Customer Reviews

Plague Time: How Stealth Infections Cause Cancer, Heart Disease, and Other Deadly Ailments

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This book clearly deserves more than five stars. This is one of the three best books published so far in 2000 that I have read.

Plague Time is an important book for the future health of all. It is the most articulate argument I have seen for improving the basic mechanisms of studying and preventing disease in the most effective ways. And it shows important lessons about what is needed to overcome stalled progress in any field. Professor Ewald is a profound stallbuster! We will only get full benefit from his work though, if this thinking is quickly absorbed by the medical community, as a sort of idea virus.

The perspective of this book will be new to many readers. Evolutionary biology is something that few have learned in school. Basically, the field looks at a germ's eye view of the world.

For example, if a germ kills the host it feeds on too quickly, that's bad for the germ. The germ hasn't yet had time to spread to a new host. On the other hand, if it takes too long to spread to other hosts, that's bad for a germ also. So germs will do best that are able to spread quickly from host to host, and keep the host alive to provide more food. That spells a prescription for the prevalence of many chronic diseases that are associated with long-lived infections from bacteria and viruses.

The germ theory of disease is only about 120 years old. So it is fairly recent that we have been using hygiene (washing between patients and clean water to drink), vaccines (to help the body's immune system prepare for a larger invasion), and antibiotics (to kill bacteria) to control disease-producing agents. From this work, we have learned that acute diseases are almost always linked to a bacterial or virus invasion of our bodies. These invasions can come from other people (sneezes, blood, or germs on a surface) or vectors (agents like mosquitos).

What many will not realize is that many chronic diseases are turning out to be caused by such invasions as well. For example, most peptic ulcers (once thought to be caused by stress and too much stomach acid) are now easily treated by antibiotics. Cervical cancer is also related to an infection. It is estimated that 15 percent of all cancers are now shown to be caused by such infections. Cancer researchers also can account for only about 50 percent of cancer risk from environmental factors. That remaining 35 percent gap could well turn out to be related to unsuspected infection links, working in combination with environmental factors.

Professor Ewald proposes a number of interesting hypotheses that would appear to deserve serious attention. First, the evolutionary biology view would suggest that sexually transmitted infections as a primary source of chronic disease in wealthier countires. These infections live in the host for a long time without immediately killing the host, and are highly contagious. The sites of many diseases also show the presence of these same infections (examples include c. pneumoniae -- related to Chlamydia -- found in the brains of Alzheimer's patients and damaged artery walls experiencing arteriosclerosis). Other sexually-transmitted diseases may also have these effects on other chronic diseases. Further, people are reluctant to talk about having sexually-transmitted diseases so partners are often kept in the dark.

The book also takes an interesting look at the dangers of being ravaged by some new biobomb or spread of disease from one part of the underdeveloped world to the developed world. These problems do not seem to be as great as the popular press would suggest. Basically, anything really virulent tends to extinguish itself by killing the hosts too rapidly.

The fascinating part of the book to me, though, was the description of why we are so slow to look at these hypotheses. Professor Ewald points out that doctors are used to drawing their hypotheses from close associations in frequency and time in their own practices. Minor infections from sexually-transmitted diseases that cause chronic diseases decades later deny doctors that easy association.

His proposal is brilliant: Keep records of everyone who gets better or worse unexpectedly from a chronic disease to find out what other medications or lifestyle factors may be involved. For example, peptic ulcers were being treated with antiobiotics successfully in a few hospitals 40 years before that became common practice. A database that showed that result could have stimulated an NIH study much sooner. If we find that everyone who takes a certain antiobiotic improves in some chronic disease, this may suggest a linkage to a bacterial infection. I hope this idea will get top priority!

The author also takes on the medical model of looking for things that "kill" germs in a "war-like" environment. It turns out to be much faster, simplier and cheaper to adopt treatments that encourage germs to evolve into milder versions. By trying to kill them, all we do is create more virulent versions. So the whole approach to antibiotics needs rethinking along the lines of this book.

By the way, chances are your doctor is unaware of this line of thinking. I mentioned the potential risk of infection causing arteriosclerosis to my primary care physician, and asked what antibiotic I should take. He laughed, and said that if it was that simple, everyone would already know about it. Apparently, he did not know about the peptic ulcer experience.

