Do asthma and allergy influence subsequent pet keeping? An analysis of childhood and adulthood

BACKGROUND: Asthma and allergy might influence the choice of keeping pets, leading to apparent protective effects of pets on allergic disease. OBJECTIVE: We investigated the effects of asthma and allergy on subsequent pet keeping in childhood and adulthood. METHODS: Information about asthma and pet keeping at ages 0 to 4, 5 to 15, 20 to 44, and 26 to 56 years was provided by 9812 subjects participating in the 9-year follow-up of the European Community Respiratory Health Survey. RESULTS: In childhood asthma debut at younger than 5 years was associated with less cat keeping at 5 to 15 years (odds ratio [OR], 0.60; 95% CI, 0.44-0.82), an effect only observed when the parents did not have asthma or allergy (P(interaction) = .045). Childhood asthma did not influence adult pet ownership, unless there were adult symptoms. Adults less often acquired cats at follow-up if they had 3 or more asthma symptoms (OR, 0.78; 95% CI, 0.64-0.95), were taking asthma medication (OR, 0.48; 95% CI, 0.31-0.74), had hay fever (OR, 0.75; 95% CI, 0.62-0.91), had atopy (OR, 0.75; 95% CI, 0.61-0.91), or had specific IgE to cat (OR, 0.57; 95% CI, 0.39-0.82) at baseline. Adults who already had pets usually continued keeping the same type of pet, except that the presence of 3 or more asthma symptoms was associated with less subsequent dog keeping (OR, 0.69; 95% CI, 0.53-0.89). Pet removal between surveys to reduce allergen was reported by 4.7%. CONCLUSION: Selective avoidance subsequent to asthma or allergy was observed for childhood cat keeping and adult cat acquisition. Avoidance would produce an apparent protective effect of cats on childhood asthma (large OR, 0.83). Avoidance was generally not observed for dogs or birds. CLINICAL IMPLICATIONS: A part of the protective effects of childhood cats on asthma and allergy can be attributed to selective avoidance.     

NAC Manchester Asthma and Allergy Study (NACMAAS): risk factors for asthma and allergic disorders in adults

Asthma and atopic disorders are the most common chronic diseases in the developed countries. Knowledge of the risk factors for these disorders may facilitate the development of preventive strategies aimed at reducing prevalence rates. To investigate the risk factors for asthma and allergic diseases in a large number of adults who are the parents of children in the National Asthma Campaign Manchester Asthma and Allergy Study. All pregnant women and their partners attending "Booking" antenatal clinics were invited to take part in the study. Questionnaire data were collected including the history of asthma and other atopic diseases, pet ownership and smoking habits, and skin prick tests were performed. The prevalence of atopy and the risk factors for asthma and allergic disorders were investigated in all subjects who completed the questionnaire and underwent skin testing. Statistical analysis was carried out using logistic regression. Initially, risk factors were assessed by univariate analysis to see how each potential explanatory variable affected the probability of having allergic disease. Variables were then tested in a forward stepwise multivariate analysis. In 5687 adult subjects there was a very high (48.2%) prevalence of atopy, and 9.7% of subjects had a diagnosis of asthma. In a multivariate regression analysis sensitization to dust mite, cat, dog and mixed grasses were all independently associated with asthma. The odds ratios for current asthma increased with the increasing number of positive skin tests (any two allergens - OR 4.3, 95% CI 3.3-5.5; any three allergens - OR 7.0 95% CI 5.3-9.3; all four allergens - OR 10.4, 95% CI 7.7-14; P < 0.00001). Dog ownership (OR 1.31, 95% CI 1.10-1.57; P = 0.003) and current smoking (OR 1.36, 95% CI 1.15-1.62; P = 0.0004) were significantly and directly associated with "asthma ever". Thirteen per cent of participants reported a history of eczema. In the multivariate analysis the strongest independent associate of eczema was sensitization to dog (OR 1.37, 95% CI 1.14-1.63, P < 0.0001). Apart from dog, the strength of the association between sensitization to common allergens and eczema appeared to be much lower than in the case of asthma. The prevalence of hay fever was high (20.6%), and in the multivariate analysis the association between sensitization to pollen and hay fever was extremely strong (OR 13.6, 95% CI 11.3-16.3; P < 0.0001). The results of the current study emphasize the importance of sensitization to indoor allergens in asthma. However, evidence of a possible direct role of allergen exposure in asthma causation remains unclear.     

