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PubMed2006

Relationship between childhood atopy and wheeze: what mediates wheezing in atopic phenotypes?

BACKGROUND: The nature of the relationship between childhood wheeze and atopy remains uncertain. OBJECTIVE: To characterize childhood wheeze among atopic phenotypes in a longitudinal birth cohort study. METHODS: A whole population birth cohort (N = 1,456) was recruited in 1989. Children were seen at birth and at 1, 2, 4, and 10 years of age to obtain information on asthma and allergic disease development and relevant risk factors for these states. Skin prick testing at ages 4 (n = 980) and 10 (n = 1,036) years was used to define atopic phenotypes. Wheezing in these states was characterized, and logistic regression was used to identify independent risk factors for wheeze onset in different atopic phenotypes. RESULTS: Wheeze ever occurred in 37% of never atopics, 38% of early childhood atopics, 65% of chronic childhood atopics, and 52% of delayed childhood atopics. Chronic childhood atopics had significant wheezing morbidity and bronchial hyperresponsiveness. Their wheezing was associated with male sex, early eczema, family history of eczema, and early tobacco exposure. Never atopic wheeze was related to maternal asthma, parental smoking, and respiratory tract infections. Exclusive breastfeeding protected against early childhood atopic wheeze. Maternal asthma, family history of urticaria, and dog ownership increased delayed childhood atopic wheeze. CONCLUSIONS: In many respects, chronic childhood atopy is the atopic phenotype associated with the most significant forms of childhood wheezing. In such children, heritable drive, allergens, and synergy with other environmental triggers seem to be crucial determinants of wheeze onset. Where such sensitization is absent, numerous environmental factors plus genetic predisposition may assume importance for wheezing.

Age of Onset↗
PubMed1997

Transfer of atopy following bone marrow transplantation.

BACKGROUND: Bone marrow transplantation is an optimal treatment of acute leukemia and aplastic anemia. Allergic manifestations in recipients long after bone marrow transplantation have been reported. A case involving transfer of atopy manifested as food allergy-induced-atopic dermatitis is reported. METHODS: The donor and the patient were investigated by prick tests and RAST to the same food allergens. Single blind, oral challenge to egg documented food allergy in the recipient. RESULTS: A 5-year-old boy without history of atopy developed severe atopic dermatitis after bone marrow transplantation from his HLA-identical sister for acute lymphoblastic leukemia. The patient's course had been marked previously by acute graft versus host disease and cytomegalovirus infection. Immunoallergic evaluation showed an exquisite sensitization to egg, peanut, and soybean. Total IgE was 6400 KIU/L. Concomitantly, the donor showed the same sensitizations. Absolute avoidance resulted in the regression of atopic dermatitis. Subsequently, new sensitization to wheat flour, Dermatophagoides pteronyssinus, birch, and plantain pollens was detected. The donor developed asthma. CONCLUSIONS: This case gives evidence of the transfer of sensitization from donor to recipient. The passive transfer of memory cells within the bone marrow inoculum is a possible mechanism. The current concept of allergy supports down regulation of Th1 cells to the benefit of Th2 cells. Additional deregulation induced by acute graft versus host disease, cytomegalovirus infection, and immunosuppression is possible.

Bone Marrow Transplantation↗
PubMed2006

Effect of animal contact and microbial exposures on the prevalence of atopy and asthma in urban vs rural children in India.

BACKGROUND: Environmental factors, including microbial exposures and close animal contact, are implicated in the lower prevalence of asthma and allergy in rural vs urban children. OBJECTIVES: To determine (1) the prevalence of asthma, rhinitis, eczema, and atopic sensitization in rural and urban children in India; (2) differences in microbial and animal exposures in these locales; and (3) whether differences in environmental exposures account for the different rates of asthma and atopy in these locales. METHODS: One child from each of 50 urban (Mysore) and 50 rural (Vinobha) households in southern India was randomly selected for data analysis. Allergy, asthma, health, environment, and lifestyle information was obtained using a questionnaire and household inspections. Atopy was determined via skin prick testing for common allergens. Endotoxin content was measured in house dust samples. RESULTS: Children from rural vs urban areas had lower prevalences of self-reported asthma (8% vs 30%; P = .005), rhinitis (22% vs 42%; P = .03), and atopic sensitization (36% vs 58%; P = .03). Higher median dust endotoxin loads were found in rural vs urban households (6.50 x 10(4) EU/m2 vs 1.27 x 10(4) EU/m2; P < .001). In multivariate analysis, close indoor animal contact (adjusted odds ratio [OR] 0.2; 90% confidence interval [CI], 0.05-0.9), outdoor animal contact (OR, 0.3; 90% CI, 0.1-0.8), and exclusive breastfeeding for at least 6 months (OR, 0.2; 90% CI, 0.1-0.5) were associated with lower atopic sensitization; mud flooring was associated with lower self-reported wheezing (OR, 0.1; 90% CI, 0.02-1.0). CONCLUSION: Children in India who live with close animal contact and mud flooring and who were exclusively breastfed in infancy are less likely to develop asthma, rhinitis, and atopic sensitization.

