'Superbugs' aren't as much of a threat as terrorism: they're hundreds of times more dangerous than that

By Tom Chivers Science Last updated: March 11th, 2013

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I don't know why we continue to use "the threat of international terrorism" or similar as a yardstick to measure how dangerous something is. On the face of it at least, "international terrorism" really isn't very threatening at all.

This week it's Prof Dame Sally Davies, the Chief Medical Officer, who has very sensibly pointed out that resistance to antibiotics is a "ticking time bomb": unnecessary use of antibiotics, and the failure of drug companies to come up with new ones, could lead to a situation in which all the boring little infections that we thought we'd beaten suddenly become dangerous again. “If we don’t act now, any one of us could go into hospital in 20 years for minor surgery and die because of an ordinary infection that can’t be treated by antibiotics," she says, entirely accurately. It's the reason you really don't want a creationist GP.

But it's the comparison with terrorism that I find interesting. The World Health Organisation estimates that multidrug-resistant tuberculosis (MDR-TB) causes about 150,000 deaths worldwide; the Office for National Statistics blames methicillin-resistant Staphylococcus aureus(MRSA) for 1,652 deaths in 2006 in Britain alone, almost all of them in hospitals. By comparison, in the worst ever year for terrorist deaths – 2001, obviously – there were 3,547 deaths worldwide, according to the Patterns of Global Terrorism report.

That's not the whole story, of course. As His Worshipfulness Nate Silver points out, like earthquakes and meteorite strikes, the risk of terror attacks of different magnitudes displays a power-law pattern: there are lots of little ones, but they get exponentially rarer the bigger they get. His data, taken from Aaron Clauset's study of terrorism in Nato member countries, suggested that attacks that kill 100 or more people should happen about once every five years. (In fact there have been seven such attacks in the last 31 years: pretty close.) Attacks causing 1,000 or more deaths should happen about once every 22 years, and September 11-style attacks about once every 40 to 80 years, depending on whether or not you include September 11 in your data. The attacks form a remarkably straight line when plotted on a double-logarithmic scale.

What's interesting about that is that it allows us to make predictions. Just as we could have predicted the possibility of mega-earthquakes like the one that hit Japan in 2011 by looking at the likelihood of smaller ones, we can say that "magnitude 9 terror attacks" (as Silver describes them, putting September 11 at magnitude 8), which would kill tens or hundreds of thousands, should not be unthinkable, just rare. On the power-law graph, a terror attack killing one million people in a Nato country should happen about once every 1,600 years: but that would be such a massive event that it would constitute the large majority of the total number of deaths caused by terrorism in that entire millennium-and-a-half period. In that time, at the current rate of deaths, 240,000,000 people would have died worldwide from MDR-TB alone, and 2,643,200 from MRSA in Britain.

Of course, deaths from terrorism are different from deaths from diseases, because they are (obviously) terrifying. They kill, but also they frighten, because they are so dramatic and memorable: it's been pointed out that as well as the thousands who died in 9/11, there were about another 1,500 indirect deaths caused by people who decided to drive long-distance instead of flying and so got into traffic accidents. Terrorism's main threat is that it causes us to live our lives differently, making us live in fear, sacrificing liberties for security. This is a serious thing that we should acknowledge; terrorism is not just about the deaths.

But that's precisely why we shouldn't inflate the risk of terror, to place it in our mind as the type specimen of "threats". Right now a single resistant bug, MDR-TB, is causing as many deaths per year as a hypothetical once-every-few-centuries terrorist attack could be expected to. Your odds of dying in a terrorist attack are literally about the same as those of your dying in an asteroid strike; your odds of dying from an antibiotic-resistant hospital-acquired infection are, shall we say, not. By all means remind us of the dangers of evolved superbugs. But don't do it with a false comparison with terror, that cheap flag waved by idiot politicians. It's already far, far more dangerous than that.