Germ exposure & asthma risk - Shorts - Brief Article

Townsend Letter for Doctors and Patients, Jan, 2003 by Jule Klotter

A Swiss study, published in The New England Journal of Medicine (September 19, 2002), found that children who live on farms have lower incidence of hay fever and allergy-related asthma than children who also live in rural areas but not on farms. The children, ages 6 to 13, all live in rural areas of Austria, Germany, and Switzerland; 319 live on farms and 493 do not. The research team, led by Dr. Charlotte Braum-Fahrlander of the Institute of Social and Preventive Medicine (Basal, Switzerland), found that 4.1% of the farm children and 10.5% of the non-farm children had hay fever. Only 3.1% of the farm children had allergy-related asthma while 5.9% of the non-farm children did. The researchers attribute the difference to the dirt, manure, and animals found on farms, which expose children to more bacteria.

To support their hypothesis, the researchers measured the level of endotoxin in dust taken from the children's mattresses. Samples from the farm mattresses had higher levels of endotoxin, used as a marker for bacteria exposure, than those from non-farming homes. Interestingly, the level of endotoxin corresponded directly to the rates of asthma and hay fever. A New York Times article by Denise Grady reported that the children whose mattresses showed the highest endotoxin level had the lowest rate of hay fever ([approximately equal to] 2-3 percent). Those exposed to the lowest endotoxin exposure had the highest hay fever rate ([approximately equal to]15 percent). The researchers say that greater exposure to bacteria, as evidenced by the higher endotoxin levels, may "help an infant's immune system to motive and develop tolerance -- instead of allergies -- to environmental substances like pollen and animal dander."

Grady, Denise. Environment Rich in Germs May Reduce Risk of Asthma. New York Times 2002 September 19