Current cat ownership may be associated with the lower prevalence of atopic dermatitis, allergic rhinitis, and Japanese cedar pollinosis in schoolchildren in Himeji, Japan

Prevalence, severity, and risk factors of allergic rhinitis among schoolchildren in Saudi Arabia: A national cross-sectional study, 2019

Background

Allergic rhinitis is a significant public health concern worldwide, affecting both developed and developing countries, with prevalence rates ranging between 10% and 30% in adults and over 40% in children. However, there are limited studies on allergic rhinitis prevalence in Saudi Arabia.

Objective

To explore allergic rhinitis among schoolchildren in Saudi Arabia in terms of prevalence, severity, and risk factors.

Methods

This study was conducted between March and April 2019, covering 20 regions. The study employed a multistage, stratified cluster sampling approach and selected 137 primary and 140 intermediate schools. The research utilized the methodology and questionnaires recommended by the Global Asthma Network (GAN). Data analysis was carried out using IBM SPSS Statistics (Version 23).

Results

The completed questionnaires in the analysis comprised 3614 children aged 6-7 years old and 4068 adolescents aged 13-14 years old. The study found that 5.6% of children and 14.0% of adolescents reported current rhinoconjunctivitis, with 0.5% of children and 1.3% of adolescents experiencing severe symptoms. Several risk factors were significantly associated with rhinoconjunctivitis. In children 6-7 years old, eating cooked vegetables was inversely associated with rhinoconjunctivitis, while prematurity, wheezing in infancy, and a history of pneumonia were positively associated with the condition. In adolescents, vigorous physical activity, current exposure to cats, and frequent use of paracetamol were found to be the main risk factors associated with rhinoconjunctivitis, while high consumption of pulses and eggs was found to have a protective effect.

Conclusion

In Saudi Arabia, the prevalence of rhinoconjunctivitis in children is lower than average globally, but among adolescents, it is within the global average range. However, the prevalence of severe rhinoconjunctivitis among adolescents is twice the global average. Further research is required to examine regional differences, track trends over time, and explore risk factors that contribute to allergic rhinitis.

Impact of the Family and Household Environment on Pediatric Atopic Dermatitis in Japan

Pediatric atopic dermatitis (AD) can negatively impact the family quality of life (QoL). We report data from the real-world Epidemiology of Children with Atopic Dermatitis Reporting on their Experience (EPI-CARE) study in Japanese pediatric patients, focusing on disease impact on family QoL. Children and adolescents aged 6 months to <18 years completed an online survey between September 2018-December 2019. The impact of disease severity on family QoL and its effect on parents' time were assessed using the dermatitis family impact (DFI) questionnaire. The impact of a family history of allergic conditions, current residency, second-hand smoke exposure, and household pets on AD prevalence and severity was also assessed. Family QoL decreased as AD severity increased, particularly in families with children aged <6 years; but had the greatest impact on sleep and tiredness in families with children aged <12 years. Parents spent at least 4.6 h/week caring for children <6 years, including those with mild symptoms. Most children (>80%) had a family history of allergic conditions; AD prevalence was increased in those exposed to second-hand smoke or household pets. This study demonstrated that pediatric AD in Japanese individuals has negative impacts on family QoL and that family and household environments can influence pediatric AD prevalence.

Prevalence and Influencing Risk Factors of Eczema Among Preschool Children in Hail City

Background Eczema is a common inflammatory skin disorder in the pediatric population. Although eczema is a significant public health issue with negative impacts on quality of life, studies looking at the prevalence and risk factors among preschool-aged children in Saudi Arabia are limited. Methods A descriptive, cross-sectional, online-based study was conducted among parents of preschool children in Hail City, Saudi Arabia, between July 2022 and September 2022. The self-administered, pre-tested questionnaire was distributed on social media networks for data gathering, which was subsequently analyzed using Statistical Package for the Social Sciences (SPSS, IBM Corp., Armonk, NY) software. Results Among 964 preschool children, 54.5% of the children have been diagnosed with eczema. A total of 152 (60.1%) male children had eczema compared to 231 (59.8%) female children, while 142 (43.7%) parents had children of both genders diagnosed with eczema (P = 0.001). Multivariate logistic regression showed that male gender (odds ratio [OR] = 1.41, 95% confidence interval = 1.16-1.71), smoking in the house (OR = 1.85, 95%CI = 1.37-2.50), presence of mold or dampness in the house while the mother was pregnant (OR = 1.95, 95%CI = 1.17-3.24), house renovation during the mother's pregnancy (OR = 1.54, 95%CI = 1.01-2.34), use of an air conditioner (OR = 1.57, 95%CI = 1.07-2.30), and dry skin (OR = 5.83, 95%CI = 4.27-7.96) were significant predictors for the development of eczema. Conclusion The high prevalence of eczema among preschool-aged children in Hail indicates the need for parents to take action at the household level and beyond to successfully lower the risk of eczema development in the region.

