Mite sensitization among Latina women in New York, where dust-mite allergen levels are typically low.

UNLABELLED: In New York (NY), Latinos often have greater asthma morbidity than other ethnicities, and dust-mite sensitization is common despite low allergen levels. We investigated mite allergen exposure and sensitization in atopic and/or asthmatic women, the majority being Puerto Rican. Women (n = 274) recruited for a birth cohort study were visited postnatally. Dust from their homes was analyzed for mite allergens (Der f 1, Der p 1, and Blo t 5). Serum was analyzed for total and allergen-specific IgE. Thirty-seven percent were sensitized to Dermatophagoides pteronyssinus, 34% to Dermatophagoides farinae, and 21% to Blomia tropicalis. Only 5% of NY homes had levels of Der f 1 >2 microg/g; none had Blo t 5 or Der p 1 above this level. Caribbean or Latin American birthplace (a proxy for childhood exposure) was not associated with mite sensitization. Sensitization to D. pteronyssinus and D. farinae was associated with a report of doctor-diagnosed asthma [Odds ratio (OR) = 3.27, P = 0.003; OR = 2.81, P = 0.010, respectively]; sensitization to any mite was associated with asthma medication use in the past 12 months (OR = 3.12, P = 0.004). These associations held even after adjustment for cockroach, mouse, and cat sensitization. PRACTICAL IMPLICATIONS: Despite the low concentrations of mite allergen in our community, many of the women in the atopically enriched cohort were sensitized to mites, even Blomia tropicalis which is typically found only in tropical environments.

Children living in areas with more street trees have lower prevalence of asthma.

BACKGROUND: The prevalence of childhood asthma in the USA increased by 50% from 1980 to 2000, with especially high prevalence in poor urban communities. METHODS: Data on the prevalence of asthma among children aged 4-5 years and on hospitalisations for asthma among children less than 15 years old were available for 42 health service catchment areas within New York City. Street tree counts were provided by the New York City Department of Parks and Recreation. The proximity to pollution sources, sociodemographic characteristics and population density for each area were also measured. RESULTS: Controlling for potential confounders, an increase in tree density of 1 standard deviation (SD, 343 trees/km(2)) was associated with a lower prevalence of asthma (RR, 0.71 per SD of tree density; 95% CI, 0.64 to 0.79), but not with hospitalisations for asthma (RR, 0.89 per SD of tree density; 95% CI, 0.75 to 1.06). CONCLUSIONS: Street trees were associated with a lower prevalence of early childhood asthma. This study does not permit inference that trees are causally related to asthma at the individual level. The PlaNYC sustainability initiative, which includes a commitment to plant one million trees by the year 2017, offers an opportunity for a large prospective evaluation.

Birth order, atopy, and symptoms of allergy and asthma among inner-city children attending Head Start in New York City.

BACKGROUND: In past research, children with older siblings were more likely than others to wheeze at age 2 years, but less likely by age 6 years. Higher infection transmission and a down-regulated allergic immune response as a result of these infections, respectively, were suggested as the causes. However, in a study of children aged 0-3 years in a low-income urban community in New York City, USA, with high asthma prevalence, we observed no birth-order effect. OBJECTIVE: To evaluate the association between birth order and atopy and respiratory symptoms in 4-year-old children attending Head Start programs in NYC. METHODS: Respiratory symptoms were assessed by questionnaire for 1005 children (mean age 4.0 years) living in high asthma prevalence neighbourhoods. Serum was collected from a subgroup of the children (n=494) and specific IgE responses to dust mite, cockroach, mouse, and cat allergens were measured. RESULTS: Prevalence of specific IgE (> or =0.35 IU/mL) did not differ significantly among first (35%), second (35%), and later-born children (28%) (P=0.23). Increasing birth order was associated with increasing prevalence of respiratory symptoms in the prior year, including wheeze (first 20%, second 27%, third or later 35%; P<0.001), being awakened at night by cough (28%, 33%, 38%; P=0.005), emergency department visits (14%, 17%, 21%; P=0.02) and hospitalizations for difficulty breathing (6.1%, 6.6%, 10%; P=0.04). The associations of birth order with respiratory symptoms were statistically significant only for the non-seroatopic children and those without an asthmatic parent. CONCLUSIONS: Non-seroatopic children with older siblings were more likely than those without older siblings to have respiratory symptoms at age 4 years. Although the stability of these associations over time remains to be determined, the differences in findings between this study and our previous NYC birth cohort study suggest that patterns of asthma development may vary even among low-income populations within the same city.