Childhood farm environment and asthma and sensitization in young adulthood

BACKGROUND: Farm environment in childhood may protect against sensitization, allergic rhinitis, and asthma. METHODS: Subjects were obtained from 10 667 Finnish first-year university students who responded to a questionnaire survey on IgE-mediated diseases. Two random samples were selected from 1631 respondents in Turku: subjects with asthma or wheezing, and subjects without asthmatic symptoms. A total of 296 subjects (72%) participated. Skin prick tests (SPT), measurements of IgE-antibodies, methacholine challenge, and bronchodilation tests were performed. Weighted occurrence of current asthma and sensitization among students from "childhood farm" and "childhood nonfarm" environments were analyzed. RESULTS: Current asthma was found in 3.1% of subjects with childhood farm environment, and in 12.4% with nonfarm environment (odds ratio (OR) 0.22; 95% confidence interval (CI) 0.07-0.70). There were fewer positive SPT to birch (8.3 vs. 24.2%, OR 0.28, 95% CI 0.07-1.15) and timothy pollen (12.6 vs. 30.3%, OR 0.33, 95% CI 0.09-1.20) among subjects with childhood farm environment, but more sensitization to house-dust mite (22.0 vs. 4.9%, OR 5.43, 95% CI 1.60-18.46). Sensitization to cat (RAST class >/= 3) was less common in subjects with farm compared to nonfarm environments in childhood (1.5 vs. 13.1%; OR 0.10, 95% CI 0.02-0.47). CONCLUSIONS: Farm environment in childhood protects against adult asthma and sensitization-especially to cat-the most important asthma related allergen. In contrast, sensitization to house-dust mite was more common in farming subjects.     

Asthma and sensitization in a community with low indoor allergen levels and low pet-keeping frequency

BACKGROUND: Little is known about causes of asthma and sensitization in desert countries. OBJECTIVE: To investigate risk factors associated with asthma and sensitization in Kuwait. METHODS: One hundred sixty children (9-16 years) with physician-diagnosed asthma were recruited and matched (age, sex) with 303 healthy controls. Risk factors were assessed by questionnaires, determination of sensitization status (skin tests and IgE), and home allergen exposure (mite, cat, dog, cockroach; ELISA). RESULTS: Home allergen levels and frequency of pet ownership were very low (cat, 4.1%; dog, 1.5%). The risk of cat sensitization increased significantly among cat owners (odds ratio [OR], 3.53; 95% CI, 1.33-9.41; P = .01), and in children with reported contact with cats during the first year of life (OR, 2.60; 95% CI, 1.17-5.80; P = .019). In the multivariate analysis, maternal atopy (OR, 1.77; 95% CI, 1.13-2.75; P = .01) and cat ownership (OR, 3.32; 95% CI, 1.19-9.25; P = .02) remained significant associates of cat sensitization. Current dog ownership significantly increased the risk of sensitization to dog (OR, 6.05; 95% CI, 1.33-27.54; P = .02). In the multivariate analysis, dog ownership remained the only significant associate of dog sensitization (OR, 6.02; 95% CI, 1.30-27.96; P = .02). Sensitization to Alternaria was the strongest independent associate of the asthma group. Family history of asthma, history of whooping cough, current cat ownership, and breast-feeding <2 months were other significant and independent risk factors for asthma. CONCLUSIONS: Pet ownership markedly increased the risk of sensitization to pets. Despite low allergen exposure, the pattern of childhood asthma in Kuwait follows that described in Western communities (strong association with sensitization).     

Does the use of antibiotics in early childhood increase the risk of asthma and allergic disease?

