Effect of indoor environmental factors on development of atopic symptoms in children followed up to 4 years of age

Food allergy: temporal trends and determinants

This review summarizes studies discussing temporal trends in the prevalence of food allergy as well as potential factors associated with the development of food allergy. In addition, we will address the potential hypotheses accounting for the apparent increase in food allergy prevalence. Studies suggest increased prevalence of food allergy. However, relatively little is known about its pathogenesis. This review aims to assess temporal trends in the prevalence of food allergy and discuss potential genetic, environmental, and demographic determinants. The search strategy examined the medical literature database MEDLINE (using PubMed) for the time period of January 1, 2002 to January 31, 2012. In recent decades, the prevalence of food allergy in general has increased by 0.60 % [95 % confidence interval (CI), 0.59 %-0.61 %] and the prevalence of peanut allergy by 0.027 % (95 % CI, 0.026 %-0.028 %), but it has now likely stabilized in developed countries. Genes, the environment, and demographic characteristics play a role in the pathogenesis of food allergy. Numerous environmental and demographic factors as well as gene-environment interactions may account for this increase in prevalence, but further studies are required to tease out their relative contribution.

Daycare attendance and risk for respiratory morbidity among young very low birth weight children

Daycare attendance and very low birth weight (VLBW, < or =1,500 g) are associated with respiratory morbidity during childhood. The objective of this study was to evaluate whether daycare attendance is associated with even higher risk for respiratory problems among VLBW children. We hypothesized that VLBW children attending daycare, in a private home or daycare center, are at higher risk for respiratory problems than VLBW children not attending daycare. We also investigated whether the effect of daycare is independent or synergistic with respiratory risk resulting from being VLBW, as indicated by having bronchopulmonary dysplasia (BPD) as a neonate. We conducted a prospective study of VLBW children followed from birth to age 2-3 (N = 715). Logistic regression was used to evaluate the relationship between daycare attendance and respiratory problems, adjusting for known neonatal risk factors for poor respiratory outcomes. Attending daycare in either a private home or in a daycare center was significantly associated with higher risk of lower respiratory infections than never attending. Attending a daycare center was also associated with higher risk for wheezy chest, cough without a cold, and respiratory medication use. While having BPD was associated with increased risk for respiratory problems, daycare attendance and BPD were not found to be synergistic risk factors for respiratory problems among VLBW children, but acted independently to increase risk. This implies that the increase in risk for respiratory problems associated with daycare attendance may be similar among VLBW children and those of normal birth weight.

Asthma and chemical hypersensitivity: prevalence, etiology, and age of onset

This study investigates asthma's national prevalence and potential overlap with chemical hypersensitivity. It also examines asthma's etiology, age of onset, and demographic characteristics. Data were collected from a geographically weighted random sample of the continental U.S. (1058 cases), in four seasonal cohorts (2005-2006). The study found that 12.9% of the sample report asthma, 11.6% report chemical hypersensitivity, and 31.4% of those with asthma report chemical hypersensitivity. Among asthmatics, 38% report irritation from scented products, 37.2% report health problems from air fresheners, and 13.6% report their asthma was caused by toxic exposure. Asthma cases affected each racial/ethic group in roughly the same proportion, with nearly 50% classified as childhood onset.

The impact of early lifestyle factors on wheezing and asthma in Austrian preschool children

AIM

This study investigated the influence of early lifestyle factors on the prevalence of asthma and wheezing in preschool children in Tyrol, Austria.

METHODS

A cross-sectional questionnaire survey was performed in 1761 preschool children to obtain information on wheezing and asthma in the light of early lifestyle factors.

RESULTS

Factors independently associated with an increased risk for wheezing in the past 12 months included high parental education (OR: 1.5, 95% CI: 1.1-2.1) and parental hay fever (OR: 1.5, 95%CI: 1.1-2.2). Risk factors for doctor-diagnosed asthma (DDA) were early pet contact (OR: 2.2, 95% CI: 1.1-4.8) and parental asthma (OR: 3.0, 95%CI: 1.0-9.1), whereas breastfeeding decreased the risk (OR: 0.5, 95% CI: 0.2-1.0). Boiling the pacifier/sucker daily increased the risk for wheezing in the past 12 months (OR: 1.4, 95%CI: 1.0-2.0) and revealed a tendency towards DDA (OR: 1.9, 95% CI: 0.9-4.0).

CONCLUSION

In preschool children, we established an independent association between wheezing in the past 12 months, DDA and boiling frequency of the pacifier/bottle sucker during infancy. The impact of pacifier boiling frequency on atopic diseases on the basis of the hygiene hypothesis needs further investigation.

Gut barrier dysfunction in food allergy

Intestinal permeability tests used in the diagnosis of allergic diseases in response to oral food challenge have led to the conclusion that constitutive defects of the intestinal barrier are not the primary cause of allergic diseases. However, perturbation of environmental factors (infection, stress), by increasing intestinal permeability and enhancing danger signals, may favour food allergy in susceptible individuals. The mechanisms of enhanced permeability to specific and bystander antigens have been delineated as well as the molecular events involved in the sequential phases of allergic reactions. Intestinal absorption of food antigens and immune responses are mutually dependent, and luminal (environmental) and serosal (intrinsic) factors synergize to maintain a self-perpetuating cycle in which antigens penetrate the mucosa and induce allergic inflammation.

National prevalence of asthma and chemical hypersensitivity: an examination of potential overlap

OBJECTIVE

The objective of this study was to investigate the linkage between asthma and chemical hypersensitivity.

METHODS

The authors conducted a population study with a random sample of 1057 geographically weighted cases to determine the prevalence of both asthma and chemical hypersensitivity in the American population and to explore their co-occurrence.

RESULTS

A total of 14.1% of the respondents reported being diagnosed with asthma and 11.2% reported a hypersensitivity to chemicals. Of those with asthma, 27.2% also reported being hypersensitive to chemicals and 7.4% reported also being diagnosed with multiple chemical sensitivities (MCS). Of those diagnosed with MCS, 42% reported also being diagnosed with asthma. Additionally, 29.7% of those with asthma said air fresheners caused breathing difficulties, and 37.2% found scented products irritating.

CONCLUSIONS

The results indicate that there is significant overlap between some forms of asthma and chemical hypersensitivity.