Asthma and allergy in Albania and the UK

The role of Human Development Index in the epidemiology of asthma in adolescents in Kosovo: A cross-sectional multicentre Global Asthma Network (GAN) study

BACKGROUND

Very limited information is available on the prevalence and risk factors of asthma in adolescents in Kosovo, and no study has previously addressed the role of Human Development Index (HDI) on asthma in the region. The present study addresses these two issues.

METHODS

Following the Global Asthma Network (GAN) methodology, a cross-sectional survey, through standardised self-completed questionnaires, was conducted in the following six centres of Kosovo: Ferizaj, Gjakova, Gjilan, Peja, Prishtina and Prizren. Current asthma symptoms (CAS) and severe current asthma symptoms (sCAS) were defined according to the GAN standards. Environmental questionnaire inquired about gender, exercise, screening time, siblings, truck traffic, use of paracetamol, pet ownership, and smoking habits. Height and weight were also measured. Multivariate logistic regression analyses were performed in each centre along with meta-analyses to summarise the overall effects of each factor in the centres as a whole. Meta-regression of the prevalence rates was calculated using HDI as a moderator.

RESULTS

Participation rate was high (80.0-99.9%). Prevalence of CAS ranged from 4.6% to 11.3%, and sCAS from 1.7% to 4.5%. Factors associated with CAS were exercise, computer time, paracetamol use and dog ownership. sCAS was associated with paracetamol use and physical exercise. HDI explained 46% and 80% of prevalence variability of CAS and sCAS between centres, respectively.

CONCLUSIONS

Prevalence of CAS and sCAS in Kosovo varies highly between centres. This variability is explained partly by HDI. Individual risk factors are common, with some determined in other studies conducted in other regions.

Epidemiology and direct costs of atopic dermatitis in Poland based on the National Health Fund register (2008-2017)

Introduction

Epidemiological data indicate significant differences in atopic dermatitis (AD) prevalence between countries.

Aim

The purpose of this study is to (i) analyse the recorded prevalence of atopic dermatitis (diagnoses of AD reported to the Polish National Health Fund (NHF)) and to (ii) estimate direct costs of medical care for AD incurred by the NHF.

Material and methods

The analysis was based on data reported to the database of the public payer (NHF). The prevalence rates were calculated using the NHF data and population estimates were obtained from the Central Statistical Office of Poland (GUS).

Results

In 2017, the annual prevalence rate of AD in the Polish population was 32.5 per 10,000 inhabitants (34.7/10,000 for women and 30.1/10,000 for men). The highest prevalence was observed in the youngest age groups (300/10,000 in children up to 4 years of age and 141/10,000 in 5–9-year-olds). The prevalence rate decreased with age and AD was the least prevalent in patients over 85 years of age (4/10,000). In 2008–2017, NHF expenditure on AD treatment varied between PLN 19.9 million (EUR 5.6 million) in 2008 and PLN 28.4 million (EUR 6.5 million) in 2016.

Conclusions

The prevalence rates of AD in Poland estimated on the basis of NHF data are significantly lower than those reported in previous epidemiological studies conducted in Poland and worldwide. This may indicate that the prevalence of AD in the Polish population is underestimated or that there are no adequate disease control measures in patients with a confirmed diagnosis.

ERS technical standard on bronchial challenge testing: pathophysiology and methodology of indirect airway challenge testing

Recently, this international task force reported the general considerations for bronchial challenge testing and the performance of the methacholine challenge test, a "direct" airway challenge test. Here, the task force provides an updated description of the pathophysiology and the methods to conduct indirect challenge tests. Because indirect challenge tests trigger airway narrowing through the activation of endogenous pathways that are involved in asthma, indirect challenge tests tend to be specific for asthma and reveal much about the biology of asthma, but may be less sensitive than direct tests for the detection of airway hyperresponsiveness. We provide recommendations for the conduct and interpretation of hyperpnoea challenge tests such as dry air exercise challenge and eucapnic voluntary hyperpnoea that provide a single strong stimulus for airway narrowing. This technical standard expands the recommendations to additional indirect tests such as hypertonic saline, mannitol and adenosine challenge that are incremental tests, but still retain characteristics of other indirect challenges. Assessment of airway hyperresponsiveness, with direct and indirect tests, are valuable tools to understand and to monitor airway function and to characterise the underlying asthma phenotype to guide therapy. The tests should be interpreted within the context of the clinical features of asthma.

An international comparison of asthma, wheeze, and breathing medication use among children

BACKGROUND

There is variation in childhood asthma between countries with typically higher prevalence in "Westernized" nations. We compared asthma, respiratory symptoms, and medication prevalence in Eastern and Central European regions and Canada.

METHODS

We conducted a cross-sectional survey study of children (5-15 years) from one urban centre in each of Canada, Belarus, Poland, Republic of Georgia (Adjara), Republic of Macedonia, and Ukraine. Surveys were distributed through randomly selected schools to parents (2013-2015).

RESULTS

The prevalence of asthma differed by country from 20.6% in Canada to 1.5% in Ukraine (p < 0.001). This association remained after confounder adjustment. Except for Canada (58.7%) and Poland (42.5%), less than 10% of children with a history of wheeze had a diagnosis of asthma. Regardless of country, more than 50% of children with a diagnosis of asthma used breathing medications in the past year. Finally, except for Georgia (12.1%), all countries had a prevalence of ever wheeze above 20% (23.8% in Poland to 30.9% in Macedonia).

CONCLUSIONS

Despite large differences in asthma prevalence, respiratory morbidity was more comparable suggesting asthma prevalence may be underestimated. Further validation of asthma diagnosis is needed. It is important to promote best diagnostic practices among first contact physicians.

