FRIDAY, Sept. 9 (HealthDay News) -- Good hygiene has saved millions of lives, protecting people from countless bacterial and viral infections, according to the U.S. Centers for Disease Control and Prevention.
But there is growing concern that strict adherence to good hygiene, though a valuable means of protecting health, has left humans open to other forms of illness.
Proponents of the "hygiene hypothesis" believe that reduced exposure to bacteria, viruses and parasites have impaired the immune system's ability to properly respond to environmental challenges.
Researchers have identified the hygiene hypothesis as a possible cause or exacerbating factor in a number of illnesses and medical problems, said Dr. Graham A.W. Rook, a professor in the department of infection at the Centre for Clinical Microbiology at the University College London. These include:
"The evidence for all this is very, very powerful," Rook said. "It's very easy to show if you live on a farm or keep a dog, you're less likely to have these disorders. If you are the youngest child in a big family, you're less likely to have these disorders."
The hygiene hypothesis has its roots in the theory of evolution, he said.
"The bottom line is organisms that were present in mud, untreated water and feces were with us right from the start of humanity," Rook explained. Proponents of the hygiene hypothesis believe that the human body adapted to these organisms and began using them as a means of training the immune system.
"What has happened over the course of evolution is, because these bugs had to be tolerated, they came to activate the tolerance of the immune system," Rook said.
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