In one of his later stand-up specials, the poet-saint George Carlin rebuked the quintessentially American fear of germs. As a boy growing up in New York, he said, none of the kids in his neighborhood got polio because they swam in the raw sewage of the Hudson River to cool off in the summer. How else could you expect an immune system to get strong?
A new Dutch study puts some empirical rigor to the Carlin school of child-rearing. Researchers tracked the incidence of acute gastroenteritis (a common stomach flu also known as AGE) in 2,200 children in the city of Utrecht over their first six years of life, 83 percent of whom started day care before they turned 1 year old. The study found that while the incidence rate of AGE was similar for the kids who attended day care and those who didn’t, the timing was different: The day-care-goers (and their parents) were more likely to suffer through AGE’s vomiting, feverish, diarrhea-filled course during their first two years of life, and less likely to get it afterward.
It’s further evidence of the manifold benefits of high-quality childcare. American studies have found that day care has long-term academic consequences, like the fact that high-schoolers who attended high-quality day care score better on tests and get in less trouble, while adults who went to day care as kids were almost four times more likely to earn a college degree than a control. And while much of Europe is falling off a population cliff, state-sponsored day care has been identified as a key in keeping the birthrates in France and Norway high — since it allows parents to get back to work sooner. While previous research has found that putting kids into day care correlates with infection, this study shows that, as study senior author Marieke de Hoog tells the New York Times, that can, in the case of AGE, be a good thing.
“We think if you are infected at an early age you build up immunity against these viruses or bacteria,” the University Medical Center Utrecht epidemiologist explained. “There is even a possibility that the protective effect we have seen will continue when children grow up — we need more research.”
The researchers tracked the illnesses by primary-care visits, meaning that secondary-care visits — like trips to the hospital — were missed by the study. And since the study ended with age 6, it can’t say anything about later cases of AGE. But it does say, as Carlin so rightly predicted, that your immune system — like the rest of you — needs to push through some difficulty in order to get stronger.