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This question reminded me of a theory that was proposed several years ago by Paul W. Ewald, an evolutionary biologist. He “argues that many common diseases of currently unknown Etiology, such as cancers, heart attacks, stroke and Alzheimer’s, may likewise be also caused by chronic low-level microbial infection(Paul W. Ewald). I was quite taken by this idea while reading some of his work. I found especially compelling his argument that the theory and practice of modern medicine largely eschews consideration of evolutionary biology. I believe this is much to the detriment of the pace of biomedical advances.

Is Paul W. Ewald‘s theory “true”? I think it is difficult to conclusively assert it is “true” in every instance he cites in his statement but there are two examples where there is now substantial supporting evidence:

1. Peptic ulcers and Helicobacter pylori (H. pylori, a bacterium)
2. Cervical cancer and Human Papilloma virus

In fact, Barry Marshall and Robin Warren were awarded the Nobel Prize in Physiology or Medicine for 2005 for their discovery of “the bacterium Helicobacter pylori and its role in gastritis and peptic ulcer disease(The 2005 Nobel Prize in Physiology or Medicine to Barry J. Marshall and J. Robin Warren).

I remember reading that these researchers had a Herculean challenge in gaining acceptance for their idea among their peers since the prevailing paradigm at the time was that ulcers were caused by stress. In fact, Barry Marshall recounts in his Nobel acceptance speech (Barry J. Marshall – Biographical) that at one point he even swallowed H. pylori in an attempt to demonstrate the association between this bacterium and peptic ulcers:

At the same time I was successfully experimentally treating patients who  had suffered with life threatening ulcer disease for years. Some of my patients  had postponed surgery which became unnecessary after a simple 2 week course  of antibiotics and bismuth. I had developed my hypothesis that these bacteria  were the cause of peptic ulcers and a significant risk for stomach  cancer. If I was right, then treatment for ulcer disease would be revolutionized.  It would be simple, cheap and it would be a cure. It seemed to me that for the  sake of patients this research had to be fast tracked. The sense of urgency  and frustration with the medical community was partly due to my disposition  and age. However, the primary reason was a practical one. I was driven to  get this theory proven quickly to provide curative treatment for the  millions of people suffering with ulcers around the world.

Becoming increasingly frustrated with the negative response to my work  I realized I had to have an animal model and decided to use myself. Much  has been written about the episode and I certainly had no idea it would become  as important as it has. I didn’t actually expect to become as ill as  I did. I didn’t discuss it with the ethics committee at the hospital.  More significantly, I didn’t discuss it in detail with Adrienne.  She was already convinced about the risk of these bacteria and I knew I would  never get her approval. This was one of those occasions when it would be  easier to get forgiveness than permission. I was taken by surprise by  the severity of the infection. When I came home with my biopsy results showing  colonization and classic histological damage to my stomach, Adrienne suggested  it was time to treat myself. I had a successful infection, I had proved my  point.

Like many such accounts of scientific discoveries, it is an engaging read on how they tend to happen: often in the face of odds, preceded by substantial resistance from peers, and through paradigm shifts occurring through incremental gathering of data by others working in the same field, data at odds with the prevailing paradigm.

Coming back to Paul W. Ewald‘s theory, isn’t it interesting to ponder the association, if any, between “chronic low-level microbial infection” and other “common diseases of currently unknown etiology such as cancers, heart attacks, stroke and Alzheimer’s” where strong cases have not yet been made?

What are some unusual scientific theories that aren’t well known but actually true?