IT BEGINS with a threat. A terrorist group declares that unless its demands
are met within 48 hours, it will release anthrax over San Francisco. Two days
later, a private plane flies across the Bay, spreading an aerosol cloud that
shimmers briefly in the sunlight before disappearing.
Scenario one: thousands are killed in the panic as 2 million people flee the
city. Another 1.6 million inhale anthrax spores. Antibiotics are rushed in, but
the hospitals are overwhelmed and not everyone receives treatment. Most of the
country’s limited stock of anthrax vaccine has already been given to soldiers.
Emergency crews provide little help as there are only four germ-proof suits in
the whole city. More than a million of the Bay Area’s 6.5 million residents
die.
Scenario two: in the two days before the attack, citizens seal their doors
and windows with germ-proof tape. They listen to the radio for instructions,
their gas masks, drugs and disinfectants ready. Few panic. When sensors around
the city confirm that the cloud contains anthrax spores, hospitals receive the
appropriate antibiotics and vaccines. Trained emergency teams with germ-proof
suits and tents set up in the places where automated weather analyses show the
deadly cloud will drift. With advance preparation and rapid response only 100
000 people die.
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A terrorist who plans to drop anthrax over San Francisco tomorrow can count
on causing the murder and mayhem described in the first scenario—at least
according to the simulation that generated these scenarios last year. The
question facing policy makers now is: how do we move toward the second
scenario?
That terrorists may someday turn to biological weapons is no longer a matter of debate
(see “All fall down”, New Scientist, 11 May 1996, p 32).
“Terrorism has changed,” says Brad Roberts of the US government-backed Institute
for Defense Analyses in Virginia. “Traditional terrorists wanted political
concessions,” he says. “But now, some groups say their main aim is mass
casualties. That makes biological weapons appealing.”
Terrorists would have little trouble getting their hands on the technology.
Hearings in South Africa in June revealed that the apartheid government produced
terrorist weapons containing anthrax, Salmonella and cholera. Soviet
scientists who have prepared weapons-grade anthrax and smallpox are known to
have emigrated, possibly to well-funded terrorist groups like the one run by
Osama bin Laden in Afghanistan. Even small groups such as the Aum Shinrikyo sect
in Japan have been able to cook up vats of Salmonella or botulin, the
toxin that causes botulism.
With bioweapons so readily available, how can governments protect us from a
terrorist armed with anthrax, smallpox or plague? In May, scientists, policy
makers and security experts gathered in Stockholm to discuss how to limit the
devastation of a biological attack on civilians. Until now, most biological
defence strategies have been geared to protecting soldiers on the battlefield
rather than ordinary people in cities. The situations are quite different, and
novel technologies are needed for civilian defence.
Suppose a commuter stumbled across a time bomb filled with anthrax on an
underground railway platform. Until this year, no police force in the world had
any way to disarm such a device safely. One novel solution that attracted
attention at Stockholm was a tent full of antiseptic foam. Researchers at Irvin
Aerospace in Fort Erie, Ontario, have developed a dome-shaped tent made of
ultratough Mylar that can be filled with a stiff foam—the exact
composition of which is a closely guarded secret—that kills germs and also
neutralises chemical weapons. Once covered by the foam-filled tent, the bomb can
be safely detonated.
But what if germs are already in the air? The protective suits and masks used
by most emergency services don’t have seals tight enough to exclude
microorganisms, making them useless against biological attacks, says Jack
Sawicki, a former fireman who now works for Geomet Technologies near Washington
DC. And the lack of standards for gas masks sold to civilians in most countries
makes it as likely that a mask will suffocate you as save you, he says. The
suits developed for the military do work—their tight joints and zippers
keep bugs out—but they are too pricey for the average fire department.
Both Geomet and Irvin Aerospace are about to market civilian bio-suits. In
the meantime, other companies are designing protective gear that actually kills
pathogens. Molecular Geodesics in Cambridge, Massachusetts, for example, is
developing a suit made of a tough, sponge-like polymer that traps bacteria and
viruses, which are then destroyed by disinfectants incorporated into the
fabric.
Stealthy attack
None of this gear will do any good, however, if the emergency services do not
know there has been an attack. And an assault may not be obvious. A terrorist
might not use a weapon that goes off with a dramatic bang, or even produces an
obvious cloud of germs. The first hint of a biological attack may be a sudden
cluster of sick people.
Even that will be missed unless someone is watching. And few are. In the US,
financial cutbacks have crippled programmes to track disease outbreaks, natural
or deliberate. Some could be either, such as food poisoning caused by
Escherichia coli O157 or Salmonella. Medical agencies fear that
the extra money requested by President Bill Clinton this spring as part of an
anti-terrorist initiative will not be enough to create an adequate surveillance
network.
