The letters were handwritten in untidy block capitals. There was a date, “09-11-01”, and the words “ALLAH IS GREAT” and “WE HAVE THIS ANTHRAX”. It was only weeks after 9/11 and a lethal biological agent had been sent through the US postal system. Five people were dead, killed after inhaling deadly spores concealed in envelopes addressed to two senators, a news anchor and a newspaper editor.


Al-Qaeda had already spilled blood on American soil. Earlier that month it had slammed passenger jets into the sides of skyscrapers as a global audience watched on live TV. Could it be that it had now followed up those attacks with a sophisticated biological weapon? The answer to that question would not come overnight, but the 'war on terror' that was set to follow would not only be concerned with bombs, bullets and hijacked airliners. Biology had become a threat – and that threat is as real in 2009 as it was the day the anthrax letters were posted.

“Twenty years ago, nobody really talked about biological weapons,” says Dr Piers Millett. As a political affairs officer at the Biological Weapons Convention Implementation Support Unit, Millett advises member states on all issues concerning the technology. “Now, it’s a common belief that terrorists are seeking them.”

It is little wonder. Bioweapons are easier to handle and transport than conventional weapons. Detection is difficult, even after they have been released, and symptoms may not appear for some time after exposure. They can ignite mass panic and make no mistake – they are deadly.
Human beings share the world with any number of microorganisms that are perfectly equipped to kill us. And thanks to old state-run programmes, we know that some of them, including Q fever, brucellosis and plague, can be turned into weapons. It now looks as though terrorists are actively pursuing weapons of their own.

In Malaysia, an individual arrested by Interpol in connection with the militant group Jemaah Ismaliyah has been linked to a plan to obtain biological agents and build weapons from them. A raid on the office of two nuclear scientists in Kabul, meanwhile, uncovered documents suggesting an interest in anthrax, including calculations about how to disperse the material from a balloon. And in January of this year, unconfirmed reports emerged of a plague outbreak in Algeria. Forty members of an Al-Qaeda cell had allegedly been killed, and it had happened as they attempted to make a weapon containing the disease.

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Millett always treats such reports with care. “The key is the level of weapon you’re talking about,” he says. “If I sneezed on somebody enough I could infect them, but that’s not headline news. And terrorists probably have the capacity to get hold of something more dangerous than a cold.”

“The question is how to deliver biological material on the air in such a way that it doesn’t die very quickly and is in a suitable form to be taken into the body”

Building bioweapons

There were flat rebuttals from the Algerian government and others when it was reported that Al-Qaeda had been experimenting – unsuccessfully, it has to be said – with a plague weapon.

But Millett says those rebuttals concern the claim that the terrorists were using plague in particular, more than their aim to acquire biological weapons in general. “They’re trying to create a very basic weapon equivalent to what a military might have had 50 years ago,” he says.

Thankfully, making an effective biological weapon is not easy. Assuming that the best way to infect a large number of people is by releasing a toxic agent as an aerosol, a terrorist still has a lot of work to do. First, they have to circumvent stringent security measures in place to keep biological agents safe. If they did get their hands on a sample, they would also need the biological know-how to select the most appropriate strain and maintain its virulence right up to the point that it’s released on the public. And according to Malcolm Dando, professor of international security at the University of Bradford, even then there are huge uncertainties.

“The question,” Dando says, “is how you deliver material on the air in such a way that it doesn’t die very quickly and is in a suitable form to be taken into the most vulnerable part of the body – the respiratory tract. You need the material in a very particular size range for it to go in and stay in.”

There’s also a question of making sure the agent survives in the environment that it’s released into. Unleashed outdoors, it could be blown away and either miss its target completely or decay before it does any damage. Some biological agents degrade in the Sun’s UV radiation. That’s why an attack on an underground system is one of the most commonly discussed scenarios.

British military experiments in the 1960s found that anthrax-like spores could spread 30km through the London Underground in just a couple of hours. Above ground, it is possible that an agent could be enclosed in a nanosphere or some other protective shielding. But far more likely, at least for now, is that terrorists would choose a pathogen that is particularly hardy – like anthrax.

The 2001 letter attacks were relatively small-scale incidents. Compared with 9/11, the loss of life was tiny, but the letters demonstrated that somebody had not only the ability to handle biological agents, but were also willing to use them against civilians. Could Al-Qaeda have been capable of pulling that off?

A desperate forensic investigation began almost immediately. Tests on spinal fluid from the first victim confirmed that it was anthrax before he had even died. The sample also revealed the particular strain of anthrax that had been used. It was a variant known as Ames, originally isolated from a diseased cow in 1981 and sent to US Army laboratories, as well as international labs including Porton Down in the UK. Nobody knew for sure how widespread the strain was or whether terrorists could have acquired it.

Investigators scoured the mailing rooms that the letters had passed through as well as the offices where they were finally delivered. Each location was contaminated, and because anthrax is extremely hardy in its spore form, the cost to clean up these ‘hot zones’ ran into hundreds of millions of dollars. The good news was that the authorities had plenty to analyse.

Examinations continued for years, but eventually 10 genetic mutations were found that existed only in the Ames strain used in the attacks. These were matched to samples that could only have come from one source: a single flask of spores kept at the US Army Medical Research Institute for Infectious Diseases in Maryland.

Al-Qaeda was not responsible. The anthrax had come from within the US, from a state programme. The man responsible for the identified flask was Bruce Ivins, a biodefence researcher who had originally helped the FBI with its investigation. Colleagues and family members have since protested Ivin’s innocence, but it seems that we’ll never know for sure if he was responsible for the attacks – Ivins committed suicide last July.

