BCG immunization at birth and atopic diseases in a homogeneous population of Spanish schoolchildren

Impact of Allergic Disease on the Risk of Mycobacterial Disease

BACKGROUND

The association between allergic diseases and the risk of mycobacterial disease is unclear.

OBJECTIVE

To evaluate the association between allergic diseases and mycobacterial diseases.

METHODS

This was a population-based cohort study of 3,838,680 individuals, without prior mycobacterial disease, who participated in the 2009 National Health Screening Exam. We evaluated the incidence of mycobacterial disease (tuberculosis or nontuberculous mycobacterial infection) in participants with allergic disease (asthma, allergic rhinitis, or atopic dermatitis) and those without allergic disease. We followed the cohort up until the date of mycobacterial disease diagnosis, follow-up loss, death, or December 2018.

RESULTS

During a median follow-up of 8.3 (interquartile range, 8.1-8.6) years, 0.6% of participants developed mycobacterial disease. The incidence of mycobacterial disease was significantly higher in those with allergic diseases than in those without allergic diseases (1.0 vs 0.7/1000 person-years; P < .001), with an adjusted hazard ratio of 1.13 (95% CI, 1.10-1.17). Asthma (adjusted hazard ratio, 1.37; 95% CI, 1.29-1.45) and allergic rhinitis (adjusted hazard ratio, 1.07; 95% CI, 1.04-1.11) increased the hazard of mycobacterial disease, whereas atopic dermatitis did not. The association between allergic diseases and hazard of mycobacterial disease was more prominent in older (age ≥ 65 years, P for interaction = .012) and obese (body mass index ≥ 25 kg/m2, P for interaction < .001) participants.

CONCLUSION

Allergic diseases including asthma and allergic rhinitis were associated with an increased risk of mycobacterial disease, whereas atopic dermatitis was not.

Do bacterial vaccines/adjuvants prevent wheezing episodes in children?

PURPOSE OF REVIEW

To discuss recently discovered mechanisms of action of some bacterial vaccines that may account for their clinical benefit in the prevention of recurrent wheezing and asthma exacerbations in infants and early childhood.

RECENT FINDINGS

Trained immunity has been shown to confer innate immune cells with a quite long-term nonspecific protection against a broad spectrum of pathogens. Inducers of trained immunity include some bacterial vaccines. Trained immunity-based vaccines (TIbV) of bacterial origin have the capability to induce nonspecific responses to a variety of pathogens, including respiratory viruses, in addition to their nominal bacterial antigens. Clinical data, from epidemiological surveys to well designed randomized clinical trials, indicate that TIbV formulated with bacteria prevent respiratory tract infections of viral cause, such as those associated with recurrent wheezing or asthma exacerbation, in children. Administration of these vaccines by the mucosal route may be important for their outcome in respiratory infections.

SUMMARY

Mucosal bacterial immunotherapy, including certain TIbV, confer protection against a broad spectrum of pathogens, such as viruses, through a mechanism mediated by trained immunity. Clinical studies on the use of these preparations against recurrent wheezing reflect these mechanistic effects. These findings open a new avenue for the development of new strategies for this condition.

Prevalence and temporal evolution of asthma symptoms in Spain. Global Asthma Network (GAN) study

INTRODUCTION

The temporal evolution of the prevalence of asthma described in the ISAAC (International Study of Asthma and Allergies in Childhood) in 2002 is unknown, or if the geographical or age differences are maintained in Spain.

OBJECTIVE

To describe the prevalence of asthma symptoms in different Spanish geographic areas and compare it with that of those centers that participated in the ISAAC.

METHODS

Cross-sectional study of asthma prevalence, carried out in 2016-2019 with 19,943 adolescents aged 13-14 years and 17,215 schoolchildren aged 6-7 years from 6 Spanish geographical areas (Cartagena, Bilbao, Cantabria, La Coruña, Pamplona and Salamanca). Asthma symptoms were collected using a written questionnaire and video questionnaire according to the Global Asthma Network (GAN) protocol.

RESULTS

The prevalence of recent wheezing (last 12 months) was 15.3% at 13-14 years and 10.4% at 6-7 years, with variations in adolescents, from 19% in Bilbao to 10.2% in Cartagena; and in schoolchildren, from 11.7% in Cartagena to 7% in Pamplona. These prevalences were higher than those of the ISAAC (10.6% in adolescents and 9.9% in schoolchildren). 21.3% of adolescents and 12.4% of schoolchildren reported asthma at some time.

CONCLUSIONS

There is a high prevalence of asthmatic symptoms with an increase in adolescents and a stabilization in Spanish schoolchildren with respect to the ISAAC. Geographic variations in asthma prevalence are not so clearly appreciated, but areas with high prevalences maintain high numbers.

BCG Vaccination in Early Childhood and Risk of Atopic Disease: A Systematic Review and Meta-Analysis

Background

Several large-scale studies suggest that Bacille Calmette–Guerin (BCG) vaccination in early childhood may reduce the risk of atopic diseases, but the findings remain controversial. Here, we aimed to investigate the potential correlation between early childhood BCG vaccination and the risk of developing atopic diseases.