Asthma, body mass, gender, and Hispanic national origin among 517 preschool children in New York City.

BACKGROUND: Striking differences in asthma prevalence have been reported among Hispanic adults and children living in different cities of the USA. Prevalence is highest among those of Puerto Rican and lowest among those of Mexican origin. We hypothesized that body size would mediate this association. METHODS: Parents of children in New York City Head Start programs completed a questionnaire including demographic factors, health history, a detailed history of respiratory conditions, lifestyle, and home environment. Children's height and weight were measured in home visits. Logistic regression was used to model the association of asthma with body mass index percentile (<85th percentile, gender/age specific vs>or=85th percentile, gender/age specific), national origin, and other factors. RESULTS: Of 517 children at mean age of 4.0 +/- 0.6 years, 34% met the study criteria for asthma, and 43% were above the 85th percentile. Asthma was strongly associated with non-Mexican national origin, male gender, allergy symptoms, and maternal asthma, and marginally with body size. The odds of asthma among boys of non-Mexican origin was 5.9 times that among boys of Mexican origin [95% confidence interval (CI): 2.9-12.2]; the comparable odds ratio (OR) among girls was 1.8 (95% CI: 0.9-3.6). Body mass was associated with asthma among girls [OR = 2.0 (95% CI: 1.1-3.7)], but not boys [OR = 1.4 (95% CI: 0.8-2.6)]. CONCLUSIONS: The association of asthma with both body mass and national origin was gender-specific among the children in our study. Ours is one of the first studies to report on pediatric asthma in different Hispanic populations in the same city, by gender.

Asthma during the primary school ages--prevalence, remission and the impact of allergic sensitization.

BACKGROUND: Childhood is the most important time for asthma development. The aims of this study were to study changes in prevalence of asthma and wheeze, remission of asthma and changes in risk factor pattern from age 7-8 to age 11-12 in a cohort of school children. METHODS: In 1996, 3525 children aged 7-8 years in northern Sweden were invited to participate in a parental expanded ISAAC questionnaire survey. The cohort has been followed prospectively with yearly follow-ups to age 11-12, with a 97% yearly response rate. Skin prick tests were conducted at age 7-8 and 11-12. RESULTS: The prevalence of physician-diagnosed asthma increased from 5.7% at age 7-8 to 7.7% at age 11-12. Life-time prevalence of wheeze was 34.7% at age 11-12. The remission of asthma was 10% yearly and inversely related to allergic sensitization. Relapses were common, and remission persisting throughout the observation period was 5% yearly. Allergic sensitization was associated with current asthma at age 7-8 [adjusted odds ratio (OR) 4.9 (95% confidence interval (CI) 3.3-7.3)] and when the children were 4 years older [OR 5.6 (3.9-8.2)]. A family history of asthma was associated with current asthma at age 7-8 [OR 3.0 (2.1-4.5)] and 11-12 (OR 2.8 [2.0-3.9]). Ever having lived with a cat was significantly negatively associated with current asthma. CONCLUSIONS: The prevalence of asthma increased continuously during the primary school ages. Among several significant risk factors, allergic sensitization and a family history of asthma were the most important. With increasing age many known risk factors lost significance. Remission was inversely related to allergic sensitization.

Mouse and cockroach allergens in the dust and air in northeastern United States inner-city public high schools.

