Children who grow up in traditional Amish communities in the United States are largely protected against asthma because their immune system is strengthened by their constant contact with germs animal farms where they live.
In reaching these conclusions, a study published in the August 4 edition of the New England Journal of Medicine compared two very similar traditional communities, the Amish in Indiana (north) and the Hutterites in South Dakota (north ), which have different rearing methods.
The Amish live on dairy farms where they use horses as transportation and field work. The Hutterites for their use modern tools to operate their farms common: they are thus less direct contact with animals.
Most aspects of the life of these communities are also quite similar. They have common genetic ancestors of migrants from Central Europe, and their diets, identical to those of Germanic traditional farms, are similar.
They drink raw milk, immunize their children and they are breastfed when they are babies.They have no pets inside their homes.
But despite these important similarities, asthma rates they suffer are very different: only 5% of children of school age have asthma in the Amish, half the US national average. Conversely, Hutterite children experiencing unusually high asthma rate, to 21.3%, the study finds.
“There are more than 10 years our colleague Erika von Mutius discovered that growing up on a farm could protect against asthma,” says Carole Ober, co-author of the study, professor of human genetics at the University of Chicago.
“Our new study, based on its work shows that it is not the mere fact of living on a farm that is important in this area, and we found more specific reasons on which can protect against asthma ‘ , she adds.
Dust in homes
The researchers found that the difference was the type of dust inside their homes: those in homes Amish “are richer in microbial production”, points out the study.
“Neither homes nor those Amish Hutterites are dirty,” like to note the authors. “They are clean. However, the Amish barns are closer to the homes and children run through, often barefoot all the time. There is no apparent dirt in Amish homes, but that’s just in the air, in the dust. ”
And it is this dust which the immune system of children’s asthma.
Blood tests conducted on 30 children Amish and Hutterites 30 aged 7 to 14 years have shown that the former had more critical cells to fight infections, known as neutrophils. They also had fewer cells triggering allergic reactions (eosinophils).
“We hope our findings will allow the identification of relevant substances which will open the way to new strategies to prevent asthma and allergies,” said Erika von Mutius yet, professor at Munich University Hospital, Germany, also study co-author.
The Amish are a religious group that rejects modern life. They have their own schools, speak a German dialect, wear traditional clothing, travel by horse-drawn cart and refusing to much electricity. There are about 280,000 US.