Methods

Eligible studies published on PubMed, EMBASE, and Cochrane CENTRAL were systematically sourced from 1950 to July 2021. Studies with over 100 participants and focusing on the association between BCG vaccine and atopic diseases including eczema, asthma, and rhinitis were included. Preliminary assessment of methods, interventions, outcomes, and study quality was performed by two independent investigators. Odds ratio (OR) with 95% confidence interval (CI) was calculated. Random effects of the meta-analysis were performed to define pooled estimates of the effects.

Results

Twenty studies with a total of 222,928 participants were selected. The quantitative analysis revealed that administering BCG vaccine in early childhood reduced the risk of developing asthma significantly (OR 0.77, 95% CI 0.63 to 0.93), indicating a protective efficacy of 23% against asthma development among vaccinated children. However, early administration of BCG vaccine did not significantly reduce the risk of developing eczema (OR 0.94, 95% CI 0.76 to 1.16) and rhinitis (OR 0.99, 95% CI 0.81 to 1.21). Further analysis revealed that the effect of BCG vaccination on asthma prevalence was significant especially in developed countries (OR 0.73, 95% CI 0.58 to 0.92).

Conclusion

BCG vaccination in early childhood is associated with reduced risk of atopic disease, especially in developed countries.

BCG for the prevention and treatment of allergic asthma

Allergic diseases, in particular atopic asthma, have been on the rise in most industrialized countries for several decades now. Allergic asthma is characterized by airway narrowing, bronchial hyperresponsiveness, excessive airway mucus production, eosinophil influx in the lungs and an imbalance of the Th1/Th2 responses, including elevated IgE levels. Most available interventions provide only short-term relief from disease symptoms and do not alter the underlying immune imbalance. A number of studies, mostly in mouse models, have shown that Mycobacterium bovis bacillus Calmette-Guérin (BCG) treatment is capable of preventing or reducing an established allergen-driven inflammatory response, by redirecting pathogenic Th2 towards protective Th1 and/or regulatory T cell responses. Dendritic cells stimulated by BCG appear to be a crucial first step in the immunomodulatory effects of BCG. While the protective and therapeutic effects of BCG against allergy and asthma are well documented in animal models, they are less clear in humans, both in observational studies and in randomized controlled trials. The purpose of this article is to provide an up-to-date overview of the available evidence on the anti-allergy, in particular anti-asthma effects of BCG in mice, rats and humans.

Vaccines do not cause atopic dermatitis: A systematic review and meta-analysis

BACKGROUND

Previous studies found conflicting results about the association of vaccinations and likelihood of atopic dermatitis (AD).

OBJECTIVES

To determine whether vaccinations increase the likelihood of AD.

METHODS

A systematic review was performed of all published studies in MEDLINE, EMBASE, LILACS, Scopus, and Web of Science databases. At least 2 reviewers conducted title/abstract, full-text review, and data extraction. Quality of evidence was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Forty-four studies met inclusion criteria; 37 had sufficient data for meta-analysis. There were no associations any vaccine regimen (random-effects logistic regression: odds ratio [95% confidence interval]: 0.961 [0.822-1.124]; n = 21 studies) BCG (0.927 [0.701-1.226]; n = 8), pertussis (0.790 [0.416-1.499]; n = 4), single (1.031 [0.920-1.155]; n = 17) or multiple vaccines (0.902 [0.608-1.338]; n = 7) with likelihood of AD. This remained true in studies with high-quality (NOS ≥ 7) (OR [95% CI]: 0.941 [0.793-1.117]; n = 13 studies) or low-quality (NOS < 7) (OR [95% CI]: 1.058 [0.669-1.674]; n = 8 studies).

LIMITATIONS

No randomized controlled trials.

CONCLUSIONS

No vaccine regimen was consistently associated with developing AD.

Mycobacterium-Induced Th1, Helminths-Induced Th2 Cells and the Potential Vaccine Candidates for Allergic Asthma: Imitation of Natural Infection

Bronchial asthma is one of the most chronic pulmonary diseases and major public health problems. In general, asthma prevails in developed countries than developing countries, and its prevalence is increasing in the latter. For instance, the hygiene hypothesis demonstrated that this phenomenon resulted from higher household hygienic standards that decreased the chances of infections, which would subsequently increase the occurrence of allergy. In this review, we attempted to integrate our knowledge with the hygiene hypothesis into beneficial preventive approaches for allergic asthma. Therefore, we highlighted the studies that investigated the correlation between allergic asthma and the two different types of infections that induce the two major antagonizing arms of T cells. This elucidation reflects the association between various types of natural infections and the immune system, which is predicted to support the main objective of the current research on investigating of the benefits of natural infections, regardless their immune pathways for the prevention of allergic asthma. We demonstrated that natural infection with Mycobacterium tuberculosis (Mtb) prevents the development of allergic asthma, thus Bacille Calmette-Guérin (BCG) vaccine is suggested at early age to mediate the same prevention particularly with increasing its efficiency through genetic engineering-based modifications. Likewise, natural helminth infections might inhabit the allergic asthma development. Therefore, helminth-derived proteins at early age are good candidates for designing vaccines for allergic asthma and it requires further investigation. Finally, we recommend imitation of natural infections as a general strategy for preventing allergic asthma that increased dramatically over the past decades.

