Pets and the development of allergic sensitization

Characteristics of children with cat sensitivity: a prospective cross-sectional study

BACKGROUND

Animal dander is one of the most common respiratory allergens in children, and there is evidence that cat sensitivity is a risk factor for asthma and allergic rhinitis. In this study, it was aimed to evaluate children with cat sensitivity and to identify their demographic and clinical characteristics.

METHODS

Patients who were found to be sensitive to cats following skin prick tests performed in our allergy clinic over a period of one year (and two control groups), were included in the study. Patients in the study and control groups filled in a questionnaire including demographic and clinical characteristics.

RESULTS

The prevalence of cat sensitivity in our allergy clinic was 6% (182/3033). The most common diagnoses in patients were 41.8% allergic rhinitis, 25.8% asthma, and 13.2% allergic rhinitis + asthma. Allergic rhinitis symptoms were the most prevalent symptom associated with cat contact (29.4%), whereas 28% of the patients were asymptomatic. Only 17.3% had a cat at home and 13.4% had cat exposure apart from home but having a cat at home was significantly higher than the control groups (p < 0.05). Eosinophilia was present in 54.6% of the patients, and 17.3% had blood tIgE levels of >1000 IU/mL. Eosinophilia and tIgE levels were significantly higher than both control groups (p < 0.05).

DISCUSSION

Cat ownership can affect the development of cat sensitivity but the majority of patients with cat sensitivity are not cat owners. Elevated tIgE levels (> 1000 IU/mL) may be associated with cat sensitivity, these patients should be evaluated for cat sensitivity, even if they do not report symptoms with cat contact.

Effects of mechanical washing and drying on the removal of pet allergens

Background: In Korea, the number of households with indoor pets is rapidly increasing in parallel with changes in cultural lifestyles. The sensitization rate of pet allergens is also increasing in Korea. Objective: We evaluated the effectiveness of washing machines to remove dog and cat hair and their allergens. In addition, this study aimed to investigate whether only a mechanical dryer without mechanical washing could be used for pet allergen removal. Method: We brushed cats and dogs, and thereafter collected their hair and used a residential vacuum cleaner to obtain dust and other particulate matter from a household. The contents of the vacuum bag were sifted through a 300-μm sieve filter. Some of the contents were placed in phosphate-buffered saline solution with 0.5% Tween 20 to make a liquid extract. Hair, dust, and liquid extract-contaminated fabric samples after mechanical washing or after drying without mechanical washing were analyzed for pet allergens (Fel d l [cat], Can f 1 [dog]) by using a two-site enzyme-linked immunosorbent assay. We assessed the remaining allergens in the contaminated fabrics after mechanical drying and washing. Results: The mean Fel d l and mean Can f 1 removal ratios after mechanical washing with detergent were > 99.99% for the dust, hair, and liquid extract. The removal ratios after mechanical washing without a detergent were lower for both Fel d 1 and Can f 1, for hair, dust, and their respective liquid extracts (p < 0.05). Mechanical drying was just as effective as mechanical washing with detergent for removing Can f 1 but was less effective for Fel d 1 (p < 0.05). Conclusion: Mechanical washing with detergent is important to remove pet allergens from contaminated fabrics. If washing is difficult, then using just a dryer without washing can be an alternative method to remove allergens from contaminated bedding or clothing.

Asthmatic patient's preferences regarding frequency of physician consultation

Background & Objective

To identify patient’s factors from their clinical picture and demographics, and recognize their association and influence on frequency of physician visit.

Method

Study was conducted in Karachi from January – December 2019. Primary data was collected from 255 asthmatic patients that visited different hospitals, homeopathic and herbal clinics. Questionnaire included patient’s demographic details, treatment choice for asthma and satisfaction level with different treatments. Collected data was analyzed by SPSS 20.

Result

Among 255 asthmatic patients, 101 visited 5 – 7 times to physician from the past year, 48 visited 8–10 times and 27 went to physician more than 10 times in past 12 months. While 30 patients did not visit the physician even once and only 20 patients visited 1–2 times in the last year. From clinical factors, association of severity (p = 0.0001), limitation (p = 0.0001) and side effects (p = 0.003) with physician visit were found to be statistically significant. In addition, among demographics, age (p = 0.004), education (p = 0.0001), income (p = 0.0001) and having pets (p = 0.007) were found to be significant factors associated with physician visit for asthma in the past year.

Conclusion

Most of the asthmatic patients covered in the study visited the physician more than five times during the last year and chose allopathic treatment for asthma. Age, education, severity and side effects of asthma treatment were some of the significant factors associated with physician visit. Patients with frequent follow up visits to the physician were satisfied with their treatment.

Furry pet-related wheeze and rhinitis in pre-school children across China: Associations with early life dampness and mould, furry pet keeping, outdoor temperature, PM10 and PM2.5

BACKGROUND

Few Chinese population studies exist on early life risk factors for furry pet allergy.

OBJECTIVES

We studied childhood respiratory symptoms when in contact with furry pets in relation to early life exposure. Moreover, we studied similar environmental associations for rhinitis not related to furry pets.

METHODS

Children aged 3-6 y from day care centres in seven Chinese cities participated (N = 39,782). Parents answered a questionnaire on home environment and children's health, including rhinoconjunctivitis and wheeze when in contact with furry pets, and diagnosed rhinitis. Prenatal and postnatal outdoor temperature, PM_2.5, PM₁₀, and NO₂ were calculated using data from monitoring stations. Associations were estimated by multilevel logistic regression.

RESULTS

Totally 2% had cats, 4% dogs, and 3.2% had rhinoconjunctivitis or wheeze when in contact with furry pets (FP symptoms). Moreover, 1.1% had furry pet related diagnosed rhinitis and 7.5% had diagnosed rhinitis not related to furry pets (other diagnosed rhinitis). Prenatal PM_2.5 and PM₁₀, especially in second trimester, and a colder climate were risk factors for FP symptoms. ETS, dampness and mould, condensation on windows in wintertime, and cats and dog keeping were associated with FP symptoms. Breast feeding and frequent window opening were protective. Similar indoor associations were found for furry pet related diagnosed rhinitis. ETS, dampness and mould, window condensation, urbanization and mechanical exhaust ventilation were risk factors for other diagnosed rhinitis. Cooking with an electric stove and early life exposure to animals (cats, dogs, farm environment during pregnancy) were protective for diagnosed rhinitis not related to furry pets.

CONCLUSIONS

Prenatal outdoor PM₁₀ and PM_2.5 can be risk factors for symptoms suggestive of furry pet allergy. Early life dampness and mould can be risk factors for rhinitis related and not related to furry pets. Exposure to animals (cats, dogs, farm environment) may reduce diagnosed rhinitis not related to furry pets.

Maternal Distress During Pregnancy and Recurrence in Early Childhood Predicts Atopic Dermatitis and Asthma in Childhood

BACKGROUND

Early-life stress is becoming an important determinant of immune system programming. Maternal prenatal distress is found to be associated with atopic disease in offspring but the separate effects of postnatal distress are not well-studied.

RESEARCH QUESTION

Does the likelihood of asthma and atopic dermatitis in children increase when they are exposed to maternal distress pre- and postnatally in a sex-specific manner?

STUDY DESIGN AND METHODS

Using data from a provincial newborn screen and health-care database for 12,587 children born in 2004, maternal distress (depression or anxiety) was defined as prenatal, self-limiting, recurrent, or late-onset postpartum. Atopic dermatitis (AD) and asthma at ages 5 years and 7 years of age were diagnosed by using hospitalization, physician visit, or prescription records. Associations between maternal distress and childhood asthma and AD were determined by using multiple logistic regression.