UNLABELLED: Considering that high school students spend a large proportion of their waking hours in the school environment, this could be an important location for exposure to indoor allergens. We have investigated the levels of mouse and cockroach allergens in the settled dust and air from 11 schools in a major northeastern US city. Settled dust samples were vacuumed from 87 classrooms, three times throughout the school year. Two separate air samples (flow = 2.5 lpm) were collected by 53 students over a 5-day period from both their school and their home. Mouse allergen (MUP) in the dust varied greatly between schools with geometric means ranging from 0.21 to 133 microg/g. Mouse allergen was detectable in 81% of the samples collected. Cockroach allergen (Bla g 2) ranged from below limit of detection (<0.003 microg/g) to 1.1 microg/g. Cockroach allergen was detected (>0.003 microg/g) in 71% of the dust samples. Bla g 2 was detected in 22% of airborne samples from the schools. By comparison, mouse allergen was only detected in 5%. These results indicate that the school may be an important location for exposure to allergens from mice and cockroaches and is an indoor environment that should be considered in an overall allergen intervention strategy. PRACTICAL IMPLICATIONS: To date, cockroach and mouse allergen intervention strategies have been mainly focused on the home environment. Considering that children spend a significant amount of time in schools, some studies have assessed cockroach allergen levels in schools. This study provides a clearer picture of the distribution and variability of not only cockroach allergen, but also mouse allergen in the school environment. In addition, this study describes limitations of personal air sampling in a student population. Our results suggest that although cockroach and mouse allergens are commonly recovered in classroom dust samples of inner city schools, cockroach allergens are recovered in the personal air samples with a greater frequency relative to mouse allergens.

Sub-lethal exposure of cockroaches to boric acid pesticide contributes to increased Bla g 2 excretion.

BACKGROUND: Several epidemiology studies have found an increase in the major cockroach allergen Bla g 2 with reported pesticide use. AIMS OF THE STUDY: Our aim was to investigate the effect on the excretion of Bla g 1 and Bla g 2 allergens by cockroaches exposed to sub-lethal doses of the pesticides, boric acid and hydramethylnon gel. METHODS: German cockroaches in separate colonies were fed either boric acid or hydramethylnon gel at concentrations of 0.2, 0.1 and 0.01% in their water supply over a 2 week period. Ten colonies were exposed to each treatment concentration. Bla g 1 and Bla g 2 in fecal pellets were measured by ELISA. RESULTS: Cockroaches exposed to boric acid excreted fecal pellets with significantly higher concentrations of Bla g 2 (35,400 U/g) than did controls (12,700 U/g) (P = 0.001). Bla g 1 concentrations were not significantly different. There was no difference in either Bla g 1 or Bla g 2 concentrations between cockroaches that ingested hydramethylnon gel and those in the controls colonies. CONCLUSIONS: The application of boric acid, a common pesticide, appears to paradoxically increase the production of Bla g 2, a major allergen, by the surviving cockroaches. This may have important implications in avoidance strategies.

IgE and IgG antibody responses to recombinant Alt a 1 as a marker of sensitization to Alternaria in asthma and atopic dermatitis.

BACKGROUND: Sensitization to Alternaria alternata is a risk factor for the development of wheezing and asthma. Alt a 1 is the major Alternaria allergen causing sensitization in asthmatics. Some atopic dermatitis (AD) patients have very high immunoglobulin (Ig)E antibody (ab) to Alternaria as analysed by Pharmacia CAP, however, it is not clear whether these are specific responses or whether Alt a 1 is involved in disease symptoms. OBJECTIVE: The aim of this study was to analyse specific IgE and IgG ab responses to recombinant Alt a 1 in asthmatic and AD patients and to compare these results to IgE ab against Alternaria measured by CAP. METHODS: Sera from individuals who were IgE positive to Alternaria by CAP were obtained from 58 patients with asthma/rhinitis, 19 patients with AD, and 20 patients with cystic fibrosis (CF) who were included as specificity controls. IgE and IgG ab to recombinant Alt a 1 were measured by radioimmunoassay (RIA). RESULTS: Of 43 asthma/rhinitis patients having an Alternaria CAP score > 2, a high percentage (93%) had both IgE and IgG ab to Alt a 1, emphasizing its importance as a major allergen. Only, 47% of AD patients with CAP score greater than 2 had ab to Alt a 1, and their levels were low when compared to the asthmatics. For CF controls, 75% of these patients had no IgE ab to Alt a 1, and those which were positive to Alt a 1 by RIA were also positive by CAP. Overall, patients with a low CAP (1-2) had a low prevalence (20-30%) of IgE or IgG ab to Alt a 1. CONCLUSION: IgE and IgG ab to Alt a 1 in asthmatics are good markers for sensitization to Alternaria. Although AD patients gave high Alternaria CAP scores, they had low or undetectable levels of IgE to Alt a 1, suggesting that other Alternaria allergens may be important in AD or that the CAP results are non-specific. Recombinant allergens may provide more specific measures of sensitization to fungi.