Bronchial hyperresponsiveness in childhood: A narrative review

Bronchial hyperresponsiveness (BHR) is an important but not asthma-specific characteristic and can be assessed by direct and indirect methods, based on the stimulus causing airway obstruction. BHR has been proposed as a prognostic marker of asthma severity and persistence, and may also be used to control pharmacological management of asthma. The most recent data on the prevalence and development of BHR in childhood and its predictive value for subsequent asthma development in late adolescence and adulthood is discussed in this review. According to the BHR-related scientific articles written in the English language and indexed in the publicly searchable PubMed database, the prevalence of BHR varies based upon the methods used to assess it and the population examined. In general, however, BHR prevalence is reduced as children grow older, in both healthy and asthmatic populations. While asthma can be predicted by BHR, the predictive value is limited. Reduced lung function, allergic sensitization, female sex, and early respiratory illness have been identified as risk factors for BHR. The collective studies further indicate that BHR is a dynamic feature related to asthma, but asymptomatic BHR is also common. Ultimately, the prevalence of BHR varies depending on the population, the environment, and the evaluation methods used. While both the methacholine challenge and the exercise test may predict asthma in adolescence or early adulthood, the predictive value is higher for the methacholine challenge compared to the exercise test. The collective data presented in the present study demonstrate how BHR develops through childhood and its relation to bronchial asthma.

Atopic dermatitis, asthma and allergic rhinitis in general practice and the open population: a systematic review

OBJECTIVE

To examine whether significant differences exist between the self-reported prevalence of atopic disorders in the open population compared with physician diagnosed prevalence of atopic disorders in general practice.

METHODS

Medline (OvidSP), PubMed Publisher, EMBASE, Google Scholar and the Cochrane Controlled Clinical Trials Register databases were systematically reviewed for articles providing data on the prevalence of asthma, allergic rhinitis and eczema in a GP setting. Studies were only included when they had a cross-sectional or cohort design and included more than 100 children (aged 0-18 years) in a general practice setting. All ISAAC studies (i.e. the open population) that geographically matched a study selected from the first search, were also included. A quality assessment was conducted. The primary outcome measures were prevalence of eczema, asthma and allergic rhinitis in children aged 0-18 years.

RESULTS

The overall quality of the included studies was good. The annual and lifetime prevalences of the atopic disorders varied greatly in both general practice and the open population. On average, the prevalence of atopic disorders was higher in the open population.

CONCLUSION

There are significant differences between the self-reported prevalence of atopic disorders in the open population compared with physician diagnosed prevalence of atopic disorders in general practice. Data obtained in the open population cannot simply be extrapolated to the general practice setting. This should be taken into account when considering a research topic or requirements for policy development. GPs should be aware of the possible misclassification of allergic disorders in their practice. Key Points Epidemiological data on atopic disorders in children can be obtained from various sources, each having its own advantages and limitations. On average, the prevalence of atopic disorders is higher in the open population. GPs should take into account the possible misclassification of atopic disorders in their practice population. Policymakers should be aware that data obtained in the open population cannot simply be extrapolated to the general practice setting.

Exercise-induced bronchospasm related to different phenotypes of rhinitis without asthma in primary schoolchildren: the French Six Cities Study

BACKGROUND

Exercise-induced bronchospasm (EIB) is frequent among asthmatic children. However, opinions differ on the relation between EIB and rhinitis in the absence of asthma.

OBJECTIVES

We assessed the relationship between EIB and various phenotypes of rhinitis according to asthmatic status at the general population level in the Six Cities Study.

METHODS

Of 7781 schoolchildren with a mean age of 10 years underwent an EIB test and skin prick test to assess allergic sensitization. Their parents completed a standardized questionnaire recording asthma-like symptoms and past-year rhinoconjunctivitis, ever hay fever (EHF), and a score for allergic rhinitis (SFAR) ≥7 as a marker of 'past-year allergic rhinitis'. Exercise-induced bronchospasm was defined as a fall in peak expiratory flow rate ≥15% after exercise.

RESULTS

Of the 6813 schoolchildren retained for analysis, 227 (3.33%) experienced EIB after exercise. Odds ratios [95% confidence intervals] between EIB and allergic rhinitis phenotypes in the absence of asthma were 1.56 [0.92-2.63] for EHF, 1.97 [1.16-3.35] for past-year rhinoconjunctivitis, and 1.84 [1.16-2.91] for a SFAR ≥7. Results were unchanged after adjustment for confounders. Multiple correspondence analysis showed that EIB, although related to asthma, constitutes a separate entity. Exercise-induced bronchospasm was not significantly related to familial history of asthma.

CONCLUSION

In our large population-based sample of children, different phenotypes of atopic rhinitis were associated with EIB, independently of asthma. Exercise-induced bronchospasm, although related to asthma, seems to constitute a separate entity.

CLINICAL RELEVANCE

In this large (6813) sample of 10-year children drawn from the general population, EIB is associated with rhinitis phenotypes in the absence of asthma. Furthermore, it constitutes an entity independent from asthma and is not related to a familial history of asthma. Thus, investigating these symptoms could be important in this disease, as a specific nasal treatment might improve EIB in these children.

Epidemiology of Respiratory Allergies and Asthma

Asthma has puzzled and confused physicians from the time of Hippocrates to the present day. The word “asthma” comes from a Greek word meaning “panting” (Keeney 1964), but reference to asthma can also be found in ancient Egyptian, Hebrew, and Indian medical writings (Ellul-Micallef 1976; Unger and Harris 1974). There were clear observations of patients experiencing attacks of asthma in the second century and evidence of disordered anatomy in the lung as far back as the seventeenth century (Dring et al. 1689).

What is asthma? Pathophysiology, demographics, and health care costs

Asthma is an obstructive pulmonary disorder with exacerbations characterized by symptoms of shortness of breath, cough, chest tightness, and/or wheezing. Symptoms are caused by chronic airway inflammation. There are multiple cell types and inflammatory mediators involved in its pathophysiology. The airway inflammation is frequently mediated by Th2 lymphocytes, whose cytokine secretion leads to mast cell stimulation, eosinophilia, leukocytosis, and enhanced B-cell IgE production. Although various genes have been identified as likely contributors to asthma development, asthma is largely environmentally triggered and has a multifactorial cause. Asthma is extremely common, especially in poor, urban environments. Asthma is the third most common reason for pediatric hospitalizations.