Adolescent↗
PubMed2002

A retrospective study of hyposensitization in canine atopy based on a polyclonal ELISA test.

Compliance with the treatment protocol and the most significant reasons encountered in general practice for the discontinuation of treatment in hyposensitized dogs are examined. The data are based on (1) a review of order forms for the hyposenzitization mixture and information sheets for an ELISA test and (2) telephone interviews with dog owners. Most of the owners (81%) gave their dogs allergen injections at home. Non-compliance was defined as discontinuation of treatment in the induction period; 33.9% of the owners became non-compliant. A large proportion of non-compliant owners (51.2%) claimed to be unaware of the length of the induction period. Furthermore, 70.2% of the owners were not aware that treatment would most likely need to be lifelong if it was to remain effective. Although 67.5% of the owners perceived that their dogs had beneficial effects from hyposensitization, only 36.3% of the dogs were receiving maintenance injections at the time of the telephone interview, considerably reducing the long-term benefit from treatment. Canine atopy is a chronic disease characterized by remission and relapses. Since no control group was available in this study, the beneficial outcome of treatment reported by the owners could be partly due to the natural course of the disease. Nevertheless, the results indicated that the long-term effect of hyposensitization in canine atopy will be reduced by premature discontinuation of treatment in the maintenance period. The discontinuation of treatment could be a reflection of the treatment becoming less effective, owing to the development of new hypersensitivities or to a reduction in the placebo effect that may occur in 'new' treatments. However, poor client education and follow-up seem to be important reasons for both noncompliance and discontinuation of the treatment in the maintenance period.

Allergens↗
PubMed2000

Relationships between natural T cells, atopy, IgE levels, and IL-4 production.

BACKGROUND: Th2 cells govern allergic disorders. Mechanisms leading to the Th2 commitment are dominated by the requirement of IL-4. A potential source of this triggering IL-4 could be the CD4 + subset of a small population of T cells, natural T (NT) cells. Indeed, this subset is involved in IgE responses in mice and produces promptly high amounts of IL-4 in both mice and man. METHODS: NT cells were identified in peripheral blood by flow cytometry with antibodies against Valpha24 and Vbeta11, recognizing the T-cell receptor specific for NT cells. Simultaneous staining with anti-CD3, anti-CD4, or anti-CD8 antibodies was performed. The frequency of NT cells in man was studied according to the presence of atopy defined by the positivity of skin tests, according to total IgE levels in serum, and according to IL-4 concentration of whole-blood culture supernatants determined by a flow cytometer microsphere-based assay. RESULTS: Seventy subjects were included, of whom 30 were atopic. The number of CD4+ NT cells was higher in atopics than in nonatopics (P=0.009). This number was correlated to the total IgE levels (r = 0.34, P = 0.03). In addition, the number of CD4 + NT cells, but also of CD8 + NT cells, was correlated to the levels of IL-4 (r=0.71, P=0.01, and r=0.6, P=0.03, respectively). CONCLUSIONS: These results show that the number of NT cells, particularly the CD4+ subset, is related to atopy, IL-4 production, and IgE levels. Therefore, this population of T cells is likely to play a role in the Th2 commitment initiating atopic diseases.

Adolescent↗
PubMed2001

Epidemiology of food allergy/food intolerance in adults: associations with other manifestations of atopy.

