Atopy and asthma in rural Poland: a paradigm for the emergence of childhood respiratory allergies in Europe

A conversation on allergy: recognizing the past and looking to the future

Allergy is an ever-evolving group of disorders, which includes asthma, atopic dermatitis, rhinitis and food allergies and that currently affects over 1 billion people worldwide. This group of disorders has exploded in incidence since around the start of the 20th century, implying that genetics is not solely responsible for its development but that environmental factors have an important role. Here, Fabio Luciani and Jonathan Coquet, in their role as editors at Immunology & Cell Biology, asked nine prominent researchers in the field of allergy to define the term 'allergy', discuss the role of genetics and the environment, nominate the most important discoveries of the past decade and describe the best strategies to combat allergy at the population level going forward.

Is the "farm effect" hypothesis still current? Atopy and allergic diseases in rural and urban children in Poland

OBJECTIVE

The prevalence of allergic diseases has reached epidemic proportions in the Western world. Although farm-living has been associated with a lower prevalence of asthma and atopy, a marked increase in atopy among rural populations after accession to the European Union has been recently reported in Poland. Here, we aimed to investigate the effect of living environment on the prevalence of atopy and allergic diseases in Polish children.

METHODS

400 schoolchildren aged 10-14 years from the capital city (223) and from traditional rural part of the country (177) were recruited from June to November 2011. Data on allergic diseases and symptoms were collected by means of questionnaire and physical examination. Atopy was assessed based on skin prick tests (SPTs) reactivity to inhalant allergens in 350 children.

RESULTS

A high discrepancy between the prevalence of allergic symptoms (46.7%) and doctor-diagnosed allergic diseases (25%) was demonstrated (p < 0.0001). Urban children had a higher overall prevalence of allergic diseases and atopy than children living in rural areas, 29.3% versus 17.1% (p = 0.007) and 33.5% versus 20% (p = 0.0045), respectively. However, no significant differences in the rates of particular allergic diseases were noted (p > 0.05). There was higher SPT positivity to trees, grass, corn, weeds, animal dander, and molds in urban children (p < 0.05).

CONCLUSIONS

Our data support the protective effect of farm-living on the prevalence of atopy and overall allergic diseases, albeit not on particular allergic diseases, in children in Poland. The underlying mechanisms are not identified, but current socioeconomic changes may be responsible.

Allergies in urban versus countryside settings in Poland as part of the Epidemiology of the Allergic Diseases in Poland (ECAP) study - challenge the early differential diagnosis

Introduction

The incidence of allergies depends on a number of factors, including adopting an urban “western” lifestyle, genetic predispositions, and different regions of residence.

Aim

To compare the prevalence of allergic conditions (seasonal allergic rhinitis (SAR) and perennial allergic rhinitis (PAR), bronchial asthma (BA), atopic dermatitis (AD)) in a group of countryside versus urban residents in Poland.

Material and methods

The prevalence of allergic conditions in urban versus countryside settings was assessed using the translated and approved questionnaire developed for international ECRHS II and ISAAC studies. Respondents were selected via random multistage sampling, with proportionate stratified sampling, and the Polish Resident Identification Number (PESEL) as the basis. A total of 18,617 respondents took part in the study. Subsequently, approximately 25% of the subjects underwent outpatient assessments: skin-prick, lung function, peak nasal inspiratory flow (PNIF) tests, as well as history-taking.

Results

Allergic rhinitis (AR) proved to be the most common condition in the entire study population. Children residing in the countryside were twice more likely to be diagnosed with BA (8.33% vs. 4%; p < 0.05). Conversely, in the adult subgroup, BA was more commonly observed in urban areas. Whereas reported symptom rates were much higher in AR and AD patients, symptomatic BA was proportionately lower with respect to the official diagnoses (underdiagnosed BA phenomenon). Atopic dermatitis was considerably more common in the metropolitan population. One factor that significantly correlated with allergic diseases was a positive family history.

Conclusions

Inhabitants of metropolitan areas are to a greater extent predisposed to allergic conditions. One factor significantly contributing to allergies is genetic predisposition. Given the scale of the problem, there is an urgent need to implement measures for early prevention and diagnosis of allergies to minimize distant health effects.

Outcome modelling strategies in epidemiology: traditional methods and basic alternatives

Controlling for too many potential confounders can lead to or aggravate problems of data sparsity or multicollinearity, particularly when the number of covariates is large in relation to the study size. As a result, methods to reduce the number of modelled covariates are often deployed. We review several traditional modelling strategies, including stepwise regression and the ‘change-in-estimate’ (CIE) approach to deciding which potential confounders to include in an outcome-regression model for estimating effects of a targeted exposure. We discuss their shortcomings, and then provide some basic alternatives and refinements that do not require special macros or programming. Throughout, we assume the main goal is to derive the most accurate effect estimates obtainable from the data and commercial software. Allowing that most users must stay within standard software packages, this goal can be roughly approximated using basic methods to assess, and thereby minimize, mean squared error (MSE).

