Dust Mite Allergen Levels Research Articles

Efficiency of neem tree extract (Milbiol) in decreasing the level of house dust mite allergens

Efficiency of neem tree extract (Milbiol) in decreasing the level of house dust mite allergens

Prevalence of Indoor Allergen Exposures among New Orleans Children with Asthma

Studies of inner-city asthmatic children have shown significant regional variation in dust allergen exposures. The home environment of asthmatic children in the Gulf South region of the USA has not been characterized. This study describes indoor dust allergen levels in the homes of 86 asthmatic children in New Orleans and explores regional variability in dust allergen exposure. Data were used from baseline home visits of children in the New Orleans Healthy Homes Initiative. Interview, visual observation, and environmental dust sampling data of 86 children between 4 and 17 years of age were analyzed. Seventy-seven percent of households had moderate (>2.0-9.9 microg/g) or high (> or =10.0 microg/g) levels of either Der p 1 or Der f 1 dust mite allergen and 56.6% had moderate (>2.0-8.0 U/g) or high (>8.0 U/g) levels of cockroach allergen (Bla g 1). The prevalence of high (>10 microg/g) levels of dog (Can f 1) allergen was 26.5%, and few households (6.0%) had high cat allergen (Fel d 1) levels (>8.0 microg/g). Households with average humidity levels >50% were three times more likely to have elevated dust mite levels (odds ratio = 3.2; 95% confidence interval = 1.1, 9.3; p = 0.03). Home ownership and education level were inversely associated with cockroach and dust mite allergen levels, respectively. Our findings reinforce the evidence of regional variability in dust allergen exposure levels. Asthmatic children living in the Gulf South are exposed to multiple indoor allergen exposures and live in a highly allergenic environment.

Regional Variation in Dust Allergen Levels in the Homes of Urban Children with Asthma

Studies of inner-city asthmatic children have shown significant regional variation in dust allergen exposures. The home environment of asthmatic children in the Gulf South region of the U.S. has not been characterized. This study describes indoor dust allergen levels and characteristics of asthmatic children in New Orleans and explores regional variability in dust allergen exposure. Data were used from baseline home visits of children in the New Orleans Healthy Homes Initiative. Interview, visual observation and environmental dust sampling data of 86 children between 4–17 years of age were analyzed. Seventy-seven percent of households had moderate (> 2.0–9.9 μg/g) or high (≥10.0 μg/g) levels of either Der p 1 or Der f 1 dust mite allergen and 56.6% had high (> 2.0–8.0 U/g) or very high (> 8.0 U/g) levels of cockroach allergen (Bla g 1). The prevalence of high (>10 μg/g) levels of dog (Can f 1) allergen was 25.3% and few households (4.8%) had high cat allergen (Fel d 1) levels (>8.0 μg/g). Households with average humidity levels > 50% were three times more likely to have elevated dust mite levels (odds ratio = 3.2; 95% CI =1.1, 9.3; p=0.03). Home ownership and education level was associated with roach and dust mite allergen levels. Our findings reinforce evidence of regional variability in dust allergen exposure levels. Children living in the Gulf South may be exposed to a greater number of allergens at levels known to cause sensitization than in other regions of the country.

Home environment and suspected atopic eczema in Japanese infants: The Osaka Maternal and Child Health Study

Atopic eczema is most commonly diagnosed in children under the age of 5 yr. Environmental factors during pregnancy or in early life may confer risk for childhood atopic eczema. The present prospective study examined the relationship of the perinatal home environment and the risk of suspected atopic eczema among Japanese infants under the age of 1. Study subjects were 865 parent-child pairs. The term 'suspected atopic eczema' was used to define an outcome based on our questionnaire at 2-9 months postpartum. Adjustment was made for maternal age, gestation, family income, maternal and paternal education, maternal and paternal history of asthma, atopic eczema, and allergic rhinitis, time of delivery before the second survey, baby's older siblings, baby's sex, and baby's birth weight. A high mite allergen level from maternal bedclothes and mold in the kitchen during pregnancy were significantly associated with an increased risk of suspected atopic eczema. Frequent vacuuming practices during pregnancy and giving the infant a bath or shower at least once a day were significantly inversely related to the risk of suspected atopic eczema. Maternal smoking, maternal use of a synthetic duvet and pillow, carpet use in the living room and maternal bedroom, indoor domestic pets, no ducted heating appliance, and gas use for cooking during pregnancy and household smoking in the same room as the infant, infant's synthetic duvet, carpet use in the infant's room, or vacuuming the infant's room were not related to the risk of suspected atopic eczema. High house dust mite allergen levels and mold in the kitchen during pregnancy may increase the risk of infantile atopic eczema, whereas frequent vacuuming practices during pregnancy and giving the infant a bath or shower at least once a day may protect against infantile atopic eczema.