BACKGROUND: Food allergy and food intolerance (FA/FI) are believed to be frequent medical problems; however, information from epidemiologic studies in adults is scarce. The objective was to determine the frequency of FA/FI and allergic sensitization to food in a large adult sample. Furthermore, the associations between FA/FI and other outcomes of atopy were studied. METHODS: Within a population-based, nested, case-control study, a standardized interview was performed to obtain detailed information on FA/FI and the history of atopic diseases. In addition, a skin prick test with 10 common food and nine aeroallergens was performed. RESULTS: Overall, 20.8% of the 1537 studied subjects (50.4% female, age median 50 years) reported FA/FI (women 27.5%, men 14.0%; OR 2.35, CI 1.80-3.08). Nuts, fruits, and milk most frequently led to adverse effects, and the sites of manifestation were oral (42.9%), skin (28.7%), gastrointestinal (13.0%), systemic (3.2%), and multiple (12.2%). One-quarter of the subjects (25.1%) were sensitized to at least one food allergen in the prick test, with hazelnut (17.8%), celery (14.6%), and peanut (11.1%) accounting for most of the positive reactions. The corresponding frequency estimates for the representative study base (n=4178) were 15.5% for reported adverse reactions and 16.8% for allergic sensitization. Relevant concomitant sensitization to food and aeroallergens was observed. Food-allergic subjects (positive history and sensitization to corresponding allergen) suffered significantly more often from urticaria, asthma, atopic eczema, and especially hay fever (73.1%) than controls (3.0%). Furthermore, hay fever was treated significantly more often in subjects who suffered from concomitant food allergy. CONCLUSIONS: FA/FI in adults is frequently reported and associated with other manifestations of atopy. Hay fever in conjunction with FA/FI tends to be clinically more severe since therapeutic needs are enhanced.

Adult↗
PubMed2001

Increased prevalence of atopy among children exposed to mold in a school building.

BACKGROUND: The purpose of this study was to assess the occurrence of immunoglobulin E sensitization to common environmental allergens (atopy) and new allergic diseases among schoolchildren after starting school in a water-damaged school building. The staff and pupils of a Finnish elementary school with visible water damage and mold complained of respiratory and skin symptoms. The school building was examined and widespread moisture damage was found. A control school with no visible water damage was also examined. No indication of exceptional microbial growth was found in the samples taken from this school. METHODS: History of allergic diseases and the year of diagnosis were established by a questionnaire. IgE antibodies to the common environmental allergens were determined from randomly selcted groups from both schools. RESULTS: Elevated IgE values were significantly more common among the exposed children, as was the occurrence of new allergic diseases after the children started at the school. CONCLUSIONS: The odds ratios for the IgE values of the study groups indicated a possible relationship between exposure to microorganisms and IgE sensitization. Exposure to spores, toxins, and other metabolites of molds may have complex results with unknown immunogenic effects that may act as a nonspecific trigger for allergic sensitization leading to the development of atopy.

Child↗
PubMed2002

The atopy patch test -- reproducibility and comparison of different evaluation methods.

BACKGROUND: There is still a lack of standardization of the atopy patch test (APT) in test procedures and evaluation methods. Our aim was to examine the reproducibility of APT results and to compare visual evaluation to chromametry and laser Doppler imaging. METHODS: Fifty-two volunteers with atopic eczema/dermatitis syndrome (AEDS) were included. The APT was performed on tape-stripped and unstripped test fields on their backs using cat dander, house dust mite and grass pollen allergens from two different suppliers. Responders were re-tested 4-12 weeks later with the same allergens on their forearms. RESULTS: Using Allergopharma allergens, 14 (26.9%) volunteers showed one or more positive reactions. The reproducibility rate was 56.3%. The Erlangen atopy score in APT-positive and negative volunteers was 19 +/- 6 vs 15 +/- 6. The test agreement in volunteers tested with both allergens, from Allergopharma and Stallergènes, was poor. Correlation of the results between the three evaluation methods was significant (P < or = 0.001). CONCLUSIONS: The low reproducibility rate of APT results and the poor inter-test-agreement using allergens from different suppliers show that much work remains to make the APT a reliable tool in identifying relevant aeroallergens that lead to flare ups of AEDS. Compared to chromametry and laser Doppler imaging, visual scoring was superior in differentiation between irritative and allergic reactions.

Adolescent↗
PubMed2003

Atopy in Norwegian and Russian adults: a population-based study from the common border area.

