LONDON (AP) _ It is a nightmare that has gained the public's attention since Sept. 11: a terrorist walks into an airport and releases the smallpox virus, a scourge that killed millions of people before it was eradicated more than two decades ago.
Seventeen unsolved cases of anthrax in the United States have made the threat of a chemical or biological terrorist attack seem more real and have prompted the U.S. government to start stockpiling enough smallpox vaccine _ 300 million doses by the end of 2002 _ to protect every American citizen. Other Western countries are taking similar steps.
However, smallpox's potency and unpredictability could have a boomerang effect. Scientists say that once it is released, the disease would probably spread quickly throughout the world, infecting many of the same people in whose name the terrorists say they are fighting.
Would Osama bin Laden's al-Qaida network unleash a disease that could end up killing millions of Muslims?
Scientists say the developing world will be least ready to deal with smallpox, which would entail paying for the production of millions of doses of new vaccine and then administering the drugs to the population.
``The industrialized countries are, and will be, much better equipped to contain it than are developing countries,'' said Dr. David Heymann, executive director for communicable diseases at the World Health Organization.
Smallpox was one of the most devastating diseases known to humanity. Repeated epidemics swept across continents, decimating populations and changing the course of history. It used to kill 3 to 4 million people a year and left millions more disfigured, blind or both.
Its demise in 1979, after a 12-year worldwide vaccination program headed by the World Health Organization, was considered one of the great achievements in medicine.
Poorer nations would need a lot more help from the industrialized world this time, health officials say. Industrialized countries were keen to help their poorer neighbors wipe out the disease in the 1970s largely because they knew eradication would be a good investment.
``It's not clear that we could muster up any will to do another eradication program. I think it would be hard to sell because if you do eradicate it again, you're in the same vulnerable situation we are in now,'' Heymann said.
As the only disease ever to have been wiped off the face of the earth, smallpox would have an almost clear run if it were released again because nobody has been vaccinated against it for 25 years.
Experts fear most, if not all, of that immunity has worn off by now and that the disease could spread rapidly from an isolated outbreak to the other side of the globe.
While it may seem unimaginable for al-Qaida or other terrorists to use a weapon that could kill those in their own backyards, terrorism experts say that risk would not deter some radical groups, especially those motivated by religious fervor, like al-Qaida.
``These terrorists believe that Muslims will rise up and strike down the secular governments of the West,'' said Michael Swetnam, chairman of the Potomac Institute for Policy Studies in Arlington, Va. ``That kind of fundamentalist approach can easily support the belief that any tool was rational and usable because Allah is on your side. Allah will protect the faithful.''
After the disease was eradicated, governments agreed to concentrate stocks of the live virus in two secure laboratories _ one at the Centers for Disease Control in Atlanta and one in Russia's Siberia region.
There is no firm evidence of smallpox outside of those two centers. But former Soviet scientists have claimed that Russia intensified its biological weapons research after smallpox was eradicated, producing tons of the virus at least into the 1990s. Others worry that scientists who worked on Russia's smallpox bioweapons effort might have sold ampules of the virus to high-paying terrorists or rogue nations such as North Korea or Iraq.
President Bush said recently that the U.S. had evidence bin Laden was seeking to acquire chemical, biological and nuclear weapons, but it is unclear whether he has been successful.
Swetnam said the possibility of a smallpox attack should be taken seriously, but he added that other weapons _ like a conventional bomb, chemical attack or other type of biological attack _ are more likely to be used because smallpox is hard to get ahold of.
Still, exaggerating the risk of a smallpox attack might not be a bad thing, Swetnam said.
``If we blow it out of proportion and we make sure we stockpile enough vaccine for everybody, then there's no incentive for them to use it,'' Swetnam said. ``It will cost us a lot of money ... but we'll probably prevent it from happening. You can call it overreacting, but it's buying insurance.''