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

A systematic review of associations between environmental exposures and development of asthma in children aged up to 9 years

OBJECTIVES

Childhood asthma is a complex condition where many environmental factors are implicated in causation. The aim of this study was to complete a systematic review of the literature describing associations between environmental exposures and the development of asthma in young children.

SETTING

A systematic review of the literature up to November 2013 was conducted using key words agreed by the research team. Abstracts were screened and potentially eligible papers reviewed. Papers describing associations between exposures and exacerbation of pre-existing asthma were not included. Papers were placed into the following predefined categories: secondhand smoke (SHS), inhaled chemicals, damp housing/mould, inhaled allergens, air pollution, domestic combustion, dietary exposures, respiratory virus infection and medications.

PARTICIPANTS

Children aged up to 9 years.

PRIMARY OUTCOMES

Diagnosed asthma and wheeze.

RESULTS

14,691 abstracts were identified, 207 papers reviewed and 135 included in the present review of which 15 were systematic reviews, 6 were meta-analyses and 14 were intervention studies. There was consistent evidence linking exposures to SHS, inhaled chemicals, mould, ambient air pollutants, some deficiencies in maternal diet and respiratory viruses to an increased risk for asthma (OR typically increased by 1.5-2.0). There was less consistent evidence linking exposures to pets, breast feeding and infant dietary exposures to asthma risk, and although there were consistent associations between exposures to antibiotics and paracetamol in early life, these associations might reflect reverse causation. There was good evidence that exposures to house dust mites (in isolation) was not associated with asthma risk. Evidence from observational and intervention studies suggest that interactions between exposures were important to asthma causation, where the effect size was typically 1.5-3.0.

CONCLUSIONS

There are many publications reporting associations between environmental exposures and modest changes in risk for asthma in young children, and this review highlights the complex interactions between exposures that further increase risk.

Cat and dog exposure and respiratory morbidities in cystic fibrosis

OBJECTIVE

To understand the triggers that may impact respiratory health in cystic fibrosis (CF), including the effects of pets, because environmental factors contribute to one-half of the variation in lung function in patients with CF.

STUDY DESIGN

A total of 703 subjects with CF were recruited through the US CF Twin-Sibling Study. Questionnaires were used to determine the presence/absence of cats and dogs in households with a child with CF. Questionnaires, chart review, and US CF Foundation Patient Registry data were used to track respiratory and infection outcomes.

RESULTS

Within the sample, 47% of subjects reported owning a dog, and 28% reported owning a cat. After adjustment for demographic factors, dog ownership was not associated with any adverse clinical outcomes, and cat ownership was associated an increased risk in developing nasal polyps (aOR 1.66; P = .024) compared with noncat owners. Subjects who owned both cats and dogs were twice as likely to report wheezing compared with other subjects (aOR: 2.01; P = .009). There were no differences in prevalence and age of acquisition for the common CF respiratory pathogens Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus between cat/dog owners and noncat/dog owners.

CONCLUSIONS

Cat ownership was associated with a greater frequency of developing nasal polyps and combined cat-dog ownership was associated with a greater rate of wheezing. Prospective studies are needed to confirm these associations and the potential psychosocial benefits of cat and/or dog ownership.

Risk factors affecting asthma prevalence in adolescents living in Istanbul, Turkey

BACKGROUND

Asthma is one of the most important diseases of childhood. The aim of this study was to evaluate the prevalence of asthma symptoms and risk factors affecting asthma.

METHODS

In a cross-sectional study design, 9991 children, aged 13-14 years in 61 primary schools in 32 districts of Istanbul were evaluated. Asthma prevalence among the children was assessed using the ISAAC protocol.

RESULTS

In our study, a total of 10,894 questionnaires were distributed to 13-14 years old children, and of these 9991 questionnaires were suitable for analysis with an overall response rate of 91.7%. The rates of wheeze ever, wheezing in last 12 months and lifetime doctor diagnosed asthma prevalence were 17.4%, 9.0%, and 11.8%, respectively. There were 4746 boys (47.9%) and 5166 girls (52.1%) with M/F ratio of 0.92. Atopic family history, fewer than three siblings living at home, tonsillectomy or adenoidectomy history, consumption of fermented foods, mixed pickles, margarine and meat were found to be associated with an increased asthma risk. Use of paracetamol in the last 12 months, consumption of fruit and animal fats acted as a protective factor against asthma. The Mediterranean-style diet was not associated with the prevalence of asthma.

