Robert Lee Hotz looks at The Body as Bacterial Landlord:
When scientists discovered that bacteria, not stress, caused most stomach ulcers, the insight overturned a century of medical dogma, transformed clinical practice and garnered a 2005 Nobel Prize for the two researchers who made the connection so many others had missed. After people adopted antibiotics to treat gastric distress, though, microbiologist Martin Blaser and his colleagues at New York University began to document an odd medical trend.Ulcers did drop dramatically, as expected. So did the incidence of stomach cancer. As the bacteria, called Helicobacter pylori, virtually disappeared among children, however, cases of asthma tripled. So did rates of hay fever and allergies, such as eczema. Among adults, gastric reflux disease became more common, as did some forms of esophageal cancer, researchers noted.
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Until recently, half of humanity harbored these H. pylori stomach bacteria, according to a 2002 study in the New England Journal of Medicine. Indeed, we appear to have evolved together. Among those born in the U.S. during the 1990s, however, only 5% or so still carry these microbes, largely due to the indiscriminate use of antibiotics.After analyzing health records of 7,412 people collected by the National Center for Health Statistics, Dr. Blaser and NYU epidemiologist Yu Chen reported this summer in the Journal of Infectious Diseases that children between three and 13 years old who tested positive for H. pylori bacteria were 59% less likely to have asthma. They also were 40% to 60% less likely to have hay fever or rashes.