Asthma is a chronic illness in childhood that is frequently triggered by allergies. The dramatic increase in this condition in westernized countries suggests that both genetic and environmental factors are at play. Previous studies in Europe have shown significant protection from developing asthma and allergies in children raised on traditional dairy farms where there is extensive contact with farm animals and high microbial bacteria exposure. A recent article in the New England Journal of Medicine looked at the effect of traditional farming practices on the immune system in two genetically similar populations - one that uses traditional farming practices and the other that uses highly industrialized communal farms.
The Amish are characterized by living on single-family dairy farms and using horses for fieldwork and transportation. The Hutterites originated from Northern Italy and live on large, highly industrialized, communal farms. Both groups are similar genetically and with respect to large family size, high rates of childhood vaccinations, diets rich in fat, salt and raw milk, low rates of childhood obesity, long duration of breast-feeding, minimal exposure to tobacco smoke or air pollution and taboos against indoor pets.
The frequency of asthma in Amish versus Hutterite (similar to westernized countries) schoolchildren is 5.2% versus 21.3% and allergic sensitization is 7.2% versus 33.3%. Environmental samples from these two groups demonstrate similar levels of common allergens (cat, dog, cockroach and dust mites) but very high levels of endotoxin in the Amish households. Endotoxins are proteins released from the cell wall of certain microbes that can trigger the immune system. Blood samples from the Amish children showed higher levels of some proteins involved in their immune response. These findings suggest that in the Amish, intense and sustained exposure to microbes activates innate pathways that shape downstream immune responses leading to less allergies and asthma in childhood.
The body’s immune system has evolved to sense the environment and send signals to help direct the adaptive part of our immune system. The risk of developing allergies and asthma may increase when immune stimulation is low. Maybe the future treatment of allergies and asthma will stress exposure to endotoxin, either through small family farming lifestyle or other sources. Could this offer a new preventive treatment? Time will tell.
Dr. Tracie Overbeck
Allergy Partners of Central Kentucky
Reference: Stein, M.M., Hrusch, C.L., Gozdz, J., Igartua, C., Pivniouk, V.,Murray, S.E., Ledford, J.G.,Marques dos Santos, M., Anderson, R.L., Metwali, N., Neilson, J.W., Mainer, R.M., Gilbert, J.A., Holbriech, M., Thorne, P.S., Martinez, F.D., von Mutius, E., Vercelli, D., Ober, C., and Sperling, A.I. Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children. NEJM 2016; 375: 411-421.
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