As the author points out, our tests of medical effectivenesss are too high in some cases. If we find that a certain treatment almost always works, we can begin to use that treatment long before the 14 year study is completed that explains exactly why it works. After all, we are still learning the basics of why aspirin works, but many people use aspirin anyway.

After you have read (and shared this book with everyone you know), I suggest you also think about where causes and effects may not too obvious because of long time lags. What research is not being done in those areas?

Enjoy better health by having health researchers ask better questions today!

Ewald's startling thesis is that "infection is at the root of the major chronic diseases of our time" (p. 271). These diseases include the two big killers, cancer and heart disease, and possibly Alzheimer's. His thesis is a heresy to a significant part of the medical establishment, and if correct, a revolution in the making. The conventional wisdom believes that cancer and heart disease are caused by a combination of factors including hereditary predisposition (bad genes), environmental catalysts (pollution), bad life style choices (fatty diet, alcohol, cigarettes), stress, etc. But what Ewald is saying is that there is a bacterium or a virus that causes these chronic diseases.

One of the powerful ideas behind Ewald's belief is the growing realization from evolutionary medicine that a major human disease cannot possibly be caused by bad genes since natural selection would have weeded them out long ago (pp. 55-56). Diseases caused by bad genes can only occur in a small percentage of a given population. The only exception would be a "bad gene" that has a compensating adaptive characteristic, such as the gene for sickle cells which confers immunity to malaria. Consequently, "the best bet is that they [chronic diseases] have infectious causes" (p. 56).

The practical evidence, evidence that has been consistently explained away or ignored, is the actual presence of disease agents in the tissues. Thus cervical cancer is now known to be caused by a papillomavirus that hides in the tumors and as such is a sexually transmitted disease. Peptic ulcers are now known to be caused by a bacterium, Helicobacter pylori, and not worry or stress or booze, although these may be contributing factors. Chlamydia pneumoniae bacteria are increasingly being implicated in heart disease. In Chapter Eight, Ewald makes the case for C. pneumoniae being the cause not only of atherosclerosis but Alzheimer's disease as well! Again, if correct, this is a revolution. The interesting (and terrible) thing about the peptic ulcer story is that it was known as long ago as the forties that peptic ulcers could be successfully treated with antibiotics, but that knowledge somehow became lost (!) until the early nineties (p. 99).

There is more: Ewald reports that Japanese researchers found the Borna disease virus "in one third of their patients diagnosed with chronic fatigue syndrome" and that this same virus "has been implicated in schizophrenia and bipolar disorder" (p. 162). I would not be surprised to learn that other chronic diseases of unclear etiology such as fibromyalgia, certain kinds of arthritis, and even unexplained chronic pain are caused or at least initiated by infectious agents, probably viruses. (Actually I wouldn't be surprised to learn that a new kind of infectious agent, something smaller and stealthier than a virus is the cause of some human diseases. But then I used to write science fiction.)

One of Ewald's main arguments is that we can lessen the virulence of pathogens by the way we interact with them. An insight from evolutionary medicine is that a pathogen cannot afford to kill its host before it can spread from that host. However, if it can spread from the dead corpse of its host, then it can be as virulent as it likes. In places in the world where there are no screens and mosquitoes have easy access to their victims, the malaria protozoan tends to weaken its victims so much they can't even swat mosquitoes (protecting its vector!). However in areas where the buildings are made mosquito proof, the protozoan dare not be so virulent since the mosquitoes can only get to the hosts that are still able to be up and out of doors. Similarly, sexually transmitted diseases are more benign in populations that tend to be monogamous or to change partners infrequently. In populations that practice promiscuous sex frequently, the pathogen can afford to be very nasty because it will get transmitted often. But if the host is not going to be having sex with anyone new or soon, the germ must be nice and bide its time without knocking its host out of action. This principle also applies to cholera. If people have access to clean water the cholera bacterium must be relatively benign because it is going to take a long time to get passed on. But if the water supply is befouled with human feces, then the bacterium can be massively virulent, and in fact is rewarded for being so as its progeny come pouring out of the dying bodies of its victims and into the water supply.

