By studying children from two communities, scientists have come to understand, in part, why little Amish are affected by asthma so little.
In recent decades, respiratory allergies and asthma have increased exponentially. Globally, some 235 million people have asthma while millions more suffer from allergies. The causes of these respiratory pathologies are still unknown, but we know that genetics and the environment can work against our lungs.
However, the environment can also be an ally. Work carried out in Switzerland has shown that children raised on farms and exposed to livestock on a daily basis are protected from these chronic diseases. A theory confirmed within the Amish community. The prevalence of asthma in these children is much lower than in European children raised in the countryside. This protection would be conferred by an ultra-developed immune system, according to a study published in the New England Journal Medicine and carried out in two rural communities: the Amish and the Hutterites.
These two Anabaptist communities have lived far from the modern world since their creation in the 17th century in Alsace and Germany. Established in the United States for over 200 years, the Amish and Hutterites have always been farmers and ranchers. But over time, their farming practices have differentiated. The Amish continue to cultivate the land using horses, while the Hutterites have opted for modernity. The education of children is also different. While Amish children get up at dawn to feed the animals, clean the barn, and play barefoot near the animals, Hutterite children are not required to perform these tasks.
No asthma among the Amish
To understand the impact of the environment on the development of asthma, researchers from the University of Arizona and Chicago (United States) followed 60 children from 7 to 14 years old. Of the 30 Amish children, none suffered from asthma, compared to 6 among the Hutterites. Analysis of blood samples reveals that Amish children have a much more diverse immune system, and a higher number of white blood cells, allowing them to respond better to a pathogen. According to the researchers, the living conditions of Amish children shaped their innate immunity – the body’s first line of defense active from birth – making it much more effective and able to protect them from allergies and asthma.
In addition, genetic tests confirm that the genetic heritage of the two communities are very similar, as they share a common European ancestor. These results show that the differences in the prevalence of asthma are not attributable to genetics, thus suggesting the predominant role of the environment.
Scientists therefore took samples from 20 houses. Frequent allergens such as cat and dog hair or the presence of mites in the dust are found in 40% of Amish houses against only 10% of Hutterite houses. The microbial composition between the outbreaks is also very different.
A protective germ
A hypothesis confirmed in an asthmatic mouse model. After inhaling dust collected from Amish homes, the guinea pigs did not exhibit any allergic or asthmatic symptoms while the samples collected from the Hutterites caused a reaction.
Researchers thus suggest that a microorganism (bacteria or mold), still unknown, present in Amish houses plays a protective role by activating innate immunity. But they still do not know how long children must be exposed to this germ to be protected. The protection may be put in place before birth.
.