Importance of allergy in asthma: an epidemiologic perspective

There has been a global epidemic of asthma during the past half-century. More recently, the prevalence has leveled off or declined in many Western countries, whereas the prevalence in less affluent nations is still increasing. The reasons for this and the different geographical patterns of asthma prevalence remain unclear. This paper provides an epidemiologic perspective on whether allergen exposure and allergies can explain these trends. In particular, the paper discusses 1) geographical and temporal trends in asthma and the role of allergens and allergy, 2) the importance of nonallergic mechanisms, 3) nonallergenic exposures that may modify the risk of allergies and asthma, and 4) new and emerging risk and protective factors. Although allergy and asthma are closely related, allergen exposure and allergy alone cannot explain current time trends and geographical patterns of asthma. Population-based studies focusing on recently identified risk and protective factors may provide further insight.

International variations in bronchial responsiveness in children: findings from ISAAC phase two

RATIONALE

Bronchial responsiveness is an objectively measurable trait related to asthma. Its prevalence and association with asthma symptoms among children in many countries are unknown.

OBJECTIVES

To investigate international variations in bronchial responsiveness (BR) and their associations with asthma symptoms and atopic sensitization.

METHODS

Bronchial challenge tests were conducted in 6,826 schoolchildren (aged 8-12 years) in 16 countries using hypertonic (4.5%) saline. FEV(1) was measured at baseline and after inhalation for 0.5, 1, 2, 4, and 8 min. BR was analyzed both as a dichotomous (bronchial hyperreactivity, BHR, at least 15% decline in FEV(1)) and as a continuous variable (time-response slope, BR slope, individual decline in FEV(1) per log(min)).

RESULTS

Prevalence of wheeze last year ranged from 4.4% in Tirana (Albania) to 21.9% in Hawkes Bay (New Zealand) and of BHR from 2.1% in Tirana to 48% in Mumbai (India). The geometric mean BR slope varied between 3.4%/log(min) in Tirana and 12.8%/log(min) in Mumbai and Rome (Italy). At the individual level, BHR was positively associated with wheeze during the past 12 months both in affluent countries (OR = 3.6; 95% CI: 2.7-5.0) and non-affluent countries (OR = 3.0; 1.6-5.5). This association was more pronounced in atopic children. There was a correlation (rho = 0.64, P = 0.002) between center-specific mean BR slope and wheeze prevalence in atopic, but not in non-atopic children.

CONCLUSIONS

BR to saline in children varied considerably between countries. High rates of BR were not confined to affluent countries nor to centers with high prevalences of asthma symptoms. The association between wheeze and BHR at the individual level differed across centers and this heterogeneity can be largely explained by effect modification by atopy. Pediatr. Pulmonol. 2010; 45:796-806. (c) 2010 Wiley-Liss, Inc.

Reduced helminth burden increases allergen skin sensitization but not clinical allergy: a randomized, double-blind, placebo-controlled trial in Vietnam

BACKGROUND

Observational evidence suggests that infection with helminths protects against allergic disease and allergen skin sensitization. It is postulated that such effects are mediated by helminth-induced cytokine responses, in particular IL-10.

OBJECTIVE

We tested this hypothesis in a rural area of central Vietnam where hookworm infection is endemic.

METHODS

One thousand five hundred and sixty-six schoolchildren aged 6-17 were randomly allocated to receive either anti-helminthic therapy or a placebo at 0, 3, 6, and 9 months. We compared changes in the prevalence of exercise-induced bronchoconstriction, allergen skin sensitization, flexural eczema on skin examination, questionnaire-reported allergic disease (wheeze and rhinitis symptoms), and immunological parameters (hookworm-induced IFN-gamma, IL-5, IL-10) between 0 and 12 months.

RESULTS

One thousand four hundred and eighty-seven children (95% of these randomized) completed the study. The most common helminth infections were hookworm (65%) and Ascaris lumbricoides (7%). There was no effect of the therapy on the primary outcome, exercise-induced bronchoconstriction (within-participant mean percent fall in peak flow from baseline after anti-helminthic treatment 2.25 (SD 7.3) vs. placebo 2.19 (SD 7.8, P=0.9), or on the prevalence of questionnaire-reported wheeze [adjusted odds ratio (OR)=1.16, 95% confidence interval (CI) 0.35-3.82, P=0.8] and rhinitis (adjusted OR=1.39, 0.89-2.15, P=0.1), or flexural dermatitis on skin examination (adjusted OR=1.15, 0.39-3.45, P=0.8). However, anti-helminthic therapy was associated with a significantly higher allergen skin sensitization risk (adjusted OR=1.31, 1.02-1.67, P=0.03). This effect was particularly strong for children infected with A. lumbricoides at baseline (adjusted OR=4.90, 1.48-16.19, P=0.009). Allergen skin sensitization was inversely related to hookworm-specific IL-10 at baseline (adjusted OR=0.76, 0.59-0.99, P=0.04). No cytokine tested, including IL-10, changed significantly after the anti-helminthic therapy compared with the placebo.

CONCLUSION

A significant reduction in worm burden over a 12-month period in helminth-infected children increases the risk of allergen skin sensitization but not of clinical allergic disease. The effect on skin sensitization could not be fully explained by any of the immunological parameters tested.

High prevalence of allergic diseases and sensitization in a low allergen country

BACKGROUND

The prevalence of adult atopic diseases in Iceland is lower than in other West European countries, despite an affluent lifestyle, but limited data are available on children. The main aim of this study was to investigate the prevalence of atopic diseases and sensitivity to common allergens in 10- to 11-year-old Icelandic schoolchildren as part of phase II of the International Study of Asthma and Allergies in Children (ISAAC).

METHODS

Nine hundred and forty-six children and their parents answered a questionnaire about atopic diseases. Skin prick tests with six allergens were performed on 773 children and they were examined for signs of atopic dermatitis (AD).

RESULTS

The 12-month prevalence of allergic rhinoconjunctivitis and asthma was 11.5% and 8.9% respectively. The reported prevalence of AD was 27%, but only 9.2% had signs when inspected. A positive skin prick test (SPT) was found in 24.4% of the children, that is 18.8% to grass, 12.9% to cat, 3.6% to trees, 3.0% to Dermatophagoides pteronyssinus, 1.4% to D. farinae and 0.5% to Alternaria.

