Reduced atopic dermatitis in Wisconsin farm children

Published: July 06, 2020

Atopic dermatitis is a chronic itchy skin disease that most commonly begins in early childhood. Infants with atopic dermatitis are more likely to develop other allergic diseases such as food allergies, allergic rhinitis and asthma. This progression is known as the “atopic march” and makes understanding atopic dermatitis during early in life very important. Previous studies have suggested that children who grow up on farms may have fewer allergic diseases and asthma, but studies examining farm effects on atopic dermatitis have had mixed results.

Steiman and colleagues at the University of Wisconsin and the Marshfield Clinic Research Institute conducted a study published recently in the The Journal of Allergy and Clinical Immunology (JACI) to identify patterns of exposures in Wisconsin family farms that reduce the risk for developing atopic dermatitis in early childhood. The investigators enrolled 111 families from central Wisconsin farms (mostly dairies) and 129 families from small towns and rural areas in the same region. The families recorded environmental exposures (e.g. farm animals, barns, pets, smoking) during the pregnancies and infancy. Investigators then analyzed this information to identify exposures related to the development of atopic dermatitis in the first two years of life. Within the farm families, exposure to animals varied quite a bit depending on the type of farm and the mother’s and infant’s daily activities. Investigators used this information to classify mothers and infants into three farm exposure groups that differed in the number of interactions with animals and animal feed.

Overall, children of farm families were about one third less likely to develop atopic dermatitis by two years of age (P=0.03). Within farm families, exposures including poultry (3% vs 28%, P=0.003), pig (4% vs 25%, P=0.04), feed grain (13% vs 34%, P=0.02) and the overall number of animal species were associated with reduced risk for developing atopic dermatitis. In the farm families, breastfeeding and C-section delivery were also associated with lower risk of atopic dermatitis. Among the three farm exposure groups, children in families with diverse or more intense animal and barnyard exposures had reduced rates of atopic dermatitis, while low-exposure infants developed atopic dermatitis at rates similar to those of non-farm children.

In summary, infants in Wisconsin farm families were less likely to develop atopic dermatitis, and this was especially true for mothers and children with close contact with multiple animal species. These findings suggest that exposure to diverse farm animals, feed and bedding during the prenatal period and in early infancy reduces the risk of early-onset atopic dermatitis. Because other allergic diseases often follow atopic dermatitis, these findings also suggest that expanding early life exposures could have the added benefit of lowering the risk for multiple allergic diseases.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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