BACKGROUND: One of the mechanisms evoked to explain the increasing prevalences of asthma and allergy, in particular among children, is the 'Western lifestyle' or 'hygiene' hypothesis. As early childhood infections are assumed to hold a protective effect on the development of asthma and allergies, the use of antibiotics at that sensitive age may lead to an increased risk of asthma and allergy. OBJECTIVE: The aim of this study is to investigate the association between the use of antibiotics in the first year of life and the subsequent development of asthma and allergic disorders. METHODS: In a population-based sample of 7-and-8-year-old children questionnaire and skin prick test data were collected from 1206 and 675 subjects, respectively. Prevalence rates of asthma, allergic disorders and skin test positivity were compared between children with and without early life use of antibiotics, taking into account other possible risk factors including early respiratory infections. The effect of genetic predisposition was investigated by stratified analyses of children with and without parental hay fever. RESULTS: The use of antibiotics during the first year of life was significantly associated with asthma (OR = 1.7, 95% CI 1.0-3.1), hay fever (OR = 2.3, 95% CI 1.3-3.8) and eczema (OR = 1.3, 95% CI 1.0-1.8). No significant relationship was found with skin test positivity (OR = 1.1, 95% CI 0.7-1.7). After stratification for the presence of parental hay fever, children without parental hay fever did not show any significant associations between antibiotics use and asthma or allergy, whereas in children with parental hay fever the use of antibiotics was significantly related with asthma (OR = 2.3, 95% CI 1.1-5.1), hay fever (OR = 2.8, 95% CI 1.5-5.1) and eczema (OR = 1.6, 95% CI 1.0-2.6), and of borderline statistical significance with skin test positivity (OR = 1.6, 95% CI 0.9-3.0). CONCLUSION: Early childhood use of antibiotics is associated with an increased risk of developing asthma and allergic disorders in children who are predisposed to atopic immune responses. These findings support recent immunological understanding of the maturation of the immune system.     

Exposure to pets, and the association with hay fever, asthma, and atopic sensitization in rural children

BACKGROUND: An increasing number of studies report pet exposure to be associated with lower risk of asthma and allergies. This 'protective pet effect' has been suggested to result from a modified T-helper (Th)2-cell response, or because of increased microbial load in homes where pets are kept. We examined the associations between pet contact and the occurrence of asthma and allergies in children of the rural Allergy and Endotoxin (ALEX) population, taking farm animal contact, endotoxin and cat allergen levels in mattress dust into account. METHODS: Information about contact with pets and farm animals, asthma and allergy were collected for 812 children by a standardized parents' questionnaire and an interview. Mattress dust endotoxin and cat allergen levels as well as specific IgE and IgG4 antibodies to Fel d1 were determined. RESULTS: Current contact with dogs was inversely associated with diagnosed hay fever (OR 0.26, 95% CI 0.11-0.57), diagnosed asthma (OR 0.29, 95% CI 0.12-0.71), sensitization to cat allergen (OR 0.48, 95% CI 0.23-0.99) and to grass pollen (OR 0.55, 95% CI 0.33-0.94), but not with increased IgG4 levels. Early and current contact with cats were associated with reduced risk of wheezing (OR 0.48, 95% CI 0.23-1.00, and OR 0.49, 95% CI 0.26-0.92, respectively) and grass pollen sensitization. Adjustment for farm animal contact but not for endotoxin and cat allergen exposure attenuated these associations and the effect of pet was stronger among farmers' children. CONCLUSION: Although pet exposure was very frequent in this rural population, the inverse relation between current dog contact, asthma and allergy was mostly explained by simultaneously occurring exposure to stable animals or was restricted to farm children. In addition, a subtle form of pet avoidance may contribute to the protective effect of pet.     