The microbial environment and its influence on asthma prevention in early life

There is accumulating evidence to suggest that the environmental microbiome plays a significant role in asthma development. The very low prevalence of asthma in populations highly exposed to microbial environments (farm children and Amish populations) highlights its preventive potential. This microbial diversity might be necessary to instruct a well-adapted immune response and regulated inflammatory responses to other inhaled and ingested environmental elements, such as allergens, particles, and viruses. Like the internal gut microbiome, which is increasingly recognized as an important instructor of immune maturation, the external environmental microbiome might shape immune responses on the skin, airway mucosal surfaces, and potentially also the gut early in life. The diversity of the external microbial world will ensure that of the many maladapted pathways leading to asthma development, most, if not all, will be counterbalanced. Likewise, important contributors to asthma, such as allergen sensitization and allergic manifestations early in life, are being suppressed. Thus the facets of innate immunity targeted by microbes and their compounds and metabolites might be the master switch to asthma and allergy protection, which has been found in environments rich in microbial exposures.

Changes in atopy prevalence and sibship effect in rural population at all ages

BACKGROUND

We examined the associations of family size and birth order with atopy prevalence in rural Poland at two time periods.

METHODS

Two cross-sectional surveys were conducted in the same villages and a small town of lower Silesia at an interval of 9 years. In 2003, 1700 (88% of eligible individuals), and in 2012, 1730 (86%) inhabitants aged 5 years or more completed a questionnaire and had a skin prick test for atopy.

RESULTS

There was an inverse association between family size and atopy in the village population in 2003; the prevalence of atopy was the highest for those with no siblings (15.2%) and decreased to 5.4% for those with three and more siblings (OR = 0.22; 0.07-0.66). In contrast, there was little or no such protective effect in the town population where the prevalence of atopy was much higher (7.3% in the villages, 20.0% in the town). Nine years later, the prevalence of atopy had increased in the village to be similar to that in the town (19.6% and 19.9% respectively), and the protective effects of family size and birth order in the villages were much weaker (OR = 0.64; 95% CI 0.33-1.27 for three or more siblings). Both protective effects were strongest among children.

CONCLUSIONS

The protective effects of family size and birth order on atopy were much stronger in children than in adults and among those living in a village. They largely disappeared with the steep increase in atopy prevalence at all ages; this followed environmental changes on the village farms.

Atopy and allergic respiratory disease in rural Poland before and after accession to the European Union

BACKGROUND

In 2003, we recorded a striking difference in the prevalence of atopy between village and small-town populations in southwest Poland. Nine years later, we undertook a second survey of the same area.

OBJECTIVE

We sought to assess whether rapid changes in farming practices, driven by accession to the European Union in 2004, were accompanied by an increase in atopy, asthma, and hay fever in these villages.

METHODS

In 2012, we surveyed 1730 inhabitants older than 5 years (response rate, 85%); 560 villagers and 348 town inhabitants who had taken part in the earlier survey. Participants completed a questionnaire on farm-related exposures and symptoms of asthma and hay fever. Atopy was assessed by using skin prick tests.

RESULTS

In 2012, far fewer villagers had contact with cows (4% vs 24.3% in 2003) or pigs (14% vs 33.5%), milked cows (2.7% vs 12.7%), or drank unpasteurized milk (9% vs 35%). Among the villagers, there was a significant increase at all ages in the prevalence of atopy between 2003 and 2012 both in the total population (7.3% vs 19.6%, P < .0001) and among those who took part in both surveys (7.9% vs 17.8%, P < .0001). Among the townspeople, the prevalence of atopy did not change substantially (20% vs 19.9% and 21.7% vs 18.5%, respectively). Hay fever increased 2-fold in the villages (3.0% vs 7.7%) but not in the town (7.1% vs 7.2%); there was little or no change in asthma prevalence in the villages (5.0% vs 4.3%) or town (4.3% vs 5.0%).

CONCLUSIONS

We report a substantial increase in atopy at all ages and in a remarkably short period of time in a Polish population whose farm-related exposures were dramatically reduced after their country's accession to the European Union.

Asthma and allergies: is the farming environment (still) protective in Poland? The GABRIEL Advanced Studies

BACKGROUND

Evidence exists that a farming environment in childhood may provide protection against atopic respiratory disease. In the GABRIEL project based in Poland and Alpine regions of Germany, Austria and Switzerland, we aimed to assess whether a farming environment in childhood is protective against allergic diseases in Poland and whether specific exposures explain any protective effect.

