Asthma protection tied to wide-ranging microbial exposure

Many investigations have shown that children who have a high level of environmental exposure to microorganisms-namely those who grow up on farms-are protected from childhood asthma and atopy. Now a new study demonstrates that exposure to microbial diversity enhances the protective effect of the farming environment on development of childhood asthma.

Investigators used data from 2 large-scale observation studies of schoolchildren living in predominantly rural areas of Germany to compare the prevalence of asthma and atopy and diversity of microbial exposure among children who lived on farms with other children who did not live on farms (reference group).

In 1 study, samples of mattress dust were screened for bacterial DNA using single-strand conformation polymorphism analyses to detect environmental bacteria that cannot be measured by culturing. In the other study, samples of dust from children's rooms were evaluated for bacterial and fungal taxa using culture techniques.

Commentary

This study offers another piece of a puzzle. When the puzzle is complete, it will explain the doubling of the prevalence of asthma over the last 30 years. It may also lead to therapeutic interventions, including intentional exposure to diverse populations of microbes, to prevent asthma even in children who have left the farm. -Michael Burke, MD