BACKGROUND: Several studies have concluded that atopy is more common in Western than in Eastern Europe. We aimed to study whether a similar difference exists between Norwegian and Russian adults living in geographically adjacent areas. METHODS: A cross-sectional population-based study was performed in Sør- Varanger municipality (Norway) and in the cities of Nikel and Zapolyarny (Russia). The Russian cities are heavily polluted by sulfur dioxide from local nickel industry. In addition to questionnaire information, results on IgE sensitization (S-Phadiatop, Pharmacia & Upjohn, Uppsala, Sweden) were obtained from 3134 Norwegian and 709 Russian participants. RESULTS: A positive Phadiatop was found in 20.7% of the Norwegians (men 21.9%, women 19.7%) and in 27.5% of the Russians (men 35.7%, women 23.0%); the sex- and age-adjusted relative risk of testing positive in Russia being 1.49 (95% CI 1.23-1.81). The Norwegian participants reported more atopic dermatitis and hay fever, although this difference was statistically significant only for atopic dermatitis in women. CONCLUSION: IgE sensitization was more common in Russia than in Norway, unlike findings from other east-west European studies. The Russians did not, however, report more atopic diseases. This discrepancy might reflect different awareness of allergies in the two countries and demonstrates the need for objective markers of atopy when comparing prevalence in different populations.

Adult↗
PubMed1999

Frequency of infections and risk of asthma, atopy and airway hyperresponsiveness in children.

The role of repeated infections early in life in the development of childhood asthma and allergies has not been clarified. The aim of this study was to investigate the effect of repeated episodes of fever and antibiotic treatments during the first years of life on the prevalence of asthma, bronchial hyperresponsiveness (BHR), and atopy at school age in a representative population. Random samples of schoolchildren aged 5-7 yrs (n=7,545) and 9-11 yrs (n=7,498) were studied using the International Study of Asthma and Allergies in Childhood (ISAAC) phase II protocol. To assess the prevalence of disease and early childhood exposures, parental questionnaires were administered (response rates 82.2% and 85.3%, respectively). In addition, children underwent skin prick tests, hypertonic saline challenge and blood sampling for the measurement of serum immunoglobulin (Ig)E. Repeated episodes of fever and antibiotic treatment in early life were strongly associated with the prevalence of asthma (odds ratio (OR)=7.95; 95% confidence interval (CI) 6.02-10.50) and current wheeze at school age. Within asthmatic children the number of fever episodes and antibiotic courses were strongly inversely related to the prevalence of atopy (OR=0.25; 95% CI 0.11-0.54 for skin test reactivity) and BHR (OR=0.31; 95% CI 0.10-0.92). Furthermore, asthmatic children with recurrent early childhood infections were at a lower risk of being symptomatic at school age. When considering atopic and nonatopic asthmatic children separately, the highest risk of asthma with repeated early childhood infections was found for nonatopic asthma (OR=24.29; 95% Cl 11.86-49.76). These findings suggest that a subgroup of children with a triggering or inducing of asthmatic symptoms through repeated early childhood infections exists within the "asthma syndrome" which has a better prognosis and is less related to the atopic phenotype.

Adolescent↗
PubMed2003

NOS1 polymorphism is associated with atopy but not exhaled nitric oxide levels in healthy children.

Exhaled nitric oxide (FENO) is raised in atopy. The mechanism for this is unclear. The aim of this study was to investigate whether the number of AAT repeats in intron 20 of the NOS1 gene, recently associated with variations in FENO in adults with asthma and cystic fibrosis, was associated with the raised FENO in healthy atopic children. Eighty-seven healthy children (44 girls, 42 atopic, age range 6-18 years) underwent measurements of FENO, spirometry, airway responsiveness and skin prick testing. Genotyping was carried out to determine the number of AAT repeats. There was no association between the number of AAT repeats and FENO in either the whole sample of healthy children (n = 87) or in the subsample of healthy atopics (n = 42). However, a greater number of atopic children had two high repeat alleles compared with non-atopic children (33.3% vs. 13.6%, respectively, p = 0.03). This suggests that variations in the NOS1 gene may contribute to atopy without this relationship being reflected by FENO.

Adolescent↗
PubMed1996

Atopy and the ectopic immune response.

A hypothesis if formulated for the mode of action of the 'atopy gene': the gene(s) causing an increased tendency to mount an IgE immune response to trivial environmental antigens. It is postulated that some antigens are not efficiently transported to the lymphoid organs, the location of the 'eutopic' immune system; migratory lymphoid cells may occasionally react and start an inefficient immune response in sites not so destined. This is called an ectopic immune response. This response lacks the regulatory influences prevailing in the lymphoid organs, which results in approximately equal quantities of the various immunoglobulin isotypes, including IgE. The atopy gene(s) work by increasing the risk of such an ectopic immune response.

Animals↗
PubMed2006

Asthma and atopy are associated with DEFB1 polymorphisms in Chinese children.

