Can the house dust of a rural farming community hold clues to protecting people from developing asthma?

Researchers from several universities studied 60 children ages 7-14 from two similar, but slightly different, farming communities. Thirty were Amish children. Thirty were Hutterite.

These groups are similar in that they share a common ancestry and have remained relatively isolated in their communities after immigration to the United States. They share other factors known to have influenced asthma risk.

Both communities:

• Get childhood vaccinations
• Have large families
• Breastfeed their children
• Drink raw milk
• Have minimal exposure to air pollution or tobacco smoke
• Don’t allow indoor pets

But there are differences.

The Amish live as single families. They use horses to plow their fields and for transportation. On their dairy farms, their children work closely with the animals and play in the barns.

The Hutterites live on large communal farms. They use industrial farm machinery. Their kids are not exposed to farm animals in the same way that the Amish kids are.

About 5% of Amish children 6 to 14 have asthma. But 21.3% of Hutterite children in that age range have asthma.

By comparison, 10.3% of children ages 5 to 14 in the U.S. have asthma.

Researchers compared the types of immune cells in the children’s blood. And they collected airborne dust from Amish and Hutterite homes.

The Amish had more of the type of blood cells needed to fight infection. They had fewer of the blood cells that encourage allergic inflammation.

Next, the researchers took dust samples from Amish bedrooms and living rooms. They also collected samples from Hutterite homes.

They tested the dust on mice. Then the researchers repeatedly exposed the mice to allergens to trigger asthma symptoms.

Amish dust protected the mice from asthma flare-ups. But the dust from Hutterite households did not.

The difference is that the Amish dust was loaded with germs and bacteria – presumably, from the children tracking it in from the barns.

In another experiment, they gave the Amish dust to mice that have a deficiency in several components of the natural or “innate” immune response. In mice that do not mount this natural immune response, the Amish dust did not protect the mice. That seems to suggest that there is something in the Amish environment that protects children from developing asthma through the stimulation of components of the innate immune response.

There were some limits to the study. Only 60 children took part, and researchers collected dust from an even smaller sample of homes - ten from the Amish and ten from the Hutterites. They were unable to study children younger than six years of age.

However, the study is the latest to show that the so-called “hygiene hypothesis” – how clean our environments are – assist in the development of allergic disease. The hygiene hypothesis speculates that environments that do not contain certain naturally occurring bacteria create immune systems in children that are under stimulated. The authors hope the study will lead to new strategies to fight asthma and allergy.

Or, as one of the study authors said in a university statement:

“You can’t put a cow in every family’s house,” said Prof. Carole Ober, chairman of human genetics at the University of Chicago, “but we may be able to protect children from asthma by finding a way to recreate the time-tested Amish experience.”

Reference:
Stein. M. M., et al. (2016). “Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children.” The New England Journal of Medicine. 

Medical Review August 2016.