House dust mite and cockroach exposure are strong risk factors for positive allergy skin test responses in the Childhood Asthma Management Program

BACKGROUND: Children with asthma have a high prevalence of environmental allergies, especially to indoor allergens. The relationships of exposure to indoor allergens (dust mites, cat, dog, cockroach, and molds) and other host factors to allergy sensitization have not been evaluated simultaneously in a large cohort. OBJECTIVES: We studied 1041 children aged 5 to 12 years with mild-to-moderate asthma to determine risk factors associated with having positive allergy skin test responses to indoor allergens. Also, we described, compared, and contrasted 6 allergens in the home environments of these children from 8 North American cities. METHODS: Data were used from baseline visits of the Childhood Asthma Management Program. Patients' sensitivities to house dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus), cats, dogs, cockroaches, and molds were examined for relationships to demographic variables, home dust allergen exposures, number of other positive allergy skin test responses, total serum IgE levels, and smoking in the home. RESULTS: San Diego (78.5%) and Toronto (59.3%) had the topmost percentages of homes with moderate-to-high house dust mite levels. Boston (21.5%), St Louis (16.3%), and Baltimore (13.4%) had the highest percentages of homes with detectable levels of cockroach allergen. For house dust mites, the higher the level of allergen exposure, the more likely patients were to have positive allergy skin test responses, with relative odds of 9.0 (95% confidence interval, 5.4-15.1) for those exposed to high mite levels (>10.0 microg/g dust) relative to those unexposed. Even exposure to low levels of mite allergen (0.020-2.0 microg/g) was found to be a significant risk factor for sensitization. For cockroach allergen, those with detectable home exposure were more likely to have positive skin test responses (relative odds, 2.2; 95% confidence interval, 1.3-3.8) than those with undetectable exposure. In contrast, levels of exposure to cat, dog, and mold allergens were not related to sensitization rates. For cat allergen, this may reflect lower rates of cat ownership among highly sensitized subjects. Furthermore, the number of allergy skin test responses that were positive, excluding the test for the outcome of interest for each model, and total serum IgE levels were strong independent predictors of sensitization. CONCLUSIONS: Levels of exposure determined by house dust analysis are important determinants of sensitization for dust mite and cockroach allergen. This relationship was not demonstrable for cat, dog, or mold allergens, possibly because of confounding factors. For all allergens studied, the degree of atopy, determined by the total number of positive skin test responses or by total serum IgE levels, is an important contributing risk factor for sensitization.     

Metropolitan home living conditions associated with indoor endotoxin levels

BACKGROUND: Household endotoxin exposure in allergy and asthma has been gaining attention for its dual potential to exacerbate these conditions in individuals with established disease and to abrogate atopy before disease onset. OBJECTIVE: We sought to better understand the home environmental and lifestyle factors influencing house dust endotoxin levels. METHODS: From the homes of 86 infants with wheeze in metropolitan Denver, Colorado, house dust endotoxin (detected with a standardized Limulus Amebocyte Lysate assay) and common indoor allergen (Fel d 1, Can f 1, Der p 1, Der f 1, and Bla g 1) contents were quantified. Comprehensive home environment and lifestyle questionnaires were completed during home visits by trained study staff and parents. RESULTS: House dust endotoxin levels were associated with only 2 home environmental features: animals in the home and the presence of central air conditioning. The strongest positive associations were found with animals in the home. Interestingly, the homes without cats or other animals revealed a negative correlation between house dust Fel d 1 and endotoxin (P =.03). Central air conditioning, especially during months of typical use, was associated with lower house dust endotoxin levels. No significant associations between house dust endotoxin levels and home dampness, number of household inhabitants or young children, cleaning frequency, or presence of tobacco smokers in the home were found. CONCLUSIONS: Indoor endotoxin exposure can be increased by the presence of animals in the home and decreased with central air conditioning. In some homes without animals, where allergen exposure adequate for sensitization still occurs, there are lower levels of house dust endotoxin. Therefore in homes without animals, factors that influence allergen and endotoxin levels in house dust probably differ. Households with detectable allergen levels but low endotoxin levels may provide a predisposing environment for animal allergen sensitization.     

