A US study of a birth cohort at high risk for asthma (n = 560) found that in inner-city environments children with the highest exposure to specific allergens and bacteria during their first year were least likely to have recurrent wheeze and allergic sensitization. First-year exposure to cockroach, mouse, and cat allergens was negatively associated with recurrent wheeze. Exposure to high levels of both allergens and specific house dust bacterial content in the first year of life was most common among children without atopy or wheeze. Early exposure to microbes on farms has been linked to protection against asthma and other allergic disease as well. Source: http://www.jacionline.org/美国一项包括560名哮喘高风险性出生群组的研究发现，出生后第一年在内城区环境中暴露于特定的过敏原和病菌最多的孩子们最不容易有反复发作的哮喘和变态反应。出生后第一年暴露于蟑螂，老鼠和猫过敏原与反复哮喘呈负相关。出生后第一年暴露于高水平的过敏原和特定的房屋灰尘细菌含量最常见于没有过敏体质或哮喘的孩子。早期接触农场的微生物也已被证实与防护哮喘和其他过敏性疾病有关。来源： http://www.jacionline.org/
