Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children
Stein MM, Hrusch CL, Gozdz J, et al N Engl J Med. 2016;375:411-421
Background
The hygiene hypothesis of atopy was first introduced in 1989,[1] but there has not been a uniform definition of the term. The surge in atopic disease has been ascribed to reduced childhood viral infections owing to vaccination, increased antibiotic use, reduced helminth exposure, and urban living.[2]
Although some of these theories are debatable,[3] the inverse correlation between farm animal exposure and atopy has been one of the more intriguing observations. However, the mechanism of and the degree of exposure necessary for this protection had not been established.
The Study
Stein and colleagues compared the Amish community of Indiana with the Hutterites of South Dakota. These two insular farming communities are strikingly similar genetically and environmentally, except that the Amish practice "traditional farming" on single-family farms, whereas the Hutterites' farms are highly industrialized. Past studies have noted that the respective rates of atopy and asthma are much higher in the Hutterites (33% and 21%, respectively)[4] than the Amish (7% and 5%).[5]
The study looked at asthma prevalence and the clinical and immunologic characteristics of atopic disease of children in both groups, and assessed the human and mouse model responses to house dust.
