We Share More Of Our Germs With Dogs Than We Do With Our Children

Lee Rannals for redOrbit.com — Your Universe Online

Researchers writing in the new online science and biomedical journal eLIFE say parents share more bacteria with family dogs than children.

The team, led by the University of Colorado-Boulder, looked at the types and transfer modes of microbes from the guts, tongues, foreheads and palms of 60 American families and their canines. In all, they sampled 159 people and 36 dogs.

Researchers swabbed various parts of the body to obtain microbial samples of the couples, children and their dogs, looking to detect individual microbial communities. Dogs were sampled similarly, except that fur was sampled instead of skin.

“One of the biggest surprises was that we could detect such a strong connection between their owners and pets,” said Associated Professor Rob Knight. “In fact, the microbial connection seems to be stronger between parents and family dogs than between parents and their children.”

He said studies of human microbiome have become one of the hottest areas of biological research. The number of microbes living on and inside a human is about 100 trillion, which outnumbers human cells by about 10 to one. The microorganisms humans carry around have been linked to a wide range of health issues, including diabetes, asthma and depression.

“There is mounting evidence that exposure to a variety of environmental sources of microbes can affect long-term health, findings known as the ‘hygiene hypothesis,'” said doctoral student Se Jin Song in a statement.

The team found the composition of human bacteria is affected by factors like age and environmental exposure. Song said our skin microbiota seems to be the most malleable by our immediate surroundings.

According to Knight, the primary results indicate that the family unit had a strong effect on human microbial community composition across all sites. The weakest relationship on body sites was father-to-infant connection on the forehead and palms.

The study showed parents share more tongue and gut communities with their own children than with other children, but only after age three. Knight says this indicates it is easier to exchange skin microbes on home surfaces or indoor air than tongue or gut bacteria.

“These previous studies were conducted on humans only, and we wanted to determine whether similar patterns exist when we considered nonhuman co-inhabitants,” he said. “And since so many people consider their pets truly a part of the family, it seemed appropriate to include them in a study involving family structure.”

Knight is also working on the American Gut project. This is a crowd funded effort that allows members of the public to learn more about individual microbes, as well as those being carried by dogs.

A study released last year showed that babies who lived in a home with a dog had fewer weeks of cough, ear infections and running noses compared to those who did not have a canine friend. Researchers in this study also found that infants had less of a chance of needing antibiotics than those babies who lived at home without pets.

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