Home intervention in the treatment of asthma among inner-city children.

BACKGROUND: In Atlanta, as in other major urban areas of the United States, asthma is a leading cause of school absenteeism, emergency department use, and hospitalization. Recent guidelines for asthma management recommend reducing exposure to relevant allergens, but neither the feasibility nor the efficacy of this form of treatment has been established for children living in poverty. OBJECTIVE: We sought to investigate allergen avoidance as a treatment for asthma among inner-city children. METHODS: One hundred four children with asthma living in the city of Atlanta were enrolled into a controlled trial of avoidance without being skin tested. The children were randomized to an active avoidance group, a placebo avoidance group, and a second control group for which no house visits occurred until the end of the first year. Avoidance included bed and pillow covers, hot washing of bedding, and cockroach bait. Eighty-five children completed the study, and the outcome was measured as unscheduled clinic visits, emergency department visits, and hospitalization for asthma, as well as changes in mite and cockroach allergen levels. RESULTS: There was a significant decrease in acute visits for asthma among children whose homes were visited (P < .001). However, there was no significant difference between the active and placebo homes either in the effect on asthma visits or in allergen concentrations. When the children with mite allergy were considered separately, there was a significant correlation between decreased mite allergen and change in acute visits (P < .01). The avoidance measures for cockroach allergen appeared to be ineffective, and the changes observed did not correlate with changes in visits. CONCLUSIONS: Applying allergen avoidance as a treatment for asthma among children living in poverty is difficult because of multiple sensitivities and problems applying the protocols in this environment. The current results demonstrate that home visiting positively influences the management of asthma among families living in poverty. Furthermore, the results for children with mite allergy strongly suggest that decreasing relevant allergen exposure should be an objective of treatment in this population.

Use of specific IgE in assessing the relevance of fungal and dust mite allergens to atopic dermatitis: a comparison with asthmatic and nonasthmatic control subjects.

BACKGROUND: Although allergens have been implicated as aggravating factors in atopic dermatitis (AD), there is little epidemiologic data on the significance of specific IgE. OBJECTIVE: We sought to compare sensitization to dust mite and fungi between patients with AD and asthmatic and nonasthmatic control subjects. METHODS: Total IgE and specific IgE to Dermatophagoides pteronyssinus, Alternaria alternata, Aspergillus fumigatus, Candida albicans, Malassezia furfur, and Trichophyton rubrum were measured in 73 patients with moderate to severe AD. Total IgE and IgE specific for D pteronyssinus, A alternata, and M furfur were also measured in sera from 156 asthmatic and 212 nonasthmatic control subjects. RESULTS: Positive correlations were found between total IgE and IgE antibodies specific for each of the antigens. IgE specific for M furfur was observed more frequently in adults compared with children with AD (P <.01). AD sera had higher levels of total IgE and a higher prevalence of positive sera to D pteronyssinus (95% vs 42% and 17% for subjects with AD, asthmatic subjects, and nonasthmatic subjects, respectively), M furfur (53% vs 1% and 0.5%), and A alternata (49% vs 29% and 18%). Among the sera from subjects allergic to mites, the contribution of IgE specific for D pteronyssinus to the total IgE levels was similar regardless of the clinical status. CONCLUSIONS: Our results demonstrate that moderate-to-severe AD is strongly associated with sensitization to dust mite andM furfur (odds ratios, 45.6 and 132 vs pooled control sera). These results suggest that both environmental allergens and colonizing fungi contribute to the severity of disease, which is consistent with the view that mite avoidance and antifungal treatment can be beneficial in the treatment of these patients.

