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This study showed a strong association between asthma, hay fever, and eczema in the same child. The presence of pets outdoors but not indoors appeared to be associated with an increased incidence of wheezing in children. Use of the traditional Gulf incense also appeared to be a precipitating factor for asthma in this study. There were also statistically significant relationships between asthma and exposure to dust at home from air conditioner blasts, which is consistent with studies elsewhere. Moreover, in this study, passive exposure to tobacco smoking at home did not appear to have any significant relationship with asthma. There was, however, a statistically significant relationship between asthma and exposure to pollen from indoor plants, which is also consistent with studies elsewhere. Parental asthma but not parental atopy was a significant risk factor for asthma in offspring, a finding which agrees with other studies that have shown that parental atopy may enhance the likelihood of the expression of asthma, but does not, on its own, impact as a risk factor in the same way as parental asthma. There was a statistically significant difference in the prevalence of asthma and the symptoms of asthma between different areas across the United Arab Emirates, but not for eczema or hay fever. This is most likely attributable to the impact of radically different environmental conditions on the development of allergies in two genetically homogenous populations of United Arab Emirates nationals. Asthma, wheeze, dyspnoea and nocturnal cough were more prevalent in coastal humid Dubai, compared to dry inland Al-Ain. However, there was no statistically significant difference in the prevalence of eczema and hay fever between coastal and inland areas in the United Arab Emirates. An environmental survey carried out in Dubai and Al-Ain to study the effect of air pollution among asthmatic children showed that overall air quality in both Dubai and in Al-Ain is good, except during adverse weather conditions, strong winds and dust storms, in summer time, where the level of Respirable Particulates (PM10) is occasionally high in Dubai. However, a previous study of seasonal trends in hospital admissions for asthmatic children in Dubai showed that the highest numbers of admissions for asthmatic children occurred between the months of October and February. These are the coldest months of the year in the United Arab Emirates. Therefore air pollution from dust storms was not the cause of the high prevalence of asthma in Dubai. Although the prevalence of asthma and wheezing was lower in the United Arab Emirates than in some developed countries, it was still higher than other chronic diseases. This study demonstrated that symptoms suggestive of asthma are quite common and constitute a major health problem in the United Arab Emirates. High rates of consanguineous marriage, a buoyant economy, rapid industrialization, development of the agricultural sector, an increase in the domestication of animals and dairy farms, combined with an emphasis on 'greening' the environment, may have resulted in an increase of the prevalence of asthma. World-wide trends have been in this direction. Therefore, a concentrated effort should be made to implement therapeutic and non-therapeutic programmes for the management of asthma by parents, teachers and physicians.

This thesis is designed to explore the hypothesis that settled dust in a domestic environment can contain significant levels of allergens and that common cleaning methods employed to remove dust can result in sufficient airborne exposure to potentially trigger an allergic reaction. Qualitative feedback from respondents in studies of furniture dusting habits indicated that household furniture dusting could elicit an allergic response. A consumer questionnaire was fielded to confirm the problem and it's magnitude. This indicated that it affected approximately 20% of allergy sufferers (or approximately 5% of the total UK population). Further work was performed to estimate the level of allergen exposure during dusting. Additional consumer research was fielded to ascertain the surface area being dusted, (approximately 54000cm2 for frequently dusted areas and 10000cm2 for frequently dusted areas). Domestic dusting habits were probed for the relative frequency of dusting method, which split evenly between dry dusting, wet dusting with water and wet dusting with a furniture polish. Surface sampling techniques were adapted to make in-home measurements of the rate of dust settling which was found to be approximately 3.19x10 -7 g.cm-2,day-1. In-home sampling was also undertaken to measure the mean allergen content of surface dust for major allergens, yielding 24667ng.g-1 combined dust mite, 47696ng.g-1 Fel d 1 and approximately 126 8 08ng.g-1 Can f 1. Laboratory-based studies determined the relative amount of dust rendered airborne during dusting of different furniture surface types and comparing different cleaning methods. This was found to be between 2.3- 43.0%. From these experiments, a model "average" home was constructed and used to estimate the exposure towards dust allergens during a typical dusting task. Exposure was estimated to be as much as 16500ng total dust mite, 124000 mug (31000 mU) cat allergen and 275000 ng (IU) dog allergen per dusting method. These results indicated that allergen exposure, under certain circumstances, could exceed the threshold levels that have been proposed for the onset of sensitisation.