RESULTS

After adjusting for risk factors, a significant association between maternal prenatal (OR, 1.27; 95% CI, 1.11-1.46), recurrent postpartum (OR, 1.28; 95% CI, 1.11-1.48), and late-onset postpartum (OR, 1.19, 95% CI, 1.06-1.34) distress was found with AD at age 5 years. Asthma at age 7 years was also associated with maternal prenatal distress (OR, 1.57; 95% CI, 1.29-1.91) and late-onset postnatal distress (OR, 1.22; 95% CI, 1.01-1.46). Self-limiting postnatal distress was not found to be a risk factor for either atopic condition. Associations with AD or asthma were of a similar magnitude in boys and girls; the exception was recurrent postnatal distress, which increased risk for asthma in boys only.

INTERPRETATION

This population-based study provides evidence for sex-specific associations between maternal prenatal and postnatal distress, as well as the development of AD and asthma. The findings support recommendations for greater psychosocial support of mothers during pregnancy and early childhood to prevent childhood atopic disease.

Indoor Particulate Matter From Smoker Homes Induces Bacterial Growth, Biofilm Formation, and Impairs Airway Antimicrobial Activity. A Pilot Study

Background: Particulate matter (PM) air pollution causes deleterious health effects; however, less is known about health effects of indoor air particulate matter (IAP). Objective: To understand whether IAP influences distinct mechanisms in the development of respiratory tract infections, including bacterial growth, biofilm formation, and innate immunity. Additionally, we tested whether IAP from Iowa houses of subjects with and without recent respiratory exacerbations recapitulated the National Institute of Standards and Technology (NIST) IAP findings. Methods: To test the effect of NIST and Iowa IAP on bacterial growth and biofilm formation, we assessed Staphylococcus aureus growth and Pseudomonas aeruginosa biofilm formation with and without the presence of IAP. To assess the effect of IAP on innate immunity, we exposed primary human airway surface liquid (ASL) to NIST, and Iowa IAP. Lastly, we tested whether specific metals may be responsible for effects on airway innate immunity. Results: NIST and Iowa IAP significantly enhanced bacterial growth and biofilm formation. NIST IAP (whole particle and the soluble portion) impaired ASL antimicrobial activity. IAP from one Iowa home significantly impaired ASL antimicrobial activity (p < 0.05), and five other homes demonstrated a trend (p ≤ 0.18) of impaired ASL antimicrobial activity. IAP from homes of subjects with a recent history of respiratory exacerbation tended (p = 0.09) to impair ASL antimicrobial activity more than IAP from homes of those without a history respiratory exacerbation. Aluminum and Magnesium impaired ASL antimicrobial activity, while copper was bactericidal. Combining metals varied their effect on ASL antimicrobial activity. Conclusions: NIST IAP and Iowa IAP enhanced bacterial growth and biofilm formation. ASL antimicrobial activity was impaired by NIST IAP, and Iowa house IAP from subjects with recent respiratory exacerbation tended to impair ASL antimicrobial activity. Individual metals may explain impaired ASL antimicrobial activity; however, antimicrobial activity in the presence of multiple metals warrants further study.

Crystal structure of the dog allergen Can f 6 and structure-based implications of its cross-reactivity with the cat allergen Fel d 4

Several dog allergens cause allergic reactions in humans worldwide. Seven distinct dog allergens, designated Canis familiaris allergen 1 to 7 (Can f 1-Can f 7), have been identified thus far. Can f 6 shows high sequence similarity and cross-reactivity with Fel d 4 and Equ c 1, major cat and horse allergens, respectively. This study was conducted on the allergenic epitopes of Can f 6 based on its structural characterization. We demonstrated that sera from 18 out of 38 (47%) dog-sensitized patients reacted to recombinant Can f 6 protein (rCan f 6). We then determined the crystal structure of rCan f 6 by X-ray crystallography, which exhibited a conserved tertiary structural architecture found in lipocalin family proteins. Based on the tertiary structure and sequence similarities with Fel d 4 and Equ c 1, we predicted three IgE-recognizing sites that are possibly involved in cross-reactivity. Substituting three successive amino acids in these sites to triple alanine decreased IgE reactivity to the allergen. However, the degree of reduction in IgE reactivity largely depended on the site mutated and the serum used, suggesting that Can f 6 is a polyvalent allergen containing multiple epitopes and Can f 6-reactive sera contain varied amounts of IgE recognising individual Can f 6 epitopes including those predicted in this study. We also demonstrated that the predicted epitopes are partly involved in IgE cross-reactivity to Fel d 4. Interestingly, the effect of the mutation depended on whether the protein was structured or denatured, indicating that the bona fide tertiary structure of Can f 6 is essential in determining its IgE epitopes.

Crystal structure of the dog allergen Can f 6 and structure-based implications of its cross-reactivity with the cat allergen Fel d 4

Several dog allergens cause allergic reactions in humans worldwide. Seven distinct dog allergens, designated Canis familiaris allergen 1 to 7 (Can f 1-Can f 7), have been identified thus far. Can f 6 shows high sequence similarity and cross-reactivity with Fel d 4 and Equ c 1, major cat and horse allergens, respectively. This study was conducted on the allergenic epitopes of Can f 6 based on its structural characterization. We demonstrated that sera from 18 out of 38 (47%) dog-sensitized patients reacted to recombinant Can f 6 protein (rCan f 6). We then determined the crystal structure of rCan f 6 by X-ray crystallography, which exhibited a conserved tertiary structural architecture found in lipocalin family proteins. Based on the tertiary structure and sequence similarities with Fel d 4 and Equ c 1, we predicted three IgE-recognizing sites that are possibly involved in cross-reactivity. Substituting three successive amino acids in these sites to triple alanine decreased IgE reactivity to the allergen. However, the degree of reduction in IgE reactivity largely depended on the site mutated and the serum used, suggesting that Can f 6 is a polyvalent allergen containing multiple epitopes and Can f 6-reactive sera contain varied amounts of IgE recognising individual Can f 6 epitopes including those predicted in this study. We also demonstrated that the predicted epitopes are partly involved in IgE cross-reactivity to Fel d 4. Interestingly, the effect of the mutation depended on whether the protein was structured or denatured, indicating that the bona fide tertiary structure of Can f 6 is essential in determining its IgE epitopes.

Factors associated with asthma expression in adolescents

Objective:

To evaluate risk factors associated with asthma symptoms in adolescents in the 13- to 14-year age bracket.

Methods:

This was a cross-sectional study involving adolescents enrolled in randomly selected public schools in the city of Belo Horizonte, Brazil, and conducted with the use of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and its supplementary module for risk factor assessment. The ISAAC questionnaire was completed by the students themselves, whereas the supplementary questionnaire was completed by their parents or legal guardians. Variables showing p ≤ 0.25 in the univariate analysis were included in the multivariate analysis. Stepwise regression with backward elimination was used for variable selection.

Results:

We evaluated 375 adolescents, 124 (33.1%) of whom had asthma symptoms. The final multivariate analysis model revealed that asthma symptoms were associated with birth weight < 2,500 g (p < 0.001), day care center or nursery attendance (p < 0.002), maternal history of asthma (p < 0.001), contact with animals during the first year of life (p < 0.027), current contact with animals outside the home (dogs, cats, or farm animals; p < 0.005), and more than 20 cigarettes per day smoked by parents or other household members (p < 0.02).

Conclusions:

Exposure to animals in and outside the home is associated with asthma symptoms, as is environmental tobacco smoke exposure. Families, health professionals, and administrators of health care facilities should take that into account in order to prevent asthma and reduce asthma morbidity.