Risk factors for wheezing in a subtropical environment: role of respiratory viruses and allergen sensitization

BACKGROUND: Risk factors for acute wheezing among children in subtropical areas are largely unknown. OBJECTIVE: To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old. METHODS: One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression. RESULTS: In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing. CONCLUSIONS: Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations.     

Exposure to cockroach allergen in the home is associated with incident doctor-diagnosed asthma and recurrent wheezing

BACKGROUND: Indoor inhaled allergens have been repeatedly demonstrated to worsen asthma in sensitized individuals, but their role in incident asthma is more controversial. OBJECTIVE: We investigated the relationship between exposure to allergens (dust mite, cat, and cockroach) measured in the home and incident doctor-diagnosed asthma and recurrent wheezing in children born to parents with asthma, allergies, or both. METHODS: From an ongoing longitudinal family and birth cohort study, we identified 222 siblings (median age, 2.87 years) of the index children. Allergen levels in the home were measured from dust samples obtained at the beginning of the study. Incident doctor-diagnosed asthma and recurrent wheezing were determined from questionnaires administered at 14 months and 22 months after the initial questionnaire. RESULTS: Thirteen (5.9%) children were reported to have incident asthma, twenty (9.0%) children had recurrent asthmatic wheezing, and 18 (8.1%) had recurrent wheezing without asthma. Compared with children living in homes with Bla g 1 or 2 levels of less than 0.05 U/g, children exposed to Bla g 1 or 2 levels of 0.05 to less than 2 U/g had a relative risk for incident asthma of 8.27 (95% confidence interval, 1.04-66.04), whereas children exposed to Bla g 1 or 2 levels of 2 U/g or greater had a relative risk for incident asthma of 35.87 (95% confidence interval, 4.49-286.62). Cockroach allergen exposure was likewise a significant predictor for recurrent asthmatic wheezing. Neither dust mite nor cat allergen levels were significantly associated with either outcome. These findings remained after control for several covariates. CONCLUSION: Exposure to cockroach allergen early in life may contribute to the development of asthma in susceptible children.     

Allergen exposure in infancy and the development of sensitization, wheeze, and asthma at 4 years

BACKGROUND: The relationship between mite and pet allergen exposure in infancy and the subsequent development of sensitization and asthma is complex. OBJECTIVE: We prospectively investigated the effect of allergen exposure at 3 months of age on the development of sensitization, wheeze, and physician-diagnosed asthma in the first 4 years of life in a birth cohort of children with and without an atopic mother. METHODS: Children participated in the Prevention and Incidence of Asthma and Mite Allergy study. Allergen exposure at 3 months of age was determined from mattress dust samples. Specific IgE to inhalant allergens was measured at 4 years of age, and information about wheeze and physician-diagnosed asthma was collected with yearly questionnaires. RESULTS: Mite and cat allergen exposure in infancy were associated with an increased risk of specific sensitization to house dust mite and cat, respectively, at 4 years of age. There were borderline significant associations between cat allergen exposure and persistent wheeze in the total study population and between dog allergen exposure and persistent wheeze in children with a nonatopic mother. In children with an atopic mother, there was some indication of a positive association between mite allergen exposure and physician-diagnosed asthma. CONCLUSION: Early house dust mite and cat allergen exposure might lead to sensitization and, in case of cat allergen exposure, to persistent wheeze. Early mite and dog allergen exposure might lead to asthma and persistent wheeze, respectively, but only in subgroups defined by maternal atopy.     

