TRAFFIC: Carl Zimmer and Richard Preston

May 12, 2011
By

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Welcome back to TRAFFIC, a Chicago Blog series featuring leading figures from across the humanities and sciences, whose prescient views on current events help us to interpret contemporary culture. We’re delighted to continue this month’s Friday TRAFFIC features, led by popular science writer Carl Zimmer. This week Zimmer welcomes Richard Preston, New Yorker contributor and bestselling author, for a conversation on smallpox and the possible eradication of other viruses.
Richard Preston is the author of seven books, including The Hot Zone, The Cobra Event, and The Demon in the Freezer. He is a regular contributor to the New Yorker, and his awards include the American Institute of Physics Award and the National Magazine Award. Preston also the only person who isn’t a medical doctor ever to receive the Centers for Disease Control’s Champion of Prevention Award for public health.


Should Smallpox Be Put To Death?

Dear Carl:
There’s a debate in the scientific community about what to do with the remaining stocks of smallpox virus on the planet. Should the virus be preserved so that it can be studied? Or should the virus be destroyed, so that—in theory at least—it would become extinct and would not threaten the human species again?
Smallpox virus, or Variola major, is the cause of probably the worst infectious disease in human history. During the nineteenth and twentieth centuries, experts believe that smallpox killed half a billion people, accounting for far more deaths than all the wars of the time. Smallpox is a grisly and supremely painful disease. The disease has around a 33 percent case-fatality rate in unvaccinated patients. That is, a third of the disease’s victims who haven’t been vaccinated die. The victims suffer from an incredibly painful rash—blisters known as pustules stud the body. The survivors are typically left with scars for life. About ten percent of fatal smallpox cases consist of hemorrhagic smallpox, a manifestation of the disease in which the victim dies with hemorrhagic symptoms, including bleeding from the orifices. Smallpox virus spreads in the air from person to person, traveling in tiny droplets spewed when an infected person speaks or coughs. The vast majority of the world’s population today has little or no immunity to smallpox, because vaccination ceased during the 1970s.

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Smallpox was declared eradicated globally in 1980 by the World Health Organization (WHO), after a remarkable and heroic WHO-led effort to eradicate the virus worldwide. Today, the only remaining samples of live smallpox virus are stored in just two locations: a high-security lab at the Centers for Disease Control in Atlanta, Georgia, USA, and in the Vector State Research Center in Siberia, Russia. For a number of years, now, various member nations of the WHO have been pressing the WHO to order those stocks destroyed.
The smallpox virus stock at the CDC occupies a volume about the size of a basketball; the virus samples are frozen in small plastic tubes the size of pencil stubs. The Russian stock is probably similar. It would be very easy to destroy the virus: just heat it up.
But should it be destroyed? A series of defectors from the old Soviet Union have revealed that the Soviet Union weaponized smallpox; that the virus was a mainstay of the clandestine Soviet biowarfare program. Illicit stocks of smallpox may have been taken out of Russia; nobody knows where the virus might exist on earth today in the form of undisclosed, secret stocks of the virus.
Researchers using live smallpox virus at the CDC have been studying the virus in an effort to develop antiviral drugs that would be effective against a smallpox infection. The drugs might also be effective against genetically engineered smallpox.
The genome sequence of smallpox virus is publicly available and can be downloaded from the Internet. Some day it will probably be technically feasible to recreate live smallpox from its genome sequence. Even if all the living smallpox were destroyed, it might be brought back to life in a lab somewhere, some day.
D. A. Henderson, who led the WHO eradication of smallpox, argues that the virus should be destroyed, regardless of whether it can be recreated. He argues that if the WHO makes smallpox extinct, then anyone who later had the live virus would be committing a crime against humanity and could be prosecuted in international courts.
On the other hand, researchers who are developing defenses against smallpox argue that the disease is simply too dangerous to destroy; they argue that we must continue to study it under the principle of Sun Tzu, “Know thy enemy.”
What do you think?
Richard


Dear Richard:
Your question is a timely one. On May 16, the World Health Organization will be having their annual meeting, and one of the items on their agenda is a global consensus about what to do with the world’s remaining smallpox stocks.
If WHO does decide on eradication, it will be an historical moment. We humans have only eliminated two viruses from the wild. Smallpox was the first. The second, as of last October, is rinderpest, a devastating scourge of cattle. For now, both smallpox and rinderpest remain in laboratory stocks. But if WHO decides to get rid of the smallpox lab stocks, too, the virus may be eliminated from the planet.
The prospect of such a milestone raises the question of why we haven’t been able to wipe out any of the other viruses that plague us. In some cases, it’s because viruses have escape routes. In 2004, for example, SARS burst on the scene, killing 774 people in total before quarantines and other public health measures beat it back. There have been no reported cases of SARS since then in humans, but SARS is probably thriving. It spread from animal hosts—bats and civets—to humans, and it doubtless retreated back to them.
Some viruses are hard to eradicate because they’re lurkers. HIV takes years to produce symptoms, making it hard to recognize and treat infected people. By the time it makes itself known, people may have spread it to many other victims. And doctors still lack vaccines for HIV and many other viruses.

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SARS virus

In all these respects, smallpox is a peculiar virus. Unlike SARS, smallpox only infects humans. Unlike HIV, smallpox makes itself known in a matter of days. It’s also unusual in that there’s a cheap, effective smallpox vaccine. Combined, these three factors made it possible to effectively break the transmission cycle of smallpox and thereby drive it towards extinction.
Whenever a species goes extinct, we lose the opportunity to get to know it better. I’m sure no one would shed a tear at the extinction of smallpox, but, as you note, there’s a lot we still don’t understand about the virus. I don’t think getting the opportunity to try people for crimes against humanity is worth giving up the chance to learn more about smallpox.
Even if smallpox never rears its ugly head again, that knowledge could still be valuable. Studies on smallpox DNA suggest that it evolved just a few thousand years ago from a pox that infected African rodents. Many closely related pox strains infect animals today, and they have plenty of chances to evolve into a new human pox. In 2003, for example, people in the Midwest came down with monkeypox, an African virus that is closely related to smallpox. It was baffling at first that an African pox could infect American victims. Eventually public health workers determined that the victims got the virus from prairie dogs they all bought at the same Missouri pet store.
If smallpox can help us prepare for the next pox, we should resist the urge to annihilate it.
Carl


Stay tuned for next Friday’s installment of TRAFFIC, featuring a conversation between Zimmer and Timothy Lu on phage therapy. And for more info on A Planet of Viruses, please visit the book’s UCP page here.
This blog and the book A Planet of Viruses are part of the World of Viruses project, funded by the National Center for Research Resources at the National Institutes of Health through the Science Education Partnership Award (SEPA), Grant No. R25 RR024267. Additional materials, including those directed at a K-12 audience, can be found on the World of Viruses website.

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