High Incidence of Atopic Dermatitis among Children Whose Fathers Work in Primary Industry: The Japan Environment and Children's Study (JECS)

The hygiene hypothesis assumes a low incidence of allergic diseases in families engaging in farming work. However, a few studies have indicated rural life as a potential risk factor for atopic dermatitis (AD). Using a large Japanese birth cohort dataset, we calculated the accumulated incidence of AD in children aged 6 months and 1, 2, and 3 years by family business and the hazard ratio. We adjusted for confounding factors. The father's job was considered the family business. We analysed data on 41,469 father-child pairs at 6 months of age, 40,067 pairs at 1 year, 38,286 pairs at 2 years, and 36,570 pairs at 3 years. We found the highest accumulated incidence of AD among children with fathers engaged in primary industry, with 2.5% at the age of 6 months, 6.6% at 1 year, 12.0% at 2 years, and 15.4% at 3 years. Among primary industry occupations, forestry was associated with the highest incidence of AD across these ages. The hazard ratio of AD was also highest for children whose family business was primary industry. In conclusion, the highest incidence and hazard ratio of AD were observed among children whose fathers worked in primary industry.

Effect of Exposure to Cats and Dogs on the Risk of Asthma and Allergic Rhinitis: A Systematic Review and Meta-analysis

BACKGROUND

Controversies persist regarding whether exposure to cat or dog increases the risk of asthma and allergic rhinitis.

OBJECTIVE

This meta-analysis aimed to assess the associations between exposure to cats or dogs and the development of asthma and allergic rhinitis.

METHODS

A systematic review was performed to identify case-control and cohort studies before May 2019, evaluating the association between exposure to cats and dogs and the risk of asthma and rhinitis. The risk of bias was assessed using the Newcastle-Ottawa Scale. The odds ratios (ORs) and risk ratios (RRs) were pooled for case-control and cohort studies, respectively. Subgroup analyses were performed on prespecified study-level characteristics.

RESULTS

The meta-analysis of 34 cohort studies showed a protective role of exposure to cats [RR: 0.88, 95% confidence interval (CI): 0.77-0.99] or dogs (RR: 0.85, 95% CI: 0.73-0.97) in the development of asthma. The subgroup analysis of birth cohort (RR: 0.74, 95% CI: 0.56-0.93) and children population (RR: 0.83, 95% CI: 0.70-0.96) also suggested a favorable role of exposure to dogs in the development of asthma. Pooled evidence from 13 case-control studies indicated no significant impact of cats (OR: 1.66, 95% CI: 0.39-2.94) and dogs (OR: 1.22, 95% CI: 0.92-1.52) on the development of asthma. A pooled analysis of five cohort studies showed a favorable effect of exposure to cats (RR: 0.60, 95% CI: 0.33-0.86) or dogs (RR: 0.68, 95% CI 0.44-0.90) on the development of allergic rhinitis.

CONCLUSION

The findings indicated a protective effect of exposure to cats and dogs, especially ownership, on the development of asthma and allergic rhinitis.

Analysis of factors associated with cedar pollen sensitization and development of pollinosis in a young Japanese adult population

BACKGROUND

Genetic and environmental factors are proposed to be involved in cedar pollen allergy sensitization and onset. The impact of these factors will provide key information for the prevention of cedar pollen sensitization and allergy onset, which we investigated in this cross-sectional study.

METHODS

Subjects were 382 young adult volunteers who completed a self-administered questionnaire on self-reported subjective symptoms of pollinosis, physician-diagnosed pollinosis, and background factors. We also measured their serum IgE antibody titers specific for cedar, cypress, and mites. Factors associated with subjective symptoms, physician diagnosis, and the three specific antigens were determined using both univariate and multivariate analyses.

RESULTS

Sensitization to cedar, cypress, and mites, defined as specific IgE levels of class 1 or above, was found in 78.8%, 64.4%, and 56.0% of subjects, respectively. The prevalence of cedar pollinosis was 41.2% based on subjective symptoms and 22.2% based on physician diagnosis. Factors associated with increased cedar pollen sensitization were mite sensitization, comorbid allergic rhinitis, and family history of cedar pollinosis. Risk-reducing factors for cedar pollen sensitization were keeping a cat, number of common colds, and hours of sleep. Risk-increasing factors for both subjective pollinosis symptoms and physician-diagnosed pollinosis were comorbid allergic rhinitis and family history of cedar pollinosis.