Pediatric allergic diseases in the Indian subcontinent-Epidemiology, risk factors and current challenges

INTRODUCTION

India is low-middle-income country (LMIC) with a population of 1.3bn, comprising about 20% of the global population. While the high-income Western countries faced an "allergy epidemic" during the last three decades, there has been a gradual rise in prevalence of allergic diseases in India.

METHODS

Narrative review.

RESULTS AND DISCUSSION

Allergic diseases occur as a consequence of a complex interplay between genetic and environmental factors. There are multiple contrasting determinants that are important to consider in India including high levels of air pollution, in particular PM_2.5 due to burning of fossil fuels and biomass fuels, diverse aero-biology, tropical climate, cultural and social diversity, religious beliefs/myths, linguistic diversity, literacy level, breastfeeding and weaning, diet (large proportion vegetarian), and high incidence rates of TB, HIV, malaria, filariasis, parasitic infestations, and others, that not only shape the immune system early in life, but also impact on biomarkers relevant to allergic diseases. India has a relatively weak and heterogeneous healthcare framework, and allergology has not yet been recognized as an independent specialty. There are very few post-graduate training programs, and allergic diseases are managed by primary care physicians, organ-based specialists, and general pediatricians. Adrenaline auto-injectors are not available, there is patient unaffordability for inhalers, nasal sprays, and biologics, and this is compounded by poor compliance leading to 40%-50% of asthmatic children having uncontrolled disease and high rates of oral corticosteroid use. Standardized allergen extracts are not available for skin tests and desensitization. This article provides a critical analysis of pediatric allergic diseases in India.

Association Between Bacillus Calmette-Guérin Vaccination and Childhood Asthma in the Quebec Birth Cohort on Immunity and Health

We estimated the association between bacillus Calmette-Guérin (BCG) vaccination and childhood asthma in a birth cohort using administrative databases, and we determined the impact of adjusting for potential confounders collected from a subset of the cohort members. Data were collected in 2 waves: 1) Administrative data for 76,623 individuals (stage 1) was gathered from the Quebec Birth Cohort on Immunity and Health (1974-1994), including BCG vaccination status, perinatal and sociodemographic characteristics, and use of health services for asthma; and 2) self-reported asthma risk factors were collected in 2012 by telephone interviews with 1,643 participants (stage 2) using a balanced 2-stage sampling design. We estimated odds ratios and 95% confidence intervals for asthma using logistic regression and correcting for the known sampling fractions from stage 1 to stage 2, overall and sex-stratified. In total, 35,612 (46.5%) individuals were BCG vaccinated, and 5,870 (7.7%) had asthma. The final odds ratio, integrating results from both stages of sampling, was 0.95 (95% confidence interval: 0.87, 1.04). Results did not differ according to sex (P for interaction = 0.327). To our knowledge, this is the largest study ever conducted on this topic, and using the best possible comprehensive adjustment for confounders, we found no association between BCG vaccination and asthma.

Sex-Related Allergic Rhinitis Prevalence Switch from Childhood to Adulthood: A Systematic Review and Meta-Analysis

BACKGROUND

A sex-related switch in the prevalence of asthma from childhood (male predominance) to adulthood (female predominance) has been described, but for allergic rhinitis this remains unclear. We aimed to examine sex- and age-group-specific differences in allergic rhinitis prevalence by systematically evaluating studies from across the globe.

METHODS

A systematic search of MEDLINE and Embase for population-based cross-sectional studies was performed regardless of the language of publication. The search was restricted to the present millennium (2000 to June 2014). Study quality was defined by the sampling method, response rate, sample size, and data collection method. To assess sex differences in the prevalence of self- or parent-reported symptoms of rhinitis, calculated pooled estimates of the male-female ratio (MFR) were obtained using random-effects model meta-analyses due to heterogeneity. A meta-regression analysis was also performed.

RESULTS

Out of 6,539 publications identified, 67 cross-sectional population-based studies (291,726 males and 301,781 females) were included in our meta-analysis. In children (<11 years of age) significantly more boys than girls had rhinitis symptoms (MFR 1.21, 95% CI 1.17-1.25), whereas in adolescents (11 to <18 years of age) males were significantly less often affected than females (MFR 0.90, 95% CI 0.85-0.95). No sex-specific prevalence difference was observed in adults (MFR 0.96, 95% CI 0.83-1.17). These findings were consistent in all continents except in Asia, where the male predominance remained beyond childhood.

CONCLUSIONS

The male predominance of rhinitis prevalence in childhood changed towards a female predominance in adolescence across the globe, except in Asia. Longitudinal studies are needed to confirm these cross-sectional data and examine possible determinants and underlying mechanisms.

Does BCG vaccination protect against childhood asthma? Final results from the Manchester Community Asthma Study retrospective cohort study and updated systematic review and meta-analysis

BACKGROUND

The Manchester Community Asthma Study (MANCAS) found a protective effect against the risk of wheeze at age 6 to 11 years for children given neonatal BCG vaccination. Our subsequent systematic review and meta-analysis suggested that BCG vaccination did not protect against allergic sensitization but might have exerted a protective effect against nonatopic asthma.