One of the highlights of the book is Chapter Four, "The Magnificent Defense" in which Ewald describes the immune system and how it works in language that is vivid and easy to comprehend. In a startlingly apt analogy he compares the immune system to our brain. Both are incredibly complex systems constructed through the laborious trial and error mechanism of evolution. And both are "decision-making systems" (p. 67). I like this analogy and predict that researchers who have knowledge of both systems will make the scientific breakthroughs of the future. I would add that knowledge of the elaborate, brain-like social systems of bees, ants, and termites would also be valuable.

Ewald concludes the book with some guidance on how we might better co-exist with pathogens. One of the ideas is simple: stay home and don't go to work with a cold or flu. Staying home will keep the pathogen relatively benign (p. 210). He insists that we need more education about evolution in our schools, and even in college. I couldn't agree more. In the United States people that approve text books tend to be so terrified of know-nothing "creationist" types that high school biology texts typically mention evolution only as a side note, when in fact it is, as Ewald has it on page 237, "the fundamental unifying principle of biology."

About halfway through Plague Time, the author notes the reaction of the evolutionary biologist William D. Hamilton to the theory that AIDS was caused by a contaminated vaccine. He states that Hamilton did not say that a contaminated vaccine definitely introduced AIDS into humans, but instead stated that the idea needed to be evaluated rigorously because it was being dismissed without adequate evidence for dismissal. I think that same statement could apply to the ideas presented in Plague Time.

Ewald does a marvelous job of taking the readers through the intricacies of evolutionary biology. He effectively demonstrates how evolutionary biology theories can help explain many of the mysteries surrounding diseases that are currently attributed to a multitude of causes. It should be noted that he never definitively proves that viruses and bacteria are the causes of these diseases. But, he does present enough evidence to justify further exploration of the idea.

The book is not perfect. Some of the language gets a little technical at times. Also, Ewald has a tendency to repeat the same examples, thus giving the impression that there is some "filler" in the book. But, these points don't detract from the fact that this is a very persuasive work. The theories inside it may prove to be invalid, but they are certainly worth further exploration by both the scientific community and the reader attempting to educate themselves on their health.

Not genes but germs cause most chronic diseases. So argues evolutionary biologist Paul Ewald in his new book, "Plague Time: How Stealth Infections Cause Cancers, Heart Disease, and Other Deadly Ailments," (Free Press, 282 pp, ...).

The Amherst professor is trying to drag the medical establishment into the Darwinian age. While modern research often aims to uncover genetic factors in major diseases, Ewald contends that "human genome mania" often violates the fundamental principle of biology, Charles Darwin's theory of natural selection. Darwin argued that families with harmful hereditary traits will die out over time, asserts Ewald, and would be replaced by lineages whose hereditary constitution better enables them to survive and reproduce.

Ultimate goals aside, Ewald has made sure that lay readers will find his book interesting and intelligible. He believes that patients are often more open-minded than their doctors.

In an interview, Ewald claimed that the health benefits of the Human Genome Project are over hyped because "most diseases aren't genetic." He said research funds dedicated to improve antibiotics would bring greater payoffs than those spent on the glamour field of genetic research.

Ewald, who is not a medical doctor, said, "My goal is to bring into medicine all of biology, especially evolution."

So far, he has had more success persuading other biologists than the medical establishment. The late William D. Hamilton of Oxford University, England -- considered by the likes of Edward O. Wilson and Richard Dawkins to be the most important evolutionary thinker of recent decades -- commented on Ewald's theory, "It opens our eyes to many quite weird possibilities about disease that most medical scientists, tending to be unaware of current evolutionary thought, don't think of."

Ewald contends there are only three fundamental causes of disease:

-- First, nonliving environmental agents like radiation, poisons, and nutrition. Too many cigarettes cause lung cancer; too little Vitamin D causes rickets.

-- Second, infections. Long ago, people figured out that smallpox, measles, and chicken pox passed from one person to another. Since then, an ever-growing number of diseases have been shown to be induced by bacteria, viruses, or protozoa.

Historically, infectious agents have been harder to identify than nonliving poisons as the cause of diseases because germs can evolve ways to hide. Simple chemicals cannot.