Influence of dog ownership and high endotoxin on wheezing and atopy during infancy

BACKGROUND: Increased exposure to microbial products early in life may protect from development of atopic disorders in childhood. Few studies have examined the relationship of endotoxin exposure and pet ownership on atopy and wheezing during infancy. OBJECTIVE: Evaluate relationships among high endotoxin exposure, pet ownership, atopy, and wheezing in high-risk infants. METHODS: Infants (n = 532; mean age, 12.5 +/- 0.8 months) with at least 1 parent with confirmed atopy were recruited. A complete medical history and skin prick testing to foods and aeroallergens were performed at age 1 year. House dust samples were analyzed for endotoxin. RESULTS: Prevalences of wheezing were not independently associated with dog or cat ownership or endotoxin levels. Percutaneous reactivity to at least 1 allergen was observed in 28.6% of infants. Univariate analyses showed significant associations of any wheezing, recurrent wheezing, and recurrent wheezing with an event with daycare attendance, number of siblings, respiratory infections, maternal smoking, and history of parental asthma. Logistic regression adjusting for the latter variables showed that recurrent wheezing (odds ratio, 0.4; 95% CI, 0.1-0.9) as well as 2 other wheeze outcomes were significantly reduced in homes with high endotoxin exposure in the presence of 2 or more dogs. CONCLUSION: Pet ownership or endotoxin did not independently modify aeroallergen sensitization or wheezing during infancy. However, high endotoxin exposure in the presence of multiple dogs was associated with reduced wheezing in infants. CLINICAL IMPLICATIONS: A home environment with many dogs and high levels of endotoxin may be conducive to reduced wheezing in infancy.     

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.     

Pets and vermin are associated with high endotoxin levels in house dust

BACKGROUND: Previous studies have shown that the risk for allergic sensitization is lower in children who grew up on farms and in young adults who were exposed to dogs in early childhood. A higher microbial exposure in general and in particular to endotoxin in early childhood might contribute to this lower risk of atopy. OBJECTIVE: We examined whether the presence of pets or vermin in the home is associated with higher endotoxin concentrations in settled house dust. METHODS: House dust was sampled in a standardized manner on the living room floors of 454 homes of German children aged 5-10 years (participation rate 61%). Endotoxin was assessed with a quantitative kinetic chromogenic Limulus Amebocyte Lysate (LAL) method. Associations between endotoxin levels, pets and vermin are presented as ratios of the crude and confounder adjusted geometric means (means ratios) in the category of study vs. a reference category using multiple linear regression models. RESULTS: Endotoxin concentrations in living room floor dust sampled in homes without pets and vermin were lower (1246 ng per square meter, 1519 ng endotoxin/g dust, n = 157) than those sampled in homes with pets or vermin (2267 ng per square meter, 2200 ng endotoxin/g dust, n = 296). After adjustment for city of residence, season of dust sampling, age of the building and story of the dwelling, means ratios for endotoxin expressed per gram of dust were statistically significantly increased for dog (1.64, 95% CI 1.09-2.46), for cat (1.50, 95% CI 1.03-2.18) and for cockroach (3.01, 95% CI 1.37-6.60), whereas no major statistically significant associations were found for other pets, ants and mice. CONCLUSION: Keeping a dog or a cat in the home is consistent with higher exposure to endotoxin and might therefore contribute to the lower risk of atopy in later life.     

Infant home endotoxin is associated with reduced allergen-stimulated lymphocyte proliferation and IL-13 production in childhood