OBJECTIVES

We sought to assess whether the protective effect of BCG vaccination on wheeze observed in the MANCAS cohort was maintained at age 13 to 17 years and to incorporate the findings from this final MANCAS analysis into an updated systematic review and meta-analysis.

METHODS

BCG vaccination status was determined from health records and respiratory outcomes from questionnaire responses. We updated the systematic review and used fixed-effects and random-effects modeling to undertake meta-analyses.

RESULTS

There were 1608 participants in the final MANCAS analysis. The 12-month prevalence of wheeze was 15.1%. There was no difference in prevalence between those who were and were not BCG vaccinated (15.8% vs 14.3%; relative risk, 1.05; 95% CI, 0.94-1.19). The updated meta-analysis incorporated 4 new studies: this showed that the protective effect of BCG vaccination against the development of asthma identified in our previous meta-analysis was attenuated (odds ratio, 0.95; 95% CI, 0.89-1.00). No protective effect of BCG was seen for sensitization, eczema/atopic dermatitis, rhinoconjunctivitis, or allergy in general.

CONCLUSIONS

Taken together, the final results of the MANCAS cohort and the updated systematic review and meta-analysis provide clearer evidence that any protective effect of BCG vaccination on childhood asthma is likely to be transient.

The 'Hygiene hypothesis' and the sharp gradient in the incidence of autoimmune and allergic diseases between Russian Karelia and Finland

Autoimmune and allergic diseases have become a major health problem in the Western world during past decades. The hygiene hypothesis suggests that decreased microbial exposure in childhood leads to increasing prevalence of these diseases. This review summarizes epidemiological evidence and current immunological knowledge concerning the hygiene hypothesis. Recent results from Russian Karelia and Finland imply that environmental factors have greatly contributed to the increasing prevalence of immune-mediated disorders. Infections, or lack of them, may indeed be strongly involved in the development of both autoimmune and allergic diseases.

Engaging fathers in child protection services: A review of factors and strategies across ecological systems

Current policy regarding child protection services places increasing demands for providers to engage fathers whose children are involved in the child protection process. This requisite brings to the fore the ongoing challenges that fathers have historically faced in working within these systems. Despite this need, there is little empirical evidence regarding the factors and strategies that impact the engagement of fathers in interventions relevant to child protection services. This comprehensive and systemic review synthesizes the available literature regarding factors and strategies that may foster paternal involvement in the child protection system and their services. We organize the literature concerning paternal engagement in child and family services around an ecological model that examines paternal engagement from individual, family, service provider, program, community, and policy levels. We consider factors and strategies along a continuum of engagement through intent to enroll, enrollment, and retention. This review advances theory by elucidating key factors that foster father engagement. The review also highlights the gaps in the literature and provides strategies for how researchers can address these areas. Future directions in the arenas of practice and policy are discussed.

Tuberculosis, bacillus Calmette-Guérin vaccination, and allergic disease: findings from the International Study of Asthma and Allergies in Childhood Phase Two

Some have suggested a protective effect of tuberculosis (TB) infection on allergic disease risk, but few studies have examined the association between the two. We therefore investigated whether TB disease and bacillus Calmette-Guérin (BCG) vaccination in early life protect against allergic disease. Information on allergic disease symptoms, past TB disease, and BCG vaccination as well as potential confounding factors was gathered by parental questionnaire from a randomly selected subset of 23,901 8- to 12-yr-old schoolchildren in 20 centers in both developed and developing countries. Children were also physically examined for flexural eczema and underwent skin prick testing. Pooled odds ratio (OR) estimates and corresponding 95% confidence intervals (CIs) across study centers were calculated, using random effects meta-analysis models. There were 245 (1.0%) reported cases of TB disease, and 66.3% (15,857) of all children received the BCG vaccine. Asthma, hay fever, and flexural eczema symptoms in the past year as well as flexural eczema on skin examination were all positively linked to a history of TB (adjusted pooled OR 'wheeze in the past year' = 2.27, 95% CI 1.52-3.41; adjusted pooled OR 'hay fever symptoms in the past year' = 2.23, 1.22-4.09; adjusted pooled OR 'flexural eczema symptoms in the past year' = 3.21, 2.01-5.12; adjusted pooled OR 'flexural eczema on skin examination' = 4.04, 1.71-9.56). Even higher risk estimates were seen for severe asthma and eczema symptoms [adjusted OR = 4.02 (2.17-7.47) and adjusted OR = 6.31 (2.19-18.17), respectively]. There was no significant association between past TB and skin prick test positivity (adjusted pooled OR = 1.32, 0.87-2.02). BCG vaccination during the first year of life was also not associated with any of the allergy outcomes. We found a uniform positive association between TB and all allergic disease outcomes, including eczema on skin examination. As this was a cross-sectional study, it is unclear whether this positive association is attributable to a causal relationship, and further longitudinal studies are required.

BCG vaccination and allergy: a systematic review and meta-analysis

BACKGROUND

There is conflicting evidence on whether BCG vaccination might represent an effective primary preventative strategy against the development of allergic sensitization and disease.

OBJECTIVES

We sought to systematically review the relationship between BCG vaccination and the risk of sensitization, eczema/atopic dermatitis, allergic rhinoconjunctivitis, asthma, and other allergic conditions, such as food allergy and anaphylaxis.