Relevance of allergens from cats and dogs to asthma in the northernmost province of Sweden: schools as a major site of exposure.

BACKGROUND: The prevalence of asthma in the northernmost region of Sweden has been estimated at 6% to 8% in spite of the very dry climate. The causes of the increase in asthma are not clear, but conditions are unfavorable for dust mite growth, and domestic animals are thought to be the primary source of indoor allergens. OBJECTIVES: We sought to investigate the relationship between asthma, exposure, and sensitization in Northern Sweden, with a focus on the role of schools. METHODS: Serum was collected from 110 asthmatic children, 55 children with symptoms of asthma but no established diagnosis, and 63 control children (age, 7 and 8 years). Total IgE and specific IgE to 7 allergens were measured. Dust samples were collected from the classrooms of 7- and 8-year-old children in 22 schools from Kiruna and Luleâ, Sweden. For comparison, dust was also collected from 24 homes in Kiruna and 2 schools in Virginia in the United States. RESULTS: Serum IgE antibody assays on 165 children with respiratory symptoms confirmed that there was a high degree of sensitization to cat, dog, and birch in Northern Sweden. Cat and dog allergens were present in almost all of the school samples in Sweden. By contrast, dust mite and cockroach allergens were generally unmeasurable. The highest levels of cat and dog allergens were found in samples from desks and chairs. Cat and dog allergen levels in the schools were comparable with but higher than those in the homes without pets. The schools in Virginia had similar allergen levels, except that samples from this humid region also had significant mite allergen. CONCLUSIONS: In this climate the primary sensitization associated with asthma is to cat dander and dog dander but also to birch pollen. Mite and cockroach allergens were not present in the dust samples, and sensitization to these allergens was not significant. The schools appear to be a major site of exposure to cat and dog allergens. These results are relevant both to an understanding of the reasons for the increase in asthma in this region and to any proposal to reduce exposure to allergens.

Evaluation of materials used for bedding encasement: effect of pore size in blocking cat and dust mite allergen.

BACKGROUND: Mattress and pillow encasings are recommended for patients allergic to dust mites. Many encasements block allergen and are vapor permeable but do not allow free passage of air through the material. Recently, breathable fabrics made from tightly woven synthetic fibers or nonwoven synthetics have been recommend as encasements. OBJECTIVE: The purpose of this study was to develop a method for testing encasement materials made of breathable fabrics. METHODS: Dust samples containing a known quantity of allergen (Der f 1, Der p 1, and Fel d 1) were pulled across a variety of fabrics using a modified dust trap. Airflow through the dust trap was controlled with a vacuum pump. Five minutes after dust was introduced, the pump was shut off. A filter located downstream of the fabric collected allergen passing through the fabric during the test and was assayed with ELISA for the relevant allergen. Fabrics to be tested were obtained from manufacturers and specialty catalogs. RESULTS: As the average pore size decreases, the airflow through a fabric becomes restricted, and the pressure differential created by the vacuum pump increases. Dust mite allergens (Der f 1 and Der p 1) were blocked below detectable limits by fabrics of less than 10 microm in pore size. Fabrics with an average pore size of 6 microm or less blocked cat allergen (Fel d 1). CONCLUSION: The method we developed provided a rigorous and reliable test for leakage of common indoor allergens through breathable barrier fabrics. Our results show that tightly woven fabrics and nonwoven synthetic fabrics can block common indoor allergens but still allow airflow.

Association of sensitization to Alternaria allergens with asthma among school-age children.