CONCLUSIONS

Lifetime doctor diagnosed asthma prevalence was found to be 11.8% in 13-14 year olds. History of tonsillectomy and/or adenoidectomy and consumption of fermented foods, mixed pickles, margarine and meat may increase the symptoms of asthma. Usage of paracetamol and consumption of animal fats may be investigated as a protective factor against asthma.

Animal allergen sensitization in veterinarians and laboratory animal workers

BACKGROUND

Animals secrete allergens into the environment and exposure to these in the workplace may cause sensitization.

AIMS

To identify the frequency of animal allergen sensitization and symptoms in animal workers.

METHODS

Using skin prick tests (SPT), we assessed sensitization to 15 mammal and bird allergens in animal workers and controls. We also recorded symptoms and pulmonary function tests.

RESULTS

There were 100 animal workers and 50 controls included in the study. Thirty-six per cent of animal workers and 10% of controls had positive SPT (P < 0.001, odds ratio [OR] = 5.1, 95% CI 1.7-16.0). The most common sensitizations were to horse (16% in animal workers versus 0% in controls, P < 0.01), canary (16% in animal workers versus 2% in controls, P < 0.05, OR = 9.3, 95% CI 1.2-194), cattle (13% in animal workers versus 0% in controls, P < 0.05), cat (12% in animal workers versus 6% in controls, not significant), rabbit and hamster (10% each in animal workers versus 0% in controls, P < 0.05). Allergy symptoms were reported by 52 animal workers, but only 36 of them had positive SPT. Twelve animal workers had abnormal pulmonary function tests and six had positive SPT.

CONCLUSIONS

Animal workers are at high risk of occupational sensitization to animal allergens. Exposure should be minimized through control measures and worker education about the risks of exposure and sensitization.

Early life phthalate exposure and atopic disorders in children: a prospective birth cohort study

The role of phthalate exposure at different stages in the immune system and atopic disorders is not well-known. This study aims to evaluate the effects of prenatal and postnatal phthalate exposures on immunoglobulin E (IgE) levels and atopic dermatitis (AD) in children by objective biomarkers. We conducted a prospective Taiwan Birth Panel cohort study with 483 mother/infant pairs. Finally, 161 urine specimens at 3rd trimester of pregnancy, 219 urine specimens from children at age 2, and 192 urine specimens at age 5 were analyzed after excluding missing data and loss to follow-up. Urine monoethyl phthalate (MEP), monobutyl phthalate (MBP), monobenzyl phthalate (MBzP), and mono-(2-ethylhexyl) phthalate (MEHP) at 3rd trimester of pregnancy and at ages 2 and 5 were measured by ultra-performance liquid chromatography coupled with tandem mass spectrometry. At ages 2 and 5, information on the development of AD and serum total IgE was collected. The association between urine phthalate metabolite levels at different stages and serum IgE and AD was evaluated by multivariate linear regression and logistic regression. Urine phthalate metabolite levels were higher at age 2 than those at pregnancy and age 5. At each period, urine MBP levels were higher than MEP, MEHP, and MBzP. MEHP levels at age 2 positively correlated with serum IgE levels (per ln-unit: β=0.191, p=0.02). Analyses stratified by gender revealed that MEHP levels positively correlated with serum IgE levels only in boys (per ln-unit: β=0.256, p=0.03). When dividing into quartiles, urine MBzP levels at age 2 had a significant association with AD. We found no statistically significant association of other phthalate metabolites with IgE and AD. Early life phthalate exposure may increase the risk of allergic sensitization and atopic disorders.

Association between environmental factors and current asthma, rhinoconjunctivitis and eczema symptoms in school-aged children from Oropeza Province--Bolivia: a cross-sectional study

BACKGROUND

In recent years, the prevalence of asthma, rhinoconjunctivitis and eczema symptoms in childhood has considerably increased in developing countries including Bolivia, possibly due to changes in lifestyle, environmental and domestic factors. This study aimed to assess the association between environmental factors and asthma, rhinoconjuctivitis and eczema symptoms in school-aged children from Oropeza Province in Chuquisaca, Bolivia.

METHODS

A cross-sectional study was performed in 2340 children attending the fifth grade in 36 randomly selected elementary schools in Oropeza province. The prevalence of symptoms was determined using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Environmental factors were assessed by the ISAAC environmental questionnaire including questions related to exposure to pets, farm animals, indoor and outdoor pollution, presence of disease vectors at home and precarious household conditions. Generalized linear mixed-effects models were adjusted for age, sex and place of living.