BACKGROUND: Infant endotoxin exposure has been proposed as a factor that might protect against allergy and the early childhood immune responses that increase the risk of IgE production to allergens. OBJECTIVE: Using a prospective study design, we tested the hypothesis that early-life endotoxin exposure is associated with allergen- and mitogen-induced cytokine production and proliferative responses of PBMCs isolated from infants with a parental history of physician-diagnosed asthma or allergy. METHODS: We assessed household dust endotoxin at age 2 to 3 months and PBMC proliferative and cytokine responses to cockroach allergen (Bla g 2), dust mite allergen (Der f 1), cat allergen (Fel d 1), and the nonspecific mitogen PHA at age 2 to 3 years. RESULTS: We found that increased endotoxin levels were associated with decreased IL-13 levels in response to cockroach, dust mite, and cat allergens, but not mitogen stimulation. Endotoxin levels were not correlated with allergen- or mitogen-induced IFN-gamma, TNF-alpha, or IL-10. Increased endotoxin levels were associated with decreased lymphocyte proliferation after cockroach allergen stimulation. An inverse, although nonsignificant, association was also found between endotoxin and proliferation to the other tested stimuli. CONCLUSION: Increased early-life exposure to household endotoxin was associated with reduced allergen-induced production of the TH2 cytokine IL-13 and reduced lymphoproliferative responses at age 2 to 3 years in children at risk for allergy and asthma. Early-life endotoxin-related reduction of IL-13 production might represent one pathway through which increased endotoxin decreases the risk of allergic disease and allergy in later childhood.     

Change in IFN-gamma-producing capacity in early life and exposure to environmental microbes

BACKGROUND: Exposure to environmental microbes in early life might lead to type 1-skewed T cell responses and therefore reduce the risk of allergic diseases. OBJECTIVE: To investigate whether the cytokine responses at birth and at age 3 months are associated with environmental factors, especially exposure to microbes. Living in a farm, level of house dust endotoxin, cleanliness of the home, and presence of cats and dogs in the household were studied as possible determinants of cytokine production. METHODS: Twelve farmers' and 17 nonfarmers' children were studied. Production of IL-4, IL-6, TNF-alpha, and IFN-gamma in cord blood and in peripheral blood at 3 months was measured after 8-hour and 24-hour stimulation with phorbol ester plus concanavalin A. RESULTS: IFN-gamma responses at age 3 months were associated with farming (median, 53 vs 17 pg/mL; P = .019) and cats and dogs (49 vs 14 pg/mL; P = .014) (8 hours). Change in IFN-gamma-producing capacity from birth to 3 months was larger in children with higher than median endotoxin concentration in bed dust (P = .038) and in children with a cat or dog (P = .005) (8 hours). Increased IL-6 responses at birth were associated with cat or dog exposure (P = .004; 8 hours) and endotoxin level in settled dust (P = .039; 24 hours). CONCLUSION: The development of IFN-gamma-producing capacity during the first 3 months of life is associated with farming, endotoxin in house dust, and cat and dog exposure. These environmental characteristics may indicate some microbial exposure capable of driving developing immune system toward T(H)1 responses.     

Cat and dust mite sensitivity and tolerance in relation to wheezing among children raised with high exposure to both allergens

BACKGROUND: Recent evidence has suggested that high exposure to cat allergens is associated with decreased prevalence of sensitization to cat and, in some studies, decreased asthma. OBJECTIVE: Our objective was to study antibodies to cat and mite allergens and their relationship to wheezing in a country with high exposure to both allergens. METHODS: Sera from 112 wheezing and 112 control children aged 10 to 11 years in a nested case-control study in New Zealand were assayed for specific IgE antibody, as well as IgG antibody and IgG4 antibody, to Der p 1 and Fel d 1. RESULTS: IgE antibody to both mite (99/224) and cat (41/224) were strongly associated with wheezing (odds ratios, 5.2 and 6.5, respectively). Children who had ever lived with a cat were less likely to have IgE antibody to cat (20/141 vs 21/83, P < .04); however, cat ownership had no effect on IgE antibody to mite (67/141 vs 32/83, P = .23). Among sensitized children, cat ownership was associated with a lower prevalence of IgE antibody to cat (28% vs 66%, P < .001), and this analysis remained significant after exclusion of children whose families had chosen not to own a cat. Among sensitized subjects, the mean titer of IgE antibody to cat (1.7 IU/mL) was 10-fold lower than for mite (22.1 IU/mL). A cat in the home had no significant effect on endotoxin or mite allergen in house dust, whereas cat allergen was much higher (40.8 vs 3.3 microg/g). CONCLUSION: The response to these 2 allergens was distinct on the basis of the prevalence of sensitization, the titer of IgE antibody, and the effect of cat ownership. The results suggest that induction of tolerance to cat allergen is an allergen-specific phenomenon that cannot be attributed to endotoxin or family choice. The strength of the IgE antibody response to dust mite in humid climates could contribute to the increased prevalence and severity of asthma.     