In Europe, disease surveillance is only beginning to be organised on the
continent-wide scale needed to track a biological emergency. But in addition to
monitoring infected people, Nicholas Staritsyn of the State Research Centre for
Applied Microbiology near Moscow says that more effort should be made to find
out which bugs live where. For example, a particular variety of anthrax may
occur naturally in South Africa, but not in Canada. Having access to such
information could help authorities to distinguish between natural outbreaks and
deliberate attacks.
Even when infected people start turning up at local hospitals, early
diagnosis of their illness might not be easy, says Steve Morse, who heads the US
programme on new diagnostic technologies run by the Defense Advanced Research
Projects Agency (DARPA). The first symptoms of anthrax, plague and many other
potential agents of bioterrorism resemble those of flu: headaches, fevers,
aching muscles, coughing. What’s more, some of these symptoms might be brought
on by panic attacks, which are likely to be widespread among people who have
just been told that they are the victims of a biological attack.
One answer discussed in Stockholm would be for hospitals to have the type of
high-tech detectors being developed to identify airborne pathogens on the
battlefield. With a detector at each bedside, doctors could pick out the
volatile molecules released by damaged lung membranes at a very early stage of
infection and instantly tell whether a patient was a victim of a biological
attack, says Mildred Donlon, head of environmental detection research at
DARPA.
Eventually, DARPA would like to develop a detector that weighs no more than 2
kilograms, can identify as few as two particles of 20 different biological
agents in a sample of air, costs less than $5000 and does not give false
negatives. Such detectors could be deployed around cities to give early warning
of airborne disease.
In the meantime, researchers led by Wayne Bryden at Johns Hopkins University
in Baltimore are working on revamping the traditional laboratory workhorse, the
mass spectrometer, for use in the field or in hospitals. They’ve reduced this
unwieldy piece of equipment to a suitcase-sized machine that can distinguish
between, say, Shigella, which causes dysentery, and Salmonella.
A shoebox-sized version, says Bryden, could be ready in five years.
Other researchers are experimenting with devices that would not seem out of
place in an episode of Star Trek: Voyager. Tiny electronic chips that
contain living nerve cells may someday warn of the presence of bacterial toxins,
many of which are nerve poisons. Like a canary in a coal mine, the neurons on
the chip will chatter until something kills them. “Anything that stops it
singing is immediate cause for alarm,” says Donlon.
While the “canary on a chip” could detect a broad range of toxins, other
devices are designed to identify specific pathogens. One prototype consists of a
fibre-optic tube lined with antibodies coupled to light-emitting molecules. In
the presence of plague or anthrax bacteria, or the toxins botulin or ricin, the
molecules light up.
Outwitting our defences
Devices based on antibodies are far from foolproof. First, you need to have
the correct antibodies—not easy when you consider the vast number of
pathogens you’d need to include, and their ever-changing repertoire of surface
proteins. “And even the right antibodies can identify only what is on the
outside of a particle,” Donlon points out. Bugs can be encapsulated in gels or
biological polymers to foil antibodies, or normally harmless bacteria engineered
to carry nasty genes. “I want to know what is on the inside,” she says.
To do this, DARPA-funded researchers are developing identification techniques
based on RNA analysis. Unlike DNA, which is now used to identify unknown
organisms, RNA is plentiful inside cells and need not be amplified before
identification begins. And messenger RNA molecules reveal not only what a
microorganism is, but what toxins it is making.
Once the biological agent has been identified, how do you combat it?
Vaccinating people before they are exposed is one answer. This is the strategy
the military is betting on. Last year, the US military launched a programme to
develop vaccines against potential biological weapons. It will create jabs for
diseases for which none exist, such as Ebola, and improve existing
vaccines—including the 30-year-old anthrax vaccine being given to 2.4
million American soldiers.
But vaccines are no cure-all. An attacker need only generate a germ that
sports different antigens to those used in a vaccine to render that vaccine
ineffective. Plus, as bioterrorists get more sophisticated, they will develop
novel, possibly artificial, pathogens against which conventional vaccines will
be useless, predicts Morse.
To get around these problems, DARPA is looking at ways of developing vaccines
quickly enough for them to be created, mass-produced and distributed after an
attack. The first step, which many researchers including those in the fast-paced
field of genomics are now working on, involves speeding up DNA sequencing so
that an unknown pathogen’s genes could be detailed in a day. The resulting
sequences could then be the basis for developing an instant DNA vaccine.
Making the vaccine is only half the problem, however. Soldiers can be ordered
to take shots, but immunising the rest of the population is another matter.
