House dust rich in microbes may explain why Amish children are much less prone to asthma than other American youngsters. That’s the conclusion of a fascinating new study in the New England Journal of Medicine.
What’s the Deal on House Dust?
The investigators studied an Amish community in Indiana and a Hutterite community in South Dakota. Both have similar lifestyles and genetic backgrounds. But the rate of asthma among Amish youngsters is half that of other American kids in their age bracket. More startling, it’s one fourth the rate of asthma among Hutterite children.
Differences in Immune Function:
The researchers found that the Amish children had immune function that was distinctly different from the Hutterite young people. They had more white blood cells fighting infection and fewer blood cells that are linked to inflammation and allergies. To explain these phenomena, the investigators looked at house dust and found substantial differences.
The Amish children are raised on single family dairy farms that rely on horse power rather than tractors. The animals are kept in barns close to the homes.
In Hutterite communities the farming is communal and mechanized. Animals are kept much farther from the living quarters.
Dust from Amish Homes Is Richer in Microbes:
This may explain why dust from Amish houses contains more microbes as well as a greater variety of bacteria and fungi. Presumably this is because of the proximity of the farm animals. This finding supports the hygiene hypothesis: These organisms appear to train the innate immune system to attack infection and calm inflammation.
A mouse study showed that Amish house dust could protect the animals from asthma in a similar manner. Mice that has been genetically engineered to impair their innate immunity did not benefit from exposure to the same house dust. If researchers can figure out a way to mimic the Amish environment for other young children it may be possible to reduce asthma rates dramatically.