CONCLUSION

The high prevalence of atopic diseases in children at 10-11 years is surprising, as the prevalence in adults is low in Iceland. The findings resemble those in developing countries. Iceland has had an affluent lifestyle for a considerable time, but the absence of dust mites, low pet ownership and relatively low pollen counts in the country raise doubts about the role of exposure levels in the development of sensitization and atopic diseases.

Atopic disorders and parasitic infections

This chapter examines the relationship between atopic disorders and parasitic infections. Atopy is an exaggerated IgE-mediated Type-1 immune response in predisposed individuals. Conflicting information exists in regard to the relationship of parasitic infections and the classic allergic diseases, that is, atopic dermatitis, allergic rhinitis and asthma. Attention is paid to the explanations for these discrepancies in the literature found within both human and animal studies on atopy with particular emphasis on helminthic infections. The factors that cause only a proportion of atopic individuals to develop clinical disease have not been defined although helminths confer protection in many studies examined. Early childhood infections help induce a Th1-biased immunity and prevent the induction of the Th2 system that causes atopy. Acute parasitic infections may increase manifestations of allergy, whereas chronic infections with parasites decrease atopic predisposition. Nonetheless, a causal association between geohelminth infection and atopic disorders has not been established. Some helminthic substances, especially the cytokines, have respiratory and anti-allergic effects, and may therefore become useful as therapeutic modalities for many atopic and allergic disorders.

Prevalence of asthma in a large group of Israeli adolescents: influence of country of birth and age at migration

BACKGROUND

The occurrence of asthma has geographic variations and is lower in developing compared with industrialized countries. Both environmental and genetic factors may influence its prevalence. We aimed to evaluate the importance and effect of immigration (country of birth and age at immigration to Israel) on the prevalence of asthma in a large group of Israeli adolescents.

METHODS

Computerized medical records of 17-year-old adolescents, who underwent routine examination before military recruitment, were studied. The sample comprised both native-born Israelis (NBI) and immigrants from Ethiopia, the Former Soviet Union (FSU), and Western countries (WC). Asthma was defined as clinical symptoms and signs compatible with the disease accompanied by abnormal spirometry or documented chronic use of inhaled steroids.

RESULTS

Our cohort consisted of 1 466 654 adolescents, including 1 317 556 (89.8%) NBI and 149 098 (10.2%) immigrants. The prevalence of asthma at age 17 was higher in NBI compared with Ethiopian immigrants [4.7% (61 921) vs 2.6% (418), respectively, P < 0.0005], lower compared with immigrants from WC [5.6% (2177), P < 0.0005], and similar to immigrants from the FSU. Further analysis of the association between age at immigration and the risk for developing asthma showed that the younger immigrants from the FSU and Ethiopia arrived to Israel, the higher their prevalence of asthma at the age of 17 was.

CONCLUSIONS

Both environmental and genetic factors seem to influence the prevalence of asthma in 17-year-old adolescents. However, the higher risk for developing asthma associated with young age of immigration points toward an environmental predominance.

Residential proximity fine particles related to allergic sensitisation and asthma in primary school children

BACKGROUND

Fine particulate matter has been linked to allergies by experimental and epidemiological data having used aggregated data or concentrations provided by fixed-site monitoring stations, which may have led to misclassification of individual exposure to air pollution.

METHODS

A semi-individual design was employed to relate individual data on asthma and allergy of 5338 school children (10.4 +/- 0.7 years) attending 108 randomly chosen schools in 6 French cities to the concentrations of PM2.5 (fine particles with aerodynamic diameter 2.5 microm) assessed in proximity of their homes. Children underwent a medical visit including skin prick test (SPT) to common allergens, exercise-induced bronchial (EIB) reactivity and skin examination for flexural dermatitis. Their parents filled in a standardised health questionnaire.

RESULTS

After adjustment for confounders and NO2 as a potential modifier, the odds of suffering from EIB and flexural dermatitis at the period of the survey, past year atopic asthma and SPT positivity to indoor allergens were significantly increased in residential settings with PM2.5 concentrations exceeding 10 microg/m3 (WHO air quality limit values). The relationships were strengthened in long-term residents (current address for at least 8 years).

CONCLUSIONS

Findings support the hypothesis that changes in allergy prevalence observed in recent decades might be partly related to interactions between traffic-related air pollution and allergens. Further longitudinal investigations are needed to corroborate such results.

The prevalence of atopy in asthmatic children correlates strictly with the prevalence of atopy among nonasthmatic children

BACKGROUND

Because asthma preferentially burdens persons with atopy, atopy is simplistically considered a primary 'cause' of asthma. Yet at the population level, the percentage of asthma cases 'attributable' to atopy ranges from less than 10% to more than 60%. Seeking to understand the rationale for the variability of atopy-attributable cases of asthma, we systematically reviewed the results of our own previous epidemiological studies and several studies conducted by others in children.

METHODS

From each of the 37 random pediatric populations selected by a Medline search combining the key words 'IgE or skin tests or hypersensitivity, immediate' with 'epidemiological studies, cross-sectional, case-control, prevalence, longitudinal, epidemiology of asthma' (12 from our previous pediatric surveys and a further 25 reported from 19 studies in children), we extracted the population prevalence of asthma and atopy among asthmatic subjects and among the nonasthmatic part of the population.

RESULTS

No correlation was found between the prevalence of asthma (range 1.8-44.1%) and atopy (range 5.8-63.9%) in these 37 populations of children (r = 0.052, p = 0.761). Nevertheless, the prevalence of atopy among asthmatics strictly correlated with the prevalence of atopy in nonasthmatics (r = 0.900, p < 0.001, slope 1.364).

CONCLUSION

The prevalence of asthma and atopy varies worldwide and at various time points and independently undergoes the influence of powerful environmental factors. The almost perfect correlation we found between atopy in asthmatics and atopy in the nonasthmatic part of the childhood population shows that the prevalence of atopy in asthma depends on environmental factors that simultaneously induce atopy in asthmatic and nonasthmatic subjects.

