Study: larger families have more illnesses

Researchers say more children really does mean more germs


SALT LAKE CITY, Utah – Never get sick? Try having children. Many parents will tell you, sharing your home with kids is like living in a petri dish.

Not surprisingly, a new study confirms that the more children there are in a household -- the more likely it is that someone will get sick.

Researchers at the University of Utah School of Medicine analyzed germ swab samples from each member of 26 households each week for a year.

They found people living in childless households were infected with viruses on average 3 to 4 weeks during the year. In households with one child, that number jumped to 18 weeks, and for families with six children, there was virus in the household for up to 45 weeks out of the year. That means 87 percent of the time, someone in the family had a virus.

"A lot families go through wave after wave of illness. In fact, some of the kids we monitored had symptoms for 20 to 25 weeks in a row," says co-first author Dr. Carrie Byington. "This study helps us to understand what is normal in young children, and can help us determine when illness should be a cause for concern."

The good news -- not everyone who tested positive for a virus actually showed symptoms, and most of the infections were simple runny noses.

When germs do spread, the youngest members of the family are often to blame. Children under five had at least one virus detected in their nasal mucus for 50 percent of the year. That's twice as often as older children and adults. Younger kids were also more more likely to suffer symptoms.

But children don't suffer alone. Their parents were also sick 1.5 times more often than adults who did not live with young kids.

The full results of the study are published in the journal "Clinical Infectious Diseases."