Human beta-defensin (HBD)-1 is constitutively expressed in the airway, and hBD-1 plays crucial roles in innate immunity against respiratory pathogens. Asthma was associated with DEFB1 polymorphisms in Caucasians. This study investigates whether three single nucleotide polymorphisms (SNPs) in 5'-untranslated region of DEFB1 are associated with asthma phenotypes in Chinese children. Subjects aged 5-18 years were recruited from general pediatric clinics. Plasma IgE concentrations were measured by immunoassays. DEFB1 SNPs were characterized by restriction fragment length polymorphism. In all, 305 asthmatics and 156 controls were recruited. For asthma diagnosis, atopy and plasma total IgE, higher percentages of subjects with these outcomes had the minor alleles -20A and -52G (P = 0.041-0.0002). For log-transformed total IgE, the covariate was positive and significant for G-20A under recessive model (P = 0.001) and for G-52A under both recessive and codominant models (P = 0.008 and 0.035). The recessive model covariate was also positive and significant (P = 0.020) for C-44G on peripheral blood eosinophil count. The GCA haplotype of DEFB1 was significantly associated with asthma (odds ratio (95% confidence interval): 1.64 (1.05-2.57); P = 0.029). These results suggest that DEFB1 is a candidate gene for asthma and atopy in children.

Adolescent↗
PubMed1999

Role of the atopy score and of single atopic features as risk factors for the development of hand eczema in trainee metal workers.

This study was performed as part of PROMETES (Swiss Prospective Metal Worker Eczema Study) to examine the role of atopy as a possible risk factor for the development of hand eczema in trainee metal workers. In a cohort of 201 young men without any skin problems at the start of their apprenticeship, 9.5% developed signs of dermatitis on their hands within a period of 6 months. The 2. 5-year incidence was 23%. We did not find a significantly increased risk for hand eczema in those participants with an atopic skin diathesis according to the atopy score of Diepgen et al. (Dermatosen 1991; 39: 79-83) Analysis of individual atopic signs and symptoms showed reported metal reactivity to have a significant influence on the onset of early skin damage within 6 months, whereas a history of flexural eczema appeared to be significantly related to the overall incidence over 2.5 years.

Adolescent↗
PubMed1998

Linkage and allelic association of atopy and markers flanking the IL4-receptor gene.

BACKGROUND: Atopy, a clinical syndrome characterized by heightened IgE responsiveness, is largely determined by genetic factors. The disease may well be heterogeneous but the mode of inheritance is unknown. Several genes have been named which affected IgE responsiveness. However, results are conflicting reflecting heterogeneity and a complicated inheritance pattern of the atopic syndrome. In 1994 linkage of the 5q32 gene region and elevated total IgE levels were reported, leaving the IL4 gene as a prominent candidate. OBJECTIVES: We were interested in a possible involvement of the IL4-receptor gene in the development of atopy. METHODS: We employed sib-pair linkage analysis using highly polymorphic microsatellite markers within and flanking the IL4 receptor gene in atopic families, characterized for specific sensitization to inhalant allergens and elevated total serum IgE. Allele sizes were determined for all microsatellite probes to allow transmission disequilibrium analysis. RESULTS: We found significant sharing of maternal but not paternal alleles in affected sibs from two independent populations, both of which presented enhanced IgE responsiveness. Linkage and maternal inheritance could be confirmed by transmission disequilibrium analysis. CONCLUSIONS: We conclude from our findings that maternal inheritance of a gene in the chromosome 16p12 region increases the risk for enhanced IgE responsiveness. The most prominent candidate in this region is represented by the IL4 receptor gene.

Adolescent↗
PubMed1999

Atopy patch test reactions are associated with T lymphocyte-mediated allergen-specific immune responses in atopic dermatitis.

BACKGROUND: Positive test reactions to epicutaneous application of aeroallergens served as a model of 'early' eczema in atopic dermatitis (AD) in a number of dermato-immunological studies. However, no quantitative evaluation has been performed so far comparing specific T-cell activation parameters in the peripheral blood of AD patients with positive or negative atopy patch tests (APT). OBJECTIVE: The purpose of this study was to investigate specific immunological parameters in patients with atopic dermatitis showing positive or negative atopy patch tests reactions. METHODS: APT results (n = 96) were compared with allergen-specific IgE, specific lymphocyte proliferation, and the expression of 'activation' markers on peripheral blood T-cells upon in vitro stimulation with house dust mite, cat or grass pollen allergens. RESULTS: Only a subpopulation (48%) of patients sensitized to aeroallergens (i.e. specific IgE > 0.7 kU/L) developed APT-reactions to the corresponding allergen. APT reactions were, however, significantly associated with allergen specific lymphocyte proliferation (p < 0.0001), and a higher number of CD54+ or CD30+ T-cells (p < 0.05) upon in vitro stimulation. CONCLUSION: The association of delayed skin reactions with allergen specific T-cell parameters in the blood points to an immunologically mediated mechanism leading to positive reactions in the APT.