Parental and child factors associated with inhalant and food allergy in a population-based prospective cohort study: the Generation R Study

The prevalence of allergic diseases in children is markedly increasing to epidemic proportions. The aim of this study is to describe the presence and examine associated parental and child characteristics of allergic sensitization and physician-diagnosed allergy in Dutch children at age 10 years. This study among 5471 children was performed in a population-based prospective cohort from fetal life onwards. Allergic sensitization was measured by skin prick tests. Physician-diagnosed allergy and parental and child characteristics were collected by questionnaires. In children aged 10 years, inhalant and food allergic sensitization was present in 32.2% and 7.1%, and physician-diagnosed inhalant and food allergy in 12.4% and 2.3%. Maternal and paternal history of allergy, eczema or asthma was associated with increased risks of physician-diagnosed inhalant allergy (aOR (95% CI) 1.44 (1.23-1.70) and 1.59 (1.30-1.94), respectively), but not with food allergy. Asthma and eczema ever at age 10 years were associated with increased risks of physician-diagnosed inhalant allergy (4.60 (3.55-5.96) and 2.42 (1.94-3.03), respectively). Eczema ever at age 10 years was associated with an increased risk of physician-diagnosed food allergy (5.78, 3.04-9.52), with the highest risk of cashew (7.36, 3.20-16.94) and peanut (5.58, 3.08-10.10) food allergy.Conclusions: We found strong effects of parental history of allergy, eczema or asthma on the presence of physician-diagnosed inhalant allergy in children at age 10 years. Eczema ever at age 10 years was a strong risk factor for the development of physician-diagnosed inhalant and food allergy. What is Known: • The prevalence of allergic diseases in children has markedly increased. • Early-life influences are critically important in the development of allergic diseases. What is New: • Maternal and paternal history of allergy, eczema or asthma is associated with increased risks of physician-diagnosed inhalant allergy but not with food allergy. • Eczema ever at age 10 years is associated with an increased risk of physician-diagnosed food allergy, with the highest risk for cashew and peanut food allergy.

Modeling household transmission dynamics: Application to waterborne diarrheal disease in Central Africa

Introduction

We describe a method for analyzing the within-household network dynamics of a disease transmission. We apply it to analyze the occurrences of endemic diarrheal disease in Cameroon, Central Africa based on observational, cross-sectional data available from household health surveys.

Methods

To analyze the data, we apply formalism of the dynamic SID (susceptible-infected-diseased) process that describes the disease steady-state while adjusting for the household age-structure and environment contamination, such as water contamination. The SID transmission rates are estimated via MCMC method with the help of the so-called synthetic likelihood approach.

Results

The SID model is fitted to a dataset on diarrhea occurrence from 63 households in Cameroon. We show that the model allows for quantification of the effects of drinking water contamination on both transmission and recovery rates for household diarrheal disease occurrence as well as for estimation of the rate of silent (unobserved) infections.

Conclusions

The new estimation method appears capable of genuinely capturing the complex dynamics of disease transmission across various human, animal and environmental compartments at the household level. Our approach is quite general and can be used in other epidemiological settings where it is desirable to fit transmission rates using cross-sectional data.

Software sharing

The R-scripts for carrying out the computational analysis described in the paper are available at https://github.com/cbskust/SID.

Consensus document on dog and cat allergy

The prevalence of sensitization to dogs and cats varies by country, exposure time and predisposition to atopy. It is estimated that 26% of European adults coming to the clinic for suspected allergy to inhalant allergens are sensitized to cats and 27% to dogs. This document is intended to be a useful tool for clinicians involved in the management of people with dog or cat allergy. It was prepared from a consensus process based on the RAND/UCLA method. Following a literature review, it proposes various recommendations concerning the diagnosis and treatment of these patients, grounded in evidence and clinical experience. The diagnosis of dog and cat allergy is based on a medical history and physical examination that are consistent with each other and is confirmed with positive results on specific IgE skin tests. Sometimes, especially in polysensitized patients, molecular diagnosis is strongly recommended. Although the most advisable measure would be to avoid the animal, this is often impossible and associated with a major emotional impact. Furthermore, indirect exposure to allergens occurs in environments in which animals are not present. Immunotherapy is emerging as a potential solution to this problem, although further supporting studies are needed.

Prevalence of Irritable Bowel Syndrome in Singapore and Its Association with Dietary, Lifestyle, and Environmental Factors

Background/Aims

The prevalence of irritable bowel syndrome (IBS) has risen considerably over the past decade in Singapore. We aim to explore the contribution of changes in diet, lifestyle and habits that may contribute to the increased prevalence and development of IBS.

Methods

This is a survey-based cross-sectional population study aimed to gather demographic, socio-economical, lifestyle, dietary, antibiotic usage and other related information. Subjects were adult male or female Singaporeans aged 21 years or above. Association of the factors gathered with the presence or absence of IBS (by Rome III criteria) was assessed using chi-square or Fisher's exact test. Variables with a level of statistical significance of 0.1 or less in the univariate analysis were entered into a stepwise logistic regression model.

Results

A total of 297 subjects participated in the study (female 60.3%). Overall, 20.9% subjects fulfilled the Rome III IBS criteria. Univariate analysis showed that IBS was associated with pet ownership, antibiotic usage, late dinner, (> 9 PM) and consumption of Western meals, coffee, and bread. The multivariate logistic regression analyses showed that IBS was independently associated with being a pet owner (P = 0.008; OR, 2.5; 95% CI, 1.278-5.037).

Conclusions

The prevalence of IBS was 20.9% using the Rome III criteria in our study. The association between IBS and pet ownership will need further investigation.

Allergy associations with the adult fecal microbiota: Analysis of the American Gut Project

BACKGROUND

Alteration of the gut microbial population (dysbiosis) may increase the risk for allergies and other conditions. This study sought to clarify the relationship of dysbiosis with allergies in adults.

METHODS

Publicly available American Gut Project questionnaire and fecal 16S rRNA sequence data were analyzed. Fecal microbiota richness (number of observed species) and composition (UniFrac) were used to compare adults with versus without allergy to foods (peanuts, tree nuts, shellfish, other) and non-foods (drug, bee sting, dander, asthma, seasonal, eczema). Logistic and Poisson regression models adjusted for potential confounders. Odds ratios and 95% confidence intervals (CI) were calculated for lowest vs highest richness tertile. Taxonomy associations considered 122 non-redundant taxa (of 2379 total taxa) with ≥ 0.1% mean abundance.

RESULTS

Self-reported allergy prevalence among the 1879 participants (mean age, 45.5 years; 46.9% male) was 81.5%, ranging from 2.5% for peanuts to 40.5% for seasonal. Fecal microbiota richness was markedly lower with total allergies (P = 10(-9)) and five particular allergies (P ≤ 10(-4)). Richness odds ratios were 1.7 (CI 1.3-2.2) with seasonal, 1.8 (CI 1.3-2.5) with drug, and 7.8 (CI 2.3-26.5) with peanut allergy. These allergic participants also had markedly altered microbial community composition (unweighted UniFrac, P = 10(-4) to 10(-7)). Total food and non-food allergies were significantly associated with 7 and 9 altered taxa, respectively. The dysbiosis was most marked with nut and seasonal allergies, driven by higher Bacteroidales and reduced Clostridiales taxa.

INTERPRETATION

American adults with allergies, especially to nuts and seasonal pollen, have low diversity, reduced Clostridiales, and increased Bacteroidales in their gut microbiota. This dysbiosis might be targeted to improve treatment or prevention of allergy.

To what extent is allergen exposure a risk factor for the development of allergic disease?