Wheeze, allergic sensitization and geohelminth infection in Butajira, Ethiopia

BACKGROUND: The effect of geohelminth infection on wheeze and allergen sensitization is inconsistent across different epidemiological studies. OBJECTIVE: To investigate the association between self-reported wheeze, self-reported asthma, allergic sensitization and geohelminth infection in urban and rural areas of Butajira, southern Ethiopia. METHODS: Questionnaire data on wheeze, asthma and a range of confounding variables was gathered in a cross-sectional study of 7649 people aged 5 years or more from the Butajira Rural Health Project database. Allergic skin sensitization to Dermatophagoides pteronyssinus and cockroach was measured, and a stool sample collected for qualitative and quantitative geohelminth analysis. RESULTS: Wheeze was weakly associated with allergic sensitization to D. pteronyssinus and cockroach (odds ratios (OR) 1.21, 95% confidence interval (CI) 0.98-1.51, and 1.27, 95% CI 1.00-1.62, respectively). Self-reported asthma was related to sensitization to D. pteronyssinus only (OR 4.09, 95% CI 2.86-5.84). Geohelminths were present in 33.8% of participants, and the median egg load in infested individuals was 6 eggs/g. Overall, presence of any geohelminths was associated with a diminished risk of cockroach sensitization (adjusted OR 0.82, 95% CI 0.68-0.99) but there were no significant protective effects of any geohelminth infection against wheeze or asthma. CONCLUSION: In a developing country community with relatively low geohelminth prevalence and intensity, we found weak association between allergic sensitization and wheeze, but no evidence of a protective effect of geohelminths against wheeze or asthma.     

Timing and intensity of early fevers and the development of allergies and asthma

BACKGROUND: Early childhood fevers appear to protect against later allergies and asthma. What is not known is the time in which fevers exert this effect and whether the degree of temperature increase is important. OBJECTIVE: We sought to examine the relationship between the time and degree of early fevers and later allergies and asthma. METHODS: Eight hundred thirty-five children from southeast Michigan were enrolled at birth. Clinic records from their first 2 years were abstracted for episodes of fever. At age 6 to 7 years, children underwent allergy testing. We examined fevers occurring within 6-month intervals in the first 2 years of life and outcomes at age 6 to 7 years. The primary outcome measures were allergic sensitization, asthma, asthma with allergic sensitization, and asthma without allergic sensitization. RESULTS: In the unadjusted analysis each episode of fever between 7 and 12 months of age was associated with a lower odds of allergic sensitization (odds ratio [OR], 0.71; 95% CI, 0.54-0.93) and asthma with allergic sensitization (OR, 0.43; 95% CI, 0.21-0.90) at age 6 to 7 years. Likewise, every 1 degrees C increase in the maximum temperature between 7 and 12 months was associated with a lower odds of allergic sensitization (OR, 0.77; 95% CI, 0.61-0.96) and asthma with allergic sensitization (OR, 0.62; 95% CI, 0.40-0.94). After adjusting for potential confounders, each episode of fever between 7 and 12 months was associated with a lower likelihood of asthma with allergic sensitization (adjusted OR, 0.33; 95% CI, 0.11-0.94) at age 6 to 7 years. CONCLUSIONS: Both the timing and intensity of childhood fevers appear to be important factors in the development of allergies and asthma.     

Early predictors for developing allergic disease and asthma: examining separate steps in the ''allergic march''

BACKGROUND: Sensitization and symptoms of allergic disease are strongly correlated, but little is known about the early clinical precursors of the development of allergen sensitization in childhood. The aim of this study was to identify these predictors, and to examine separately the effect of early sensitization on subsequent wheeze, asthma, rhinitis and eczema. METHODS: In the Childhood Asthma Prevention Study, children with a family history of asthma were assessed for allergen sensitization, total serum IgE, wheeze, asthma, eczema and rhinitis at ages 18 months and 5 years. To examine predictors, at 18 months, for subsequent sensitization, children who were non-sensitized at 18 months and had data on sensitization at 5 years were investigated, n=375. To examine the predictors, at age 18 months, of subsequent onset of symptoms, children who did not have wheeze, asthma, eczema or rhinitis at 18 months were followed-up at 5 years, n=177. RESULTS: Among children who were non-sensitized at age 18 months, the presence of eczema [adjusted relative risk (aRR), 1.67, 95% confidence interval (CI) 1.20-2.33], but not wheeze, asthma or rhinitis, was an independent predictor of the onset of sensitization by age 5 years. Among children who were asymptomatic at age 18 months, sensitization to any allergen at 18 months was an independent predictor for the presence of wheeze (aRR 2.41, 95% CI 1.28-4.55), asthma (aRR 4.66, 95% CI 1.88-11.54) and rhinitis (aRR 1.77, 95% CI 1.08-2.90), but not for the development of eczema (aRR 0.78, 95% CI 0.23-2.64) at 5 years. CONCLUSION: In non-sensitized children, eczema, but not wheeze, asthma or rhinitis is a predictor for subsequent development of sensitization. This suggests that early childhood eczema, rather than wheeze and rhinitis, may promote subsequent allergen sensitization and raises the possibility that early management of eczema may reduce the prevalence of sensitization in children.     