CONCLUSIONS

Sensitization to cedar pollen in this population was extremely high. Both common and distinct factors were associated with sensitization to pollen and with the development of pollinosis. The distinct factors were associated with sensitization to cedar and cypress antigens.

Current asthma, respiratory symptoms and airway infections among students in relation to the school and home environment in Japan

OBJECTIVE

To study associations between the school and home environment and current asthma, respiratory symptoms and airway infections among Japanese students.

METHODS

Japanese students (12-15 y) (N = 1048) in four schools responded to a questionnaire on respiratory health, allergy and the home environment. Temperature, relative air humidity (RH) and student density (students/m² floor area) was measured in the classrooms: dust was collected from floors and in classroom air and analysed for cat (Fel d 1) and dog (Can f 1) allergens. Health associations were analysed by multi-level logistic regression.

RESULTS

Doctor's diagnosed asthma was common (13.4%), 8.8% reported cat allergy and 6.1% dog allergy. The median level in floor dust was 41 ng/g (IQR 23-92) for Fel d 1 and 101 ng/g (IQR 54-101) for Can f 1. The median level in air was 18.6 ng/ m²/ day (IQR5.9-25.1) for Fel d 1 and 18.6 ng/ m²/ day (IQR 6.0-13.3) for Can f 1. High RH, high student density and airborne cat allergen was associated with airway infections. In the home environment, recent indoor painting, new floor materials, odour, having cats as pets, window pane condensation in winter, and dampness in floor construction were associated with respiratory illness.

CONCLUSION

High relative air humidity, high student density and airborne cat allergens at school may increase the risk of airway infections. Having cats as pets, chemical emissions from paint and new floor materials, odour and dampness can constitute domestic risk factors for respiratory symptoms while having dogs as pets could be protective.

Assessment of pet exposure by self-report in epidemiological studies of allergy and asthma: a systematic review

OBJECTIVE

In epidemiological studies that aim to investigate the relationship between pet exposure and allergy/asthma, pet exposure is often ascertained by means of a questionnaire, but it is unclear which questionnaire items are used. The objective of this study was to systematically review self-reported pet exposure assessment in questionnaires used in epidemiological studies which explore the associations between pets and allergy/asthma.

METHODS

A systematic literature search was conducted in PubMed and papers were selected according to pre-specified eligibility criteria. The pet exposure questions used were classified within a framework including direct pet contact, indirect pet contact (e.g. through carers or grandparents) and avoidance behaviour. Authors were contacted when the questions used were not reported in detail.

RESULTS

Ninety-six full text papers were systematically reviewed. All studies assessed direct pet contact, but less than half (45%) explicitly assessed whether pets were allowed indoors. The vast majority of studies assessed both pet exposures during the first year of life and after the first year of life. The minority (13%) assessed whether pet(s) were kept at places regularly visited by the child and pet exposure in utero (15%). Even fewer studies assessed indirect contact to pets (n = 8) and avoidance behaviour (n = 10).

CONCLUSIONS

In epidemiological studies, the ascertainment of pet exposure through questionnaires appears to vary greatly. This variation might partly explain the inconsistent and contradictory results of the effects of pet exposure on the development of allergy and asthma.

Epidemiology of pediatric allergic diseases in the Ogasawara Islands

BACKGROUND

The Ogasawara Islands, away from mainland Japan, belong to a subtropical area. Although the daily eating habits and food are relatively similar to that on the mainland, the living environment is quite different. The prevalence of allergic diseases in the Ogasawara Islands is unknown. This study aimed to identify the prevalence of allergic diseases in the Ogasawara Islands.

METHODS

A survey was conducted among all children belonging to preschool, elementary school, and junior high school in the Ogasawara Islands. A questionnaire was prepared in accordance with the International Study of Asthma and Allergies in Childhood (ISAAC) core written questionnaire in bronchial asthma (BA) and the West Japan Study of Asthma and Allergies in Childhood core written questionnaire for atopic dermatitis (AD), allergic rhinitis (AR), and food allergy (FA). At the same time, height, weight, duration of dwelling on the island, home environment, lifestyle, and exercise habits were also asked.

RESULTS

The target population comprised 352 children, of whom 284 (80.6%) completed the questionnaires. The current prevalence was 9.3% for BA, 4.3% for AD, 17.8% for AR, and 3.0% for FA. Significantly lower rates of current BA and AD were observed compared to previous reports from Japan. The percentage of children belonging to sports clubs, and exercising more than 3 times per week at the Ogasawara Islands is higher compared with the national average.

CONCLUSIONS

The lower prevalence of BA and AD in the Ogasawara Islands implies the influence of differences in the living environment and exercise habits.

