with them and vaccinating their close contacts, forming a "ring" of immunization as a barrier to the spread of the disease.

Diluent - liquid used to reconstitute the vaccine before use.

National Pharmaceutical Stockpile - a program from the Centers for Disease Control and Prevention (CDC) to ensure the availability and rapid deployment of life-saving pharmaceuticals, antidotes, other medical supplies, and equipment necessary to counter the effects of nerve agents, biological pathogens, and chemical agents. The NPS Program stands ready for immediate deployment to any U.S. location in the event of a terrorist attack using a biological toxin or chemical agent directed against a civilian population.

Family of Orthopox viruses includes:
Variola - the virus which causes smallpox.
Vaccinia - the virus used as a vaccine which helps the body to develop immunity against smallpox.

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Information provided by the Center for Disease Control and Prevention and the Ohio Department of Health
Contact: ODH Public Affairs (614) 644-8562 for additional information.

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Last Updated: 05/05/2004