METHODS

In rural Poland, 23 331 families of schoolchildren completed a questionnaire enquiring into farming practices and allergic diseases (Phase I). A subsample (n = 2586) participated in Phase II involving a more detailed questionnaire on specific farm exposures with objective measures of atopy.

RESULTS

Farming differed between Poland and the Alpine centres; in the latter, cattle farming was prevalent, whereas in Poland 18% of village farms kept ≥1 cow and 34% kept ≥1 pig. Polish children in villages had lower prevalences of asthma and hay fever than children from towns, and in the Phase II population, farm children had a reduced risk of atopy measured by IgE (aOR = 0.72, 95% CI 0.57, 0.91) and skin prick test (aOR = 0.65, 95% CI 0.50, 0.86). Early-life contact with grain was inversely related to the risk of atopy measured by IgE (aOR = 0.66, 95% CI 0.47, 0.92) and appeared to explain part of the farming effect.

CONCLUSION

While farming in Poland differed from that in the Alpine areas as did the exposure-response associations, we found in communities engaged in small-scale, mixed farming, there was a protective farming effect against objective measures of atopy potentially related to contact with grain or associated farm activities.

Consumption of unpasteurized milk and its effects on atopy and asthma in children and adult inhabitants in rural Poland

BACKGROUND

Consumption of unpasteurized cow's milk has been identified as a possible protective factor for atopy and asthma. Most studies have been conducted among children and in farming populations. We investigated the effects of consumption of unpasteurized milk in early life on atopy, asthma, and rhinitis in village and town inhabitants in a region of Poland and assessed whether any protective effects of milk consumption differed according to place of residence and farming status.

METHODS

We surveyed the inhabitants (aged >5 years) of a small town and seven nearby villages in southwest Poland (n = 1700, response rate 88%). Participants (or their parents for those <16 years of age) completed a questionnaire on farm exposures and symptoms of asthma and rhinitis. In particular, information was collected on unpasteurized milk consumption in early life. Atopy was assessed using skin prick tests.

RESULTS

Consumption of unpasteurized milk in the first year of life was inversely associated with atopy and asthma both among town and village inhabitants - town: adjusted odds ratio (aOR) for atopy 0.46 [95% confidence interval (CI) 0.37-0.52] asthma 0.51 (0.32-0.74); villages: atopy 0.59 (0.44-0.70) and asthma 0.59 (0.42-0.74). For atopy, the protective effect was more clearly seen among nonfarmers (0.42; 0.34-0.46) than in farmers (0.82; 0.54-1.11). For doctor-diagnosed hay fever and current rhinitis symptoms, the protective effect was only observed among town inhabitants and/or nonfarmers.

CONCLUSIONS

Early-life exposure to unpasteurized milk may protect against atopy, asthma, and related conditions, independently of place of residence and farming status, and in both children and adults.

Association of house dust allergen concentrations with residential conditions in city and in rural houses

BACKGROUND

The aim of the study was to evaluate the relationship between house dust mite, cat and dog allergen levels with household characteristics in the houses of children living in urban and rural areas in central Poland.

METHODS

Dust samples were collected from 141 urban and 191 rural houses. Der f1 + Der p1, Can f 1, and Fel d1 levels were measured and associated with residential conditions and atopy-related health outcomes assessed by clinical examination and skin prick testing.

RESULTS

Concentrations of mite allergens were lower, and cat and dog allergen levels were higher in urban houses. Fel d1 and Can f1 levels depended on the presence of a respective animal in the house. In urban houses, Der p1 + Der f1 concentration was lower in households with central heating, whereas Can f1 concentration was related to building age. Multivariate analyses revealed that the concentrations of house dust mite and dog allergens were associated with relative humidity, number of people in the household, and the presence of a dog at home. There was no significant association between allergen level and sensitization or atopic diseases.

CONCLUSIONS

Concentrations of indoor allergens in urban and rural houses differ significantly, and residential conditions associated with allergen levels seem to be different in both environments.

The GABRIEL Advanced Surveys: study design, participation and evaluation of bias

Exposure to farming environments has been shown to protect substantially against asthma and atopic disease across Europe and in other parts of the world. The GABRIEL Advanced Surveys (GABRIELA) were conducted to determine factors in farming environments which are fundamental to protecting against asthma and atopic disease. The GABRIEL Advanced Surveys have a multi-phase stratified design. In a first-screening phase, a comprehensive population-based survey was conducted to assess the prevalence of exposure to farming environments and of asthma and atopic diseases (n = 103,219). The second phase was designed to ascertain detailed exposure to farming environments and to collect biomaterial and environmental samples in a stratified random sample of phase 1 participants (n = 15,255). A third phase was carried out in a further stratified sample only in Bavaria, southern Germany, aiming at in-depth respiratory disease and exposure assessment including extensive environmental sampling (n = 895). Participation rates in phase 1 were around 60% but only about half of the participating study population consented to further study modules in phase 2. We found that consenting behaviour was related to familial allergies, high parental education, wheeze, doctor diagnosed asthma and rhinoconjunctivitis, and to a lesser extent to exposure to farming environments. The association of exposure to farm environments with asthma or rhinoconjunctivitis was not biased by participation or consenting behaviour. The GABRIEL Advanced Surveys are one of the largest studies to shed light on the protective 'farm effect' on asthma and atopic disease. Bias with regard to the main study question was able to be ruled out by representativeness and high participation rates in phases 2 and 3. The GABRIEL Advanced Surveys have created extensive collections of questionnaire data, biomaterial and environmental samples promising new insights into this area of research.