Asthma, allergy and atopy in southern Chinese school students

In order to determine the prevalence of asthma, allergy and atopy in southern China and the relative importance of atopy and parental history in predicting asthma and allergic diseases, we carried out a cross-sectional study on 737 secondary school students aged 12-20(492 boys, 245 girls; mean age = 16.4 years, so = 1.8 years) in the city of San Bu, Guangdong, China. Standard questionnaires on respiratory and allergic symptoms were distributed for completion by parents with an overall response of 98.6%. Skin-prick tests to common aeroallergens were performed on 647 subjects (87.8%) to determine atopic status. The prevalence (and 95% CI) of a history of hay fever, eczema, wheeze or asthma ever and wheeze in past 12 months were 1.6% (0.7-2.5), 10.4% (8.2-12.6), 1.9% (0.9-1.9) and 1.1% (0.3-1.9) respectively. Forty-nine per cent (45.2-52.9) of students had one or more positive skin tests to common aeroallergens. Amongst atopic subjects, 87.3% reacted to house dust mite (Dermatophagoides pteronyssinus) and 73.3% to cockroach. There was a close association between the degree of atopy and the prevalence of a history of wheeze (P < 0.05) but not with hay fever or eczema. After adjusting for age and sex, parental histories of hay fever, eczema and wheeze were strongly associated with the respective symptoms in the subjects (OR = 17.4 (3.2-93.9) for hay fever, 27.4 (12.7-59.0) for eczema, 79.4 (21.9-288.4) for wheeze). It is concluded that respiratory and allergic symptoms were uncommon in Chinese school students despite a high prevalence of atopy, and that parental history is more important in predicting asthma and allergy than atopy.     

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. Cite this as: J. Lampi, D. Canoy, D. Jarvis, A.‐L. Hartikainen, L. Keski‐Nisula, M.‐R. Järvelin and J. Pekkanen, Clinical & Experimental Allergy, 2011 (41) 987–993.     

Number of offspring and maternal allergy

The consistent association seen between family size and childhood allergy has led to the 'hygiene hypothesis', namely that a lower frequency of infections in early childhood is associated with an increased risk of asthma and hay fever. Maternal atopy, however, is a strong predictor of childhood asthma and hay fever. If maternal atopy is inversely related to the number of siblings then the role of siblings in the development of childhood atopy, the basic tenet of the 'hygiene hypothesis', is challenged. We evaluated the association between number of pregnancies and number of live births with lifetime occurrence of maternal wheeze, asthma, allergic rhinitis, and allergic conjunctivitis in a cross-sectional study in four areas in Italy. A total of 1755 (35-74 year old) nonsmoking women filled a questionnaire on reproductive history as well as on lifetime occurrence of symptoms/diseases. The number of live births was inversely related to lifetime allergic rhinitis (P-value for trend=0.031) and allergic conjunctivitis (P-value for trend=0.011). The odds ratios for those with 4+ children (in comparison with those having 0-1) were: 0.53 (95% CI: 0.27-1.04) and 0.42 (95% CI: 0.22-0.81), respectively. A similar trend was seen for number of pregnancies, although not statistically significant. No association was found between number of pregnancies and number of live births with wheeze or asthma. The results may be interpreted as an indication that maternal atopy influences pregnancy outcomes or that pregnancy itself has an effect on maternal atopy.     