Risk factors for asthma and allergy associated with urban migration: background and methodology of a cross-sectional study in Afro-Ecuadorian school children in Northeastern Ecuador (Esmeraldas-SCAALA Study)

Background

Asthma and allergic diseases are becoming increasingly frequent in children in urban centres of Latin America although the prevalence of allergic disease is still low in rural areas. Understanding better why the prevalence of asthma is greater in urban migrant populations and the role of risk factors such as life style and environmental exposures, may be key to understand what is behind this trend.

Methods/design

The Esmeraldas-SCAALA (Social Changes, Asthma and Allergy in Latin America) study consists of cross-sectional and nested case-control studies of school children in rural and urban areas of Esmeraldas Province in Ecuador. The cross-sectional study will investigate risk factors for atopy and allergic disease in rural and migrant urban Afro-Ecuadorian school children and the nested case-control study will examine environmental, biologic and social risk factors for asthma among asthma cases and non-asthmatic controls from the cross-sectional study. Data will be collected through standardised questionnaires, skin prick testing to relevant aeroallergen extracts, stool examinations for parasites, blood sampling (for measurement of IgE, interleukins and other immunological parameters), anthropometric measurements for assessment of nutritional status, exercise testing for assessment of exercise-induced bronchospasm and dust sampling for measurement of household endotoxin and allergen levels.

Discussion

The information will be used to identify the factors associated with an increased risk of asthma and allergies in migrant and urbanizing populations, to improve the understanding of the causes of the increase in asthma prevalence and to identify potentially modifiable factors to inform the design of prevention programmes to reduce the risk of allergy in urban populations in Latin America.

Effect of albendazole treatments on the prevalence of atopy in children living in communities endemic for geohelminth parasites: a cluster-randomised trial

BACKGROUND

Epidemiological studies have shown inverse associations between geohelminth (intestinal helminth) infection and atopy, leading to the suggestion that geohelminths might protect against allergy. Periodic deworming of school children with anthelmintics is a widely implemented intervention and has raised concerns that such programmes could increase allergy. We investigated the effect of repeated anthelmintic treatments with albendazole over 12 months on the prevalence of atopy and clinical indices of allergy.

METHODS

We did a cluster-randomised controlled trial in schoolchildren from 68 rural schools. Children were randomly assigned by school to either albendazole (34 schools, 1164 children) every 2 months for 12 months, or to no intervention (34 schools, 1209 children). The intervention schools received a total of seven albendazole treatments. The primary outcome was atopy at 12 months (allergen skin-test reactivity), and analysis was by intention-to-treat for whole-school analyses and per protocol for children. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN61195515.

FINDINGS

Data for analysis were available for all schools and from 67.4% (784 of 1164) and 70.1% (848 of 1209) of children in albendazole and no-treatment groups, respectively. Albendazole treatment caused large reductions in geohelminth prevalence over the study period (adjusted odds ratio 0.13, 95% CI 0.09-0.19, p<0.001), but there was no evidence that treatment was associated with an increase in atopy prevalence (0.97, 0.68-1.39, p=0.862), or clinical allergy (wheeze, 1.07, 0.54-2.11, p=0.848) in the albendazole compared with the no-treatment group.

INTERPRETATION

We saw no increase in the prevalence of atopy or clinical allergy associated with albendazole treatment. Deworming programmes for schoolchildren are unlikely to be accompanied by an increase in allergy.

Physician-diagnosed asthma and allergic rhinitis in Manitoba: 1985-1998

BACKGROUND

A worldwide increase has been noted in the prevalence of asthma, but the data for other allergic disorders are less consistent.

OBJECTIVE

To study 14-year trends in utilization of physician resources for asthma and compare them to trends for allergic rhinitis.

METHODS

We studied visits to physicians by Manitoba residents for asthma (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 493) and allergic rhinitis (ICD-9 code 477) between 1985 and 1998. Prevalence and incidence of physician resources utilization were calculated annually for the total population and by age groups. Aggregate statistics and frequency of physician resources utilization were also analyzed.

RESULTS

The prevalence and incidence of physician resources utilization for asthma increased more than for allergic rhinitis; differences were most striking in the youngest age groups. In adults, the differences were smaller and changed little with time. Most of the increase in asthma care occurred in children and in people without allergic rhinitis. Overall, 17% of Manitobans were diagnosed as having asthma, and the average asthmatic patient made 6 visits. Approximately 14% had an allergic rhinitis diagnosis, each person being seen twice on average. Coexistence of asthma and allergic rhinitis led to increased physician resources utilization for each of the conditions.

CONCLUSIONS

Trends in utilization of physician resources for allergic rhinitis differed strikingly from trends for asthma, particularly in the youngest age group. Asthma and allergic rhinitis affected comparable proportions of the population, but a diagnosis of asthma resulted in much higher utilization of physician resources. The relationship of physician-diagnosed asthma and atopy, as indicated by the diagnosis of allergic rhinitis, appears to have weakened with time in children but not in adults.

Long-term exposure to background air pollution related to respiratory and allergic health in schoolchildren

BACKGROUND

The impact of air pollution on asthma and allergies still remains a debate.

OBJECTIVE

Our cross-sectional study was intended to analyse the associations between long-term exposure to background air pollution and atopic and respiratory outcomes in a large population-based sample of schoolchildren.

METHODS

Six thousand six hundred and seventy-two children aged 9-11 years recruited from 108 randomly schools in six French cities underwent a clinical examination including a skin prick test (SPT) to common allergens, exercise-induced bronchial reactivity (EIB) and skin examination for flexural dermatitis. The prevalence of asthma, allergic rhinitis (AR) and atopic dermatitis was assessed by a standardized health questionnaire completed by the parents. Three-year-averaged concentrations of air pollutants (NO2, SO2, PM10 and O3) were calculated at children' schools using measurements of background monitoring stations.