Active or passive exposure to tobacco smoking and allergic rhinitis, allergic dermatitis, and food allergy in adults and children: a systematic review and meta-analysis

BACKGROUND

Allergic rhinitis, allergic dermatitis, and food allergy are extremely common diseases, especially among children, and are frequently associated to each other and to asthma. Smoking is a potential risk factor for these conditions, but so far, results from individual studies have been conflicting. The objective of this study was to examine the evidence for an association between active smoking (AS) or passive exposure to secondhand smoke and allergic conditions.

METHODS AND FINDINGS

We retrieved studies published in any language up to June 30th, 2013 by systematically searching Medline, Embase, the five regional bibliographic databases of the World Health Organization, and ISI-Proceedings databases, by manually examining the references of the original articles and reviews retrieved, and by establishing personal contact with clinical researchers. We included cohort, case-control, and cross-sectional studies reporting odds ratio (OR) or relative risk (RR) estimates and confidence intervals of smoking and allergic conditions, first among the general population and then among children. We retrieved 97 studies on allergic rhinitis, 91 on allergic dermatitis, and eight on food allergy published in 139 different articles. When all studies were analyzed together (showing random effects model results and pooled ORs expressed as RR), allergic rhinitis was not associated with active smoking (pooled RR, 1.02 [95% CI 0.92-1.15]), but was associated with passive smoking (pooled RR 1.10 [95% CI 1.06-1.15]). Allergic dermatitis was associated with both active (pooled RR, 1.21 [95% CI 1.14-1.29]) and passive smoking (pooled RR, 1.07 [95% CI 1.03-1.12]). In children and adolescent, allergic rhinitis was associated with active (pooled RR, 1.40 (95% CI 1.24-1.59) and passive smoking (pooled RR, 1.09 [95% CI 1.04-1.14]). Allergic dermatitis was associated with active (pooled RR, 1.36 [95% CI 1.17-1.46]) and passive smoking (pooled RR, 1.06 [95% CI 1.01-1.11]). Food allergy was associated with SHS (1.43 [1.12-1.83]) when cohort studies only were examined, but not when all studies were combined. The findings are limited by the potential for confounding and bias given that most of the individual studies used a cross-sectional design. Furthermore, the studies showed a high degree of heterogeneity and the exposure and outcome measures were assessed by self-report, which may increase the potential for misclassification.

CONCLUSIONS

We observed very modest associations between smoking and some allergic diseases among adults. Among children and adolescents, both active and passive exposure to SHS were associated with a modest increased risk for allergic diseases, and passive smoking was associated with an increased risk for food allergy. Additional studies with detailed measurement of exposure and better case definition are needed to further explore the role of smoking in allergic diseases.

New insights into the epidemiology of childhood atopic dermatitis

There is a growing desire to explain the worldwide rise in the prevalence of atopic dermatitis (AD). Trend data on the burden of AD suggest that the picture in the developing world may soon resemble that of wealthier nations, where AD affects over 20% of children. This, combined with significant variations in prevalence within countries, emphasizes the importance of environmental factors. Many hypotheses have been explored, from the modulation of immune priming by hygiene, gut microbiota diversity, and exposure to endotoxins through farm animals to the effects of pollution, climate, and diet. The discovery of the filaggrin skin barrier gene and its importance in AD development and severity has brought the focus on gene-environment interactions and the identification of environmental factors that impact on skin barrier function. This article reviews our current understanding of the epidemiology of AD, with an emphasis on the findings reported in the international literature over the last 5 years.

Prevalence and diversity of allergic rhinitis in regions of the world beyond Europe and North America

BACKGROUND

There is comparatively little information in the public domain on the diversity in prevalence and triggers/factors associated with allergic rhinitis (AR) or allergic rhinoconjunctivitis (AR/C) in countries beyond western-Europe and North America.

OBJECTIVE

To review the prevalence and the sensitizing agents/triggers and factors associated with AR/C in several countries in Africa, the Asia-Pacific region, Australia, Eastern Europe, Latin America, Middle East and Turkey.

METHODS

Articles published in English in peer-reviewed journals were assessed and selected for further review, following an extensive literature search using the Medline database.

RESULTS

This review demonstrated that prevalence of AR and AR/C in these regions has predominantly been investigated in children; with studies indicating wide inter- and intra-regional variations ranging from 2.9% AR and 3.8% AR/C in 10-18-years-old children from one region in Turkey to 54.1% AR and 39.2% AR/C in 13-14-years-old children in one region in Nigeria. Moreover, the prevalence of AR and AR/C has increased markedly over the last decade particularly in some of the more affluent African countries, China-Taiwan and several Middle East countries, likely as a consequence of improved living standards leading to increased exposure to multiple traditional and non-traditional sensitizing agents and risk factors similar to those noted in western-Europe and North America.

