Local environments affect asthma type, study concludes,,,,
MONDAY, Sept. 17 (HealthDay News) -- Where you live may affect the type of asthma you develop, new research suggests.
The international study found that youngsters in affluent, developed countries had more allergy-triggered asthma symptoms than did children in poorer, less developed countries.
"The link between atopic sensitization and asthma symptoms in children differs strongly between populations and increases with economic development," the study's authors wrote.
Results of the study are published in the September issue of the American Journal of Respiratory and Critical Care Medicine.
An estimated 20 million Americans have asthma, according to the American Academy of Allergy, Asthma and Immunology. About half of that group -- 10 million people -- has what's known as allergic asthma. That means their asthma symptoms, such as wheezing, shortness of breath and a feeling of tightness in the chest, are triggered by allergens, such as dust mites, mold and pollen.
The exact cause of asthma still isn't known, but some experts have suggested that the rise in asthma incidence may be related to more sterile homes and the use of antibiotics. The "hygiene hypothesis" theorizes that without real challenges -- like those from bacteria and viruses -- the human immune system may begin responding to harmless substances, such as animal dander, causing allergy and asthma symptoms. While this theory is still controversial, some studies have supported the idea, according to the academy.
The new study, while not specifically designed to examine the hygiene hypothesis, sought to assess the differences in allergic sensitization and the types of asthma experienced in different countries.
The study included almost 55,000 children between the ages of 8 and 12 from 22 countries. The countries represented a wide range of livin
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