Exposure to dust mite allergen and endotoxin in early life and asthma and atopy in childhood

There has been no longitudinal study of the relation between concurrent exposure to dust mite allergen and endotoxin in early life and asthma and atopy at school age. To examine the relation between exposure to dust mite allergen and endotoxin at age 2 to 3 months and asthma, wheeze, and atopy in high-risk children. Birth cohort study of 440 children with parental history of atopy in the Boston metropolitan area. In multivariate analyses, early exposure to high levels of dust mite allergen (> or =10 microg/g) was associated with increased risks of asthma at age 7 years (odds ratio [OR], 3.0; 95% CI, 1.1-7.9) and late-onset wheeze (OR, 5.0; 95% CI, 1.5-16.4). Exposure to endotoxin levels above the lowest quartile at age 2 to 3 months was associated with reduced odds of atopy at school age (OR, 0.5; 95% CI, 0.2-0.9). In contrast with its inverse association with atopy, endotoxin exposure in early life was associated with an increased risk of any wheeze between ages 1 and 7 years that did not change significantly with time (hazard ratio for each quartile increment in endotoxin levels, 1.23; 95% CI, 1.07-1.43). Among children at risk of atopy, early exposure to high levels of dust mite allergen is associated with increased risks of asthma and late-onset wheeze. In these children, endotoxin exposure is associated with a reduced risk of atopy but an increased risk of wheeze. Early endotoxin exposure may be a protective factor against atopy but a risk factor for wheeze in high-risk children.

Cat and dust mite allergen levels, specific IgG and IgG 4, and respiratory symptoms in adults

Exposure to allergen may induce a modified T(H)2 response characterized by high IgG(4) levels, absence of IgE sensitization, and a decreased risk of allergic respiratory symptoms. To assess the association of IgG(4) level with allergic respiratory symptoms in a community-based sample of adults. Information on exposure to cats, respiratory symptoms, and mattress allergen levels was obtained from 2780 adults. Levels of cat and house dust mite (HDM) specific IgE, IgG, and IgG(4) were measured. The association of exposure to allergen with IgG(4) and of IgG(4) with symptoms was assessed. Geometric mean (GM) cat specific IgG and IgG(4) was higher in subjects who had a cat that was allowed in the bedroom than in subjects without a cat (adjusted ratio of GM IgG(4), 1.41; 95% CI, 1.25-1.57). Levels of HDM specific IgG and IgG(4) were similar in subjects with undetectable and high (>20.22 microg/g) mattress Der 1 levels (adjusted ratio of GM IgG(4), 1.02; 95% CI, 0.89-1.17). There was no evidence that high cat or HDM specific IgG(4) levels were associated with less IgE sensitization or with fewer symptoms. In this community-based sample of adults, high IgG(4) levels to cat or HDM were not associated with a lower risk of allergic respiratory symptoms. In adults, high cat allergen exposure does not protect against respiratory symptoms.

High-throughput fluorescent multiplex array for indoor allergen exposure assessment

Current enzyme immunoassay methods for detection of common indoor allergens in environmental dust samples are labor-intensive and time consuming. To develop and validate a fluorescent multiplex array to measure 6 (Der p 1, Der f 1, Der p 2, Der f 2, Fel d 1, and Can f 1) indoor allergen levels simultaneously. A multiplex array for 6 allergens, using mAbs covalently coupled to fluorescent microspheres, was developed using a single universal standard composed of purified natural allergens. The multiplex array was validated by comparing the measured dust mite, cat, and dog allergen levels in household dust samples to those obtained by standard ELISA methods. Linear regression analysis showed a highly significant quantitative correlation between the multiplex array and ELISA for dust mite, cat, and dog allergens: R(2) values ranging from 0.90 to 0.99 (P < .001). In addition, the sensitivity, limit of detection (<0.1 ng/mL), reproducibility, intra-assay coefficient of variance (<5%), and interassay coefficient of variance (<25%) of the fluorescent multiplex array were shown to be equal to or better than the ELISA method. A multiplex array has been developed to measure simultaneously 6 indoor allergens from a single sample. The array will facilitate epidemiologic studies and indoor air quality assessments and can, in principle, be expanded to include other allergens and biologics. The multiplex array lends itself to clinical studies, population-based environmental surveys, and allergen avoidance studies comparing allergen exposure in large populations over several time points.