CONCLUSIONS AND CLINICAL RELEVANCE

Our findings suggest that the greater diversity in prevalence of AR or AR/C in populations in these regions is in contrast to the lower diversity of AR or AR/C in the 'western populations (USA and Europe), which tend to be more uniform. This review provides a comprehensive database of the important allergens and triggers which are likely to influence the prevalence of allergic rhinitis in these diverse regions, where the prevalence of allergic rhinitis is increasing and its adverse impact on the quality of life of affected individuals is increasingly recognised.

Risk factors for wheezing, eczema and rhinoconjunctivitis in the previous 12 months among six-year-old children in Himeji City, Japan: food allergy, older siblings, day-care attendance and parental allergy history

BACKGROUND

The aim of this study was to clarify whether some environmental and genetic factors (food allergy, older siblings, early day-care attendance and parents' allergy history) are related to the development of allergic symptoms (wheezing in the previous 12 months [WP], eczema symptoms in the previous 12 months [EP], and rhinoconjunctivitis symptoms in the previous 12 months [RP]) in Japanese children.

METHODS

Using the modified version of the International Study on Asthma and Allergies in Childhood (ISSAC) questionnaire, we studied the prevalence of WP, EP and RP among six-year-old children attending 72 primary schools throughout Himeji City, Japan, during the two years from 2005 to 2006.

RESULTS

Food allergy and parents' history of allergy showed a significant relationship with the prevalence of WP, EP and RP. Day-care attendance in the first two years of life and presence of older siblings showed a significant inverse relationship with the prevalence of RP. However, neither day-care attendance nor presence of older siblings was related to the development of W and ER.

CONCLUSIONS

Among Japanese children, food allergy and parents' history of allergy are risk factors for WP, ES or RS. However, early day-care attendance and presence of older siblings might be protective factors against RS. Infections in early life may affect the prevalence of rhinoconjunctivitis in six-year-old children.

Association between prenatal and postnatal tobacco smoke exposure and allergies in young children

BACKGROUND

Many studies have shown a positive association between environmental tobacco smoke (ETS) exposure and allergic disorders, whereas epidemiological evidence of the effect of maternal smoking during pregnancy on allergic diseases is inconsistent. We investigated the independent and joint effects of in utero exposure to maternal smoking and postnatal ETS exposure at home on allergic disorders among Japanese children.

METHODS

Study subjects were 1951 children aged 3 years. Data on maternal smoking during pregnancy and postnatal exposure to ETS at home, allergic symptoms, and potential confounders were collected through the use of a questionnaire. Outcomes were defined according to the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC).

RESULTS

The prevalence values of symptoms of wheeze, asthma, and eczema in the previous 12 months were 22.0%, 8.8%, and 17.2%, respectively. We found that postnatal ETS exposure at home in the absence of in utero exposure to maternal smoking was associated with a higher prevalence of wheeze (adjusted odds ratio (OR) = 1.30, 95% confidence interval (CI): 1.01-1.67). In contrast, in utero exposure without subsequent postnatal ETS exposure at home or exposure to postnatal ETS at home in addition to in utero exposure to maternal smoking was not associated with the prevalence of wheeze. No measurable associations were observed between fetal, postnatal, or joint exposure and the prevalence of asthma or eczema.

CONCLUSIONS

Data from this study indicate that ETS at home may be associated with a higher prevalence of wheeze among young Japanese children.

Contact to cat or dog, allergies and parental education

Whether or not associations between animal contact and allergy/atopy are homogeneous across social strata has not yet been investigated. The aim of this study was to estimate the association between animal contact (cat, dog) and allergy/atopy in 6-yr-old school beginners, stratified by parental educational level. A total of 30794, 6-yr old children participated in cross-sectional studies between 1991 and 2000 in Germany. Allergic sensitization to common aeroallergens and symptoms and diagnoses of atopic diseases (asthma, eczema, hay fever) were the dependent variables. Contact with dog/cat were the independent variables. Logistic regression was used to adjust for confounding. Analyses were stratified for parental education. Prevalences of hay fever, eczema, specific sensitization to pollen and house dust mite increased, while the prevalence of contact to cat and dog decreased with parental educational level. Globally significant positive associations between cat contact and sensitization to cat (interaction significant) and between dog contact and wheezing remained significant in the highest and medium/highest educational strata respectively. A globally significant inverse association between cat contact and hay fever remained significant in the highest educational stratum only. The inverse association of contact to dog with eczema was globally significant, but not in the strata. When estimating the associations between animal contact and allergy/atopy in children, effect modification by social status should be considered. Cat contact seems to increase the odds of sensitization to cat only in children whose parents have a high level of education.