Daycare centers and schools as sources of exposure to mites,cockroach, and endotoxin in the city of São Paulo,Brazil

BACKGROUND: Public places, including schools, have been identified as sources of exposure to allergens derived from mites, cockroach, cat, and dog and to endotoxin. OBJECTIVES: The purposes of this study were to assess and compare exposure to allergens and endotoxin in 4 types of public child-care facilities in Brazil and to investigate whether the presence of children and the performance of cleaning procedures could have an influence on allergen and endotoxin levels. METHODS: We have analyzed dust from bedding, floors, chairs, and tables of daycare centers (DCs), preschools, kindergartens, and elementary schools (ESs). Major allergens from mites, cockroach, cat, and dog were quantitated by means of ELISA, and endotoxin content was determined by using the Limulus Amebocyte Lysate assay. RESULTS: Group 1 mite allergens were greater than 2 microg/g in 67% of DC and preschool samples and in 8.9% and 2.2% of kindergarten and ES samples, respectively. The presence of bedding in DCs and preschools accounted for increased levels of mite allergens in these settings. Levels of Bla g 1 were higher in ES floors compared with those found in DC and preschool floors. Low levels (<1 microg/g) of Fel d 1 e Can f 1 were found in most samples. Levels of endotoxin in DCs and preschools were 3 times higher than in ESs. CONCLUSIONS: DCs and schools in Brazil should be considered as important sources of exposure to dust mites and cockroach allergens and to endotoxin. Recommendations for mite allergen avoidance should include appropriate care of bedding in DCs and preschools.     

Longitudinal study on the relationship between cat allergen and endotoxin exposure, sensitization, cat-specific IgG and development of asthma in childhood--report of the German Multicentre Allergy Study (MAS 90)

BACKGROUND: Controversial data have emerged regarding the question whether cat exposure in childhood favours or decreases the risk of sensitization and allergic airway disease. In a prospective birth-cohort study, we assessed the association between longitudinal cat allergen exposure, sensitization (immunoglobulin E, IgE), IgG antibody (ab) levels to cat and the development of asthma in children up to the age of 10 years. METHODS: Of 1314 newborn infants enrolled in five German cities in 1990, follow-up data at age 10 years were available for 750 children. Assessments included yearly measurements of specific serum IgE to cat and at age 6 and 18 months, 3, 4 and 10 years measurement of cat allergen Fel d 1 in house dust samples. Additionally, Fel d 1-specific IgG ab were determined in 378 serum samples of 207 children. Endotoxin exposure in mattress dust was measured in a subgroup of 153 children at age 10 years. From age 4 years on, International Study of Asthma and Allergy in Childhood (ISAAC) questionnaires were completed yearly in order to assess the prevalence of wheeze and asthma. RESULTS: Serum IgG-levels to cat showed a large variation, however, intraindividually values showed rather constant concentration over a longer time period. The IgG levels at school-age correlated with cat allergen exposure during the first 2 years of life. Specific IgE to cat was clearly associated with wheeze ever, current wheeze and bronchial hyperresponsiveness (BHR), this was also observed for children with specific IgE ab to cat (>0.35 kU/l) plus IgG levels above 125 U/ml. A large percentage of very highly exposed children showed high IgG but no IgE responses to cat, however, not all highly exposed children were found to be protected from sensitization. Children with IgG but without IgE ab to cat showed the lowest prevalence of wheeze ever and current wheeze despite high cat allergen exposure, however, this trend did not achieve significance. While homes of cat owners showed higher Fel d 1 concentrations than homes without cats, homes of cat owners were not found to have higher endotoxin levels in carpet dust samples than homes without cats. CONCLUSIONS: We could confirm that high cat allergen exposure in a cohort with lower community prevalence of cats is associated with higher serum IgG and IgE levels to cat in schoolchildren. Sensitization to cat allergen (IgE) is a risk factor for childhood asthma. While exposure to cat allergen during infancy is associated with sensitization (IgE), only in the very highly exposed children the likelihood of sensitization (IgE) is decreased and high IgG levels to cat without IgE were associated with low risk of wheeze. However, cat-specific IgG ab levels did not protect children with IgE-mediated sensitization from wheeze.     

