Tuesday, November 12, 2013

A Cure for the Allergy Epidemic?

Dr. Holbreich, slight and bespectacled, peppered them with questions. At what age did Mr. Mast begin working in the cowshed? “My first memory is of milking,” he said, at about the age of 5. What about his children, two straw-haired girls, then ages 2 and 3; did they spend time in the cowshed? The elder girl came to the barn at 3 months of age, he said. “People learn to walk in here.” Do expectant mothers work in the barn? “Yes,” Laura said. “We work.”

Dr. Holbreich had made his point: whatever forces were acting here, they were chronic, and they began before birth. As the sun rose, Dr. Holbreich and I sniffed the damp, fermented feed (slightly malty); shoveled fresh cow manure (“Liquid gold,” Dr. Holbreich said only half-jokingly, “the best medicine you could think of”); and marveled at the detritus floating in the air. Extrapolating from previous research, with each breath we were inhaling perhaps 1,000 times more microbes than usual. By breakfast time, grime had collected under our nails, hay clung to our clothes, and muck to our boots. “There’s got to be bacteria, mold and plant material,” Dr. Holbreich said. “You do this every day for 30 years, 365 days a year, you can see there are so many exposures.”


The challenge of identifying the important exposures — and getting them into a bottle — is a pressing one. In parts of the developing world, where allergic disease was once considered rare, scientists have noted an uptick, especially in urban areas. China offers a dramatic case in point. A 2009 study found a more than threefold difference in allergic sensitization (as judged by skin-prick tests) between schoolchildren in rural areas around Beijing and children in the city proper. Doctor-diagnosed asthma differed sixfold. Maybe not coincidentally, 40 percent of the rural children had lived on farms their whole lives.


Immigrants from the developing world to the developed tend to be less allergic than average. But the longer they reside in their adopted countries, the more allergic they become. And their native-born children seem to gain the vulnerability to asthma, sometimes surpassing it. All of which highlights a longstanding question in the allergy field. As Dr. Holbreich puts it, “What is it about westernization that makes people allergic?

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