Household environmental tobacco smoke and risks of asthma, wheeze and bronchitic symptoms among children in Taiwan

Background

Although studies show that maternal smoking during pregnancy increases the risks of respiratory outcomes in childhood, evidence concerning the effects of household environmental tobacco smoke (ETS) exposure remains inconsistent.

Methods

We conducted a population-based study comprised of 5,019 seventh and eighth-grade children in 14 Taiwanese communities. Questionnaire responses by parents were used to ascertain children's exposure and disease status. Logistic regression models were fitted to estimate the effects of ETS exposures on the prevalence of asthma, wheeze, and bronchitic symptoms.

Results

The lifetime prevalence of wheeze was 11.6% and physician-diagnosed asthma was 7.5% in our population. After adjustment for potential confounders, in utero exposure showed the strongest effect on all respiratory outcomes. Current household ETS exposure was significantly associated with increased prevalence of active asthma, ever wheeze, wheeze with nighttime awakening, and bronchitis. Maternal smoking was associated with the increased prevalence of a wide range of wheeze subcategories, serious asthma, and chronic cough, but paternal smoking had no significant effects. Although maternal smoking alone and paternal smoking alone were not independently associated with respiratory outcomes, joint exposure appeared to increase the effects. Furthermore, joint exposure to parental smoking showed a significant effect on early-onset asthma (OR, 2.01; 95% CI, 1.00-4.02), but did not show a significant effect on late-onset asthma (OR, 1.17; 95% CI, 0.36-3.87).

Conclusion

We concluded that prenatal and household ETS exposure had significant adverse effects on respiratory health in Taiwanese children.

The role of cats and dogs in asthma and allergy--a systematic review

Studies have reported contradictory effects of cat and dog exposure on allergy, resulting in inconsistent recommendations on animal avoidance. We conducted a systematic review of observational studies published in English from 2000 to January 2009. It shows in this review that the reported exposure-response relationships are contradictory. A total of 17 and 13 birth cohort studies on cat and dog exposure, respectively, are included in the review. Most of the birth cohort studies found that cat or dog exposure in early life had no effect on the development of asthma or wheezing symptoms and dog exposure during infancy was found to protect children from developing sensitization against aeroallergens. A total of 7 and 6 prospective studies in school-age children or adults on cat and dog exposure, respectively, are included in this review and most of these studies suggested an inverse association between cat exposure and asthma and wheezing symptoms. As for cross-sectional studies, 26 and 21 studies on cat and dog exposure, respectively, are included in this review, which cover a broad range of age groups and geographical areas, and reported inconsistent results. The evidence summarised in this systematic review needs to be interpreted with caution, the inconsistent study results may be due to study design, exposure assessment, and avoidance measure. The exposure-response relationships may also alter in geographical areas where the community prevalence of cats and dogs are significantly different. However, as the evidence of the effects of pet keeping on subsequent development of asthma or allergic diseases presented in this review are not overwhelmingly strong, the decision of whether to keep a cat or a dog in the family should be based on arguments other than the concern of developing asthma and allergy.

Allergen tolerance versus the allergic march: the hygiene hypothesis revisited

In addition to genetics, several environmental variables appear to impact allergic risk. Meta-analyses of epidemiologic studies presented in this article demonstrate a correlation between specific ambient exposures (eg, livestock, pets, endotoxin, and unpasteurized milk ingestion) and reduced allergic risk during childhood. Additional laboratory investigations discussed in this review characterized the intrinsic immunostimulatory activities of living environments. Considered together, results of these investigations suggest a novel paradigm by which early-life home exposures to microbial products and other allergen-nonspecific immunostimulants modify allergic risk.

Maternal smoking and environmental tobacco smoke exposure and the risk of allergic diseases in Japanese infants: the Osaka Maternal and Child Health Study

PURPOSE

It remains controversial whether environmental tobacco smoke increases the risk of allergic diseases. The present prospective cohort study examined whether in utero exposure to maternal smoking and postnatal exposure to environmental tobacco smoke were associated with the development of wheeze, asthma, and atopic eczema in Japanese infants.

METHODS

Study subjects included 763 infants. Data were obtained through the use of questionnaires completed by the mother during pregnancy and at 2 to 9 and 16 to 24 months postdelivery. Information regarding maternal smoking during pregnancy and postnatal exposure to environmental tobacco smoke was collected at 2 to 9 months postdelivery, and information on allergic symptoms was collected when the infant was between 16 to 24 months of age. Cases were defined according to criteria of the International Study of Asthma and Allergies in Childhood for wheeze and atopic eczema. Additionally, doctor-diagnosed asthma and atopic eczema were identified. Adjustment was made for maternal age, family income, maternal and paternal education, parental history of asthma, atopic eczema, allergic rhinitis, indoor domestic pets, baby's older siblings, baby's sex, birth weight, and time of surveys.