BACKGROUND: Molds in the Alternaria genus, normally found on outdoor vegetation, produce some of the most common fungal allergens to elicit a skin test response. OBJECTIVES: The objectives of this study were to evaluate a serum assay for IgE antibodies to Alternaria allergens and to establish the prevalence of sensitization to Alternaria allergens among children and adults enrolled in epidemiologic studies of asthma. In addition, the significance of sensitization to Alternaria allergens as a risk factor for asthma was compared with that of sensitization to indoor allergens or pollens. METHODS: Using the Pharmacia Capsulated Hydrophobic Carrier Polymer (CAP) system, we have evaluated the significance of Alternaria allergens by using sera from several epidemiologic studies of asthma. RESULTS: Comparisons between serum assays and skin test results suggest that this in vitro assay yields results similar to those for traditional RASTs and is as sensitive as skin prick testing. In each of the groups studied, sensitization to Alternaria allergens was more common among asthmatic than control subjects, and in two studies the relationship was highly significant. Alternaria allergens were significantly associated with asthma in middle schools in Charlottesville, Virginia and Los Alamos, New Mexico but not in Albemarle County, Virginia. Logistic regression analysis of the results for the three schools identified an association between sensitization to Alternaria allergens and asthma independent of, but not as strong as, that found between sensitization to indoor allergens and asthma (p < 0.001). CONCLUSIONS: The Pharmacia CAP system is a useful tool for measuring specific IgE to Alternaria allergens. Although not as important as sensitization to dominant local indoor allergens, sensitization to Alternaria allergens appears to be a significant independent risk factor for asthma in children in some locations of the United States.

Evaluation of different techniques for washing cats: quantitation of allergen removed from the cat and the effect on airborne Fel d 1.

BACKGROUND AND OBJECTIVE: The purpose of this study was to examine the quantity and distribution of the major cat allergen, Fel d 1, on cats and to evaluate the efficacy of washing, both in removing allergen from the cat and reducing airborne allergen levels. METHODS: Airborne samples were collected on four glass fiber filters in a 30 m3 room, before and 3 hours after serial washing of eight cats (45-minute sampling at 18 L/min for each filter). Aliquots of hair and bath water were also collected and assayed for Fel d 1 content. RESULTS: Extracting cat hair with tap water or pet shampoo for 3 minutes removed mean levels of 191 and 245 microg of Fel d 1 per gram of hair, respectively; the quantity of allergen on samples of cat hair ranged from 1 microg/gm to more than 1770 microg/gm. The highest concentration of allergen was found on hair from the neck. Estimates of the total Fel d 1 on the cat, based on shaving the whole cat, ranged from 3 to 142 mg (mean = 67 mg). Washing cats reduced airborne allergen 3 hours later. Washing three cats at weekly intervals for 5 weeks in a veterinarian's office produced a mean decrease of 44% in airborne Fel d 1 (n = 15, p < 0.02). Washing three cats by immersion for 3 minutes at weekly intervals for a 1-month period produced a mean decrease in airborne allergen of 79% (n = 12, p < 0.001). However, after repeated washing, the airborne levels before the next wash were not consistently decreased. The quantity of Fel d 1 removed by immersion varied from 1 to 35 mg. CONCLUSION: Cats carry large quantities of Fel d 1, only a small proportion of which (approximately 0.002%/hr) becomes airborne. Washing cats by immersion will remove significant allergen from the cat and can reduce the quantity of Fel d 1 becoming airborne. However, the decrease is not maintained at 1 week.

Evaluation of German cockroach (Orthoptera:Blattellidae) allergen and seasonal variation in low-income housing.

Six apartments in a low-income housing project were evaluated for German cockroach. Blattella germanica (L.), infestation and concentration of an allergen derived from these cockroaches (Bla g II). Kitchen and living room samples were collected monthly for 1 yr. In addition, airborne sampling was carried out in 5 kitchens. The kitchen had the highest allergen concentration in 65% of visits and the highest number of cockroaches trapped in 69% of visits. In the kitchen, the highest cockroach levels were seen in June, whereas the values for Bla g II peaked in August. In keeping with this, the closest correlation was between Bla g II (microgram/g dust) and the number of cockroaches found 2 mo earlier. Airborne samples were assayed for 2 separate allergens. Bla g II and Bla g I. No allergen was detectable in the absence of disturbance. By contrast, during disturbance with a vacuum cleaner both Bla g II and Bla g I were detectable in the air of each apartment. Results suggest that immunochemical assay of a major allergen in dust samples from the kitchen floor may be used to monitor exposure to German cockroaches, also that cockroach levels may be used as an indicator or predictor of allergen in dust.