Allergens↗
PubMed2001

A polymorphism in the coding region of interleukin-13 gene is associated with atopy but not asthma in Chinese children.

BACKGROUND: Interleukin (IL)-13 is an important cytokine secreted from type 2 helper T lymphocytes. It is essential for modulating IgE synthesis by human B cells. Previous studies showed that polymorphisms in the IL-13 gene were associated with serum total IgE or allergic asthma. The relationship of this marker with sensitization to individual aeroallergens has not been evaluated. OBJECTIVE: We tested whether a polymorphism in the coding region of the IL-13 gene is associated with asthma and atopy in asthmatic children in Hong Kong. METHODS: We used restriction fragment length polymorphism to detect R130Q genotype in Chinese children with asthma and control subjects. Serum total IgE was measured by microparticle immunoassay and specific IgE to common aeroallergens was measured using fluorescent enzyme immunoassay. Pulmonary function studies were performed using spirometry. RESULTS: One hundred and fifty-seven patients and 54 control children were recruited. Their mean serum total IgE concentrations were 994 kIU/L and 473 kIU/L, respectively (P < 0.0001). Atopy as defined by > or = 1 positive RAST was found in 141 patients and 32 control children. The GlnGln form of the R130Q polymorphism in the IL-13 gene was associated with serum total IgE (P = 0.005) as well as specific IgE to Der p 1 (P = 0.021), mixed cockroaches (P = 0.03) and dog (P = 0.003) but not with physician-diagnosed asthma (P = 0.621). In addition, the R130Q polymorphism did not correlate with subjective or objective indicators of asthma severity in our patients. CONCLUSION: Our results suggest that the R130Q polymorphism of the IL-13 gene is associated with elevated serum total and allergen-specific IgE but not asthma in Chinese children.

Adolescent↗
PubMed2001

Wheezing in relation to atopy and environmental factors in Estonian and Swedish schoolchildren.

BACKGROUND: The prevalence of asthma and allergic diseases is significantly lower in post socialist Eastern Europe than in Western industrialized countries. The reason for this difference is largely unknown. Different types of childhood wheezing could be related to different risk factors. OBJECTIVE: To compare the prevalence of respiratory symptoms, asthma and atopic diseases among Estonian and Swedish schoolchildren and to evaluate characteristics for wheezing in the two countries. METHODS: In a prevalence study, population-based random samples of 10-11-year-old schoolchildren in Tallinn (n = 979), Estonia and in Linköping (n = 911) and Ostersund (n = 1197), Sweden were studied by a parental questionnaire and skin prick tests (SPT). All 275 children with wheeze in the past 12 months and 710 randomly selected controls within the original cohorts were invited to a case-control study involving a parental questionnaire, examination for flexural dermatitis and bronchial challenge with hypertonic saline. The study adhered to the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. RESULTS: The prevalence of current wheezing was similar (8-10%) in the three centres, while diagnosed asthma and atopic symptoms were more common in Sweden and cold-related respiratory symptoms were more prevalent in Estonia. Frequent wheezing was more common in Sweden than in Estonia (but significantly so only in Ostersund). Wheezing children in Sweden had a high rate of positive SPT (49% in Linköping and 58% in Ostersund) bronchial hyper-responsiveness (BHR) (48% in Linköping and Ostersund) and anti-asthmatic treatment (63% in Linköping and 81% in Ostersund). In Estonia, the proportion of wheezing children with positive SPT, BHR and anti-asthmatic treatment was only 26%, 13% and 17%, respectively. Domestic crowding was inversely related to wheezing in one of the study areas (Ostersund). The mean baseline forced expiratory volume in one second (FEV1) was higher in Estonia than in Sweden, both in wheezing and non-wheezing children. CONCLUSIONS: Our study suggested that although wheezing symptoms were equally common in Estonia and Sweden, they were less severe in Estonia. More frequent symptoms and a high rate of atopy, BHR and anti-asthmatic medication characterized wheezing children in Sweden. In contrast, BHR, atopy and medication were uncommon among wheezing children in Estonia.

Bronchial Hyperreactivity↗