RESULTS

The cumulative incidence of wheeze, atopic eczema, doctor-diagnosed asthma, and doctor-diagnosed atopic eczema was 22.1%, 18.6%, 4.3%, and 9.0%, respectively. Maternal smoking during pregnancy was not related to the risk of wheeze, whereas postnatal maternal smoking in the same room as the child increased the risk of wheeze. No significant association was observed between perinatal tobacco smoke exposure and the development of asthma and atopic eczema.

CONCLUSIONS

Our findings suggest that postnatal maternal smoking might be associated with an increased risk of wheeze in Japanese infants.

Home exposures to environmental tobacco smoke and allergic symptoms among young children in Singapore

BACKGROUND

Research relating environmental tobacco smoke (ETS) exposures have focused on childhood asthma. There have been fewer studies with conflicting results performed on associations of ETS exposures with allergic symptoms. We are interested to see if ETS exposures in the homes are associated with allergic symptoms among preschool children in Singapore where public smoking is banned.

METHODS

A cross-sectional study adopting an expanded and modified ISAAC (International Study on Asthma and Allergies in Childhood) questionnaire for the evaluation of asthma and allergies was conducted on 6,794 children attending 120 randomly selected child care centers. Specific information on demographics and ETS exposures was obtained. Adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) were determined using Poisson multivariate regression with a log-link function and robust variance estimates as recommended for cross-sectional studies.

RESULTS

The response proportion was 70.0%, and 4,759 children from 97 centers participated. After adjusting for covariates, it was found that home ETS exposure was associated with increased risks of current symptoms of rhinitis (PR 1.23; 95% CI 1.01-1.50) and rhinoconjunctivitis (PR 1.79; 95% CI 1.26-2.54). These associations followed dose-response trends with respect to number of cigarettes smoked or smokers in the homes. Home ETS exposures were also associated with higher PRs of wheeze, nocturnal cough and doctor-diagnosed asthma. Compared with paternal smoking, higher risks of the above outcomes were found for maternal smoking.

CONCLUSION

Home ETS exposure is a risk factor associated with rhinitis and asthma among preschool children.

Prevalence of Asthma and Wheeze in Relation to Passive Smoking in Japanese Children

PURPOSE

Evidence remains inconclusive as to whether environmental tobacco smoke is a risk factor for allergic disorders in childhood. The present large-scale cross-sectional study examined the relationship between passive smoking at home and the prevalence of allergic disorders in Japanese schoolchildren.

METHODS

Study subjects were 23,044 children aged 6 to 15 years in Okinawa. Outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for sex, age, region of residence, number of siblings, paternal and maternal history of asthma, atopic eczema, or allergic rhinitis, as well as paternal and maternal educational level.

RESULTS

The prevalence of wheeze, asthma, atopic eczema, and allergic rhinoconjunctivitis in the previous 12 months was 10.7%, 7.6%, 6.8%, and 7.7%, respectively. Current heavy passive smoking and 7.0 or more pack-years of smoking in the household were independently related to an increased prevalence of wheeze and asthma, especially in children 6 to 10 years of age and children with a positive parental allergic history. There was no dose-response relationship between pack-years of smoking in the household and atopic eczema or allergic rhinoconjunctivitis.

CONCLUSIONS

Our findings suggested that environmental tobacco smoke might be associated with an increased prevalence of wheeze and asthma in Japanese children.

Defining a role for ambient TLR ligand exposures in the genesis and prevention of allergic diseases

Environmental variables responsible for the increasing allergic disease burden observed in developed countries over the last century have yet to be adequately characterized. Meta-analyses of epidemiological studies presented in the first half of this paper demonstrate a correlation between farm-associated exposures (i.e., livestock, pets, unpasteurized milk, and endotoxin) and a reduction in allergic risk during childhood. Laboratory investigations discussed in the second half of the paper characterize the intrinsic immunostimulatory activities of living environments. Considered together, experimental findings presented herein suggest a novel paradigm by which early life home exposures to microbial products and other allergen-nonspecific immunostimulants modify allergic risk.