RESULTS

After adjusting for confounders, EIB, lifetime asthma and lifetime AR were found to be positively related to an increase in the exposure to SO2, PM10 and O3. The adjusted odds ratios (aOR) per increase of 5 microg/m3 of SO2 was 1.39 (95% confidence interval (CI)=1.15-1.66) for EIB and 1.19 (1.00-1.41) for lifetime asthma. The aOR for lifetime AR per increase of 10 microg/m3 of PM10 was 1.32 (CI=1.04-1.68). Moreover, SPT positivity was associated with O3 (aOR=1.34; CI=1.24-1.46). Associations with past year symptoms were consistent, even if not always statistically significant. Results persisted in long-term resident (current address for at least 8 years) children. However, no consistent positive association was found with NO2.

CONCLUSIONS

A moderate increase in long-term exposure to background ambient air pollution was associated with an increased prevalence of respiratory and atopic indicators in children.

Intestinal Parasites in Healthy Subjects in Albania

The purpose of this study was to evaluate the prevalence of intestinal parasites in 277 healthy subjects in the city of Mamuras (Albania, South Eastern Europe) and the correlation between parasitic infections and possible risk factors. Faecal samples collected with sodium-acetate-formalin fixative were concentrated by formalin ethylacetate sedimentation and examined as wet mounts, permanent stains and by anti-Giardia/Cryptosporidium fluorescent antibodies. Data concerning age, sex, level of education, availability of piped water, number of people living in the same house, and residence in rural or urban area were collected for each subject. Statistical analysis was performed by chi-square test and regression logistic analysis. The overall prevalence of intestinal parasites was 183/277 (66.06%). In particular, pathogenic protozoa or helminths were found in 67 subjects (24.18%), including Trichuris trichiura in 34 (12.27%), Giardia duodenalis in 31 (11.19%), Hymenolepis nana in 5 (1.8%), Ascaris lumbricoides in 3 (1.08%). A significant correlation was observed only between parasite colonization and older age and between Trichuris trichiura infection and residence in rural areas.

Prevalence of food allergy and its relationship to asthma and allergic rhinitis in schoolchildren

BACKGROUND

Food allergy (FA) is an important health problem. However, epidemiological studies at the population level are scarce. We assessed the prevalence of FA and its associations with respiratory manifestations among schoolchildren.

METHODS

A total of 6672 schoolchildren aged 9-11 years recruited from 108 randomly chosen schools in six French cities underwent a clinical examination including skin prick test (SPT) to common food and aeroallergens and the standardized protocol of the run test to assess exercise-induced bronchial hyper-responsiveness (EIB). Asthma, allergic rhinitis (AR) and clinical symptoms of FA were determined using a standardized questionnaire completed by parents.

RESULTS

About 2.1% of the children reported symptoms of FA, 1.9% were sensitized to food allergens, and 0.1% had SP-tested FA. The AR was more prevalent than asthma (20.0% lifetime, 11.9% past year vs 9.8%, 8.7% respectively). Reported FA, food sensitization and SP-tested FA were all positively associated with asthma and AR (P < 0.001). These associations persisted also for FA not manifesting as respiratory symptoms (P < 0.001). Asthma and AR remained significantly associated with reported symptoms of FA and allergic sensitization to food allergens after adjustment for confounders as well as for sensitization to aeroallergens. No relationship existed between EIB (9.0%) and FA.

CONCLUSION

The relationships between FA and asthma and AR could be totally explained neither by the existence of respiratory manifestations of FA nor by sensitization to aeroallergens. The FA might intervene differently in asthma and AR.

Wheeze, allergic sensitization and geohelminth infection in Butajira, Ethiopia

BACKGROUND

The effect of geohelminth infection on wheeze and allergen sensitization is inconsistent across different epidemiological studies.

OBJECTIVE

To investigate the association between self-reported wheeze, self-reported asthma, allergic sensitization and geohelminth infection in urban and rural areas of Butajira, southern Ethiopia.

METHODS

Questionnaire data on wheeze, asthma and a range of confounding variables was gathered in a cross-sectional study of 7649 people aged 5 years or more from the Butajira Rural Health Project database. Allergic skin sensitization to Dermatophagoides pteronyssinus and cockroach was measured, and a stool sample collected for qualitative and quantitative geohelminth analysis.

RESULTS

Wheeze was weakly associated with allergic sensitization to D. pteronyssinus and cockroach (odds ratios (OR) 1.21, 95% confidence interval (CI) 0.98-1.51, and 1.27, 95% CI 1.00-1.62, respectively). Self-reported asthma was related to sensitization to D. pteronyssinus only (OR 4.09, 95% CI 2.86-5.84). Geohelminths were present in 33.8% of participants, and the median egg load in infested individuals was 6 eggs/g. Overall, presence of any geohelminths was associated with a diminished risk of cockroach sensitization (adjusted OR 0.82, 95% CI 0.68-0.99) but there were no significant protective effects of any geohelminth infection against wheeze or asthma.

CONCLUSION

In a developing country community with relatively low geohelminth prevalence and intensity, we found weak association between allergic sensitization and wheeze, but no evidence of a protective effect of geohelminths against wheeze or asthma.

Intestinal worms and human allergy

The immunoepidemiological interactions between intestinal worm (or geohelminth) infections and allergy are of great interest to parasitologists, immunologists, and allergists because of the close similarities between the human immune response to geohelminth parasites and environmental allergens. Allergic diseases appear to be most rare in populations living in the rural tropics with high rates of infection with geohelminth parasites, and this has led to suggestions that the relationship between geohelminth infections and allergy may be causal. Allergic sensitization and disease results from a complex interaction between environmental exposures and genetic background, and the numerous epidemiological studies that have investigated the relationship between allergy and geohelminth infections have provided conflicting findings. The strongest epidemiological evidence for a causal association is provided by intervention studies that demonstrate evidence for an effect of anthelmintic treatment on atopy or asthma risk. There is evidence also for an inverse relationship between geohelminth infection and either atopy or asthma symptoms from cross-sectional studies that have been conducted in areas of high infection prevalence. Chronic geohelminth infections could affect allergy risk by modulation of the immune response to environmental allergens, and an area of great research activity at present is the investigation of the role of regulatory T cells in modulating host inflammatory responses. However, a causal association between geohelminth infections and allergy remains to be proven, and prospective and intervention studies are required that investigate the development of allergy in early life at a time when humans are first exposed to geohelminth parasites and their antigens.