Repeated measurements of mite and pet allergen levels in house dust over a time period of 8 years

Studies of the association between indoor allergen exposure and the development of allergic diseases have often measured allergen exposure at one point in time. We investigated the variability of house dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen in Dutch homes over a period of 8 years. Data were obtained in the Dutch PIAMA birth cohort study. Dust from the child's mattress, the parents' mattress and the living room floor was collected at four points in time, when the child was 3 months, 4, 6 and 8 years old. Dust samples were analysed for Der p 1, Der f 1 and Fel d 1 by sandwich enzyme immuno assay. Mite allergen concentrations for the child's mattress, the parents' mattress and the living room floor were moderately correlated between time-points. Agreement was better for cat allergen. For Der p 1 and Der f 1 on the child's mattress, the within-home variance was close to or smaller than the between-home variance in most cases. For Fel d 1, the within-home variance was almost always smaller than the between-home variance. Results were similar for allergen levels expressed per gram of dust and allergen levels expressed per square metre of the sampled surface. Variance ratios were smaller when samples were taken at shorter time intervals than at longer time intervals. Over a period of 4 years, mite and cat allergens measured in house dust are sufficiently stable to use single measurements with confidence in epidemiological studies. The within-home variance was larger when samples were taken 8 years apart so that over such long periods, repetition of sampling is recommended.

Endotoxin Levels in Rural Thai and Urban Singaporean Homes

Background: Exposure to dust endotoxin and allergens in early childhood may influence the development of allergic diseases. Aims: This study aimed to evaluate dust endotoxin and dust mite allergens in urban Singapore and rural Thai homes of young children and study potential environmental influences. Methods: Mattress dust endotoxin and Der p 1, Der f 1, group 2 (Der f 2 and Der p 2) and Blo t 5 allergen levels were quantified in 101 infant mattress dust samples, 51 from urban Singapore and 50 from rural Thailand. Comprehensive questionnaires on the home environment and cleaning practices were completed. Results: Endotoxin levels in rural Thailand were significantly higher than in urban Singapore (geometric mean 26,334.12 ± 4.60 and 18,377.85 ± 2.52 endotoxin units/g, respectively; p = 0.032). In contrast, higher levels of Der f 1 (p = 0.02), group 2 (p < 0.01) and Blo t 5 (p < 0.01) allergens were found in Singapore homes compared with rural Thai homes. Multiple logistic regression analysis showed that the use of detergents (p = 0.001) and disinfectants (p = 0.024) to clean floors and mattress protectors (p = 0.021) were independently associated with lower endotoxin levels. Conclusion: Endotoxin levels are higher in rural compared with urban homes in South East Asia. The reverse was true for dust mite allergen levels. Certain identifiable home environmental conditions and practices accounted for the differences in endotoxin levels.

Allergens in School Settings: Results of Environmental Assessments in 3 City School Systems

Environmental allergens are major triggers for pediatric asthma. While children's greatest exposure to indoor allergens is in the home, other public places where children spend a large amount of time, such as school and day care centers, may also be sources of significant allergen encounters. The purpose of this article is to describe schoolroom allergen levels from 3 different geographic sites obtained from dust samples collected in the fall and in spring. Environmental dust samples were collected from elementary schools in Birmingham (AL), Detroit (MI), and Houston (TX), from 4 room locations, including the cafeteria, library, upper grades, and lower grades. Samples were assayed for dust mite (Dermatophagoides pteronyssinus and Dermatophagoides farinae), cat (Felis domesticus), and cockroach (Blatella germanica 2) allergen levels. Allergen levels varied by geographic location and type of schoolroom. Schoolroom settings differed by the type of flooring (hard and carpet), room characteristics and use (food service, library shelves with books, and general classroom with multiple types of materials [individual desks and different types of furniture]), and the average age of the schoolroom dwellers (younger vs. older children). Dust mite, cat, and cockroach allergens were present in all schoolrooms and all sites at varying levels by season and by type of room. Schools may be important sources of direct allergen exposure and reservoirs that could potentially contribute to allergic sensitization and disease exacerbation in children. Further studies are needed to carefully examine the environmental allergen load in schools and its effect on children.

