“All of my kids are pretty healthy,” she said. They don’t suffer from allergies, and the dogs, Minnie and Oreo, might actually be a big reason why.
Dust from a house where a dog lives has helped prevent a common infection that can lead to childhood asthma, researchers reported Tuesday. It provides further evidence for the paradoxical “hygiene hypothesis” and might lead to an innovative way to help prevent kids from developing allergies, said a researcher from Georgia Health Sciences University who is a co-author of the study.
The study, presented at the American Society for Microbiology meeting in San Francisco, told how researchers from the University of California-San Francisco, the University of Michigan and GHSU looked at dust collected from a house where a dog lives but is also allowed to go outside. Mice that were dosed with the dust did not become infected with respiratory syncytial virus, a common infection that is associated with a higher risk of developing allergies, according to the study.
Previous work by the group had found the bacterial composition of the dust is different from that in houses without dogs that go outside.
The work builds on a study published in 2002 by GHSU researcher Dennis Ownby, which found that children who lived in a house with two or more pets in the first year of life had half the risk of developing allergies. The new study is also further evidence for the “hygiene hypothesis,” which holds that being raised in too sterile an environment does not allow the immune system to form properly.
“We think the reason for that association is that when you grow up in very close association with animals, you acquire a different group of bacteria, especially bacteria in your gastrointestinal tract, than if you grow up in a very clean environment,” Ownby said.
It also ties in with recent evidence that bacteria are much more common than human cells in our body and much more involved in basic life processes, he said.
“It turns out that for every cell in my body, there are probably 10 bacterial cells in my body.” Ownby said. “So actually I’m outnumbered. Although it sounds kind of gross and weird, we could be easily thought of as a transportation and nutrition system for a huge variety of bacteria. That’s true of other animals, too.”
In this case, the difference might be dirt, he said.
“We’ve put more and more distance between ourselves and all of these soil organisms,” Ownby said. “What we think is happening is when you have cats or dogs in the home, and it is specifically cats or dogs that go outdoors and come back indoors on a regular basis, they are bringing soil, on their paws presumably, into the house. And that changes the makeup of the microbes in the house dust.
“The microbes we tend to find that are associated with a lower risk of allergic sensitivity are all microbes you tend to find in healthy soil.”
The researchers are now working on a grant to use newer technology to genetically identify previously unknown bacteria that might have a protective effect when given to children, he said.