Does atopy protect against enteric infections?

Allergic sensitization to inhaled allergens and foods is common and is linked to the development of asthma, allergic rhinitis and eczema. In view of the morbidity associated with these diseases it is not clear why the genetic predisposition to atopy is so common. Children who are atopic are less likely to develop oral tolerance to ingested foods and as a result are more likely to have manifestations of food allergy including wheezing, skin rashes and gastrointestinal symptoms. Oral tolerance also develops to micro-organisms in the gastrointestinal tract. Children who are atopic may be protected against enteric infections in early childhood because they are less likely to be tolerant of these organisms. This may explain why individuals who are atopic are less likely to have evidence of previous infection with hepatitis A and other enteric organisms although they are just as likely to have been infected with respiratory pathogens.

Change in prevalence of asthma in Danish children and adolescents

BACKGROUND

There is evidence suggesting that the prevalence of asthma has increased, especially in industrialized countries.

OBJECTIVE

To investigate whether the prevalence of asthma in Danish children and adolescents has changed during the past 15 years.

METHODS

Serial cross-sectional studies of 2 different random population samples of children aged 7 to 17 years, living in urban Copenhagen, Denmark, were performed 15 years apart. The first cohort was investigated in 1986 (n = 527) and the second in 2001 (n = 480). The same methods were applied at both occasions. Skin test reactivity was measured using standard techniques. Asthma was defined on the basis of questionnaire responses and was regarded as nonatopic (intrinsic) if no positive reactions were observed on the skin test and as atopic (extrinsic) if at least 1 positive reaction was noted. Current asthma was defined as symptoms within the preceding 12 months.

RESULTS

The prevalence of current asthma increased from 5.3% in 1986 to 11.7% in 2001. This was primarily due to an increase in intrinsic asthma, which was 4.2-fold (1.5% to 6.4%), compared with extrinsic asthma, which increased only 1.4-fold (3.8% to 5.5%). The changes were more pronounced in girls.

CONCLUSIONS

The prevalence of asthma has increased substantially during the past 15 years. The observed striking increase in intrinsic asthma suggests the possibility of a more heterogeneous disorder, involving more important factors than atopy. Furthermore, our findings suggest that asthma might be shifting toward female predominance in childhood.

Food allergy and asthma--what is the link?

Food allergy and asthma are both atopic diseases and therefore frequently co-exist. Food allergy is common in childhood, affecting approximately 8% of infants. The diagnosis is based on a suggestive history supported by skin-prick testing, serum specific IgE or food challenge. The role of diet in the aetiology of asthma and as a precipitant of exacerbations has been investigated extensively. Many people perceive diet as being an important precipitant of their asthma but objective testing suggests that it is only important in a minority. Meanwhile, there is considerable epidemiological evidence to suggest that there is a link between asthma and food allergy. Food can induce bronchospasm and food allergy has been implicated as a risk factor for life-threatening asthma. Additionally, asthma also seems to be a risk factor for life-threatening food allergy. The mechanism underlying this connection is unclear. The co-existence of food allergy should be considered in any child with asthma. Where food allergy is confirmed, steps should be taken to avoid these foods as this may considerably improve asthma control.

Allergic symptoms, atopy, and geohelminth infections in a rural area of Ecuador

Geohelminth infections may affect the expression of allergic disease. To investigate the relationship between geohelminth infections, atopy, and symptoms of allergic disease, we studied 4433 schoolchildren from 71 schools in a rural tropical area in Ecuador. Information was collected on allergic symptoms, allergen skin test reactivity, and presence of geohelminth infections. Allergic symptoms were of low prevalence (2.1% had recent wheeze), but prevalence of skin test reactivity was relatively high (18.2%). The presence of geohelminth infections was protective against allergen skin test reactivity (odds ratio 0.62, 95% confidence interval 0.50-0.76, p < 0.001) and symptoms of exercise-induced wheeze (odds ratio 0.59, 95% confidence interval 0.40-0.87, p = 0.008) but not against other wheeze symptoms or symptoms of allergic rhinitis or atopic eczema. Infection intensity with Ascaris lumbricoides or Trichuris trichiura was associated with a reduction in the prevalence of allergen skin test reactivity but not with allergic symptoms. There was no evidence of interactions between geohelminth infection and allergen skin test reactivity on the risks of allergic symptoms. The results suggest that geohelminth infections do not explain the low prevalence of allergic symptoms in the study population.

International patterns of the prevalence of pediatric asthma the ISAAC program

Like so much research, the findings from the ISAAC program have raised more questions than they have answered. Despite their limitations, the ISAAC findings provide the basis for further studies to investigate factors that potentially contribute to these international patterns and may lead to novel public health and pharmacologic intervention strategies that reduce the prevalence and severity of asthma worldwide.

Lung hyperpermeability and asthma prevalence in schoolchildren: unexpected associations with the attendance at indoor chlorinated swimming pools

AIMS

To study whether exposure to nitrogen trichloride in indoor chlorinated pools may affect the respiratory epithelium of children and increase the risk of some lung diseases such as asthma.

METHODS

In 226 healthy children, serum surfactant associated proteins A and B (SP-A and SP-B), 16 kDa Clara cell protein (CC16), and IgE were measured. Lung specific proteins were measured in the serum of 16 children and 13 adults before and after exposure to NCl(3) in an indoor chlorinated pool. Relations between pool attendance and asthma prevalence were studied in 1881 children. Asthma was screened with the exercise induced bronchoconstriction test (EIB).

RESULTS

Pool attendance was the most consistent predictor of lung epithelium permeability. A positive dose-effect relation was found with cumulated pool attendance and serum SP-A and SP-B. Serum IgE was unrelated to pool attendance, but correlated positively with lung hyperpermeability as assessed by serum SP-B. Changes in serum levels of lung proteins were reproduced in children and adults attending an indoor pool. Serum SP-A and SP-B were already significantly increased after one hour on the pool side without swimming. Positive EIB and total asthma prevalence were significantly correlated with cumulated pool attendance indices.