Early childhood environment related to microbial exposure and the occurrence of atopic disease at school age

BACKGROUND: There is a growing body of evidence that the early childhood environment with respect to day care attendance, older siblings, pet ownership, and early life airway infections may protect from developing atopic disease. Few studies have distinguished between atopic sensitization and symptoms, and none have evaluated independent contributions for all of these different environmental conditions. OBJECTIVE: Examine independent effects on atopic sensitization and symptoms of day care attendance, older siblings, pet ownership, and early infancy's airway disease. METHODS: A cross-sectional survey among 8-13-year-old school children with complete data for 1555 children. RESULTS: After adjustment for confounders, atopic sensitization occurred less frequently in children that had attended a day care centre (OR: 0.73, 95% CI: 0.55-0.98) or had a cat or dog before 2 years of age (OR: 0.78, 95% CI: 0.61-0.99). Having older siblings yielded a nonsignificant trend towards protection (OR: 0.88, 95% CI: 0.70-1.11). For symptoms, there was no relation with having older sibs, day care attendance and pet ownership, although there was a trend towards protection for the combination of atopy and symptoms. In contrast, children with doctors' treated airway disease before age 2, more frequently reported recent symptoms of wheeze, asthma, rhinitis, or dermatitis (all P < 0.05). CONCLUSION: Early life environmental exposure to day care, or pets may protect against atopic sensitization. Protection against symptoms only occurred if atopic sensitization was present as well.     

The protective effect of rural living against atopy in Mongolia

BACKGROUND: Farm environment in childhood protects against atopy. We investigated in a population-based study in Mongolia the effects of rural living and migration from rural to urban areas on the risk of atopy. METHODS: The screening study data of 9453 subjects, aged 10-60 years, were used for taking the sample for the clinical study in which 869 subjects were examined. Asthma, allergic rhinoconjunctivitis and sensitization were clinically defined and their risk factors analysed by logistic regression. RESULTS: The risks of allergic rhinoconjunctivitis [adjusted odds ratio (OR) 0.43, 95% confidence interval (CI) 0.19-0.98] and allergic sensitization (OR 0.26, 95% CI 0.13-0.55) were the lowest in subjects living in a village from birth and intermediate in subjects who had relocated from a village to a town (OR for rhinoconjunctivitis 0.68, 95% CI 0.36-1.27, OR for sensitization 0.62, 95% CI 0.35-1.12) compared with subjects living in a town from birth. Simultaneous exposure to herd animals and dung heating decreased the risk of atopy. Keeping animals was a risk-factor for asthma only in Ulaanbaatar city. CONCLUSIONS: Continuing farm exposure after childhood may be important in reducing the risk of atopy.     

A retrospective study of the relationship between childhood asthma and respiratory infection during gestation

BACKGROUND: Wheeze in children has been found to be associated with prior antepartum haemorrhage and raised levels of IgE in cord blood, and acute wheezing episodes are intimately linked with respiratory viral infections. OBJECTIVE: To assess the relationship between maternal presentation with respiratory tract infections in pregnancy and childhood asthma, taking into account factors which could affect presentation. METHODS: This was a case-control study of 200 asthmatic children, 5-16-year-old, age-matched with one control, having no recorded history of wheeze. Data on respiratory tract infections, maternal wheeze, atopy and smoking was collected from primary care records. Deprivation score was assessed according to small residential areas and subjects were equally distributed between four general practices in Plymouth, UK. RESULTS: Presentation with respiratory tract infections during pregnancy was significantly associated with childhood asthma (OR 1.69, 95% confidence interval 1.05-2.77, P = 0.03). The association was marginally stronger for infections in the first trimester (OR 2.30, 95% CI 1.05-5.41, P = 0.04) and for those with cough during pregnancy (OR 2.24, 95% CI 1.23-4.22, P = 0.007). The associations remained significant after allowing for the effect of the independent variables (gender, maternal smoking, maternal wheeze, allergic rhinitis, eczema, asthma treatment in pregnancy and deprivation [Townsend] score), using multiple logistic regression analysis (ORs and 95% CIs 1.91, 1.14-3.22; 2.32, 1.01-5.34 and 2.29, 1.17-4.48, respectively). There was also an association between numbers of presentations with respiratory infections and childhood asthma (test for trend, P = 0.02). CONCLUSIONS: This study has shown an association between presentation with respiratory infection during gestation and childhood asthma. The results were not affected by the other independent variable factors studied and therefore provide some evidence to support the theory that respiratory viruses may be implicated in the aetiology of asthma.     