The role of allergen exposure in the development of allergic disease has been a matter of considerable debate, and our understanding of the importance of allergens has evolved over the last 25 years. Several observational and primary prevention studies have investigated these relationships, and different studies reported inconsistent, and sometimes opposite findings. It has to be emphasized that a clear understanding of how aeroallergen exposure occurs, and accurate and reproducible measurement of exposure are essential prerequisites for understanding the role of exposure. However, our current understanding of how we get exposed to allergens is not based on solid evidence, but on a number of assumptions, and we urgently need to develop better proxy measures (or indices) of exposure. In addition, the relative importance of the timing of exposure (e.g. early compared to exposure in later life) is unknown. It is also unclear which route of exposure is the most relevant (e.g. inhaled vs. oral vs. transcutaneous). Available data suggest that the dose-response relationship between allergen exposure and allergic disease may differ between different allergens, dose ranges and exposure patterns, and these relationships may further differ between different populations and geographical areas. It is increasingly clear that childhood asthma and atopy are not single phenotypes, and it is likely that allergen exposure has different effect on distinct subgroups under the umbrella terms of 'sensitization' and 'asthma'. Susceptibility to allergen exposure, other environmental exposures and their interactions may also differ between individuals with different genetic predispositions. However, the precise nature of these complex relationships is unclear. We need a holistic approach offered by systems biology, with integration of information on the standardized and reliable measures of exposures (including allergens and other relevant exposures) with genetic and biological data to fully understand the role of allergens in the development of allergic disease.

Predictors of microbial agents in dust and respiratory health in the Ecrhs

Background

Dampness and mould exposure have been repeatedly associated with respiratory health. However, less is known about the specific agents provoking or arresting health effects in adult populations. We aimed to assess predictors of microbial agents in mattress dust throughout Europe and to investigate associations between microbial exposures, home characteristics and respiratory health.

Methods

Seven different fungal and bacterial parameters were assessed in mattress dust from 956 adult ECRHS II participants in addition to interview based home characteristics. Associations between microbial parameters and the asthma score and lung function were examined using mixed negative binomial regression and linear mixed models, respectively.

Results

Indoor dampness and pet keeping were significant predictors for higher microbial agent concentrations in mattress dust. Current mould and condensation in the bedroom were significantly associated with lung function decline and current mould at home was positively associated with the asthma score. Higher concentrations of muramic acid were associated with higher mean ratios of the asthma score (aMR 1.37, 95%CI 1.17-1.61). There was no evidence for any association between fungal and bacterial components and lung function.

Conclusion

Indoor dampness was associated with microbial levels in mattress dust which in turn was positively associated with asthma symptoms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0042-y) contains supplementary material, which is available to authorized users.

The role of the early-life environment in the development of allergic disease

A consensus has been reached that the development of allergic disorders is strongly influenced by early life exposures. An overview of several prenatal and early life factors that have been investigated for their associations with development of childhood allergy is presented. Delivery mode, the gut microbiome, vitamin D, folate, breastfeeding, pets, antibiotics, environmental tobacco smoke, and airborne traffic pollutants are discussed. Although many studies suggest an effect, overall, no risk factors clearly increase or reduce the risk of allergic outcomes.

Childhood asthma-predictive phenotype

Wheezing is a fairly common symptom in early childhood, but only some of these toddlers will experience continued wheezing symptoms in later childhood. The definition of the asthma-predictive phenotype is in children with frequent, recurrent wheezing in early life who have risk factors associated with the continuation of asthma symptoms in later life. Several asthma-predictive phenotypes were developed retrospectively based on large, longitudinal cohort studies; however, it can be difficult to differentiate these phenotypes clinically as the expression of symptoms, and risk factors can change with time. Genetic, environmental, developmental, and host factors and their interactions may contribute to the development, severity, and persistence of the asthma phenotype over time. Key characteristics that distinguish the childhood asthma-predictive phenotype include the following: male sex; a history of wheezing, with lower respiratory tract infections; history of parental asthma; history of atopic dermatitis; eosinophilia; early sensitization to food or aeroallergens; or lower lung function in early life.

Association between pet ownership and the sensitization to pet allergens in adults with various allergic diseases

Purpose

As pet ownership increases, sensitization to animal allergens due to domestic exposure is a concern. Sensitization to animal allergens may occur from indirect exposure, as well as direct ownership of animals. However, there have been conflicting results regarding the association between pet ownership and sensitization to animal allergens in adults.

Methods

In total, 401 patients with various allergic diseases were enrolled in this study. We performed skin prick tests with 55 common inhalant and food allergens, including dog, cat, and rabbit allergens. A mean wheal diameter of 3 mm or greater was considered a positive reaction. The exposure modality to each animal allergen was investigated using a questionnaire and included present ownership, past ownership, occupational exposure, occasional exposure, contact with pet owner, and no contact. Present ownership, past ownership, occupational, and occasional exposure were regarded as direct exposure.

Results

The sensitization rate for animal allergens was 20.4% for dog, 15.0% for cat, and 9.0% for rabbit. Direct exposure to dogs (72.0%) was significantly higher than that of other animals (18.4% for cats and 16.7% for rabbits), whereas 'no contact' with cats (78.3%) and rabbits (83.3%) was significantly higher than with dogs (26.8%; P<0.0001). Independent risk factors for sensitization to animal allergens were sensitization to Dermatophagoides pteronyssinus (OR=2.4, P=0.052), Dermatophagoides farinae (OR=5.1, P<0.001), cat (OR=4.4, P<0.0001), and direct exposure to dogs (OR=1.5, P=0.029) for dog, and sensitization to dog (OR=4.4, P<0.0001) and rabbit (OR=2.6, P=0.036) for cats. Finally, for rabbits, the independent risk factor was sensitization to Alternaria (OR=6.0, P<0.002).

Conclusions

These results suggest that direct exposure to dogs contributes to the sensitization to dog allergens in patients with allergic diseases, whereas indirect exposure to cats and rabbits may induce sensitization to each animal's allergen.

Controversial role of pets in the development of atopy in children

BACKGROUND

Exposure to environmental allergens originating from different sources has been implicated in the sensitization to the respective allergens and development of atopic diseases. Keeping domestic animals is associated with exposure to relevant allergens but there are controversial data whether this exposure promotes or protects from the development of atopy.

DATA SOURCES

We herein reviewed the literature regarding the available data for the exposure to pets (cats and/or dogs) and the development of atopy. For this purpose, we searched the PubMed database.

RESULTS

This review attempts to answer the following questions that arise from the daily practice and the relevant studies, which are: a) is pet keeping associated with sensitization? b) is there an association between keeping pets and the development of asthma, allergic rhinitis and eczema, and, c) what is the underlying mechanism of any possible protective association? Despite the fact that several studies and meta-analyses have been conducted to explore the role of pets in the development of atopy, there are still conflicting pieces of evidence. It seems that there are different effects depending on the type of pets, the time and duration of exposure, and the genetic background of the individual.

CONCLUSION

Further appropriately designed birth cohort studies are needed to explore whether exposure to relevant allergens from pets promotes or protects from the development of atopy.

Sensitization to pets is a major determinant of persistent asthma and new asthma onset in Sweden

INTRODUCTION

Our knowledge about atopy as a longitudinal predictor of asthma is limited. The purpose of this study was to investigate the prognosis of asthma and risk factors for asthma onset, especially sensitization of specific allergens in a population sample.