RESULTS

Thirty seven percent of children reported that at least one of their parents smoked at home. Wood or coal was used as cooking fuel in 19% of the homes and 29% reported intense truck traffic on the street where they lived. With respect to hygiene conditions, 86% reported exposure to dogs, 59% exposure to cats and 36% regular contact to farm animals. More than one precarious household condition was reported by 8% of children. In the adjusted model exposure to dog (adjusted OR 1.4; CI 95% 1.0-1.9), cat (1.2; 1.0-1.5), farm animals (1.5; 1.2-1.8); intense truck traffic (1.3; 1.0-1.6), parents smoking at home (1.2; 1.0-1.5), presence of disease vectors at home (fourth quartile vs. first quartile: 1.6; 1.2-2.3) and two or more precarious household conditions (1.5; 1.0-2.2) were significantly associated with rhinoconjunctivitis symptoms. The associations were similar for asthma and eczema symptoms; however it did not reach the level of statistical significance for all items.

CONCLUSION

Our results support previous findings reported for poor communities especially in Latin America, showing that lower hygiene conditions did not have protective effect against asthma and rhinoconjunctivitis and eczema symptoms.

High prevalence of asthma symptoms in Warao Amerindian children in Venezuela is significantly associated with open-fire cooking: a cross-sectional observational study

Background

The International Study on Asthma and Allergies in Childhood (ISAAC) reported a prevalence of asthma symptoms in 17 centers in nine Latin American countries that was similar to prevalence rates reported in non-tropical countries. It has been proposed that the continuous exposure to infectious diseases in rural populations residing in tropical areas leads to a relatively low prevalence of asthma symptoms. As almost a quarter of Latin American people live in rural tropical areas, the encountered high prevalence of asthma symptoms is remarkable. Wood smoke exposure and environmental tobacco smoke have been identified as possible risk factors for having asthma symptoms.

Methods

We performed a cross-sectional observational study from June 1, 2012 to September 30, 2012 in which we interviewed parents and guardians of Warao Amerindian children from Venezuela. Asthma symptoms were defined according to the ISAAC definition as self-reported wheezing in the last 12 months. The associations between wood smoke exposure and environmental tobacco smoke and the prevalence of asthma symptoms were calculated by means of univariate and multivariable logistic regression analyses.

Results

We included 630 children between two and ten years of age. Asthma symptoms were recorded in 164 of these children (26%). The prevalence of asthma symptoms was associated with the cooking method. Children exposed to the smoke produced by cooking on open wood fires were at higher risk of having asthma symptoms compared to children exposed to cooking with gas (AOR 2.12, 95% CI 1.18 - 3.84). Four percent of the children lived in a household where more than ten cigarettes were smoked per day and they had a higher risk of having asthma symptoms compared to children who were not exposed to cigarette smoke (AOR 2.69, 95% CI 1.11 - 6.48).

Conclusion

Our findings suggest that children living in rural settings in a household where wood is used for cooking or where more than ten cigarettes are smoked daily have a higher risk of having asthma symptoms.

Pet exposure and risk of atopic dermatitis at the pediatric age: a meta-analysis of birth cohort studies

BACKGROUND

Findings on pet exposure and the risk of atopic dermatitis (AD) in children are inconsistent.

OBJECTIVE

With the aim to summarize the results of exposure to different pets on AD, we undertook a meta-analysis of epidemiologic studies on this issue.

METHODS

In August 2012, we conducted a systematic literature search in Medline and Embase. We included analytic studies considering exposure to dogs, cats, other pets, or pets overall during pregnancy, infancy, and/or childhood, with AD assessment performed during infancy or childhood. We calculated summary relative risks and 95% CIs using both fixed- and random-effects models. We computed summary estimates across selected subgroups.

RESULTS

Twenty-six publications from 21 birth cohort studies were used in the meta-analyses. The pooled relative risks of AD for exposure versus no exposure were 0.72 (95% CI, 0.61-0.85; I(2) = 46%; results based on 15 studies) for exposure to dogs, 0.94 (95% CI, 0.76-1.16; I(2) = 54%; results based on 13 studies) for exposure to cats, and 0.75 (95% CI, 0.67-0.85; I(2) = 54%; results based on 11 studies) for exposure to pets overall. No heterogeneity emerged across the subgroups examined, except for geographic area.

CONCLUSION

This meta-analysis reported a favorable effect of exposure to dogs and pets on the risk of AD in infants or children, whereas no association emerged with exposure to cats.