Distribution and determinants of house dust mite allergens in Europe: The European Community Respiratory Health Survey II

Several studies in European homes have described allergen levels from the house dust mite species Dermatophagoides pteronyssinus and to a lesser extent Dermatophagoides farinae, but geographic comparisons of exposure levels and risk factors have been hampered by a lack of standardized methods. To study the distribution and determinants of the major house dust mite allergens Der p 1 and Der f 1 in 10 European countries using a common protocol. During home visits with 3580 participants of the European Community Respiratory Health Survey II from 22 study centers, mattress dust was sampled and analyzed for Der p 1, Der f 1, and Der 2 allergen. Information on housing characteristics was obtained by both observations and interview. Der 1 and Der 2 allergens were detectable (>/=0.1 mug/g) in 68% and 53% of the samples, respectively. Large differences in allergen levels between study centers were observed, and geographic patterns for Der p 1 and Der f 1 were different. Low winter temperatures reduced Der p 1 rather than Der f 1. Important risk factors for high allergen levels included an older mattress, a lower floor level of the bedroom, limited ventilation of the bedroom, and dampness for Der p 1 but not for Der f 1. There are large qualitative and quantitative differences of house dust mite allergen levels in Europe, which can partly be explained by geographic and housing characteristics. Mite allergen exposure may be reduced by replacing the mattress regularly and increasing ventilation of the bedroom, particularly in winter.

Nonlinear relations between house dust mite allergen levels and mite sensitization in farm and nonfarm children

Low sensitization rates to common allergens have been observed in farm children, which might be due to high exposure to microbial agents. It is not known how microbial agents modify the association between specific allergen exposure and sensitization. To examine the relations between house dust mite allergen exposure and mite sensitization in farm and nonfarm children and to assess the effects of microbial agents levels on this association. Major mite allergens of Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1), endotoxin, beta(1,3)-glucans and fungal extracellular polysaccharides were measured in mattress dust of 402 children participating in a cross-sectional study in five European countries. Mite allergen (Der p 1 + Der f 1) levels were divided into tertiles with cut-offs 1.4 and 10.4 microg/g. Sensitization was assessed by measurement of allergen-specific immunoglobulin E against house dust mite. Prevalence ratios of mite sensitization for medium and high when compared with low mite allergen levels were 3.1 [1.7-5.7] and 1.4 [0.7-2.8] respectively. Highest mite sensitization rates at intermediate exposure levels were consistently observed across country (except for Sweden) and in both farm and nonfarm children. The shape of the dose-response curve was similar for above and below median mattress microbial agent levels, but the 'sensitization peak' appeared to be lower for above median levels. Our data suggest a bell-shaped dose-response relationship between mite allergen exposure and sensitization to mite allergens. In populations with high microbial agent levels and low sensitization rates, the curve is shifted down.

Influence of mattress characteristics on house dust mite allergen concentration

Exposure to a high level of house dust mite allergens (HDMAs) is considered as a risk factor for HDM sensitization and development of asthma in genetically disposed people. Mattresses are one of the most important sources of HDMA in people's living environment. The aim of this study was to evaluate the association between mattress characteristics and HDMA concentrations on mattresses. Dust samples of mattress surfaces were taken to evaluate the level of Der p 1 allergen. All participants filled in a questionnaire about the type of mattress, the type of covering (upper layer) of the mattress, dwelling characteristics and cleaning habits. Humidity and temperature of the bedroom were measured at the time of dust sampling. One hundred and sixty-eight questionnaires were filled in. Synthetic upper layer of the mattress was associated with a higher level of Der p 1 compared with cotton upper layer (2.6 vs. 0.8 microg/g Der p 1). Moreover, higher relative humidity (RH) was associated with significant higher concentrations and density of Der p 1. Two factors were associated with lower levels of Der p 1 found on mattresses, namely: a cotton upper layer of the mattress compared with a layer of synthetic material and lower RH at the time of sampling. As far as we know, the association between type of upper layer and concentration of Der p 1 has not been described before and could lead to the formulation of practical advices in order to reduce HDMA concentrations on mattresses.