CONCLUSIONS

Regular attendance at chlorinated pools by young children is associated with an exposure dependent increase in lung epithelium permeability and increase in the risk of developing asthma, especially in association with other risk factors. We therefore postulate that the increasing exposure of children to chlorination products in indoor pools might be an important cause of the rising incidence of childhood asthma and allergic diseases in industrialised countries. Further epidemiological studies should be undertaken to test this hypothesis.

Geographical variations of asthma and asthma symptoms among schoolchildren aged 5 to 8 years and 12 to 15 years in Palestine: the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

Many studies demonstrated the existence of geographic differences, within and between countries, in the prevalence of asthma, rhinitis, and eczema. However, in Palestine, there are no comprehensive Palestinian data to compare with those from other regional and international centers.

OBJECTIVE

To describe the prevalence of asthma and asthma symptoms in schoolchildren in two districts (Ramallah and North Gaza) in Palestine.

METHODS

After a two-stage stratified systematic sampling, approximately 14,500 schoolchildren, from the first and second grades of elementary school (ages 5 to 8 years) and eighth and ninth school grades (ages 12 to 15 years), were invited to participate in a survey using International Study of Asthma and Allergies in Childhood phase III questionnaires and protocols.

RESULTS

In general, younger children were reported to have a higher 12-month wheezing prevalence rate than older children (9.6 and 7.2%, respectively), and more physician-diagnosed asthma (8.4 and 5.9%, respectively). However, nocturnal cough and exercise-related wheezing were higher in the older age group compared with younger children. Younger children living in North Gaza district showed slightly higher prevalence rates for asthma and asthma symptoms, but older children had higher rates in Ramallah district. After adjustment using logistic regression analysis, male sex, living in inland areas, and younger age were shown to predict 12-month wheezing and physician-diagnosed asthma.

CONCLUSIONS

Palestinian children have asthma symptoms rates that are similar to several countries in the Mediterranean region such as Spain and Turkey, but still lower than other Middle East countries such as Saudi Arabia and Israel.

Asthma: environmental and occupational factors

Asthma is in several ways a difficult disease to study. Generally arising in childhood, its pattern is often one of remission and relapse; at any point there are difficulties in translating its characteristic, clinical features into an operational definition. Geographical and temporal patterns in its distribution - whereby the disease appears to have increased in frequency in more 'westernised' countries -suggest strong environmental determinants in its causation although there are, too, undoubted and important genetic influences on both its incidence and presentation. Recent aetiological research has concentrated on the function of allergen exposure or on the role of early-life microbial contact that may regulate the development of a range of childhood allergies, including asthma. To date the 'hygiene hypothesis' offers the most efficient explanation for the distribution of the disease in time and place although convincing evidence for it remains elusive.

Inner-city asthma and the hygiene hypothesis

OBJECTIVE

Our goals were to analyze some of the similarities and differences in the increase in asthma, hay fever, and atopic sensitization between Europe and the United States and attempt to explain "inner-city asthma" within the framework of the hygiene hypothesis.

DATA SOURCES

We reviewed historical descriptions of hay fever and asthma as well as the currently available related literature.

STUDY SELECTION

The authors' judgment was used in the selection of historical and epidemiologic evidence.

RESULTS

Analyses of patterns of risk factors for allergic rhinoconjunctivitis and asthma in Europe led to a causal theory of the epidemic: the hygiene hypothesis. This theory claims that hygiene removed a protective influence against atopy and asthma that was once provided by exposure to infections in early life. This hypothesis has been questioned in the United States, where allergic asthma since the 1970s has increased among minorities living in poverty and with suboptimal hygienic conditions (inner-city asthma). When seen from a historical perspective, the recent increasing trend in respiratory allergies among the less advantaged in the United States may be explained as the consequence of several epiphenomena linked to westernization (including declining exposure to foodborne and orofecal infections) that first affected the richest socioeconomic strata during the 19th century, expanded among the middle classes during the first half of the 20th century, and eventually cascaded down to affect the least-advantaged Americans.

CONCLUSION

Inner-city asthma may be the final stage of a class-driven urbanization and westernization that began 2 centuries ago in the United States and that is now coming full circle.

Asthma

Asthma is one of the commonest chronic diseases of affluent societies. The striking increase in prevalence of asthma over recent decades and the rarity of this disease in less affluent populations confirms the importance of environmental factors in the cause of asthma--although which environmental factors are responsible is still not clear. Family studies show that genetic factors are also important in determining individual susceptibility to asthma, with results of genetic studies suggesting that there are many genes with moderate effects rather than a few major genes. Asthmatic airways show inflammation and remodelling, with CD4+ helper cells, mast cells, and eosinophils characterising the inflammatory response. Inhaled corticosteroids remain the cornerstone of treatment with the addition of long-acting beta agonists as the next step if symptoms continue. Leukotriene antagonists, the only new drugs to reach the market in the past decade, have modest effects. However, a better understanding of the mechanisms underlying asthma and the genetic and environmental factors that predispose individuals to asthma should lead to better preventative strategies and new therapeutic approaches.

Non-eosinophilic asthma: importance and possible mechanisms

There is increasing evidence that inflammatory mechanisms other than eosinophilic inflammation may be involved in producing the final common pathway of enhanced bronchial reactivity and reversible airflow obstruction that characterises asthma. A review of the literature has shown that, at most, only 50% of asthma cases are attributable to eosinophilic airway inflammation. It is hypothesised that a major proportion of asthma is based on neutrophilic airway inflammation, possibly triggered by environmental exposure to bacterial endotoxin, particulate air pollution, and ozone, as well as viral infections. If there are indeed two (or more) subtypes of asthma, and if non-eosinophilic (neutrophil mediated) asthma is relatively common, this would have major consequences for the treatment and prevention of asthma since most treatment and prevention strategies are now almost entirely focused on allergic/eosinophilic asthma and allergen avoidance measures, respectively. It is therefore important to study the aetiology of asthma further, including the underlying inflammatory profiles.