MATERIAL AND METHODS

A cohort responded to a respiratory questionnaire in 1990 and 2003. At baseline, 2,060 subjects who, in the screening questionnaire, reported respiratory symptoms and 482 controls were investigated with interviews, spirometry, and skin-prick test. A total of 721 asthmatics and 976 subjects without respiratory disease were clinically verified. At follow-up in 2003, 340 subjects with persistent asthma and 186 subjects with asthma remission were identified, while 76 subjects reported new asthma onset.

RESULTS

Sensitization to pets and a high symptom score were significant determinants of persistent asthma (odds ratio (OR) 3.2 (95% CI 1.9-5.6) and 5.7 (2.5-13.3), respectively) and onset of asthma (OR 2.6 (1.1-6.0), and 1.7 (1.2-2.3)). A high self-reported responsiveness to airway irritants (OR 1.6 (1.1-2.2)), and more asthma medications (OR 2.0 (1.3-2.9)) were additional indicators of persistent asthma at the follow-up. Belonging to the older age group decreased the risk both of having persistent asthma and asthma onset.

DISCUSSION

Asthmatics sensitized to pets have a more severe outcome than asthmatics not sensitized to pets. Sensitization to pets was also a strong predictor for onset of asthma. Special attention should be given to asthmatics who report having severe symptoms and problems with airway irritants as such patients are more likely to have persistent problems.

Respiratory health in home and leisure pursuits

Many home-based and leisure activities can generate hazardous respirable exposures. Routine domestic activities and a variety of hobbies, avocations, and leisure pursuits have been associated with a spectrum of respiratory tract disorders. Indoor environments present a special risk for high-intensity exposures and adverse health effects. There are important knowledge gaps regarding the prevalence of specific health hazards within and across communities, exposure-response effects, population and individual susceptibilities, best management strategies, the adverse health effects of mixed exposures, and long-term clinical outcomes following exposures. The home environment presents special health risks that should be part of the health assessment.

Genetic variation of ITGB3 is associated with asthma in Chinese Han children

Previous studies have demonstrated that integrins are involved in the aetiology of asthma. Several single-nucleotide polymorphisms (SNPs) in the integrin β3 (ITGB3) gene are significantly associated with asthma in Western populations. Given the important roles of environmental exposures in the development of asthma, we evaluated the associations between six SNPs in ITGB3 and asthma in Chinese Han children. A total of 321 unrelated Chinese children with asthma and 315 healthy children were recruited for the study. SNP genotyping was performed by high-resolution melting analysis (HRM). The selected SNPs were well genotyped by HRM, and SNP rs3809865 in the 3′ untranslated region (3′UTR) of ITGB3 was found to be strongly associated with asthma (adjusted p = 0.004). The minor allele of rs3809865 showed a protective effect against asthma (OR: 0.59; 95% CI: 0.43–0.8). The seed regions of two miRNAs (hsa-mir-124 and hsa-mir-506) were predicted to bind to the sequence containing rs3809865 by TargetScan and PITA. Luciferase reporter assays demonstrated that the T allele of rs3809865 was more efficiently targeted by hsa-mir-124 than was the A allele, which suggested that rs3809865 could affect the binding of hsa-mir-124 to ITGB3. Furthermore, the transfection of A549 cells with hsa-mir-124 resulted in the downregulation of ITGB3 expression. Our results revealed that rs3809865 was significantly associated with asthma due to its effect on the binding of hsa-mir-124 to ITGB3.

An approach to preschool wheezing: to label as asthma?

Asthma is considered a chronic disease, but not all preschool wheezing is asthma since most will eventually grow out of their symptoms. Although still a matter of debate, preschool wheezing can be classified in 2 major groups: virus-induced wheezing and multitrigger wheezing, having a different prognosis and a different treatment approach. Virus-induced wheezing is the most common phenotype of preschool wheezing and is usually associated with a good prognosis. Treatment should be conservative, but if preventive treatment is required, leukotriene-receptor antagonists might be the first choice treatment. Multitrigger wheezing is associated with an allergic disposition and has a higher risk of persistent symptoms. Inhaled corticosteroids may give short-term reduction in exacerbations, but the beneficial effect of long-term use of inhaled corticosteroids and other anti-inflammatory agents have not yet been established. This review aims to give an opinion on preschool wheezing, and its association with asthma.

Exposure to cats and dogs, and symptoms of asthma, rhinoconjunctivitis, and eczema

BACKGROUND

Associations between exposure to cats and dogs and respiratory and allergic outcomes in children have been reported in affluent countries, but little is known about such associations in less-affluent countries.

METHODS

The International Study of Asthma and Allergies in Childhood, phase 3 was carried out in children aged 6-7 years and adolescents aged 13-14 years across the world. Questions about cats and dogs in the home were included in an additional questionnaire. Using logistic regression, we investigated the association between such exposures and symptoms of asthma, rhinoconjunctivitis, and eczema. Adjustments were made for sex, region of the world, language, gross national income per capita, and 10 other covariates.

RESULTS

Among children (6-7 years of age), cat exposure in the first year of life was associated with current symptoms of asthma, wheeze, rhinoconjunctivitis, and eczema, especially in less-affluent countries. Among adolescents (13-14 years of age), we found a positive association between exposure to cats or dogs and symptom prevalence in more-affluent and less-affluent countries. The global multivariate odds ratios for children with complete covariate data were 1.17 (95% confidence interval = 1.08-1.29) for current symptoms of asthma, 1.13 (1.05-1.23) for rhinoconjunctivitis, and 1.38 (1.26-1.52) for eczema. Smaller odds ratios were found for exposure to only dogs. Exposure to only cats was associated with eczema.

CONCLUSION

Early-life exposure to cats is a risk factor for symptoms of asthma, rhinoconjunctivitis, and eczema in 6- to 7-year-old children, especially in less-affluent countries. Current exposure to cats and dogs combined, and only to dogs, is a risk factor for symptom reporting by 13- to 14-year-old adolescents worldwide.

Gene-environment interactions in the development of asthma and atopy

Asthma is a complex multifactorial disorder involving a variety of different mechanisms. Little has changed in asthma treatment over the past five decades. There is evidence for a strong genetic component of asthma, but genetic studies have produced heterogeneous results with little replication, with most of the heritability remaining unexplained. The rapid increase in asthma prevalence over a short time period suggests that environmental exposures play an important role, but there is a considerable heterogeneity in the results describing the effect of different environmental exposures. There are many reasons for the lack of replication in genetic association studies and those of environmental exposures. These include the failure to consider that asthma may arise as a consequence of environmental factors, modulating the risk in genetically susceptible individuals via gene-environment interactions. In addition, many studies rely on oversimplified phenotypes often derived through aggregation of several heterogeneous conditions (e.g., 'physician-diagnosed asthma').

Does pet ownership in infancy lead to asthma or allergy at school age? Pooled analysis of individual participant data from 11 European birth cohorts

OBJECTIVE

To examine the associations between pet keeping in early childhood and asthma and allergies in children aged 6-10 years.

DESIGN

Pooled analysis of individual participant data of 11 prospective European birth cohorts that recruited a total of over 22,000 children in the 1990s. EXPOSURE DEFINITION: Ownership of only cats, dogs, birds, rodents, or cats/dogs combined during the first 2 years of life. OUTCOME DEFINITION: Current asthma (primary outcome), allergic asthma, allergic rhinitis and allergic sensitization during 6-10 years of age.

DATA SYNTHESIS

Three-step approach: (i) Common definition of outcome and exposure variables across cohorts; (ii) calculation of adjusted effect estimates for each cohort; (iii) pooling of effect estimates by using random effects meta-analysis models.