METHODS

Four international databases were searched for published epidemiologic or interventional studies. Additional online study databases were searched and vaccine manufacturers and a panel of international experts were contacted in an attempt to locate unpublished or ongoing studies. Quality assessment was undertaken by using internationally established criteria. Meta-analyses were undertaken by using fixed- or random-effects modeling. Funnel plots were used to assess for the risk of publication bias.

RESULTS

We identified 767 articles, of which 17 satisfied our inclusion criteria; there was only 1 randomized controlled trial, with the remaining studies being epidemiologic investigations. Meta-analyses did not show any protective effect of vaccination against the risk of sensitization, as judged by specific IgE tests (odds ratio [OR], 1.31; 95% CI, 1.07-1.60) or skin prick testing (OR, 0.87; 95% CI, 0.67-1.13); the risk of atopic eczema/dermatitis (OR, 0.84; 95% CI, 0.64-1.09); or the risk of allergic rhinoconjunctivitis (OR, 1.07; 95% CI, 0.89-1.28). BCG vaccination was associated with a protective effect against the risk of asthma (OR, 0.73; 95% CI, 0.56-0.95), although this might be explained by publication bias.

CONCLUSIONS

BCG vaccination is unlikely to be associated with protection against the risk of allergic sensitization and disease. The observed possible benefit in relation to the development of asthma is unlikely to be due to allergic sensitization.

Asthma prevalence and exacerbations in children: is there an association with childhood vaccination?

Infections and vaccinations may have a potential role in the normal maturation of the immune system, in the development and balance of regulatory pathways, and in the development and exacerbations of asthma. Asthma exacerbations often result from respiratory viral infections, and, while vaccination towards common viral infections may reduce the occurrence of such exacerbations, there has been concern that vaccinations can increase the risk of asthma. Current studies show that childhood vaccines, including inactivated influenza vaccine, are generally safe. However, there is some concern regarding possible exacerbations in infants or children with frequent wheezing or persistent asthma who are given live-attenuated influenza vaccination. Although severe allergic adverse events attributable to vaccination are extremely rare, all serious allergic reactions should be further assessed to detect the likely causative vaccine component, such as egg protein or gelatin. The risks of not vaccinating children far outweigh the risks of allergy and asthma exacerbations. Therefore, childhood vaccination should remain an essential part of child health programs and should not be withheld, even from children with asthma or those predisposed to allergy.

Does BCG vaccination protect against the development of childhood asthma? A systematic review and meta-analysis of epidemiological studies

BACKGROUND

Results have been conflicting as to whether Bacillus Calmette-Guérin (BCG) vaccine, a non-specific stimulator of the immune function, protects, predisposes or is unrelated to the development of childhood asthma. In this systematic review and meta-analysis, we qualitatively and quantitatively appraised the epidemiological evidence.

METHODS

Eligible studies were identified using a search strategy that included a computerized literature search and a manual search of each article's reference list, up to June 2008. A total of 23 studies were included (10 cohort, 5 case-control and 8 cross-sectional). Each study was summarized and rated for methodological quality. Pooled odds ratio (OR) estimates and 95% confidence intervals (CIs) were calculated using fixed-effects (FE) or random-effects (RE) models; if heterogeneity was present, the latter was used. Three indicators of BCG exposure were considered including BCG vaccination, tuberculin response and scar diameter.

RESULTS

The pooled estimate of association for 23 studies reporting on any of the three indicators suggested a protective effect of BCG exposure on childhood asthma occurrence. The studies were heterogeneous, especially when tuberculin response was considered. Restriction to a subgroup of 16 studies that considered BCG vaccination indicated a protective effect with no evidence of heterogeneity. The overall pooled OR using an FE model was 0.86 (95% CI 0.79-0.93). Exclusion of three studies with the lowest quality scores showed a similar association.

CONCLUSION

These results strengthen the epidemiological evidence in support of the hypothesis that exposure to the BCG vaccine in early life prevents asthma, possibly through a modulation of the immune maturation process.

Climate and prevalence of atopic eczema in 6- to 7-year-old school children in Spain. ISAAC phase III

Atopic eczema (AE) is a chronic skin disease. Recent reports indicate that the worldwide prevalence of AE is increasing and that various environmental factors are implicated in its aetiology. Climatic conditions have been related with AE prevalence, and Spain has varying climatic conditions. The aim of this study is to document the possible climatic influence on the prevalence of AE in schoolchildren aged 6-7 years in three different climatic regions in Spain. We conducted a cross-sectional population-based survey of 28,394 schoolchildren aged 6-7 years from 10 Spanish centres in three different climatic regions. The mean participation rate was 76.5%. AE prevalence was assessed using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and the Spanish Academy of Dermatology criteria used in Spain to diagnose AE. The data, including annual temperature, precipitation, relative humidity and the annual number of sunny hours per climatic region, were obtained from the Spanish National Institute of Meteorology. Different AE prevalences were found in all three climatic regions studied: Atlantic, 32.9; Mediterranean 28.3; and Continental 31.2 per 100 children studied (p < 0.005). AE was positively associated with precipitation and humidity, and was negatively associated with temperature and the number of sunny hours. The results show that AE is significantly dependent on meteorological conditions.

