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Elizabeth Fenn: The history of the smallpox virus

Elizabeth Fenn is an assistant professor of history at George Washington University. She is the author of "Pox Americana," a book studying a smallpox epidemic that took place in North America during the years of the Revolutionary War. She joined the chat room from North Carolina.

CNN: Welcome to Dr. Elizabeth Fenn. Thank you for joining us today.

DR. ELIZABETH FENN: Thank you very much, and I'm happy to be here today.

CNN: Most of us have never heard much about the major smallpox outbreak during the Revolutionary War that you discuss in your book, "Pox Americana." Can you tell us how this epidemic affected the course of the Revolutionary War?

FENN: It had a dramatic effect on the early episodes. There's some evidence that indicates that it helped to keep George Washington and the Continental Army from pursuing the British into Washington in 1775 and 1776, and also wreaked havoc on the American soldiers when they invaded Canada and tried to make Canada the 14th colony involved in the rebellion.

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    CNN: Does anyone know the source of this historic outbreak -- where it originated?

    FENN: We really don't know. It appears that smallpox was present in Canada when the American troops got there, but once it took hold in this crowded camp, the effects were devastating. Likewise, the virus appears to have been present outside of Boston at the time of the battles of Lexington and Concord.

    CHAT PARTICIPANT: Did Europeans bring this disease to Indians?

    FENN: They certainly did, in the 1500's. Smallpox was an old world disease that had never appeared in the Americas before the arrival of Europeans and Africans.

    CHAT PARTICIPANT: How is smallpox transmitted?

    FENN: Smallpox is almost exclusively transmitted from one human being directly to another. This is what makes it so interesting for a historian, because you can track connections between people, by watching epidemic smallpox move.

    CHAT PARTICIPANT: Is it true that in [those times], the patient with smallpox would actually die from the [treatment], rather than the smallpox itself?

    FENN: It certainly could be true. Medical treatments in the 18th century included ingesting great quantities of mercury, and also bleeding. Neither of these are good for the patient. American Indian treatments for smallpox sometimes included sweating in a sweat lodge, followed by immersion in an ice cold stream or lake.

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    CHAT PARTICIPANT: Is this a virus or bacterium?

    FENN: It is a virus. In the 18th century, it was a virus known as Variola major, but late in the 1800's, another smallpox virus emerged, which we now know as Variola minor. It's a different strain of the virus. It's a less virulent strain.

    CHAT PARTICIPANT: Ms. Fenn, did not the British use smallpox as a weapon in the 1800's?

    FENN: They did. The best documented incidence of this was in 1763, during Pontiac's rebellion, when officials and fur-traders at Fort Pitt, now the site of Pittsburgh, deliberately gave smallpox-contaminated blankets to the Indians.

    CNN: How long did it take to finally eradicate smallpox?

    FENN: The eradication campaign in a way can be traced back to Edward Jenner's development of vaccination in 1796, a procedure which he then wrote about in a book in 1798. It's really vaccination that enabled the eradication of smallpox to even be possible. The World Health Organization's eradication campaign really lasted for about 20 years. It culminated in the final certification of eradication in 1979.

    CHAT PARTICIPANT: Are those of us who have been vaccinated for small pox in the forties still protected?

    FENN: I wish we were! The vaccination for smallpox confers immunity only temporarily. While smallpox was still around, people were expected to be re-vaccinated periodically, every three to five years, I believe.

    CHAT PARTICIPANT: Can the smallpox virus be eliminated using ultraviolet irradiation?

    FENN: I believe it can. It does degrade when exposed to ultraviolet light.

    CNN: How great a threat is a bioterrorism attack with smallpox today?

    FENN: There are really two things to remember about smallpox. First, it depends on having a population of susceptible individuals. Second, it depends upon connections between those individuals. This is because it's a disease contagious from one person to another. In both of those regards, we are more vulnerable today, odd though it seems, than in the 1700s. So, if an incident were to occur, the consequences certainly could be disastrous.

    CHAT PARTICIPANT: It's been reported that personnel are being vaccinated against smallpox now at the Centers for Disease Control. Is this a sign of things to come in your opinion?

    FENN: I don't know. That's the best answer I can give. The people who are privy to intelligence reports could certainly answer that question better than I could. To me, it indicates that they know something that gives them great concern.

    CHAT PARTICIPANT: Is the U.S. prepared to vaccinate all?

    FENN: I know that they have some vaccines prepared already, and they are working on a diluted vaccine, and on producing more vaccine. So certainly, we can vaccinate some people. I think currently we have 15 million doses, although I'm not sure of that number.

    CHAT PARTICIPANT: What do we look for? What are symptoms, does it appear on the face? Is it contagious in its early stages, before we see the 'spots'?

    FENN: That's a great question. One of the things that's frightening about smallpox is that it has long legs. By that, I mean that because it has a 12 day incubation period, during which you have no symptoms, this disease can really travel. So you go through a 12 day incubation period, and then you start feeling crummy. You develop a fever, a headache, a terrible backache. Sometimes you develop vomiting. After three or four days of that, you develop pustules inside your mouth and throat. At this point, you are now contagious. A couple of days later, the pustules erupt on the surface of your skin, in the classic smallpox rash. You are contagious throughout this period, until, if you live, the last scab falls off. So, the entire course of the disease runs about one month.

    CHAT PARTICIPANT: Do you feel that if an outbreak of any size were to occur in today's society in the U.S. that we would be able to contain it?

    FENN: I don't know, and that's my concern.

    CNN: Do you have any closing comments for us today?

    FENN: One of the things that's striking to me about the present day, is how sad it is that all the nations of the world were able to cooperate through the belligerency of the Cold War, to eradicate this disease in 1979, in the middle of the Cold War. And now, with the Cold War over, it appears that that monumental human effort could unravel. That's a very sad thing, a human tragedy of sorts.

    CNN: Thank you for joining us today, Dr. Elizabeth Fenn.

    FENN: Thank you very much. I've enjoyed it.


    • Centers for Disease Control and Prevention
    • 'Pox Americana'

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