Steve Connor: We are facing a deadly enemy. Not anthrax, but hysteria

In a very different world, one haunted by the spectre of the Great Depression, Franklin D Roosevelt said that the only thing worth fearing was fear itself. It is a quote that suddenly seems rather apposite in the anthrax-seeded world of today.

Alan Milburn, the Health Secretary, and Liam Donaldson, his Chief Medical Officer, stumbled across Roosevelt's words etched into stone while they were wandering around the neoclassical edifices of Washington, DC, earlier this month, when they went to sign an agreement with the United States on bioterrorism.

Since then, germ warfare has catapulted from nightmare scenario to reality, with scores of people from Nairobi and New York to Kansas and Kazakhstan showing the effects of exposure to anthrax. Workplaces have been shut, employees evacuated and people hosed down and prescribed antibiotics – just in case. Most cases, however, have turned out to be hoaxes involving a harmless white powder and a suspicious package sent through the post.

The real terror of biological attacks is not so much the direct threat they pose. It is the panic and fright they can instill in a public primed by the fearful images of men dressed in full chemical and biological warfare kit like some ghastly parody of extraterrestrial beings.

But the facts are probably less scary than the public believes. Cheap explosives and rifles have wreaked far more death and suffering than biological and chemical weapons, and are likely to continue doing so. But our fear-factor for conventional weapons has decreased, while our susceptibility to panic about bio-weapons has grown.

Anthrax, we discover, is not quite the doomsday agent that we have been led to believe. It's unpleasant enough, and potentially deadly, as it was for the newspaper man in Florida who died of pulmonary anthrax apparently after he had opened a contaminated envelope sent through the post. No one should underestimate the risks posed by exposure to the bacteria. It is a seriously dangerous agent when it invades the body. But exaggerating the risks of the bug by conferring almost supernatural status to its lethal abilities plays into the hands of people who use it to spread chaos and fear.

It is easily treatable with antibiotics so long as it is caught early enough. It is also a relatively difficult disease to contract – this is especially true of the most lethal, pulmonary form, which is caused by the inhalation of between 2,500 and 10,000 spores. And not everyone who becomes infected dies.

Harry Smith, who isolated the anthrax toxin while working at the Porton Down research establishment between 1947 and 1964, emphasises that the disease is in fact far more dangerous to sheep and cattle, its usual victims, than it is to humans. Indeed, a significant proportion of the population may actually have a built-in immunity to it.

A number of studies on mill workers who handle hides and wool – which are often contaminated with anthrax spores – has demonstrated just how difficult it can be to infect someone, even though they may have been exposed to relatively high doses. Fatal cases of pulmonary anthrax were surprisingly rare in exposed workplaces even before routine vaccination was brought in.

Historically, anthrax has been the bio-weapon of choice for the simple reason that it can be grown relatively easily and, most importantly, the microbe forms highly stable spores that can be stored as a powder or liquid sludge for years without degradation. Anthrax also has the characteristic of not passing from one person to another, which was once thought to be an advantage in a military campaign where soldiers would eventually have to occupy contaminated land.

It is, in theory, possible to "weaponise" anthrax spores – in other words, to disperse them over a wide area either in the tip of a missile or as an aerosol spray. The effectiveness of both methods of dispersal, however, is open to question. Anthrax, like any agent of biological warfare, has never been tested with any success in a battlefield situation precisely because it is so difficult to disseminate and control.

Following secret experiments in 1942 on the remote island of Gruinard off the west coast of Scotland, Britain concluded that anthrax had no real military significance. The tests there showed that anthrax bombs did not succeed in contaminating wide areas. Indeed, most of the spores fell immediately to the ground rather than being wafted around in an infectious mist.

The real significance of anthrax, and indeed any chemical or biological warfare (CBW) agent, is not so much the actual threat they pose, but the public perception of the threat that they might pose. As a weapon of terror, CBW agents are extremely effective, as Saddam Hussein demonstrated in the Gulf war of 1990-91.

At that time, it was assumed that all the Scud missiles fired by Iraq at Israel were loaded with chemical or biological warheads. As a result, the Scud – a clapped-out Soviet rocket – emerged as a genuinely terrifying weapon. Every time one landed, it caused massive, if understandable, overreaction by the Israeli authorities, which had to approach each one in full CBW mode, even though no Scud was ever shown to have been loaded with chemical or biological agents.

So the application of biological weapons turns on a paradox. The reason why they are so useless in a conventional military sense explains why they are so sought-after by terrorists and terrorist states – they disseminate far more fear than is rational. They seem to herald a cheap form of mass destruction, and this view of them as the "poor man's nuclear weapon" is now widespread. Yet the scale of potential damage doesn't really warrant such a conclusion.

Unfortunately, every hoax has to be treated as genuine until proven otherwise. But the mature response to biological weapons is to treat them as a nasty and inconvenient blight to be combated calmly, and not as some sort of harbinger of doomsday against which there is no defence.

The future may be a different, more frightening country. Genetic technology will allow rogue scientists employed by terrorist states to tinker with anthrax in a way that could make the microbe resistant to antibiotics or capable of being more infectious with a smaller dose of spores. There are other agents of genuinely infectious diseases, such as smallpox or plague, that could be unleashed on a largely unvaccinated population. We are unlikely to live in a world completely free of biological threat. The nature of that threat will change over time. We must combat it, but not be controlled by it.

In this context, Roosevelt's words should guide us all. The more we succumb to the mythology of bio-terror, the more we encourage its use and the more vulnerable we will become. The best antidote is rationality.