Civilians are unlikely to volunteer for the dozens of vaccinations that would be
necessary to protect them against every conceivable biological threat. An attack
would make many change their minds, but in such circumstances there might not be
enough to go around. Although Clinton has called for the stockpiling of
vaccines, the US has only 5 million doses of smallpox vaccine—not enough
to contain a hypothetical attack, says Ken Berry, president of the American
Academy of Emergency Physicians.
Ken Alibek, the former second-in-command of the Soviet germ warfare programme
who revealed earlier this year that the Soviets had weaponised tonnes of
smallpox, argues that it is short-sighted to put too much effort into developing
vaccines. Instead, says Alibek, who is now at the Batelle Institute in Virginia,
researchers should concentrate on ways to treat victims of biological weapons.
Today’s antibiotics may be useless because germs could be equipped with genes
for resistance to all of them. Russian scientists have already created such a
strain of anthrax
(This Week, 28 February, p 4).
For any treatment to be effective amid the potential chaos of a bioterrorist
attack, speed will be of the essence. At the Stockholm meeting, researchers
reported their efforts to develop drugs that work against a wide variety of
infections and so can be used even before definitive diagnosis. Some are trying
to take advantage of recently identified similarities in the way many pathogens
produce disease to develop broad-spectrum drugs.
For example, Ebola, anthrax and plague all kill their victims by inducing a
widespread inflammatory reaction similar to toxic shock syndrome. A team in
Cincinnati is testing an anti-inflammatory drug that could stop all of them.
Another gang of bacteria—including plague, Salmonella,
Shigella and Pseudomonas aeruginosa (one of the bacteria that can
cause pneumonia and meningitis)—relies on very similar proteins to latch
onto human cells and inject toxins. Drugs that block this system might save
people from all these germs, Åke Forsberg of the Swedish Defence Research
Establishment in Umeå told the meeting.
The trouble with all these new anti-bioweapon gizmos, gadgets and medicines
is that it’s far from certain that they would be available in time to shield the
first major city targeted for a bioterrorist attack. At the moment, the US is
one of the few countries taking the bioterrorist threat seriously. Sweden,
France and Israel have trained emergency teams and stockpiled gas masks. Other
countries do not seem concerned. “The threat of bioterrorism has not seized our
European friends,” says Mike Moodie of the Chemical and Biological Arms Control
Institute, a think-tank near Washington DC. “They feel it’s too improbable.”
Perhaps they should reconsider. Berry, who helped run the doomsday
simulations that ravaged San Francisco, says: “Security experts are not asking
if a biological attack on a civilian population is going to happen, but
ɳ.”
THE LAST thing the US wanted during the Gulf War was to bomb a bioweapons
plant. A normal bomb would scatter deadly germs everywhere—especially
anthrax, which has spores that can survive fire—potentially infecting
thousands of civilians. When the war was over, the search was on for a bomb that
would safely destroy bioweapons.
The weapon the US Air Force would use if it attacked Baghdad tomorrow is
called the “Colt .45”. This smart bomb is designed to zip about inside its
target building, burning at high enough temperatures to kill the resident germs,
before it explodes. But the Colt does not always perform as intended. Sometimes
it gets stuck in a corner, where it burns up, leaving the building’s contents
alive and ready to be scattered by the final explosion.
Now the Defense Special Weapons Agency thinks it has a prototype that does
work. This bomb sits in the middle of the building and burns so hot that it
sucks everything into a small firestorm, sterilising germs before they can
escape. The combustion process also produces caustic chemicals that kill any
germs that survive the heat. The results look promising. In initial tests, the
bomb successfully sterilised buildings stocked with benign bacteria, say DSWA
officials. They hope the weapon will be ready by 2002.
SPOTTING a biological attack in time to get people into their protective gear
is no small feat. Ideally, you’d like to see the attack coming.
Part of the problem is that because the air is already full of microbes,
detecting a puff of bacteria isn’t enough to sound the alarm. Instead,
scientists are focusing on what carries the germs. One of the best ways to
disperse biological weapons is with a droplet cloud, like the mist from a
crop-spraying aeroplane. Researchers at Los Alamos National Laboratory are
testing a device called the XM-94. Mounted in a Blackhawk helicopter, the XM-94
uses lidar—a laser radar—to sense clouds of droplets in the air.
“It’s neat, it’s sensitive and it works to a 30-kilometre range,” says Robert
Karl, the XM-94’s designer. The problem? The XM-94 might find it difficult to
tell the difference between a biological strike and a patch of fog. Which could
spell trouble if the bioterrorists decide to make their strike on a day when the
weather is not set fair.