Mycobacterium bovis Bacillus Calmette-Guérin suppresses inflammatory Th2 responses by inducing functional alteration of TSLP-activated dendritic cells

Allergic diseases such as atopic dermatitis and asthma develop as a consequence of dysregulated T(h)2 responses. Recently, it has been demonstrated that interaction between dendritic cells (DCs) and thymic stromal lymphopoietin (TSLP), an IL-7-like cytokine, is essential for evoking T(h)2 responses in allergy. In this study, we investigated whether Mycobacterium bovis Bacillus Calmette-Guérin (BCG), a strong T(h)1 response-inducing adjuvant, can alter the function of DCs activated by TSLP (TSLP-DCs). We demonstrated that BCG redirects TSLP-DCs away from inducing inflammatory T(h)2 cells that produce IL-4, IL-5, IL-13 and tumor necrosis factor (TNF)-alpha and toward regulatory T(h)1 cells that produce IFN-gamma and IL-10. We also demonstrated that this functional alteration of TSLP-DCs by BCG depended on both production of IL-12 from DCs and down-regulation of OX40 ligand, a member of the TNF family, on DCs. These findings suggest that BCG might be a useful adjuvant for the treatment of allergic diseases that are triggered by TSLP.

Potential health effects from non-specific stimulation of the immune function in early age: the example of BCG vaccination

There is increasing, but still inconsistent evidence that vaccinations and childhood infections may play a role in the normal maturation of the immune system, and in the development and balance of immune regulatory pathways, both of which might impact health later in life. This review covers the epidemiological evidence regarding the role of Bacillus Calmette-Guérin (BCG) vaccination on the following inflammatory or autoimmune diseases: asthma and allergic diseases, Crohn's disease (CD), insulin-dependent diabetes mellitus (IDDM), and specific cancers. The literature is more comprehensive for asthma and allergic diseases, with 16 studies reporting the absence of an association while seven rather suggest a protective effect of BCG. We found insufficient evidence on CD to conclude at this point. Overall, the evidence for IDDM based on four studies leans towards no association, although some effects were observed in population subsets. Five epidemiological investigations provide evidence on a possible link with cancer incidence or mortality at various sites, with indications of both increased and decreased risks. Given the potential public health implications, it is imperative to acquire a better understanding of how BCG vaccination could influence the development of such chronic health conditions in the population.

Long term prognosis in preschool children with wheeze: longitudinal postal questionnaire study 1993-2004

OBJECTIVES

To follow a population of preschool children with and without parent reported wheeze over a period of 6-11 years to determine prognosis and its important predictive factors.

DESIGN

Longitudinal series of five postal surveys based on the international study of asthma and allergies in childhood questionnaire carried out between 1993 and 2004.

SETTING

Two general practice populations, south Manchester.

PARTICIPANTS

628 children aged less than 5 years at recruitment and those with at least six years' follow-up data.

MAIN OUTCOME MEASURES

Parent completed questionnaire data for respiratory symptoms and associated features.

RESULTS

Of 628 children included in the study, 201 (32%) had parent reported wheeze at the first observation (baseline), of whom 27% also reported the symptom on the second occasion (persistent asthma). The only important baseline predictors of persistent asthma were exercise induced wheeze (odds ratio 3.94, 95% confidence interval 1.72 to 9.00) and a history of atopic disorders (4.44, 1.94 to 10.13). The presence of both predictors indicated a likelihood of 53.2% of developing asthma; if only one feature was present this decreased to 17.2%, whereas if neither was present the likelihood was 10.9%. Family history of asthma was not predictive of persistent asthma among children with preschool wheeze.

CONCLUSION

Using two simple predictive factors (baseline parent reported exercise induced wheeze and a history of atopic disorders), it is possible to estimate the likelihood of future asthma in children presenting with preschool wheeze. The absence of baseline exercise induced wheeze and a history of atopic disorders reduces the likelihood of subsequent asthma by a factor of five.

Common characteristics of upper and lower airways in rhinitis and asthma: ARIA update, in collaboration with GA(2)LEN

This update aimed to review the new evidence available to support or refute prior Allergic Rhinitis and its Impact on Asthma (ARIA) statements. A Medline search of publications between 2000 and 2005 was conducted, with articles selected by experts. New evidence supports previous ARIA statements, such as: (i) allergic rhinitis (AR) is a risk factor for asthma; (ii) patients with persistent rhinitis should be evaluated for asthma; (iii) most patients with asthma have rhinitis; (iv) a combined strategy should be used to treat the airways and (v) in low- to middle-income countries, a different strategy may be needed. The increased risk of asthma has also been found among sufferers from non-AR. Recent reports show AR is a global problem. Many studies demonstrated parallel increasing prevalence of asthma and rhinitis, but in regions of highest prevalence, it may be reaching a plateau. Factors associated with a reduced risk of asthma and AR have been identified, confirming previous findings of protection related to exposure to infections. Treatment of rhinitis with intranasal glucocorticosteroids, antihistamines, leukotriene antagonists or immunotherapy may reduce morbidity because of asthma. To take advantage of the paradigm of unified airways, there is a need to rationalize diagnosis and treatment to optimize management.

