Do Amish hold clue to preventing asthma in children?
The Amish community in the US has long been famous for shunning modern technology and preserving traditional ways of life, using horses for farming and for transport.
Now it appears that their closer contact with animals could have an unexpected benefit - preventing asthma in children.
A new study from the US compared the Amish with a similar community, the Hutterites, who use more modern farming methods.
Both groups have similar genetic ancestry and follow similar diets, but researchers found that childhood asthma rates differed strongly.
About 5% of Amish schoolchildren tested in the study had asthma compared with 21.3% of the Hutterite children.
The study in the New England Journal of Medicine suggested that children's immune systems in the Amish community were being bolstered by house dust that contained more microbes from farm animals.
Barns closer to homes
The findings echo other studies that have suggested that a lack of early exposure to microbes, caused by modern hygiene, increases the risk of allergy.
The dust found in Amish homes was "much richer in microbial products," the study said.
"Neither the Amish nor the Hutterites have dirty homes," said study co-author Carole Ober, professor and chairman of human genetics at the University of Chicago.
"Both are tidy. The Amish barns, however, are much closer to their homes. Their children run in and out of them, often barefoot, all day long. There's no obvious dirt in the Amish homes, no lapse of cleanliness. It's just in the air and in the dust."
Blood tests from 30 children from each community, aged seven to 14, showed that the Amish youngsters had more neutrophils - white blood cells crucial to fighting infections.
The study found the Amish children also had fewer blood cells that promote allergic inflammation, known as eosinophils.
Laboratory mice exposed to Amish house dust were also protected against asthma-like responses while similar experiments with dust from Hutterite homes gave no protection.
Are pets a protection?
Report co-author Erika von Mutius, professor at the Dr von Hauner Children's Hospital in Munich, said it was hoped that the research could help future generations of children.
"We hope that our findings will allow the identification of relevant substances that will lead to completely novel strategies to prevent asthma and allergy," she said.
A large study from Sweden last year found that young children in a family with a pet dog were less likely to develop asthma.
The study, by JAMA Pediatrics, found that exposure to a dog in the first year of life was linked to a 13% lower risk of asthma in later childhood among the 650,000 children the authors tracked.
It also found that living on a farm with lots of animals seemed to confer even more protection.
Speaking at the time, lead scientist Prof Tove Fall, of Uppsala University in Sweden, said: "Our results confirmed the farming effect and we also saw that children who grew up with dogs had about 15% less asthma than children without dogs."
But she warned against getting a pet to try to cure an already allergic child.
"It won't work and will probably make the allergy worse," she said.