Home environment and suspected atopic eczema in Japanese infants: the Osaka Maternal and Child Health Study

Atopic eczema is most commonly diagnosed in children under the age of 5 yr. Environmental factors during pregnancy or in early life may confer risk for childhood atopic eczema. The present prospective study examined the relationship of the perinatal home environment and the risk of suspected atopic eczema among Japanese infants under the age of 1. Study subjects were 865 parent-child pairs. The term 'suspected atopic eczema' was used to define an outcome based on our questionnaire at 2-9 months postpartum. Adjustment was made for maternal age, gestation, family income, maternal and paternal education, maternal and paternal history of asthma, atopic eczema, and allergic rhinitis, time of delivery before the second survey, baby's older siblings, baby's sex, and baby's birth weight. A high mite allergen level from maternal bedclothes and mold in the kitchen during pregnancy were significantly associated with an increased risk of suspected atopic eczema. Frequent vacuuming practices during pregnancy and giving the infant a bath or shower at least once a day were significantly inversely related to the risk of suspected atopic eczema. Maternal smoking, maternal use of a synthetic duvet and pillow, carpet use in the living room and maternal bedroom, indoor domestic pets, no ducted heating appliance, and gas use for cooking during pregnancy and household smoking in the same room as the infant, infant's synthetic duvet, carpet use in the infant's room, or vacuuming the infant's room were not related to the risk of suspected atopic eczema. High house dust mite allergen levels and mold in the kitchen during pregnancy may increase the risk of infantile atopic eczema, whereas frequent vacuuming practices during pregnancy and giving the infant a bath or shower at least once a day may protect against infantile atopic eczema.

Early allergen exposure and atopic eczema

BACKGROUND

The relationship between exposure to indoor aeroallergens in early life and subsequent eczema is unclear. We have previously failed to show any significant associations between early life exposure to house dust mite and cat fur allergens and either sensitization to these allergens or wheeze. We have also previously reported a lower prevalence of parent-reported, doctor-diagnosed eczema by age 2 years for children exposed to higher concentrations of house dust mite, but no other associations with other definitions of eczema or for exposure to cat allergen.

OBJECTIVES

To extend the exposure-response analysis of allergen exposure and eczema outcomes measured up to age 8 years, and to investigate the role of other genetic and environmental determinants.

METHODS

A total of 593 children (92 x 4% of those eligible) born to all newly pregnant women attending one of three general practitioner surgeries in Ashford, Kent, were followed from birth to age 8 years. Concentrations of house dust mite and cat allergen were measured in dust samples collected from the home at 8 weeks after birth. The risk of subsequent eczema as defined by the U.K. diagnostic criteria was determined according to different levels (quintiles) of allergen exposure at birth.

RESULTS

By age 8 years, 150 (25 x 3%) children had met the diagnostic criteria for eczema at least once. Visible flexural dermatitis was recorded at least once for 129 (28 x 0%). As in other studies, parental allergic history was positively associated with most eczema outcomes, as were higher maternal education and less crowded homes. No clear linear associations between early exposure to house dust mite or cat allergen were found, regardless of the definition of eczema used. The risk of eczema appeared to increase for the three lowest quintiles of house dust mite allergen exposure (odds ratio, OR 1 x 37 for third quintile compared with first), and then to fall for the two highest quintiles (OR 0 x 66 and 0 x 71) even after controlling for confounding factors.

CONCLUSIONS

The lack of any clear exposure-disease relationship between allergens in early life and subsequent eczema argues against allergen exposure being a major factor causing eczema. If the lower levels of eczema at higher levels of house dust mite are confirmed, then interventions aimed at reducing house dust mite in early infancy could paradoxically increase the risk of subsequent eczema.

Prevalence and risk factors for allergic rhinitis in primary school children

OBJECTIVE

Allergic rhinitis is a common chronic illness of childhood. The aim of the study was to evaluate the prevalence and risk factors of allergic rhinitis in 6-12-year-old schoolchildren in Istanbul.

METHODS

A total of 2500 children aged between 6 and 12 years in randomly selected six primary schools of Istanbul were surveyed by using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire between April and May 2004.

RESULTS

Of them 2387 (1185 M/1202 F) questionnaires were appropriately completed by the parents with an overall response of 95.4%. The prevalence of physician-diagnosed allergic rhinitis was 7.9% (n=189). A family history of atopy (aOR=1.30, 95% CI=1.00-1.68), frequent respiratory tract infection (aOR=1.36, 95% CI=1.08-1.70) and sinusitis (aOR=2.29, 95% CI=1.64-3.19), antibiotic use in the first year of life (aOR=1.26, 95% CI=1.01-1.57), cat at home in the first year of life (aOR=2.21, 95% CI=1.36-3.61), dampness at home (aOR=1.31, 95% CI=1.04-1.65) and perianal redness (aOR=1.26, 95% CI=1.01-1.57) were significant for increased risk for allergic rhinitis. Frequent consumption of fruits and vegetables were inversely, and frequent consumption of lollipops and candies were positively associated with allergic rhinitis symptoms.

CONCLUSION

Our study reconfirmed that family history of atopy, frequent respiratory tract infections, antibiotics given in the first year of life, cat at home in the first year of life, dampness at home, perianal redness and dietary habits are important independent risk factors for AR. Researchers worldwide should be focused to these factors and try to develop policies for early intervention, primary and secondary preventions for allergic diseases.