RESULTS

We found no association between furry and feathered pet keeping early in life and asthma in school age. For example, the odds ratio for asthma comparing cat ownership with "no pets" (10 studies, 11489 participants) was 1.00 (95% confidence interval 0.78 to 1.28) (I(2) = 9%; p = 0.36). The odds ratio for asthma comparing dog ownership with "no pets" (9 studies, 11433 participants) was 0.77 (0.58 to 1.03) (I(2) = 0%, p = 0.89). Owning both cat(s) and dog(s) compared to "no pets" resulted in an odds ratio of 1.04 (0.59 to 1.84) (I(2) = 33%, p = 0.18). Similarly, for allergic asthma and for allergic rhinitis we did not find associations regarding any type of pet ownership early in life. However, we found some evidence for an association between ownership of furry pets during the first 2 years of life and reduced likelihood of becoming sensitized to aero-allergens.

CONCLUSIONS

Pet ownership in early life did not appear to either increase or reduce the risk of asthma or allergic rhinitis symptoms in children aged 6-10. Advice from health care practitioners to avoid or to specifically acquire pets for primary prevention of asthma or allergic rhinitis in children should not be given.

Intraregional differences in asthma prevalence and risk factors for asthma among adolescents in Split-Dalmatia County, Croatia

BACKGROUND

Our aim was to assess the differences in intraregional prevalence of asthma in adolescents in Split-Dalmatia County to determine asthma risk factors in our population and estimate the specificity and sensitivity of the questionnaire used.

MATERIAL/METHODS

We conducted the study using the European Community Respiratory Health Survey II short questionnaire supplemented by some questions from the International Study of Asthma in Childhood questionnaire. The participants suspected to have asthma were invited for examination by an asthma specialist who established the final diagnosis of asthma according to the medical history, physical examination, skin-prick tests, and peak flow measurements.

RESULTS

A total of 4027 students (51.2% male) participated in the study. According to the prevalence of wheezing during the last 12 months, asthma prevalence was estimated at 9.7%. The total prevalence of asthma confirmed by an asthma specialist in the selected population was 5.60% (95% CI, 4.93-6.36%); 6.18% in Split (95% CI, 5.37-7.09), 5.63% in Imotski (95% CI, 3.48-8.58), and 2.90% in Sinj (95% CI, 1.67-4.68) (P=0.0028). We found sensitization to aeroallergens and peanuts, and active smoking to be independent risk factors for asthma.

CONCLUSIONS

Split-Dalmatia County has moderate asthma prevalence, with a significant intraregional difference. Asthma prevalence estimated by a questionnaire (9.7%) overestimates the prevalence of asthma confirmed by an asthma specialist (5.6%) in adolescents in Croatia. Our data confirmed the need of a more complex questionnaire to evaluate the accurate prevalence of current asthma or the need for subsequent clinical evaluation of the questionnaire obtained data. Allergic sensitization to aeroallergens and active smoking were important risk factors for asthma.

Allergy in children: practical recommendations of the Finnish Allergy Programme 2008-2018 for prevention, diagnosis, and treatment

The Finnish Allergy Programme 2008-2018 is a comprehensive plan intended to reduce the burden of allergies. One basic goal is to increase immunologic tolerance and change attitudes to encourage health instead of medicalizing common and mild allergy symptoms. The main goals can be listed as to: (i) prevent the development of allergic symptoms; (ii) increase tolerance to allergens; (iii) improve diagnostics; (iv) reduce work-related allergies; (v) allocate resources to manage and prevent exacerbations of severe allergies, and (vi) reduce costs caused by allergic diseases. So far, the Allergy Programme has organized 135 educational meetings for healthcare professionals around Finland. These meetings are multidisciplinary meetings gathering together all healthcare professionals working with allergic diseases. Since the start of the program in spring 2008, more than 7000 participants have taken part. Educational material for patient care has been provided on special Web sites/therapeutic portals, which can be accessed by all physicians caring for allergic patients. Local Allergy Working Groups have been created in different parts of Finland. As a part of the Programme, a set of guidelines for child welfare clinics was prepared. Child welfare clinics have a key role in the screening of illnesses and providing advice to families with a symptomatic child. The guidelines aimed to facilitate pattern recognition and clinical decision making for public health nurses and doctors are described in this paper.

Lifetime dog and cat exposure and dog- and cat-specific sensitization at age 18 years

BACKGROUND

Prior research about whether keeping a dog or cat at home causes allergies to that pet has been limited to outcomes in early childhood.

OBJECTIVE

Evaluate the association between lifetime dog and cat exposure and allergic sensitization to the specific animal at 18 years of age.

METHODS

Participants enrolled in the Detroit Childhood Allergy Study birth cohort during 1987-1989 were contacted at the age 18 years. Sensitization to dog or cat was defined as animal-specific IgE ≥ 0.35 kU/L. Annual interview data from childhood and follow-up interviews at age 18 years were used to determine lifetime indoor dog and cat exposure (indoor was defined when the animal spent >50% of their time inside the house). Exposure was considered in various ways: first year, age groups and cumulative lifetime. Analyses were conducted separately for dogs and cats.

RESULTS

Among males, those with an indoor dog during the first year of life had half the risk [relative risk (RR)=0.50, 95% confidence interval (CI) 0.27, 0.92] of being sensitized to dogs at age 18 compared with those who did not have an indoor dog in the first year. This was also true for males and females born via c-section (RR=0.33, 95% CI 0.07, 0.97). Overall, teens with an indoor cat in the first year of life had a decreased risk (RR=0.52, 95% CI 0.31, 0.90) of being sensitized to cats. Neither cumulative exposure nor exposure at any other particular age was associated with either outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

The first year of life is the critical period during childhood when indoor exposure to dogs or cats influences sensitization to these animals.

Risk factors for asthma onset between the ages of 12 and 40. Results of the FENASMA study

OBJECTIVES

To describe the clinical profile of patients with asthma and to identify possible risk factors for its development in subjects over the age of 12.

PATIENTS AND METHODS

A multicenter study of cases and controls. Recruited for inclusion were case subjects between the ages of 12 and 40 diagnosed with asthma, with an onset of symptoms after the age of 12. Control subjects were selected, with ages between 12 and 40, who did not have childhood asthma and did not present symptoms of asthma at the time of the study.

RESULTS

We evaluated 923 subjects: 247 cases and 671 controls. 54.9% were women. Mean age of the cases was 28.3 ± 8.2; mean age of controls was 30.8 ± 7.1 (p<0.001). In the logistic regression analysis, it was observed that the determining factors for the of the presence of asthma were hypersensitivity to animals or other allergens, presence of rhinitis, family history of asthma, occupational risk/exposure to irritants and the hypersensitivity/intolerance to NSAIDs. In said analysis, it was also demonstrated that age was a protection factor, as well as level of education.

CONCLUSIONS

The risk factors for the development of asthma at an adult age are hypersensitivity to animals or other allergens, rhinitis, family history of asthma, occupational risk/exposure to irritants and the hypersensitivity/intolerance to NSAIDs, while age and level of education are protection factors.

The genetics of asthma and allergic disease: a 21st century perspective

Asthma and allergy are common conditions with complex etiologies involving both genetic and environmental contributions. Recent genome-wide association studies (GWAS) and meta-analyses of GWAS have begun to shed light on both common and distinct pathways that contribute to asthma and allergic diseases. Associations with variation in genes encoding the epithelial cell-derived cytokines, interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), and the IL1RL1 gene encoding the IL-33 receptor, ST2, highlight the central roles for innate immune response pathways that promote the activation and differentiation of T-helper 2 cells in the pathogenesis of both asthma and allergic diseases. In contrast, variation at the 17q21 asthma locus, encoding the ORMDL3 and GSDML genes, is specifically associated with risk for childhood onset asthma. These and other genetic findings are providing a list of well-validated asthma and allergy susceptibility genes that are expanding our understanding of the common and unique biological pathways that are dysregulated in these related conditions. Ongoing studies will continue to broaden our understanding of asthma and allergy and unravel the mechanisms for the development of these complex traits.