Mouse allergen exposure, wheeze and atopy in the first seven years of life

Background: Little is known about mouse allergen exposure in home environments and the development of wheezing, asthma and atopy in childhood. Objective: To examine the relation between mouse allergen exposure and wheezing, atopy, and asthma in the first 7 years of life. Methods: Prospective study of 498 children with parental history of allergy or asthma followed from birth to age 7 years, with longitudinal questionnaire ascertainment of reported mouse exposure and dust sample mouse urinary protein allergen levels measured at age 2–3 months. Results: Parental report of mouse exposure in the first year of life was associated with increased risk of transient wheeze and wheezing in early life. Current report of mouse exposure was also significantly associated with current wheeze throughout the first 7 years of life in the longitudinal analysis (P = 0.03 for overall relation of current mouse to current wheeze). However, early life mouse exposure did not predict asthma, eczema or allergic rhinitis at age 7 years. Exposure to detectable levels of mouse urinary protein in house dust samples collected at age 2–3 months was associated with a twofold increase in the odds of atopy (sensitization to >=1 allergen) at school age (95% confidence interval for odds ratio = 1.1–3.7; P = 0.03 in a multivariate analysis. Conclusions: Among children with parental history of asthma or allergies, current mouse exposure is associated with increased risk of wheeze during the first 7 years of life. Early mouse exposure was associated with early wheeze and atopy later in life.     

Children at risk for asthma: home allergen levels, lymphocyte proliferation, and wheeze

BACKGROUND: Allergic asthma is a common childhood disease. Although T-lymphocyte activation plays a critical role in allergic asthma, the environmental factors promoting lymphocyte activation in children are not well defined. OBJECTIVE: In a cohort of children at risk for asthma (n = 114), we determined whether the levels of cockroach (Bla g 1 or 2), house dust mite (Der f 1), and cat allergen (Fel d 1) in the home during infancy was associated with subsequent allergen-specific lymphocyte proliferation in later life. METHODS: Dust samples from multiple sites in the home were collected at 3 months of age and were measured for allergen levels. Serial questionnaires were applied. At a median age of 2 years, PBMCs were isolated and lymphocyte proliferation to the home allergens and PHA was determined. RESULTS: Increased lymphocyte proliferative responses to Bla g 2 were associated with higher home levels of Bla g 1 or 2 (P for trend with kitchen Bla g levels =.011), in analyses adjusting for cold in the past week. Proliferative responses to Der f 1 were higher in homes with family room levels of Der f 1 > or =10 microg/g dust than in homes with Der f 1 <2 microg/g, but differences were not significant in analyses adjusting for cold (P =. 15). Repeated wheeze in the first 2 years of life was associated with increased allergen-specific and PHA proliferative responses. CONCLUSION: Early-life cockroach allergen exposure at 3 months of age predicts allergen-specific lymphocyte proliferative responses at a median of 2 years of age.     

