New research links early allergen exposure with lower asthma risk

New research headed up by a UW-Madison scientist suggests that early exposure to allergens from pets and other sources can decrease the risk of developing asthma.

According to the Centers for Disease Control and Prevention, over 8 percent of American children have asthma. And in Wisconsin, 10 percent of adults and over 7 percent of children have the disease, according to the state Dept. of Health Services.

Asthma kills one person in Wisconsin every five days, DHS says, with emergency room visits coming much more frequently for young children, African Americans, Native Americans and Hispanics.

Previous studies have shown that reducing allergens in the home helps keep established asthma under control; the findings from this new study suggest that exposure occurring before asthma ever develops might have a preventive effect.

The ongoing Urban Environment and Childhood Asthma study is funded by NIH’s National Institute of Allergy and Infectious Diseases through its Inner-City Asthma Consortium.

“Our observations imply that exposure to a broad variety of indoor allergens, bacteria and bacterial products early in life may reduce the risk of developing asthma,” said James Gern, the principal investigator of URECA and a professor at the UW School of Medicine and Public Health. “Additional research may help us identify specific targets for asthma prevention strategies.”

URECA studies asthma risk factors in children living in urban areas, where the disease impacts more people. Since 2005, URECA has enrolled 560 newborns at high risk for developing asthma from Baltimore, Boston, New York City and St. Louis. The current research report uses data from these kids’ first seven years of life.

Of the 442 children for whom enough data was collected to assess status at age 7, 130 had asthma. Dust samples from these children’s homes were collected during the survey, linking higher concentrations of cockroach, mouse and cat allergens found at earlier ages to a lower risk of asthma by age 7.

A similar connection was noted for dog allergens, but it was not found to be statistically significant. Further analysis found that higher exposure to all four of these allergens to 3-month- old children was associated with lower risk of developing asthma down the line.

The most recent report from this ongoing survey also made a connection between the abundance of certain types of bacteria and an asthma diagnosis by age 7. This suggests that early bacteria exposure might influence long-term health, but more research is needed to flesh out the nature of this relationship. This builds upon previous findings that exposure to certain bacterias in infancy might shield 3-year-olds from recurrent wheezing, which can lead to asthma.

The seven-year results from URECA also validated previous studies which tentatively linked childhood asthma development to prenatal exposure to tobacco smoke, as well as to maternal stress and depression. URECA investigators are continuing to monitor these children to figure out what other early-life factors can lead to breathing issues later in life.

“We are learning more and more about how the early-life environment can influence the development of certain health conditions,” said Anthony Fauci, director of NIH’s National Institute of Allergy and Infectious Diseases. “If we can develop strategies to prevent asthma before it develops, we will help alleviate the burden this disease places on millions of people, as well as on their families and communities.”

–By Alex Moe