-- Third, hereditary causes. The Human Genome Project has been widely advertised as eventually leading to cures for many diseases, such as breast cancer. Ewald observed, however, "If one identical twin gets breast cancer, the other's likelihood of contracting it is only around 10 to 20 percent. This suggests that genes are not the whole story."

But the more basic logical problem with what he dubs Human Genome Mania, argued Ewald, is natural selection theory.

Such reasoning was forcefully introduced to Ewald in the early 1990s by a letter from a physicist named Gregory Cochran. After America won the Cold War, this New Mexico rocket scientist had turned to developing formulas for estimating which diseases are hereditary and which are infectious. The key number proved to be the ailment's "reproductive fitness burden." In other words: Compared to a healthy person, how many fewer descendents will a sufferer procreate?

The tendency of people with healthy genes to reproduce more than people with sick genes, Cochran and Ewald determined, makes it unlikely that there are many hereditary syndromes that are both widespread and significantly damaging to their victims ability to reproduce successfully.

We can evolve new defenses against both bad genes and bad germs. What makes infections more dangerous than genes, however, is that germs can fight back, said Ewald. They can relatively quickly counter our new resistance strategies by evolving news methods of attack -- thus antibiotic resistence, for example.

Ewald admits there are numerous hereditary diseases. But the ones produced by spontaneous mutations tend to be quite rare since the bad genes quickly get weeded out of the gene pool, he said, citing Duchenne's muscular dystrophy. This male-inherited disorder of progressive muscular degeneration may be the most widespread example, yet it only afflicts 0.02 percent of the populace, said Ewald.

Still, it's possible for more common hereditary diseases to survive down through the generations if they are a defense against something worse. The best known example is sickle cell anemia, a blood disorder that sickens and can kill those of West African descent who inherit two copies of the sickle cell gene. Those who receive only one copy from their parents, however, have greater resistance to a debilitating form of malaria.

A spokesman for the National Human Genome Research Institute, part of the National Institutes of Health, responded diplomatically to Ewald's charges that research dollars invested in genetic research would save more lives if devoted to infectious diseases instead. He suggested, "This shouldn't be a zero sum fight. As promising new areas come along, the government should spend more on health research in general."

The Bethesda, Md.-based spokesman also argued that when the Human Genome Project eventually maps the variations found among a large number of individuals, it will help us understand why some people have better resistance to particular germs. For example, he said, certain East African prostitutes appear to be immune to HIV. Understanding their genetic peculiarities might well help researchers uncover the Achilles heel of AIDS.

Nonetheless, Ewald's "Plague Time" may someday be remembered as a landmark in the development of more effective treatments for killer diseases.

Ewald sets out to show that medicine has made so little progress over the past 50 years in tackling chronic diseases like heart disease and cancer because it has been looking in the wrong places - at genetic defects and environmental factors. The medical authorities have virtually ignored infectious causes of chronic diseases.

The case for infectious causation of ulcers met with hostility and dismissal from the medical profession. The doctors who proved that heliobacter pylori caused ulcers had to struggle for years before their work was recognised. Ewald provides good evidence that many other chronic diseases are likely to have infectious causes.

The reviews here seem to divide into two camps: those who believe that Ewald has got hold of a vitally important idea that will transform the way we tackle chronic disease, and those who dismiss the book. I am firmly in the first camp. I found it clear, balanced, and full of fascinating insights.

This is a great read. Paul Ewald points out quite convincingly that medical professionals neglect the evolutionary side of disease. His theory is that most diseases including chronic diseases like some cancers and heart disease are caused by infections by micro-organisms. This is not to say that his theory is conclusively demonstrated but rather that it rests on principles that are sensible and possibly correct. Another of the important themes talked about in his book is that the virulancy of an infectious agent will evolve depending on how easily it is transmitted. An organism (bacteria or virus) in the human body is always trying to balance its fitness in reproducing in its host versus its fitness in being able to jump into another host. The outcome is decided by natural selection. Whatever evolutionary path results in the most offstring will win out. An organism which reproduces too quicky and imediately kills its host will not be very capable of being transmitted to another host. Take for example the common cold. If the effects of the common cold were much worse then people would stay home from work and the chance of the germs reaching other hosts would be much less. Ewald in fact advocates that people should stay home from work when they get a cold or the flu. This would probably benefit the employer in the long run because the flu would be less prevalent and less workers would contract it. I won't try to argue his points here but I find them quite convincing. On the other hand there are some down sides to the book. As mentioned in some other reviews the title is a bit overstated. Ewald has a theory and not conclusive evidence that things like cancer and heart disease are caused by infectious agents. Some things like cervical cancer and peptic ulcers have been shown to be caused by infectious agents in just the last few years where as the popular belief in medicine was that these were not infectious diseases. However that is not to say that all cancers and diseases are caused by infectious diseases. Ewalds obviously acknowledges this but nonetheless makes some pretty bold claims. Overall I highly recommend the book to non-specialists like myself who want to learn about infectious diseases and evolutionary biology.