House dust (1-3)-beta-D-glucan and wheezing in infants

BACKGROUND: (1-3)-Beta-D-glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1-3)-beta-D-glucan during infancy. We examined the association between (1-3)-beta-D-glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder. METHODS: (1-3)-Beta-D-glucan and endotoxin exposures were measured in settled dust collected from infants' primary activity rooms. The primary outcomes at approximately age one included parental reports of recurrent wheezing and allergen sensitization evaluated by skin prick testing to a panel of 15 aeroallergens as well as milk and egg white. RESULTS: Exposure to high (1-3)-beta-D-glucan concentration (within fourth quartile) was associated with reduced likelihood of both recurrent wheezing [adjusted OR (aOR) = 0.39, 95% CI = 0.16-0.93] and recurrent wheezing combined with allergen sensitization (aOR = 0.13, 95% CI = 0.03-0.61). Similar trends were found between (1-3)-beta-D-glucan concentrations and allergen sensitization (aOR = 0.57, 95% CI = 0.30-1.10). In contrast, recurrent wheezing with or without allergen sensitization was positively associated with low (1-3)-beta-D-glucan exposure within the first quartile (aOR = 3.04, 95% CI = 1.25-7.38; aOR = 4.89, 95% CI = 1.02-23.57). There were no significant associations between endotoxin exposure and the studied health outcomes. CONCLUSIONS: This is the first study to report that indoor exposure to high levels of (1-3)-beta-D-glucan (concentration >60 microg/g) is associated with decreased risk for recurrent wheezing among infants born to atopic parents. This effect was more pronounced in the subgroup of allergen-sensitized infants.     

Association of recurrent wheezing with sensitivity to cockroach allergen in inner-city children.

BACKGROUND: There are numerous data that show a strong relationship between early exposure and sensitization to indoor allergens and the development of asthma and persistent wheezing in children. Most studies, however, have only examined the prevalence of allergy in children who have been identified as having asthma. OBJECTIVE: To assess the prevalence of positive skin test results to common inhaled allergens and possible association with wheezing in inner-city children being seen in a general pediatric clinic. METHODS: Skin testing to common aeroallergens was performed by the prick-puncture method. Demographic and clinical data were collected. RESULTS: Seventy-five children aged 2 months to 10 years were evaluated. A total of 37% of the children had a positive skin test result to at least one allergen; 29% of the children were sensitive to dust mite, 15% to cockroach, 9% to cat, 7% to mold, 4% to grass, 3% to ragweed, and 1% to dog. Seven (64%) of 11 children with positive skin test results to cockroach had a history of wheezing compared with 21 (33%) of 64 with negative skin test results to cockroach (P = .05). CONCLUSIONS: Our results indicate that in a population of inner-city children not previously identified as atopic, more than a third showed sensitivity to at least one allergen. Although dust mite was the most common allergen to which the children were sensitized, cockroach sensitivity was the only allergen that correlated significantly with previous episodes of wheezing.     

Cockroach allergy appears early in life in inner-city children with recurrent wheezing.

BACKGROUND: Cockroach allergy and exposure to high levels of this allergen are important in the increasing asthma-related health problems among young inner-city children. However, there are very little data regarding the prevalence of cockroach allergy in infants and young children with asthma. OBJECTIVE: This retrospective study was designed to test the hypothesis that cockroach allergy appears early in life in young children with recurrent wheezing. METHODS: We reviewed the medical records of all 196 children (ages 5 months to 16 years) evaluated between January 1995 and September 1997 at the Cook County Hospital Pediatric Allergy Clinic for recurrent wheezing. The patients were assigned into two age groups, less than 4 years old and 4 to 16 years old. The percentages of IgE skin tests positive for common aeroallergens were compared within and between the two age groups. All children in the younger age group were tested for cockroach and dust mites, cat, and dog when indicated by positive environmental history. All children in the older age group were tested for indoor and outdoor allergens. RESULTS: Sixty-three children were younger than 4 years of age, and of these, 15 (23.8%) had cockroach allergen sensitivity, compared with only eight patients (12.7%) who were skin test positive to dust mite allergen (P = .01). The youngest patient with a positive reaction to cockroach allergen was 6 months old. Patients with a single allergen skin reactivity were considered as monosensitized. Nine children younger than 4 years of age (14.3%) were monosensitized only to cockroach allergen in contrast to three children (4.8%) who were monosensitized to house-dust mites (P < .05). CONCLUSIONS: Our data suggest that cockroach allergen sensitivity starts early in life and may be the only sensitizing allergen in many young inner-city children.     