“The lesson was that there is a distinct danger anywhere that these pathogens are, and that somebody might get their hands on them for malign purposes,” says Millett. “That’s why we put security regimes in place. But what you also have to remember is that these regimes are only as effective as the people running them.”

The worst-case scenario

There are two labs in the world – one in the US, one in Russia – where something far more dangerous than anthrax is kept. Smallpox had been eradicated from nature by 1980 after killing up to 500 million people in the 20th century. It was a stunning success for medical science, but afterwards came a difficult decision. Should we destroy all known samples of smallpox and wipe it out completely, or keep a limited amount back? Authorities were concerned that state weapons programmes had weaponised the disease. If that was true, and there was even a chance that those weapons were in the hands of terrorists, then at some point, we might need the virus in order to make stronger vaccines. The samples were kept.

If smallpox ever got out, the worst of worst-case scenarios would follow. The disease is virulent, contagious and just lethal enough. The mortality rate is about 30 per cent, which means that victims rarely die before they get the chance to pass it on. If the mortality rate were closer to 100 per cent, then an outbreak would burn itself out. But, unfortunately, that’s not the case with smallpox. It spreads.
“The easiest thing you could do is an attack on livestock. One case of foot-and-mouth disease in the US would cause mayhem and have a tremendous economic impact”
After the 2001 anthrax attacks, the US declared war on smallpox, and prepared for a deliberate release. It has set up a dedicated response team and vaccinated its team members. It has also stockpiled enough vaccine for every person in the country and run exhaustive, apocalyptic scenario exercises to ensure that if an attack did occur, they would be ready. The UK is also thought to have made extensive preparations for an outbreak, although, unlike the US, our policy has been not to tell anyone what they are.

Whatever the preparations are, a smallpox outbreak remains the least likely threat from bioterrorists. Far more probable is a different kind of attack, one that isn’t targeted directly at people, but at our food supply. “The easiest thing you could do is an attack on livestock,” Dando says. “One case of foot-and-mouth disease in the United States would cause mayhem.

And it would have a tremendous economic impact, as we know in the UK from natural outbreaks.” During the Cold War, both the US and the Soviet Union are believed to have made weapons containing the disease, and there were also fears that Saddam Hussein had ordered scientists to begin research in Iraq.

Another attack against agriculture could target the milk supply. A US report warned in 2005 of Jihadist websites that had published an instruction manual for infecting a milk tanker with a botulinum toxin, one of the most lethal substances to occur in the natural world. It can cause paralysis of the muscles and death by blocking victims’ airways. But they are also used in very low doses in botox treatments, making them potentially more accessible than other agents.

If an attack against agriculture is easier to execute, then it raises the question of how we would tell the difference between an intentional attack and a natural outbreak. Nobody thinks that the UK’s foot-and-mouth epidemic was caused deliberately, but if livestock became infected again tomorrow, would we consider the possibility that terrorists were responsible? Or if human beings started dying of a strange new disease, how could we tell that it wasn’t a natural outbreak?

“If you had a large-scale attack, you probably wouldn’t even know that it was an attack,” says Millett. “Differentiating between a natural outbreak and something more unusual is incredibly difficult.” It could be months before genetic sifting makes it clear that an intentional outbreak has happened – that we had been attacked. That has huge consequences for how the response is coordinated. “If it was a disease that didn’t show up, which had a latency period of a month, then how do you quarantine the country after a month of contacts?”

Preparing for an attack

The most effective response to the bioterrorism threat, Millett says, is not lab security or even having dedicated response teams on standby. The most important thing is to deal with the immediate medical emergency. “The public health response is going to come first,” he says.

“It’s about adding value to the normal public health response rather than creating a separate system just for biological weapons. Can you imagine the uproar if there were no beds in a hospital for normal surgery and a whole ward there waiting for smallpox victims?”

Basic public health may be the best first line of defence against bioterrorism, but responsibility also falls at the feet of biologists. A lot of research done in the public good has another edge to it. A new aerosol technique that makes drug delivery easier could also make a biological weapon more deadly. Technology for spraying crops could be twisted for spreading deadly bacteria. Even the fight against disease harbours a potential dark side. With the exception of smallpox, every biological agent that could be used as a weapon is endemic somewhere in the world – and equally, there are scientists trying to cure the diseases they cause.

“Most of these are good people with good intents,” says Dr Vivienne Nathanson, head of science and ethics at the British Medical Association. “But part of the problem is that they find it difficult to think there might be other people with very different motivations and very different reasons for looking at their research and wanting to use it.”

Biology research has seeped out of its ivory tower. The knowledge and equipment to grow biological cultures or synthesise genes is more widespread than ever before. What you can’t learn on a biology degree you can probably find on the internet. “You don’t need to think about people with massive laboratories and physical set-ups to be able to produce weapons,” Nathanson says. “You can do it in a much smaller space with equipment that you can pretty much buy off the shelf.”

The rise of biotechnology and synthetic biology is also good news for terrorists. As mankind’s ability to manipulate DNA and RNA increases, so too does its ability to create new weapons from scratch that are more deadly than anything dreamt up by nature. Agents could combine genes from more than one pathogen, make them work faster and more ruthlessly against our immune systems, and make them resistant to antibiotics. In the future, the biological sciences could be reduced to a battle between those attempting to develop such a weapon, and those tasked with stopping them.

“There are lots of advances going on in civil science that will eventually mean that the knowledge gap for making bioweapons will disappear,” says Dando. “It seems to me that as we go down the decades, the capability to create mayhem with biology will only get easier.”


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A former deputy editor at Science Focus, Ian once undertook a scientific ranking of the UK's best rollercoasters on behalf of the magazine. He is now a freelance writer, which is frankly a lot less fun.