Dec 30 2010

The Coming Bedbug Plague

For the last half a century (more than my entire lifetime) industrialized nations have lived a relatively bedbug-free existence. This year, however, bedbugs have started to make a comeback. Reports of bedbug infestations in hotels, theaters, stores, and homes have increased dramatically. Bedbugs, it seems, are not a thing of the past. Rather we have been living in a brief respite from these parasites, which will now resume their former levels of feasting on the blood of sleeping humans.

To me, this story was surprisingly surprising – meaning that I was initially surprised that we had not permanently dealt with the bedbug problem, and then I was curious as to why I was so surprised. Perhaps it is a result of some cognitive bias worth exploring.

But first – the story of bedbugs.

Bedbugs are small parasitic insects in the family Cimicidae, the most common species being Cimex lectularius. They are good at hiding in small spaces near warm-blooded animals, hence their preference for the bedrooms of humans. They can hide in small cracks, in electrical sockets, or between the slats of a bed. They can go up to a year without feeding, and so are very patient. When a warm blooded animal is resting nearby, they crawl out of their hiding space, bite through the skin, and fill themselves with a meal of blood. (They are technically referred to as blood-sucking ectoparasites.)

As pests go, they are not as bad as some, such as lice. They can cause a skin rash, can cause allergy in susceptible individuals, and are psychologically bothersome. Rarely, more serious skin lesions or secondary infections may result and need to be treated.  Psychological effects can be serious and may include insomnia.  Fortunately, they do not transmit any human disease. But no one wants parasites munching on them while they sleep, and the skin lesions they may cause can be annoying.

Why are they coming back? Bedbugs were mostly eradicated in industrialized nations in the 1940s, partly due to direct extermination efforts, but mostly as a side effect of widespread use of DDT and other insecticides. Since the mid 1990s reports of bedbugs have been on the rise. This is partly due to reduced use of DDT, the development of resistance in bedbugs to DDT and other insecticides, and perhaps other factors, such as the increase in international travel. Bedbugs can spread from location to location by hiding in the personal belongings of travelers.

The problem was also exacerbated by the fact that the current generation of doctors, pest controllers, and other professionals have limited or no experience with bedbugs. So signs of bedbugs were not recognized, and extermination suboptimal. This is quickly changing, of course, and 2010 seems to have been the turning point of awareness of the problem.

If you have an infestation, there are things you can do. According to the CDC, treatments include:

* using monitoring devices,
* removing clutter where bed bugs can hide,
* applying heat treatment,
* vacuuming,
* sealing cracks and crevices to remove hiding places,
* using non-chemical pesticides (such as diatomaceous earth) and
* judicious use of effective chemical pesticides

But professional extermination can be expensive, costing several thousand dollars for a single-family home.

Perhaps we will be able to keep bedbugs from returning to pre-1940 levels, through the various mechanisms listed above. But it seems that even in the best-case scenario bedbugs will return as a pest that needs to be dealt-with, rather than being relegated to quaint-sounding good-night wish.

My initial surprise at hearing this story, I think, reflects an inherent progressivist bias in our thinking. We tend to think of human history as making inexorable progress. This bias is reinforced, especially since the industrial revolution, by the fact that science and technology has been relentlessly progressive. The problem is in the default assumption that all change is progressive – whatever current system we have must be better than the old system because newer is better.

Human history, however, is more complex than our default assumptions. Sometimes history is regressive. And sometimes it is cyclical. Not all current trends will extrapolate indefinitely into the future. Today’s fad is not always the wave of the future.

In my mind bedbugs were a problem of pre- or early industrial societies, and were no longer an issue given modern hygiene and pest-control. I associated bedbugs with an earlier age, and it just seemed incongruous that they could return in the 21st century. But the details tell a different story.

We shouldn’t fall prey to assuming that because bedbugs are currently on the rise that they will continue to do so. Perhaps their return will turn out to be only a brief cycle, and then they will fade once again from our collective attention.

This is perhaps an odd example from which to derive a lesson in metacognition, but those are often the most interesting and instructive. So-called metacognition is thinking about thinking – something skeptics do quite a bit. I find that there is something to be learned about the human thought process from almost any topic, which is one of the generic benefits of education in any area. This is why I encourage my daughters to become interested in anything – pick any topic and then delve as deep as you can, so that they can learn about learning itself.

This experience also reflects a good habit to cultivate, and that is questioning your own thought process. When people tell me that they believe in “X”, often my first question is – why do you believe that? This, of course, is also an excellent question to ask yourself.

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