Tuberculin reactivity and allergic disorders in schoolchildren, Okinawa, Japan

BACKGROUND

Bacillus Calmette-Guérin (BCG) vaccination triggers a T-helper type 1 response. Whether BCG vaccination and positive tuberculin reactivity are preventive against allergic disorders remains controversial.

OBJECTIVE

The current cross-sectional study investigated the relationship of BCG vaccination and tuberculin reactivity with the prevalence of allergic disorders using data from the Ryukyus Child Health Study (RYUCHS).

METHODS

Subjects were 5717 schoolchildren aged 8-11 years in Okinawa, Japan. The RYUCHS collected information on symptoms of allergic disorders and potential confounding factors. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Data on BCG vaccination and tuberculin tests were obtained from school records. Allowance was made for grade, sex, sibship size, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level.

RESULTS

No measurable relationship was found between BCG vaccination in infants and the prevalence of allergic disorders. Among 5567 BCG-vaccinated children, positive tuberculin reactivity (induration >/=10 mm) in the first grade was independently associated with a decreased prevalence of wheeze, asthma, and atopic eczema: the multivariate odds ratios for wheeze, asthma, and atopic eczema were 0.80 (95% confidence interval [CI], 0.67-0.94), 0.78 (95% CI, 0.64-0.95), and 0.77 (95% CI, 0.62-0.95), respectively. The inverse associations were more pronounced in children with a negative parental allergic history than in those with a positive parental allergic history. There was no significant relationship between tuberculin reactivity and allergic rhinoconjunctivitis.

CONCLUSIONS

The findings suggest that positive tuberculin reactivity may be inversely associated with the prevalence of wheeze, asthma, and atopic eczema, but not allergic rhinoconjunctivitis, especially among Japanese children without a parental allergic history.

Is childhood vaccination associated with asthma? A meta-analysis of observational studies

BACKGROUND

The possible link between immunization and atopic diseases has been under intense debate in the last decade.

OBJECTIVE

The aim of this study was to systematically review the available evidence on the association of whole-cell pertussis and BCG vaccination with the risk of asthma in childhood and adolescence.

METHODS

The major medical electronic databases (Medline, National Library of Medicine Gateway, and Cochrane Library) were searched, and reference lists of the relevant publications were reviewed for relevant birth-cohort studies and randomized, controlled trials from 1966 to March 2006. Only studies that directly compared vaccinated and unvaccinated children, validated vaccination status by medical charts, and used preset criteria to define asthma were included. Data were abstracted by using a standardized protocol and computerized report form. Results were analyzed by applying a fixed-effect or random-effect model, according to the heterogeneity of the studies. Sensitivity analyses by scoring criteria were performed.

RESULTS

Seven studies of pertussis vaccination (with a total of 186,663 patients) and 5 studies of BCG vaccination (with a total of 41,479 patients) met our inclusion criteria. No statistically significant association was detected between either whole-cell pertussis or BCG vaccination and incidence rates of asthma during childhood and adolescence. This lack of a significant association proved to be robust on sensitivity analyses for BCG but not for pertussis vaccine.

CONCLUSIONS

Currently available data, based on observational studies, do not support an association, provocative or protective, between receipt of the BCG or whole-cell pertussis vaccine and risk of asthma in childhood and adolescence.

Rhinoconjunctivitis in 5-year-old children: a population-based birth cohort study

BACKGROUND

There is a paucity of data on the prevalence, risk factors and natural history of rhinitis in early childhood.

OBJECTIVE

Within the context of a whole-population birth cohort we investigated the prevalence of and risk factors for current rhinoconjunctivitis (CRC) at age 5 years.

METHODS

Children were followed prospectively to age 5 years [questionnaires (n = 815), skin testing (n = 717), specific immunoglobulin E (n = 478), lung function (n = 711), dry air challenge (n = 556)]. Endotoxin and allergen exposures were measured in dust samples.

RESULTS

The prevalence of rhinitis ever, current rhinitis and rhinoconjunctivitis was 28.2%, 26.1%, and 12.1%, respectively. Asthma, wheeze and eczema coexisted with CRC (P < or = 0.01). In a multivariate model, maternal asthma (OR 2.38, 95% CI: 1.30-4.38, P = 0.005), paternal hay fever (1.96, 1.11-3.46, P = 0.02) and sensitization to grass (3.46, 1.86-6.42, P < 0.001) and cat (2.42, 1.14-5.18, P = 0.02) remained significant and independent associates of CRC. Whilst almost half of children with CRC were nonatopic, there was little difference in risk factors between atopic and nonatopic CRC. Amongst children with current wheeze, the presence of concurrent CRC had no effect on either severity or frequency of wheezy episodes. There was no difference in specific airway resistance, forced expiratory volume in 1 second (FEV(1)) or airway reactivity between children with and without CRC after adjustment for the presence of wheeze.

CONCLUSION

Family history of allergic disease and sensitization to inhalant allergens are risk factors for rhinoconjunctivitis in preschool children. In this age group, there is no association between the presence of rhinoconjunctivitis and severity of wheeze, increased airway reactivity and reduced lung function.

Is the prevalence of wheeze in children altered by neonatal BCG vaccination?