Childhood asthma and continuous exposure to cats since the first year of life with cats allowed in the child's bedroom

Background: There are controversial data as to interdependencies of exposure to furred pets in infancy and the prevalence of asthma and hay fever in children. Does the timing, intensity and type of pet exposure matter? Methods: Cross‐sectional questionnaire data on 8216 German schoolchildren aged 5–7 years not living on a farm in ten rural districts in Bavaria in 1997 were analysed. The diagnosis of asthma and hay fever was ascertained with the International Study of Asthma and Allergies in Childhood (ISAAC) core questions. Wheeze and asthma were classified as ‘atopic’ in children who also had hay fever or atopic dermatitis. Prevalence and intensity of exposure to pets in the first year of life and at present were assessed via questionnaire. Results: Although the study was of considerable size we found no convincing association between atopic disease and pet exposure in general. Exposure to cats from the first year of life to school entry, however, was associated with a reduced prevalence of atopic asthma, if cats were allowed to be in the child's bedroom: no case of atopic asthma in 296 children exposed and an aOR 0.11 (95% CI:0.01–0.52) for atopic wheeze in the last 12 months. Conclusions: Allowing cats to be in the child's bedroom from the first year of life onwards may be an indicator of intensive exposure to cats and appears to prevent the development of childhood asthma.     

Occurrence of new-onset wheeze in a 3-year follow-up study of schoolchildren.

BACKGROUND: Different wheeze phenotypes have been identified, primarily in preschool children. OBJECTIVE: To explore the characteristics of children in primary school without a history of wheeze or asthma and the onset of wheeze during a 3-year follow-up period. METHODS: Students in grades 1 to 3 participated in a cross-sectional study in 2000 and again in 2003, creating a prospective cohort. Data were collected using questionnaires in both years. Children without a history of asthma or wheeze in or before 2000 were selected for this analysis (n = 212). Associations between baseline characteristics and an outcome of the onset of new wheeze were evaluated. RESULTS: Twenty-two children (10.4%) reported new wheeze by 2003. Significant associations were found between new-onset wheeze and body mass index (odds ratio [OR], 1.33; 95% confidence interval [CI], 1.10-1.62) and history of allergic disease (OR, 7.17; 95% CI, 2.48-20.72); significant inverse associations were found with farming exposures in the first year of life (OR, 0.17; 95% CI, 0.05-0.64) and with having a fireplace in the home (OR, 0.20; 95% CI, 0.05-0.83). After stratification by sex, the associations were typically stronger in girls than in boys. CONCLUSIONS: Allergic disease in childhood and early and current exposures affect the development of wheeze. These results support efforts to lead healthy lifestyles and direct continued research into wheeze phenotypes, especially by sex.     

Early, current and past pet ownership: associations with sensitization, bronchial responsiveness and allergic symptoms in school children

BACKGROUND: Studies have suggested that early contact with pets may prevent the development of allergy and asthma. OBJECTIVE: To study the association between early, current and past pet ownership and sensitization, bronchial responsiveness and allergic symptoms in school children. METHODS: A population of almost 3000 primary school children was investigated using protocols of the International Study on Asthma and Allergies in Childhood (ISAAC). Allergic symptoms were measured using the parent-completed ISAAC questionnaire. Sensitization to common allergens was measured using skin prick tests (SPT)s and/or serum immunoglobulin (Ig)E determinations. Bronchial responsiveness was tested using a hypertonic saline challenge. Pet ownership was investigated by questionnaire. Current, past and early exposure to pets was documented separately for cats, dogs, rodents and birds. The data on current, past and early pet exposure were then related to allergic symptoms, sensitization and bronchial responsiveness. RESULTS: Among children currently exposed to pets, there was significantly less sensitization to cat (odds ratio (OR) = 0.69) and dog (OR = 0.63) allergens, indoor allergens in general (OR = 0.64), and outdoor allergens (OR = 0.60) compared to children who never had pets in the home. There was also less hayfever (OR = 0.66) and rhinitis (OR = 0.76). In contrast, wheeze, asthma and bronchial responsiveness were not associated with current pet ownership. Odds ratios associated with past pet ownership were generally above unity, and significant for asthma in the adjusted analysis (OR = 1.85), suggesting selective avoidance in families with sensitized and/or symptomatic children. Pet ownership in the first two years of life only showed an inverse association with sensitization to pollen: OR = 0.71 for having had furry or feathery pets in general in the first two years of life, and OR = 0.73 for having had cats and/or dogs in the first two years of life, compared to not having had pets in the first two years of life. CONCLUSION: These results suggest that the inverse association between current pet ownership and sensitization and hayfever symptoms was partly due to the removal of pets in families with sensitized and/or symptomatic children. Pet ownership in the first two years of life only seemed to offer some protection against sensitization to pollen.     