Farming environment and prevalence of atopy at age 31: prospective birth cohort study in Finland

BACKGROUND

Cross-sectional studies have shown an association between the farming environment and a decreased risk of atopic sensitization, mainly related to contact with farm animals in the childhood.

OBJECTIVE

Investigate the association of a farming environment, especially farm animal contact, during infancy, with atopic sensitization and allergic diseases at the age of 31.

METHODS

In a prospective birth cohort study, 5509 subjects born in northern Finland in 1966 were followed up at the age of 31. Prenatal exposure to the farming environment was documented before or at birth. At age 31, information on health status and childhood exposure to pets was collected by a questionnaire and skin prick tests were performed.

RESULTS

Being born to a family having farm animals decreased the risk of atopic sensitization [odds ratio (OR) 0.67; 95% confidence interval (CI) 0.56-0.80], atopic eczema ever (OR 0.77; 95% CI 0.66-0.91), doctor-diagnosed asthma ever (OR 0.74; 95% CI 0.55-1.00), allergic rhinitis at age 31 (OR 0.87; 95% CI 0.73-1.03) and allergic conjunctivitis (OR 0.86; 95% CI 0.72-1.02) at age 31. There was a suggestion that the reduced risk of allergic sensitization was particularly evident among the subjects whose mothers worked with farm animals during pregnancy, and that the reduced risk of the above diseases by farm animal exposure was largely explained by the reduced risk of atopy. Having cats and dogs in childhood revealed similar associations as farm animals with atopic sensitization.

CONCLUSION AND CLINICAL RELEVANCE

Contact with farm animals in early childhood reduces the risk of atopic sensitization, doctor-diagnosed asthma and allergic diseases at age 31.

Environmental risk factors in the first year of life and childhood asthma in the Central South of Chile

BACKGROUND

Childhood asthma has a high prevalence in South America--a region of the world currently undergoing a thorough modernization and transition process. Asthma in South America is mainly associated with poor urban environment, which actually may challenge the role of the hygiene hypothesis. We systematically assessed the impact of environmental factors in the first year of life on asthma.

METHODS

A case-control study including 188 asthmatics and 294 hospital-based controls aged 6-15 years was carried out in the Central South of Chile. Parents of study participants completed a computer-assisted interview on environmental factors (such as birth order, day-care attendance, pneumonia infection, regular animal and furry pet contact, and environmental tobacco smoke exposure) in the first year of life and potential confounders. Atopy was assessed using skin prick tests. Multivariate logistic regression models were calculated to assess the association between exposures and asthma, adjusting for potential confounders.

RESULTS

Day-care attendance (OR = 0.31; 95% CI: 0.10, 0.94) and regular farm animal contact (OR = 0.38; 95% CI: 0.17, 0.85) were inversely related to childhood asthma in the logistic regression models. Pneumonia infection (OR = 2.24; 95% CI: 1.21, 4.16) and mold or dampness in the home (OR = 1.87; 95% CI: 1.18, 2.97) in the first year of life were positively associated with asthma.

CONCLUSION

Our results suggest that the hygiene hypothesis is also applicable in the Chilean setting, a South American country in epidemiological transition.

Risk factors and asthma phenotypes in children and adults with seasonal allergic rhinitis

BACKGROUND

There are few data on asthma risk factors and phenotypes in patients with seasonal allergic rhinitis (SAR).

METHODS

Thirty-three children (mean age, 8.27 ± 1.77 years) and 82 adults (mean age, 34.12 ± 10.59 years) with SAR were evaluated for asthma (history, reversibility of bronchial obstruction, increased inhaled nitric oxide). The following asthma risk factors were considered in the multiple regression analysis: male sex, family history of asthma, breastfeeding < 2 months, passive/active smoking, obesity, pets/molds exposure, high total serum immunoglobulin E (IgE), polysensitization (sensitized to 3 seasonal pollens with different structure), mixed sensitization (seasonal and perennial allergens), severe rhinitis (according to the Allergic Rhinitis and its Impact on Asthma guidelines), and lack of allergen-specific immunotherapy (SIT) for rhinitis preceding asthma diagnosis. Asthma phenotypes were characterized using the k-means clustering (silhouette method for cluster validation).

RESULTS

Asthma was diagnosed in 22 (66.7%) children and in 57 (69.5%) adults with SAR. Independent risk factors for asthma were lack of SIT preceding asthma diagnosis, both for children (P = 0.008132) and adults (P = 0.000017), and mixed sensitization for children (P = 0.035694). Asthma phenotypes identified in children according to the associated risk factors were: breastfeeding < 2 months and severe rhinitis in 16 (63.6%) patients; male, polysensitized, and severe rhinitis in 8 (36.4%) patients. Asthma phenotypes in adults were: polysensitization and severe rhinitis in 30 (52.6%) patients; male, exposure to pets, and severe rhinitis in 11 (19.3%) patients; and high total serum IgE and polysensitization in 16 (28.1%) patients.

CONCLUSION

Lack of SIT is an independent risk factor for asthma both in children and adults with SAR, whereas polysensitization is a risk factor only for children. The dominant asthma phenotype in children with SAR is breastfeeding < 2 months and severe rhinitis. In adults with SAR, the dominant asthma phenotype is polysensitization and severe rhinitis.

Effect of household pet ownership on infant immune response and subsequent sensitization

Sensitization to pets is a major risk factor for asthma. There are many reports on the relationship between household pets, sensitization to the pet, and sensitization to other allergens, often with conflicting results. Pet ownership is not random, and household pets are associated with exposures other than pet allergens. We will review some of the evidence regarding the effects of household pets on infant immune responses, focusing on data from birth cohort studies. It remains unclear precisely why some children develop specific sensitizations to pets whilst others do not in the face of equivalent exposures, but it is likely to be due to gene-environment interactions. Further long-term follow-up of children in whom neonatal and infant immune responses have been measured is necessary to understand how these events occur and how they relate to subsequent disease.

Childhood asthma and early life exposure to indoor allergens, endotoxin and beta(1,3)-glucans

BACKGROUND

Divergent results have been reported regarding early life exposure to indoor environmental agents and the risk of asthma and allergic sensitization later in life.

OBJECTIVE

To assess whether early exposure to indoor allergens, beta(1,3)-glucans and endotoxin modifies the risk of allergic diseases at 10 years of age.

METHODS

The concentrations of mite, cat and dog allergens, endotoxin and beta(1,3)-glucans were determined in dust from the homes of 260 two-year-old children with lung function measured at birth (tidal flow volume loops) in the Environment and Childhood Asthma study in Oslo. At 10 years, the health status was assessed in a follow-up study including a structured interview of the parents and an extended clinical examination.

RESULTS

Cat and dog keeping at 2 years of age was reported in 6.5% and 5.5% of the families, respectively. Mite allergens were detected in only 4/260 dust samples. The adjusted odds ratio for asthma at age 10 was 1.20 (95% confidence interval: 1.01-1.43) and 1.22 (1.02-1.46) for bronchial hyperresponsiveness (BHR) per 10 microg/g dust increase in cat allergen exposure at 2 years of age. No association was seen with allergic sensitization. Moreover, endotoxin and beta(1,3)-glucan exposure did not modify the risk of asthma or allergic sensitization. None of the measured environmental factors were associated with lung function at 10 years of age or a relative change in lung function from birth.