BACKGROUND

The prevalence of asthma and atopic disease has increased in recent decades, but precise reasons for this increase are unknown. BCG vaccination is thought to be among a group of vaccines capable of manipulating the immune system toward T(H)1 dominance and therefore reducing the likelihood of atopic disease.

OBJECTIVE

The aim of this study was to determine the influence of neonatal BCG vaccination on the prevalence of wheeze in a large community population of children.

METHOD

In a historical cohort study, a parent-completed questionnaire was used to identify the prevalence of wheeze in BCG-vaccinated and nonvaccinated children in Manchester, England.

RESULTS

There were 2414 participants aged between 6 and 11 years. In a univariate analysis neonatal BCG vaccination was associated with a significantly lower prevalence of wheeze (odds ratio, 0.69; 95% CI, 0.55-0.86), and statistical significance was retained when the analysis was adjusted for potential confounders (odds ratio, 0.68; 95% CI, 0.53-0.87).

CONCLUSION

These results demonstrate an association between asthma symptom prevalence and neonatal BCG vaccination, relating to a possible 27% reduction in prevalence, and are therefore of considerable public health importance.

CLINICAL IMPLICATIONS

The capacity of neonatal BCG vaccination to reduce the prevalence of respiratory symptoms in children warrants further investigation.

Early BCG and pertussis vaccination and atopic diseases in 5- to 7-year-old preschool children from Augsburg, Germany: results from the MIRIAM study

The role of immunization in the development of atopic disorders is still under debate. One reason might be, that because of high vaccination coverage in most countries only few and selected children are not immunized, leading to unstable and often biased effect estimates. In Germany, the situation was different between 1985 and 1991: bacillus Calmette-Guérin (BCG) and pertussis vaccination were not officially recommended leading to high numbers of non-vaccinated children in the 1990s. We report on a cross-sectional study with 1673 participants among 5- to 7-year-old preschool children conducted in 1996. We found no hint that BCG vaccination or whole-cell pertussis (WCP) vaccination may lead to higher prevalences of asthma, allergic rhinitis, eczema or allergic sensitization at preschool age. None of the associations was significantly positive. WCP vaccination may be protective against asthma OR 0.55 (95% CI: 0.31-0.98) and against symptoms of eczema in boys.

Do vaccines modify the prevalence of asthma and allergies?

Epidemiological studies suggest the hypothesis that the increase in asthma and allergies in the industrialized world can be explained by a decline in the number of infectious diseases occurring during childhood. In the context of this 'hygiene hypothesis', is immunization in early life a risk factor for promoting allergic diseases? The majority of studies, especially those conducted with more extensive populations, have not found an increased risk, and although 'not finding an increased risk' is not the same as 'the non-existence of any risk at all', it seems that the evidence is tipped in favor of the absence of risk. Conversely, although some surveys have described a protective effect of vaccination, the majority refuted this result. If there is any effect, it is probably a weak one.

Toll-like receptor ligands and atopy: a coin with at least two sides

Allergic disease prevalence rates have increased dramatically in affluent countries over the last half century. One proposed explanation is that decreased exposures to microbes caused by modern public health practices has led to deficiencies in an important source of immune education and a consequent increase in the risk of pathogenic immune responses to environmental antigens. Recently, it has become clear that innate responses to microbes are mediated in large part by Toll-like receptors (TLRs), which recognize a diverse family of ligands produced by viruses, bacteria, and fungi. In this perspectives article we will review experimental evidence suggesting that TLRs also play a dominant role in innate responses to noninfectious immunostimulatory materials present in environments of daily living. We will further discuss how ligands for different TLRs can polarize the T(H) bias of adaptive responses in opposing directions. Finally, we will consider how TLRs might contribute to the genesis of atopy and the clinical potential of pharmacologic interventions that target TLRs for the prevention and treatment of allergic diseases.

[Current prevalence of asthma in schoolchildren in San Sebastián (Spain)]

OBJECTIVE

To determine the current prevalence of asthma in children aged 6-12 years old in San Sebastian (Guipuzcoa, Spain).

PATIENTS AND METHODS

An observational, cross sectional study was performed in 6-12-year-old children in schools. The International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was employed. Bronchial hyperresponsiveness was investigated using the free running test, with peak expiratory flow (PEF) measured with a peak flow meter as the main measurement. The ISAAC questionnaire (n = 919) was distributed to 460 boys (50.1%) and 459 girls (49.9%) with a mean age of 8 years (SD 1.87). The response rate to the questionnaire was 93 % (n = 855). Participation in the free running test was 90.8% (n = 835). A total of 89.88% of the children (n = 826) completed both tests.

RESULTS

The questionnaire of symptoms and signs compatible with asthma revealed a current prevalence of asthma of 25.56% (n = 216) and a cumulative prevalence of 25.44% (n = 85). Nocturnal asthma was found in 29.37% (n = 47) and severe asthma in 9.27% (n = 14). Bronchial hyperresponsiveness was found in 23% of the participants. An epidemiological diagnosis of asthma (asthma-related symptoms plus bronchial hyperresponsiveness) was made in 6.54%.

CONCLUSIONS

The current prevalence of asthma in 6-12-year-old schoolchildren in San Sebastian, determined through symptoms and signs compatible with asthma in the previous year and a positive free running test, is similar to that reported in other national studies.