What are we to fear in this scientific age? Nuclear war? Overpopulation? Drunk drivers? No doubt these are reasonable fears. But threats to our health have a special place in the human psyche. Surely the horror of deadly plagues able to carry away incomprehensible numbers of people has been one of our greatest fears, and certainly is now. But this book is not about the infectious diseases on which the popular media have focused. It is not about the infectious threats to the rich countries from the poor countries of the world—the Ebola and West Nile viruses that captured headlines during the 1990s are in fact minor threats. The balance of evidence indicates that the major infectious plagues are not emerging from an African jungle. They are already here, embedded in every society, in rich and poor countries alike. In fact, they have been here for centuries, even millennia. They are as deadly and painful as the sensationalized plagues, but they have spread more insidiously and imperceptibly—they are slow-motion plagues that are difficult to recognize and difficult to control. The flash-fire
outbreaks that make the headlines usually burn out on their own. The serious infectious plagues aren't so easy to escape.
The plague of ancient Athens in 430 BCE, which Thucydides reported, the bubonic plague that transformed the society of fourteenth-century Europe, and the 1918 flu pandemic, which killed more than twice as many people as the weapons of the First World War, were all dreadful scourges of our past. Hardly any sane person thinks that we are suffering from any such calamity now. But we are. We live in a plague time that only a few thoughtful scientists have grasped. Our time of plague will continue for at least the next several decades, even if researchers are unusually clever. The major uncertainty is just how many infectious plagues are smoldering along, consuming the oblivious—those people who think that their bodies are just falling apart from the wear and tear of life. There are certainly several such infectious plagues; there may be many more. A substantial proportion of the pain and suffering that occurred at the dawn of this new century will, I believe, become recognized as the result of long-standing, slow-burning plagues that are infectious but were not generally accepted as being infectious in the year 2000.
This view may seem disturbing and even more frightening than the idea of nasty Ebola-like viruses waiting to catch a plane to London's Heathrow airport, or New York's JFK. But there is good news. Infectious diseases usually have vulnerable underbellies, and recognizing a disease as infectious is one of the most important steps toward discovering its vulnerability. The agents of disease, those enemies within, are often difficult to identify. They are usually invisible and their behavior is deceptive. Although modern medicine can recognize some of these enemies, it has only a few clues about most of the others. The unknown majority are swept under the
risk-factor rug, which generates a lot of tabloid journalism—Does drinking some red wine lessen your chance of heart disease? Will holidays in the south of France make you live longer? Should you eat margarine or butter?—while skirting the crux of the problem. We need to understand causes if we are to solve the big health problems.
When major problems are solved, people get a smug sense of superiority over previous generations who failed to recognize what has become an obvious solution. It now seems obvious that surgical instruments should be sterilized before surgery, that water supplies should be filtered and chlorinated to protect against diarrheal diseases, and that condoms can protect against AIDS. Soon it will seem obvious that peptic ulcers are caused by bacterial infection and can be prevented by antibiotic treatment. The task of the present is to recognize that which will be obvious to future generations. This task often requires a mix of skepticism and
creativity—skepticism to discern dogma, and creativity to develop alternative explanations that may not fit with the received wisdom. Failing to get this mix right leads to wasting time and resources on the wrong culprits. Bad genes and bad environments have often been falsely accused, or, at least, they have taken more than their share of the blame. Viruses and bacteria are the primary offenders.