Effect of environmental endotoxin exposure on development of pediatric asthma among Egypytian school children

【摘要】  Objective: The aim of this study was to assess school indoor exposure to microbial products and preva lence of asthma and allergies in rural and urban children. Methods: This study was carried on a rural and an urban school. Environmental endotoxin level was measured in multiple samples of the ambient indoor air dust collected on special aseptic filter papers from the two schools. For two hundred children history taking, clinical examination, allergen skin prick test and basic pulmonary function test were preformed. Results: Environmental endotoxin levels showed significantly higher mean values (P<0.01) in rural school (3 EU/mg) as compared to the urban school (0.1 EU/mg) with (OR=5.163; 95% CI: 0.95��28). History of allergic symptoms was significantly more in urban than rural students (P=0.01). Mean values of pulmonary function parameters were significantly lower values in urban students compared to rural students. Skin prick test results showed significant reactions to all tested allergens in urban children compared to rural children (P<0.05). Conclusion: There is an inverse association between environmental exposure to endotoxins and susceptibility for allergic manifestations in school children.

【關鍵詞】  Endotoxin; Environmental; School; Urban; Rural and pediatric asthma

　　INTRODUCTION教育教學論文發表

　　There has been a significant increase in the preva lence of allergic diseases over the past 2 to 3 decades[1]. To explain these observations, environmental factors associated with more industrialized and urban living have been studied intensively. However, there is little consistent evidence to suggest that obvious risk factors, such as increased exposure to indoor allergens, pollution, or changes in diet and breastfeeding, could account for the rise in atopic diseases[2].

　　Interestingly, atopic conditions have become more preva lent at the same time that childhood infectious diseases have become less preva lent worldwide[3]. These findings suggested that in fact infections early in life might protect from developing asthma and allergies. This is the so�瞔alled hygiene hypothesis proposed by Strachan[4] in 1989.

　　However, not all study findings support the "hygiene hypothesis"[5]. Infections of the respiratory tract have also been identified as risk factors for wheeze and asthma. This discrepancy may in part be attributable to the phenotype of wheeze under study, early transient wheeze being positively associated with infections of all kinds, whereas the atopic phenotype may be protected from increased infectious exposure[4]. Furthermore, the type of infection may play a role[5].教育教學論文發表

　　Recently, endotoxin �� a lipopolysaccharide cell�瞱all component of gram�瞡egative bacteria �瞝evel has been considered as a marker for environmental hygiene[6].

　　The aim of this study was to assess the relation between environmental exposure to microbial products (endotoxins) and the susceptibility for childhood asthma and allergies in rural and urban school children.

　　MATERIAL AND METHODS

　　Study population教育教學論文發表

　　This cross�瞫ectional pilot study was conducted in urban and rural areas of Nagaa Hammadi Governorate, Upper Egypt, on 205 school children with their ages ranging between 6��12 years, presented in 2 schools, from an Urban School (Alumnium city, Nagaa Hammadi) and from a Rural School (Ezbet Elbossa ,Nagaa Hammadi). Each child was subjected to the following before the start of the study: history (detailed history of asthma and ato