Prevalence of hay fever and allergic sensitization in farmer's children and their peers living in the same rural community

INTRODUCTION: Lower prevalence rates of allergic diseases in rural as compared with urban populations have been interpreted as indicating an effect of air pollution. However, little is known about other factors of the rural environment which may determine the development of atopic sensitization and related diseases. OBJECTIVE: The authors tested the hypothesis that children growing up on a farm were less likely to be sensitized to common aerollergens and to suffer from allergic diseases than children living in the same villages but in nonfarming families. MATERIALS AND METHODS: Three age groups of schoolchildren (6-7 years, 9-11 years, 13-15 years) living in three rural communities were included in the analyses. An exhaustive questionnaire was filled in by 1620 (86.0%) parents. A blood sample was provided by 404 (69.3%) of the 13-15 year olds to determine specific IgE antibodies against six common aeroallergens. RESULTS: Farming as parental occupation was reported for 307 children (19.0%). After adjustment for potential covariates such as family history of asthma and allergies, parental education, number of siblings, maternal smoking, pet ownership, indoor humidity and heating fuels, farming as parental occupation was significantly associated with lower rates of sneezing attacks during pollen season (adjusted OR 0.34, 95% CI 0.12-0.89) and atopic sensitization (adjusted OR 0.31, 95% CI 0.13-0.73) whereas the association with wheeze (adjusted OR 0.77 95% CI 0.38-1.58) and itchy skin rash (adjusted OR 0.86, 95% CI 0.49-1.50) was not statistically significant. The risk of atopic sensitization was lower in children from full-time farmers (adjusted OR 0.24, 95% CI 0.09-0.66) than from part-time farmers (adjusted OR 0.54, 95% CI 0.15-1.96). CONCLUSION: Factors directly or indirectly related to farming as parental occupation decrease the risk of children becoming atopic and developing symptoms of allergic rhinitis.     

Clinical atopy and associated factors in primary-school pupils

To investigate potential risk factors for clinical atopy in childhood, we obtained cross-sectional data from a cohort of 1376 8-year-old pupils. Parental atopy (hay fever, asthma, eczema), gestational age, maternal smoking habits, and the child's history of asthma, hay fever, and eczema were ascertained by questionnaire. Combining the history and the result of a skin prick test using seven aeroallergens, we defined the child's atopic diseases. Of the population evaluated, 25.4% were categorized as atopic (10.2% allergic asthma, 17.3% eczema, 6.9% hay fever). As compared with the clear nonatopics (40.2%), parental atopic diseases were more prevalent in each of the atopic groups. Significant associations of the parents' and child's disease were obvious for eczema and hay fever. Low gestational age (LGA) was more frequent in children with any atopy or with an allergic asthma (odds ratio (OR) 1.7; 95% confidence interval (CI) 1.02-2.97; OR 2.8; 95% CI 1.5-5.4). Hay fever and allergic asthma occurred less frequently in girls (OR 0.5; 95% confidence interval 0.3-0.8; OR 0.6; 95% CI 0.4-0.9). In conclusion, our data underline the importance of parental atopy for the clinical outcome in the offspring. In addition, LGA appears to be a risk factor for allergic asthma and for general atopy in later life.