Never fall in love. Oh, well, go ahead, if you must, but make sure you fall for a living being. A romance with anything else, be it a pair of shoes or a scientific theory, is only asking for trouble, so seldom will the inanimate beloved live up to your besotted expectations.
The best scientists struggle with this prohibition daily, knowing that even the most seductive data may well disappoint. But premature enthusiasm is routine among others, patients and their doctors foremost among them, with journalists smelling a scoop not far behind.
Moises Velasquez-Manoff -- a journalist and also, as it happens, a patient -- has fallen hard for an idea known as the hygiene hypothesis, whose implications, if followed out along a widely branching chain of extended supposition, threaten to unravel much of what we think we know about health and disease.
This hypothesis argues that our modern obsession with eradicating germs has backfired into an explosion of disease, specifically all the "new" diseases that have replaced infections to undermine our health. The modern immune system, the idea holds, is stymied by the sudden absence of its customary microbial targets. With nothing constructive to do, it is crazily spinning its wheels, resulting in soaring rates of food allergies and asthma, arthritis, psoriasis, multiple sclerosis and diabetes, even heart disease and cancer -- not to mention alopecia, the premature baldness from which Mr. Velasquez-Manoff suffers and which led him to the subject in the first place. (In an opinion article in The New York Times last month, he suggested that an immune disorder might account for many cases of autism.)
Clearly, if true, the hygiene hypothesis is the single greatest medical story of our time, undercutting a century of putative progress. Is it true? Probably some of it is. But Mr. Velasquez-Manoff's ambitious compendium of data and supposition -- a great dense fruitcake of a book whose 680 endnotes, the author notes apologetically, refer to only a minority of the 10,000 studies he consulted -- spins it all out in the most positive possible way with an energy, eloquence and desire to believe that is both breathtaking and a little scary.
A human being, the proponents of the hypothesis argue, is not really an individual. Instead, each person is a "superorganism," a large creature subsuming many billions of smaller ones, most of them intestinal microbes. Thriving in the colon, these "old friends" that have been with us since time immemorial are as important to our health as a limb or an organ. Altering their numbers, whether with sanitary measures, antibiotics or deworming pills, is analogous to fooling around with the liver or the spleen.
And that doesn't just mean that antibiotics may cause ruinous diarrhea. The microbes in the intestine, the hypothesis holds, educate the immune cells that travel all over the body, and any major alteration in the intestine sends some wild and crazy cells out there to wreak havoc unpoliced.
The genetic and immunologic details behind these assertions are immensely complex, but enough experimental confirmation exists to keep scientists at prestigious institutions around the world deeply engaged in sorting it out.
Other data are equally intriguing. Among them: Allergic and autoimmune conditions are far more frequent in rich countries than poor ones, even among genetically identical populations (West Germany far outpaced East Germany in their frequency, as does Finland compared with an impoverished adjacent territory under Russian control). Societies where intestinal parasites are the rule seem to lack them completely.
A misfiring immune response has long been known to explain conditions like multiple sclerosis and Crohn's disease, a chronic inflammation of the intestine. But some preliminary observations extend the immune connection to illnesses usually considered to be unrelated, obesity and depression among them.
"Is fecotherapy the wave of the future?" Mr. Velasquez-Manoff asks. Does our path to good health lie in breathing microbe-rich dust and regaining the fecal content of our ancestors (while avoiding, of course, the disabling chronic illness that often went along)?
Scientists are now beginning to treat various illnesses with probiotics, various combinations of "good" intestinal bacteria. So far results are mixed: some good, some inconclusive.
Enthusiastic patients, however, enabled by the usual cast of shady entrepreneurs, have predictably skipped the long, dull validation process and are busily infecting themselves with a variety of intestinal worms.
Mr. Velasquez-Manoff details their cases at length: Lisa's Crohn's disease improved with whipworm. Hookworm sent Dan's multiple sclerosis into remission, and likewise Josh's psoriasis. A bad case of chiggers calmed Lawrence's autistic outbursts, and whipworm infusions have improved him further still. The meaning of these isolated cases is entirely unclear, but Mr. Velasquez-Manoff follows the tenuous thread of possibility out to the horizon: Possibly, autism can be averted with something "as simple as a probiotic given to Mom" during pregnancy, he notes. Could the best treatment for depression be "microbes from a donor with a sunny disposition"?
He himself joined the "hookworm underground" in the name of research and possibly of a new head of hair, but found the intestinal side effects intolerable and the benefits small (smooth skin and clear sinuses; he is still bald).
Even the most critical reader has to give Mr. Velasquez-Manoff credit for the prodigious task he has undertaken as he shovels around reams of data, most of which he lacks the expertise to interpret. But it will take a dispassionate commentator with a better set of tools to extract the gold from the dross.
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