Prevalence of allergic diseases among Korean school-age children: a nationwide cross-sectional questionnaire study

The purpose of this study was to investigate the nationwide prevalence of childhood asthma, eczema and other allergic diseases in Korean school-age children (8-11 yr old) and to assess the difference between residential areas. Among 6,279 elementary schools, 427 schools were randomly selected according to residential area (metropolitan, provincial, rural, and industrial area) by the cluster sampling method. Parents of students completed a modified Korean version of a questionnaire formulated by the International Study of Asthma and Allergies in Childhood (ISAAC). Among 50,200 subjects, 31,026 (61.8%) responded, and 30,893 (99.6%) were analyzed. The 12-month prevalence of wheeze, flexural rash, and allergic rhinitis symptoms were 4.8%, 15.3%, and 32.9%, respectively. The prevalence of diagnosis of allergic diseases in boys was higher than that in girls, with the exception of eczema. In both boys and girls, the difference of the prevalence of allergic diseases among industrial, metropolitan and provincial areas was not statistically significant, but the differences between rural area and other areas were significant. Our results support the importance of contextual effect associated with residential area as causative agents of allergic diseases among Korean school-age children.

Calculating the prevalence of atopy in children

BACKGROUND

Atopy is an important risk factor for asthma, rhinitis, atopic eczema and urticaria. For this reason, several studies have been done to determine the prevalence of atopy in the paediatric population. The important differences among these studies do not allow the extrapolating of results. In this study, we calculate the prevalence of atopy and atopy-related diseases in a paediatric population using a different methodology.

METHODS

Retrospective study among children referred for drug allergy in which the latter was discarded. We evaluated the prevalence of atopy (measured by allergen sensitisation), asthma, rhinitis, urticaria, atopic eczema and their characteristics.

RESULTS

Three hundred and forty-two patients were studied for adverse drug reaction. This was discarded in 325/342 patients. 20 % of the children in the sample were atopic. Atopy prevalence increased with age. Some atopy related disease was observed in 83/325 (25.5 %) children. Among these children allergen sensitisation increased from 42.3 % in the 0-3 years age group to 93.3 % in the 7-14 age group (p < 0.0001). Prevalence of asthma was 11.5 %, 10.2 % and 7 % in the 0-3, 4-6 and 7-14 age groups, respectively. Prevalence of rhinoconjunctivitis increased through age groups with a prevalence of 20 % among the 7 to 14-year old children.

CONCLUSION

The use of this type of methodology seems to be correct to estimate the prevalence of atopy. Prevalence of allergen sensitisation is very high among 7 to 14-year old children with asthma and/or rhinoconjunctivitis.

Prevalence of allergy, patterns of allergic sensitization and allergy risk factors in rural and urban children

BACKGROUND

We aimed to compare the prevalence of allergic diseases and sensitization in children living in urban and rural areas and to identify potential risk/protection factors associated with allergy.

METHODS

School children 12-16 years old, from urban community (n = 201) and rural area (n = 203) were recruited. The data obtained by questionnaire were referred to doctors' diagnosis, skin prick tests (SPTs), and serum specific and total IgE assessment.

RESULTS

The prevalence of allergic diseases in urban children was significantly higher as compared with rural children [asthma 16.42%vs 1.97% (P < 0.001) allergic rhinitis 38.81%vs 10.84% (P < 0.001)]. Positive SPTs to at least one allergen was found in 63.7% of urban and 22.7% rural children (P < 0.001). Significantly higher percentage of allergic rural than urban children were monosensitized or sensitized to 2-4 allergens, but almost a fourfold higher percentage of allergic urban children was found to be sensitized to five or more allergens (P < 0.0001). The history of frequent upper respiratory factor (URT) infections, antibiotic therapy, tonsiltectomy/adenoidectomy were positively associated with development of atopy and sensitization.

CONCLUSION

Our findings confirm that residence of rural area is associated with a significant lower prevalence of allergic sensitization and symptoms in school children. Several risk and protective factors related to environment and style of life could be identified in both environments.