The title of this book should be 'How stealth infections combined with many other factors MAY cause cancers etc'. The author is very knowleadgeable about biological processes and the book reads fairly easily. It is informative and entertaining. The bad news: He does not provide new knowledge, new strategies or new insight into finding the infectious causes of any of the chronic diseases mentioned in the book. Mr. Ewald portrays himself as being in an influential position at an important university. Certainly he has the access to research labs and the funding to keep him going. If the information in the book is correct (he makes very convincing arguments), the next step is to prove it by actually doing the research. Some of the chapters in the book are great. Some others seem to have been written in a hurry--rambling information covered in previous chapters. The last chapter, which I was really looking forward to put it all together, really dissapointed me. I was hoping for advice to other biologists, doctors and other medical and research personel. Advice that would help the rest of the world finding the microbe causing the chronic disease. I guess I was hoping for a major revelation but there was no revelation--it was just one more book covering the subject of bacteria, viruses, disease transmission, bioterrorism, etc.

Professor Ewald lays out a very interesting and persuasive case for the potential involvement of infectious agents as the cause of many "non-infectious" diseases. This book offered a fascinating account into the history of disease and makes plausible predictions about future discoveries. I read this book several months ago and have since been keen to periodic news reports concerning recent discoveries linking infection as a possible cause for various chronic aliments. I believe Professor Ewald may be ahead of his time.

I'm not a medical professional, just an interested layman. Mr. Ewald's book is an easy read for a non-professional. If you're interested in the topic this book will not disappoint.

If you categorize your self as an early adopter, I think you will appreciate the words written by Paul W. Ewald concerning the strong possibility of infectious agents (germs) causing the medical conditions of heart disease, cancers, HIV and Alzheimer's. He suggests many other diseases as well may be caused by germs.
There was a time not long ago (1980's) when the cause of peptic ulcers were clearly and almost universally accepted to include stress, genetic disposition and emotional anguish. Today, as a result of the acceptance that ulcers of this type are caused by germs, are successfully treated with antibiotics.
To my knowledge, the author is one of the early advocates of this theory that germs are the cause of many of the diseases not presently associated with being caused by them. As a result, he is often subject to harsh critical review from the present generation of medical experts.
I especially appreciated his suggestion for the creation of a data base made up of anecdotal reports of unexpected positive results of the application of vaccines on chronic diseases. The data base could supply direction for future research studies to explore.
Although I have no medical expertise, I found reading the book manageable but not an especially easy read. Even so, I found the time spent was very rewarding and left me feeling as though I was getting a pretty clear view of where the future of medicine is headed.

Plague Time provides important and fascinating information about diseases, how they are acquired, their evolution, and their consequences. Professor Ewald contends that many chronic diseases such as several types of cancer, arteriosclerosis, schizophrenia, several types of arthritis, bipolar disease, fibromyalgia, chronic fatigue syndrome, or even many symptoms of aging are the result of infections. The explanations of how these infections are acquired, and situations where the infectious agents are likely to be especially virulent are of great practical value.

Dr. Ewald's thesis is that infectious agents quickly evolve to maximize their reproductive success. Their virulence and the nature of the acute or chronic symptoms they cause are a function of how they are transmitted. The discussions of microbe evolution deepened my understanding of biology and evolution. There are many examples presented.

Many sections were unnecessarily wordy, with clumsy and overly long sentence constructions and much redundancy. This made parts of the book slow and heavy going. His frequent and often lengthy criticisms of the medical establishment are justified in my view, but sometimes got tiresome. In spite of the effort required, Plague Time is well worth reading.