Allergic diseases are common in women of childbearing age. Both asthma and atopic conditions may worsen, improve or remain the same during pregnancy. Primary care physicians commonly encounter women receiving multiple medications for pre-existing atopic conditions, who then become pregnant and require medication changes to avoid potential fetal injury or congenital malformations. Each medication should be evaluated; intranasal and inhaled steroids are relatively safe to continue during pregnancy (budesonide is the drug of choice), second-generation antihistamines of choice are cetirizine and loratadine, leukotriene receptor antagonists are safe, sparing use of oral decongestants during the first trimester and omalizumab may be used for both uncontrolled asthma and for antihistamine-resistant urticaria. Medications to avoid during pregnancy include intranasal antihistamines, first-generation antihistamines, mycophenolate mofetil, methotrexate, cyclosporine, azathioprine and zilueton. Common allergic diseases may develop de novo during pregnancy, such as anaphylaxis.

Parental reports are often used in studies of asthma and allergic diseases in children. A change in respondent from parent to index subject usually occurs during adolescence. Little is known about the effects this change in method might have on the outcomes of a longitudinal study. Smoking is a major cause of respiratory symptoms among adults and environmental tobacco smoke (ETS) is a risk factor for asthma among children. Less is known about these associations among teenagers. In order to improve prevention of smoking, it is important to identify populations at risk of becoming smokers.       The aim of this thesis were to 1) evaluate the methodological change from parental to self-completion of a questionnaire about asthma and allergic diseases, and 2) to study determinants for, and respiratory health effects of ETS and personal smoking in teenagers. In 1996, a longitudinal study of asthma and allergic diseases among schoolchildren started within the Obstructive Lung Disease in Northern Sweden (OLIN) studies. All children in first and second grades (aged 7-8 years) in three municipalities, Luleå, Kiruna and Piteå (n=3,525) were invited and 97% participated by parental completion of a questionnaire. The cohort has been followed with annual questionnaires until age 16-17 years and with high participation rates (>91%). From age 12-13 years, the teenagers were the respondents and questions about their tobacco use were included. In addition to the questionnaire completed by the teenagers at age 13-14 years, a questionnaire was also distributed to a random sample of 10% of the parents and 294 participated (84%).   The parents and the teenagers reported a similar prevalence of asthma, respiratory symptoms, rhinitis, eczema and environmental factors. Two statistically significant differences were found: the teenagers reported a higher prevalence of wheezing during or after exercise (14% vs 8%, p<0.05), and having a dog in the home in the last 12 months (42% vs 29%, p<0.001). Answer agreement between parents and teenagers on questions about asthma was almost perfect with kappa values of 0.8-0.9. Corresponding kappa values for questions about respiratory symptoms and rhinitis were 0.3-0.6 and for eczema 0.5-0.6. Agreement about environmental factors varied from 0.2-0.9. Kappa values for parental smoking were 0.8-0.9. The risk factor pattern for allergic diseases was similar regardless of respondent, ie parent or teenager. The prevalence of smoking increased from 3% at 12-13 years to 6% at 14-15 years. Smoking was more common among girls, while the use of snus was more common among boys. Significant risk factors related to smoking among teenagers were smoking family members, female sex and living in an apartment. Having physician-diagnosed asthma did not prevent the teenagers from becoming smokers. Factors related to using snus were a smoking mother and male sex.  Daily smokers aged 16-17 years (9%) reported a significantly higher prevalence of wheezing and physician-diagnosed asthma compared to non-smokers. There was a significant dose-response association with higher prevalence of wheeze among those who smoked ≥11 cigarettes per day compared to those who smoked ≤10 per day. In multivariate analyses, maternal environmental tobacco smoke exposure was a significant risk factor for ever wheeze and physician-diagnosed asthma at age 16-17 years, while daily smoking was a risk factor for current wheeze. In conclusion, the methodological change of questionnaire respondent from parent to index subject did not substantially alter the findings of this longitudinal study. There were significant sex differences in the tobacco use: smoking was more common among girls and snus was more common among boys. The most important factor related to tobacco use was presence of family members who smoke. Both maternal ETS exposure and personal smoking was associated with asthma and wheeze in adolescence. ETS was associated with lifetime symptoms but daily smoking was more strongly associated with current symptoms.

