Early exposure to germs may reduce allergy, asthma risk later

In the world of antibacterial soaps, hand gels and cleaning wipes, parents may be doing their newborns a disservice by keeping things too clean, one new study reports.

According to the reesearch, published this week in The Journal of Allergy and Clinical Immunology, children are less likely to develop allergies and asthma-related breathing issues if exposed to common household allergens and bacteria early in life.

Building upon previous research in the area and getting much more specific, the researchers at the Johns Hopkins Children’s Center in Baltimore found that exposure to household germs, pet and rodent dander and even cockroach allergens helped children build their immune systems before their first birthdays. This was shown to prevent the development of allergies and wheezing, precursors to full-blown asthma, the researchers say. However, exposure after the first year did not seem to have the same protective effect.

“Our study shows that the timing of initial exposure may be critical,” says study author Dr. Robert Wood, chief of the Division of Allergy and Immunology at the Johns Hopkins Children’s Center in a statement. “What this tells us is that not only are many of our immune responses shaped in the first year of life, but also that certain bacteria and allergens play an important role in stimulating and training the immune system to behave a certain way.”

The study, conducted among 467 urban newborns from Baltimore, Boston, New York and St. Louis, tracked the health of the infants over three years. Investigators visited the subjects’ homes, measuring the levels and types of allergens present in the infants’ surroundings and testing them for allergies and wheezing. In addition, the researchers collected and analyzed the bacterial content of dust collected from the homes involved in the study.

Infants who grew up in homes with mouse and cat dander and cockroach droppings in the first year of life had lower rates of wheezing at age 3, compared with children not exposed to these allergens soon after birth. In addition, the researchers found this protective effect was additive, with infants exposed to all three allergens having lower risk than those exposed to just one or two. Wheezing was three times as common among children who grew up without exposure to such allergens. In addition, infants in homes with a greater variety of bacteria were less likely to develop environmental allergies and wheezing at age 3.

“This is a big deal and can certainly lead to many revolutionary methods to treat and even prevent allergies down the road,” says Dr. Brian Rotskoff, allergist and immunologist with Advocate Illinois Masonic Medical Center in Chicago. “We’ve been gathering evidence of this type for a number of years to show that exposures early on can reduce allergies and wheezing.”

Dr. Rotskoff says there is more and more information being gathered on the cause of allergies and asthma, but more research is needed to find “exactly what is making an impact.” However, the work is well underway, he says.