CONCLUSION

In a community with a low prevalence of pet keeping and low mite allergen levels, exposure to cat allergens early in life increased the risk of late childhood asthma and BHR, but not the risk of allergic sensitization. No risk modification was seen for dog allergens, endotoxin and beta(1,3)-glucans.

Indoor allergen exposure, sensitization, and development of asthma in a high-risk birth cohort

Contradictory findings have been observed for the association of house dust mite (HDM), cat, and dog allergen exposure with sensitization and asthma. We sought to determine the relationship between exposures to these allergens, at various points during early childhood, and specific sensitization and asthma at age 7 in a high-risk birth cohort. As part of a multi-faceted Canadian intervention program for the primary prevention of asthma in high-risk infants, children were assessed by pediatric allergists at age 7 for asthma and underwent allergy skin prick testing. House dust samples were analyzed for HDM, cat, and dog allergen levels at several time points during years 1 and 7 of life. Multiple logistic regression analyses were carried out for the combined cohort and separately for the control and intervention groups. Exposure to a higher level of HDM allergen in year 1 or year 7 was associated with a higher risk of year 7 sensitization to HDM but not asthma. Exposure to higher levels of cat allergen in year 1 or year 7 did not affect the risk of year 7 sensitization to cat or asthma. Dog ownership, or exposure to higher levels of dog allergen in year 1 or year 7, did not affect the risk of year 7 sensitization to dog; however, year 7 dog allergen exposure (intervention group only) or ownership was associated with increased year 7 asthma risk. Our findings suggest that in high-risk children, there are allergen-specific associations of exposure with sensitization and with asthma; early life-elevated HDM exposure was associated with risk of sensitization but not asthma while the opposite was true for dog exposure.

Do allergic families avoid keeping furry pets?

Studies addressing the relationship between pet keeping and development of asthma and allergies may be influenced by pet avoidance in families with a history of allergic disease. Following a cohort of 1019 children in Oslo till 10 years of age, we studied the association of pet keeping with socio-economic factors and allergic disease in the family. A family history of asthma and rhinoconjunctivitis was not significantly associated with pet ownership at birth or with pet removal by 10 years. Acquiring cats and dogs was less likely if the child had allergic rhinoconjunctivitis, whereas no association was seen with asthma (in any family member). Single parenthood increased the likelihood of acquiring a cat, smoking parents more often had cats or dogs, and having older siblings was associated with keeping dogs and other furry pets. Among 319 families reporting pet avoidance, 70% never had pets, 8% had given up pets, and 22% avoided a particular type of pet only. Twenty-four per cent of the parents failed to retrospectively report pet keeping during the child's first year of life. Overall, allergic rhinitis, but not asthma was associated with actual pet avoidance, whereas the strongest predictors for keeping pets were found to be socio-economic factors.

PRACTICAL IMPLICATIONS

Allergic disease in a child most often does not lead to the removal of the family's furry pet. Pet avoidance is associated with allergic symptoms, but not asthma. Socio-economic factors like parental education, single parenthood and smoking affects the families' decisions on pet keeping, including the type of pets the families will avoid or acquire. The large recall error demonstrated points to the need for prospective data regarding pet keeping.

Contact to cat or dog, allergies and parental education

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

Messages from the Aalst Allergy Study

BACKGROUND

The prevalence of sensitization and allergic disease has increased significantly worldwide. The aim of the "Aalst Allergy Study" was to document prevalences of sensitization and allergic symptoms, and to evaluate the effect of personal and environmental influences on these prevalences in an unbiased Belgian pediatric population.

METHODS

A cross-sectional study was performed in an unbiased population of 2021 Belgian schoolchildren (3.4-14.8 years). Skin prick testing with the most common aeroallergens was performed. Allergic symptoms as well as potential risk factors for sensitization and allergic disease were documented by a parental questionnaire.

RESULTS

The prevalence of sensitization to the most common aeroallergens and the prevalence of allergic diseases (eczema, asthma and rhinoconjunctivitis) were in line with the data in the literature. The association of current allergic symptoms with sensitization was only significant in the children aged > or =6 years. Age, gender, body mass index, bedroom environment and exposure to pets were the factors significantly associated with sensitization and allergic symptoms.

CONCLUSIONS

Our study corroborates the reported prevalences of sensitization and allergic diseases. Moreover the study illustrates the complexity of the search for factors involved in the process of sensitization and allergic disease. The impact of different potential causative factors is not only influenced by mutual interactions of these factors, but also by the existence of distinct subtypes of disease.

Risk factors and prevalence of asthma in schoolchildren in Castellon (Spain): a cross-sectional study

BACKGROUND

Research on potential risk factors of asthma can enhance our understanding of geographic differences and inform decisions on preventive strategies.

METHODS

In 2002, a cross-sectional population-based study was carried out in the area of Castellon (Spain), following the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III methodology. Asthma symptoms and related risk factor questionnaires were completed by parents of 6-7 year-old schoolchildren. Logistic regression was used in the analysis.

RESULTS

Participation rate was 88 % (4492 of 4872 schoolchildren). Prevalence of wheeze in the past year, asthma ever, and physician-diagnosed asthma were 8 %, 7 % and 6 %, respectively. Risk factors independently associated with all three asthma case definitions were history of bronchitis or pneumonia, allergic rhinitis, family members with atopic disease, and residing in an industrialised area. Risk factors for asthma ever and physician-diagnosed asthma were male sex, atopic eczema and presence of a dog at home; exclusive breast-feeding and the presence of another animal (not a dog or cat) were protective factors. Maternal age was inversely related to physician-diagnosed asthma. Residence in an area of heavy truck traffic and the father smoking at home were associated with asthma ever. Risk factors for wheeze in the past year were low social class, history of sinusitis and the father smoking at home.

CONCLUSIONS

Environmental factors are related to the presence of asthma. Preventive measures should be directed to improving air pollution, promoting breast-feeding and reducing smoking in the home.

Exposure to pets and the association with sensitization and allergic disease in Belgian schoolchildren

Prolonged domestic exposure, from birth on, to dog allergen may protect against sensitization.

Exposure to furry pets and the risk of asthma and allergic rhinitis: a meta-analysis

BACKGROUND

Exposure to pets has been implicated as a risk factor for asthma. However, this relation has been difficult to assess in individual studies because of the large potential of selection bias. We sought to examine the association between exposure to furry pets and asthma and allergic rhinitis by means of a meta-analysis.

METHODS

We retrieved studies published in any language by searching systematically Medline (1966-March 2007), Embase, LILACS and ISI Proceedings computerized databases, and by examining manually the references of the original articles and reviews retrieved. We included cohort and case-control studies reporting relative risk estimates and confidence intervals of exposure to cats, dogs and unspecified furry animals and subsequent asthma and allergic rhinitis. We excluded cross-sectional studies and those studies that did not measure exposure but rather sensitization to pets.

RESULTS

Thirty-two studies were included. For asthma, the pooled relative risk related to dog exposure was 1.14 (95% CI 1.01-1.29), that related to exposure to any furry pet was 1.39 (95% CI 1.00-1.95). Among cohort studies, exposure to cats yielded a relative risk of 0.72 (95% CI 0.55-0.93). For rhinitis, the pooled relative risk of exposure to any furry pet was 0.79 (95% CI 0.68-0.93).

CONCLUSIONS

Exposure to cats exerts a slight preventive effect on asthma, an effect that is more pronounced in cohort studies. On the contrary, exposure to dogs increases slightly the risk of asthma. Exposure to furry pets of undermined type is not conclusive. More studies with exact measurement of exposure are needed to elucidate the role of pet exposures in atopic diseases.