House dust mite allergen level and allergen sensitization as risk factors for asthma among student in Central Jakarta

This study is a community-based study to get an overview about House Dust Mite (HDM) allergen level, allergen sensitization as risk factors of asthma. This is a cross-sectional study on 3,840 students from 19 junior high schools, aged 13-14 years. All of the respondents filled out the International Study on Asthma and Allergy in Children (ISAAC) questionnaire. Of 3840 respondents, 288 (7.5%) were assigned to asthma group (experience wheezing during the last 12 months). The skin prick test was performed on 207 respondents and the house dust mite was collected from 135 respondents. Of 2601 respondents in non-asthma group, the skin prick test was randomly performed on 274 respondents and the house dust mite was collected from 165 respondents. There is no significant difference on HDM allergen concentration for Der p1, Der f1 or Group I between asthma and control group. The risk of asthma was caused especially by sen D.pteronyssinus (crude odds ration (OR): 12.68, 95% confidence interval (CI): 7.50-21.44), D.farinae (OR: 10.50, CI: 6.35-17.34) and cockroach allergen (OR:5.57, CI:3.44-9.01). The risk for asthma was not correlated with the level of house dust mite allergens but its sensitization. In conclusion, sensitization to HDM and cockroach allergen should be concerned in order to reduce risk and prevalence of asthma. (Med J Indones 2006; 15:55-9)Keywords: house dust mite, allergen sensitization, asthma, risk factor

Are house dust mite allergen levels influenced by cold winter weather?

Moisture is vitally important for house dust mites and they cannot survive in cold or hot-dry climates. To investigate the influence of two extraordinarily cold and dry winters in 1995/1996 and 1996/1997 on house dust mite levels in German homes. Dust samples were collected between June 1995 and December 2001 on the mattresses of 655 adults and 454 schoolchildren living in five different areas of Germany. We compared house dust mite allergen Dermatophagoides pteronyssinus (Der p 1) levels before and during the winters of 1995/1996 and 1996/1997 with levels after these winters. D. pteronyssinus (Der p 1) levels in samples taken after the cold winters of 1995/1996 and 1996/1997 were approximately two times lower than Der p 1 levels in dust samples collected before or during these respective winters (Geometric means: Erfurt 89 vs 33 ng/g; Hamburg 333 vs 219 ng/g; Bitterfeld, Hettstedt, and Zerbst 296 vs 180 ng/g). Except for Hamburg, the decrease in Der p 1 levels was statistically significant. D. pteronyssinus levels measured in dust samples collected in 2001 (i.e. 3 years after the two cold winters) show a statistically non-significant increase (Geometric means: Erfurt 33 vs 39 ng/g; Hamburg 219 vs 317 ng/g), suggesting that it may take a long time for mite allergen levels to increase again after a sudden decrease. We conclude that Der p 1 levels in German mattress dust samples have been approximately reduced by a factor of three to four by the two consecutive cold winters of 1995/1996 and 1996/1997.

Inner City Asthma Study: Relationships among sensitivity, allergen exposure, and asthma morbidity

Asthma-associated morbidity is rising, especially in inner city children. We evaluated the allergen sensitivities, allergen exposures, and associated morbidity for participants in the Inner City Asthma Study. We also determined geographic variations of indoor allergen levels. Nine hundred thirty-seven inner city children 5 to 11 years old with moderate to severe asthma underwent allergen skin testing. Bedroom dust samples were evaluated for Der p 1, Der f 1, Bla g 1, Fel d 1, and Can f 1. Skin test sensitivities to cockroach (69%), dust mites (62%), and molds (50%) predominated, with marked study site-specific differences. Cockroach sensitivity was highest in the Bronx, New York, and Dallas (81.2%, 78.7%, and 78.5%, respectively), and dust mite sensitivity was highest in Dallas and Seattle (83.7% and 78.0%, respectively). A majority of homes in Chicago, New York, and the Bronx had cockroach allergen levels greater than 2 U/g, and a majority of those in Dallas and Seattle had dust mite allergen levels greater than 2 microg/g. Levels of both of these allergens were influenced by housing type. Cockroach allergen levels were highest in high-rise apartments, whereas dust mite allergen levels were highest in detached homes. Children who were both sensitive and exposed to cockroach allergen had significantly more asthma symptom days, more caretaker interrupted sleep, and more school days missed than children who were not sensitive or exposed. Geographic differences in allergen exposure and sensitivity exist among inner city children. Cockroach exposure and sensitivity predominate in the Northeast, whereas dust mite exposure and sensitivity are highest in the South and Northwest. Cockroach allergen appears to have a greater effect on asthma morbidity than dust mite or pet allergen in these children.