Asthma and allergic symptoms in relation to house dust endotoxin: Phase Two of the International Study on Asthma and Allergies in Childhood (ISAAC II)

Background Several studies have consistently reported inverse associations between exposure to endotoxin in house dust and atopy. With regard to the association between house dust endotoxin and asthma, the results are inconsistent. Objectives To study the association between house dust endotoxin levels and respiratory symptoms and atopy in populations from largely different countries. Methods Data were collected within the International Study on Asthma and Allergies in Childhood Phase Two, a multi‐centre cross‐sectional study of 840 children aged 9–12 years from six centres in the five countries of Albania, Italy, New Zealand, Sweden and the United Kingdom. Living room floor dust was collected and analysed for endotoxin. Health end‐points and demographics were assessed by standardized questionnaires. Atopy was assessed by measurements of allergen‐specific IgE against a panel of inhalant allergens. Associations between house dust endotoxin and health outcomes were analysed by logistic regression. Odds ratios (ORs) were presented for an overall interquartile range increase in exposure. Results Many associations between house dust endotoxin in living room floor dust and health outcomes varied between countries. Combined across countries, endotoxin levels were inversely associated with asthma ever [adjusted OR (95% confidence interval (CI)) 0.53 (0.29–0.96) for endotoxin levels per m² of living room floor] and current wheeze [adjusted OR (95% CI) 0.77 (0.64–0.93) for endotoxin levels per gram of living room floor dust]. There were inverse associations between endotoxin concentrations and atopy, which were statistically significant in unadjusted analyses, but not after adjustment for gender, parental allergies, cat and house dust mite allergens. No associations were found with dust quantity and between endotoxin exposure and hayfever. Conclusion These findings suggest an inverse association between endotoxin levels in living room floor dust and asthma in children.     

Familial and environmental determinants for wheezing and asthma in a case-control study of school children in Palestine

BACKGROUND: Our prevalence study on Palestinian school children aged 6-12 years showed lower rates for asthma and asthma symptoms than economically developed and industrialized countries. Reasons for such differences are largely unknown, and could possibly be related to different environmental and lifestyle factors. OBJECTIVE: To investigate familial, early life exposures and indoor environmental determinants for asthma in children in Palestine. METHODS: From the population of our previous study, a group of 273 children with wheeze in the past 12 months (of whom 99 children had physician-diagnosed asthma) were matched with an equal number of non-wheezing controls. This case-control study involved a parental questionnaire; skin prick testing (SPT) with mixed house dust mites, cat and dog dander, mixed grass, mixed trees pollen, Alternaria tenuis, olive tree and cockroach extracts; and serum for total and specific IgE for the same eight allergens. RESULTS: Paternal asthma and maternal hayfever significantly tripled the risk for their children to have wheezing. Previous diagnoses of bronchial allergy, bronchitis, pneumonia, or whooping cough, and positive SPT for house dust mites and cockroaches were significantly more likely among wheezing and asthmatic children than controls. Specific IgE levels for house dust mites and cat allergens showed significantly higher risk for reported wheezing. After adjustment for several environmental and sociodemographic factors using multivariate logistic regression analysis, paternal asthma, maternal hayfever, damp houses, cat and cockroach SPT positivity proved to be strong predictors for wheezing symptoms. CONCLUSION: Our study confirmed that familial 'atopic' diseases are significant predictors of childhood asthma in Palestinian children. Moreover, indoor environment such as presence of cats and domestic moulds also appear to play a role. Our findings are consistent with studies in Canada, New Zealand, Estonia and Sweden, and show promise to explore further gene-environment interaction in the genesis of asthma.