Background: Allergic diseases are characterised by dysregulated immune responses. The first manifestation of the atopic phenotype is often food allergy, with symptoms like eczema. Food allergy in children is generally outgrown before 3 years of age, but a temporary food elimination diet is often advocated. The prevalence of allergic diseases has increased in affluent countries during the last decades, possibly as a consequence of a changed lifestyle leading to decreased microbial load. Aim: To investigate humoral, mucosal and cell-mediated immunity in association to allergy and allergy development in young children and relate this to environmental factors. Subjects: Two cohorts of children were investigated; 1) Children from countries with high (Sweden) and low (Estonia) prevalence of allergy that were followed prospectively from birth to 5 years of age. 2) Infants with eczema and suspected food allergy that were followed prospectively to 4 ½ years of age. Methods: Endotoxin levels were analysed in house dust samples. Antibodies were measured in serum and saliva samples with ELISA. Food allergen induced cytokine responses were analysed in mononuclear cells. Results: The microbial load, delineated as endotoxin levels, was higher in house dust from Estonia than Sweden and was, in Swedish children, inversely associated with sensitisation and clinical symptoms of allergy. The decreased microbial load in Sweden may have an impact on mucosal immune responses as different IgA antibody patterns were observed in Sweden and Estonian children with much lower secretory (S)IgA antibody levels and high proportion of non-SIgA, i.e. IgA antibodies lacking the secretory component, in the Swedish children. Moreover, low levels of SIgA were associated with clinical symptoms in sensitised children. High IgG4 antibody levels to food allergens during infancy were associated with faster tolerance development in food allergic children. Cytokine responses by mononuclear cells after allergen stimulation was upregulated with age in children with prolonged food allergy, but not in children who develop tolerance before 4 ½ years of age, possibly because of the prolonged elimination diet in the former group. Summary: Reduced microbial exposure in affluent countries may affect the mucosal immune responses during infancy, possibly resulting in an increased risk of developing allergic disease. High levels of IgG4 antibodies during infancy are associated with faster achievement of tolerance in food allergic children. Allergen elimination during infancy may result in a dysfunctional cytokine response.

Diss. (sammanfattning) Umeå : Umeå universitet, 2010.

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Background & Objectives: There has been few investigation of the association between the farming related activities or specific characteristics and atopic disease in rural Canadian children. In population-based studies, assuring the quality of information from questionnaires is of concern. We conducted this study in order to: first, identify the prevalence and risk factors of atopy and allergic conditions among school-age children in a rural region of Canada. Also, we sought to evaluate the validity and reliability of a questionnaire report of allergy to assess in this population. Methods: As part of a longitudinal study of lung health in rural residents, we conducted a cross-sectional baseline study in rural Saskatchewan, Canada. This included an initial survey phase followed by a clinical testing phase. A sub-sample of 584 children (grades 1-8) completed skin prick testing to assess atopic status. Of these, 480 children completed a questionnaire report of allergy and atopic outcomes and participated in skin prick testing (SPT). Atopy was defined as a positive reaction to any of 6 allergens (local grasses, wheat dust, cat dander, house dust mite, Alternaria, Clasdosporium)≥3mm compared to the negative control. Agreement between questionnaire report and objective measures of atopy was considered overall and between the specific allergens tested on SPT and those assessed on questionnaire. We considered percent concordance, Kappa, sensitivity, specificity, and the positive and negative predictive values of reported allergies or allergic conditions in comparison to SPT as the gold standard. Results: The prevalence of atopy as well as allergen-specific sensitizations was similar between farm and non-farm children but supported the notion that livestock farming is protective against atopy. Also, we found that 25.0% of children reported a history of allergic conditions by questionnaire and 19.4% were atopic detected by skin pick test. In our study, the agreement between questionnaire report of specific allergic triggers and atopy measured by SPT was high (83.0% - 89.5%). Conclusion: In children, livestock exposure has a protective effect on SPT positivity.The agreement between questionnaire report of allergic symptoms and atopy measured by SPT was high and the agreement between atopy and report of allergic conditions was moderate.