Beyond our Pages

Beyond our Pages

Domestic Exposure to Fungi and Total Serum IgE Levels in Asthmatic Children

We measured the number of airborne, viable fungi and house dust mite (HDM) allergen levels in the homes of a group of asthmatic children. Blood samples were drawn and the amounts of total and specific serum IgE were determined. The association between the number of fungal colonies, dust mite allergen exposure, and specific and total IgE was evaluated. The number of viable airborne fungi was high (20 543 CFU/m3) in those investigated houses. Der p1 concentrations on child's mattress exceeding 2 μg/g were found in 78.6% of the houses. A quantitative dose-response relationship was demonstrated between the exposure to viable, airborne molds and the amount of total IgE (r = 0.4399 and P = .0249) and the level was further increased in children with coexposure to viable fungi and HDM.

Family history, dust mite exposure in early childhood, and risk for pediatric atopy and asthma

BackgroundDust mite allergen exposure is considered a major determinant of sensitization to these allergens during childhood and a risk factor for pediatric asthma. ObjectiveBy using a birth cohort in a setting with a substantial burden of dust mite allergen, we evaluated exposure and risk for outcomes related to allergy and asthma. MethodsWe collected dust from the bedrooms of 428 children born from 1987 to 1989 and measured Der f 1 and Der p 1 (μg/g dust, combined). Follow-up at 6 to 7 years of age included clinical examination, skin prick testing, specific serum IgE measurement, and methacholine challenge. ResultsNo overall association was evident for any outcome except bronchial hyperresponsiveness (adjusted odds ratio [OR], 0.62; 95% CI, 0.38-1.00; P < .050; and OR, 0.53; CI, 0.27-1.04; P < .065 for dust mite allergen levels ≥2 μg/g and >10 μg/g, respectively). With a parental history of allergy and asthma, there was an association between a positive dust mite skin test (OR, 2.09; CI, 0.93-4.73; P < .076) and dust mite allergen level >10 μg/g. The inverse was true for children without a parental history. Dust mite exposure of >10 μg/g was associated with a decreased risk of current atopic asthma among children with a parental history (OR, 0.39; CI, 0.05-3.13; P < .376), but with increased risk if without a parental history (OR, 1.52; CI, 0.22-10.6; P < .673). ConclusionParental history is an important independent variable in the relationship between early dust mite exposure and atopic outcomes. Increased exposure during infancy is associated with a higher risk for sensitization in the presence of a positive parental history, but is protective among children of parents without a history of atopic disease.

Predictors of indoor allergen

Rationale Indoor allergens can significantly increase morbidity in atopic children with asthma. The purpose of this study was to relate allergen-specific home characteristics to measured allergen levels in the homes of asthmatic children. Methods As part of an ongoing environmental intervention study, pet, cockroach, and dust mite allergen levels were collected from the homes of 341 children. Trained inspectors documented characteristics of homes located in suburban Maryland (76%) and Baltimore City (23%). We used factor analyses and linear regressions to explore the relationship between evidence found during home inspection and allergen levels. Results Factor analyses identified groups of independent home characteristics associated with each allergen. The combined evidence of roaches, plumbing leaks, dirty cooking pots and city dwelling was significantly associated with cockroach allergen levels (t=8.6, p<0.00). However, poor kitchen cleanliness, including exposed food and surface clutter, was less clearly associated (t=1.8, p=0.08). The presence of surface clutter, detached home, and infrequent cleaning of the bedroom floor were significantly associated with dust mite allergen levels (t=2.8, p=0.01). Presence of mattress/pillow encasements, however, did not predict dust mite allergen levels. Evidence of pet ownership (t=7.7, p<0.00), detached home in a suburban setting and infrequent washing of bedding statistically predicted pet allergen levels (t=3.4, p<0.00). Conclusions Analysis of a large cohort study demonstrated that cockroach allergen could be predicted by infestation, plumbing leaks and greasy stoves, but not by kitchen debris. Mite allergen was predicted by infrequent cleaning and surface clutter, but was unaffected by presence of mattress or pillow encasements.