Dust Mite Allergen Levels Research Articles

Dust mite allergens in the office environment.

The objective of this study was to evaluate the extent of dust mite infestation and its contribution to the health complaints in office settings. The methodology recommended for residential dwellings was evaluated for use in the work environment. Der p I allergen-specific ELISA was chosen as a primary method. A liquid chromatography method for guanine is suggested as a backup method to cover a few cases where other mite species may be encountered. The levels of dust mite allergens were measured in 14 offices in response to numerous health complaints. Approximately one-half of the offices investigated were identified as having a dust mite population. Four offices showed levels of Der p I in the dust greater than 1 microgram/g. In two offices, the dust mite allergens were the source of the health complaints. In the other two offices, dust mite allergens were one of the contaminants in the office environment. In all cases, the infestation of dust mites in the offices was localized to a few specific work areas. Office chairs were the primary location where dust mites thrived. The remedial measures included regular cleanup of all fabric-covered office furnishings. Steam cleaning was recommended to eliminate dust mite populations.

House dust mite allergen levels in dust from schools with smooth and carpeted classroom floors.

A study was conducted to investigate the levels of house dust mite allergen Der p I in classroom floor dust from 49 schools with smooth (n = 18) or carpeted (n = 31) floors. Schools were located in the city of Rotterdam (n = 29) and in a number of small communities in the Province of Gelderland (n = 20). Data on building characteristics of the schools were obtained. Dust samples were analysed for Der p I content, the major allergen of the house dust mite Dermatophagoides pteronyssinus. The results showed that in schools with carpeted classroom floors, larger amounts of settled dust and higher Der p I levels either expressed as concentrations (in ng/g) or loadings (in ng/m2) were found than in schools with smooth classroom floors. However, the levels of Der p I were considerably lower than in dust collected from floors in homes. Although the Der p I levels were low, effects of several building characteristics on the levels were found. Age of the floor cover, the number of classrooms in the school and the presence of damp spots in the building were related to Der p I concentrations and loadings mainly on carpeted floors. Remarkably, schools in the rural area contained significantly more dust and Der p I than schools in the urban area. We conclude that dust from carpeted classroom floors contains more house dust mite allergen than dust from smooth classroom floors, but much less than dust from floors in homes.

Adverse effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors associated with elevated serum IgE and eosinophilia

J A LLERGY C LIN I MMUNOL 1995;95:1053-5.

Rapid House Dust Mite (Acari: Pyroglyphidae) and Storage Mite (Acari: Glycyphagidae and Acaridae) Allergen Test

Ten years ago a simple technique was described for detecting guanine from house dust mite excretions. The level of guaninine correlated well with the level of house dust mite allergens. Detection of storage mites is becoming more and more important, and these mites also produce guanine. Therefore, the above-mentioned technique provides a good indication of levels of storage mite allergens.

House dust mite allergen levels in two cities in Canada: effects of season, humidity, city and home characteristics

The homes of 120 patients with asthma, 57 in Vancouver and 63 in Winnipeg, were studied. The characteristics of the homes were assessed by a questionnaire. Dust samples were collected and the indoor relative humidity was measured four times during the year covering all four seasons in both cities. Mite allergen levels were determined using monoclonal antibodies against Der p I and Der f I by the ELISA method. The mean levels of both mite allergens in mattress and floor samples in the homes in Vancouver and in Winnipeg were relatively low for all seasons. Mite allergen levels were found to be associated with city, season and individual home differences. They were significantly higher in Vancouver than in Winnipeg. Der p I and Der f I in mattress samples in both cities and Der f I in floor samples in Vancouver, varied by season. The indoor relative humidity level in the homes in Vancouver were also significantly higher than those in Winnipeg. There was, however, no significant association between the levels of indoor relative humidity and the levels of mite allergens after adjusting for variations in city, season and individual home. Although individual home differences were highly associated with mite allergen levels, only a few home characteristics were found to be related to mite allergen levels such as the type and the age of the home, the type of heating, the use of feather pillows and the number of occupants in the homes. Whether low levels of mite allergens are partially responsible for the relatively low prevalence of childhood asthma in Canada remains to be investigated.

Ventilation in homes infested by house‐dust mites

Thirty single-family homes with either high (> or = 2000 ng/g) or low (< or = 1000 ng/g) house-dust mite (HDM) allergen levels in mattress dust were examined for ventilation, thermal climate, and air quality (formaldehyde and total volatile organic compounds (TVOC). Elevated concentrations of HDM allergen in mattress and floor dust were associated with the difference in absolute humidity between indoor and outdoor air, as well as with low air-change rates of the home, particularly the bedroom. No correlation was found between concentration of TVOC or formaldehyde in bedroom air and HDM allergen concentration. In regions with a cold winter climate, the air-change rate of the home and the infiltration of outdoor air into the bedroom appear to be important for the infestation of HDM.

Mite (Der p I, Der f I), cat (Fel d I) and dog (Can f I) allergens in dust from Swedish day‐care centres

Early exposure to allergens is important for sensitization to inhalant allergens and it has been reported that there is a causal relationship between allergen exposure and bronchial asthma. We investigated the levels of major mite (Der p I/Der f I), cat (Fel d I) and dog (Can f I) allergen levels in dust collected from various locations in seven day-care centres (22 sections). The allergen levels were related to the characteristics of the day-care centres. Children and staff were questioned about contacts with animals, and cleaning personnel were asked about methods and frequency of cleaning. Mite allergen was found in nine of the 22 sections. The concentrations varied between < 16 ng/g and 106 ng/g dust (median < 16 ng/g). Mite allergen was not detected in any floor dust sample. Cat and dog allergen was detected in all centres and sections. The concentrations of dog allergen (median 4.3 micrograms/g; range < 60 ng-21 micrograms/g) were significantly higher (P < 0.05) than that of cat allergen (median 1.6 micrograms/g; range < 16 ng-22.8 micrograms/g). Higher amounts of both Fel d I and Can f I were observed on mattresses/sofas/cushion like toys and curtains than on tables/chairs and floors. The levels of cat or dog allergen on floors significantly correlated with the total number of children and staff with either a cat or a dog at home and or frequent contacts with them. Neither cleaning methods nor the frequency of cleaning influenced the allergen concentrations. The concentration of Fel d I was significantly lower (P < 0.05) in washed than in never washed curtains.(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental control of indoor biologic agents

Environmental control of indoor biologic agents

Environmental control of indoor biologic agents

The indoor environment contains unique pollutants, such as environmental tobacco smoke and indoor allergens. In addition, air pollutants may reach higher levels indoors than outdoors, and in some instances may exceed the national standards for outdoor exposure. Nonindustrial indoor settings, such as offices, residences, and vehicles, also have air quality problems. Although the role of occupational air pollutants (organic and inorganic) in causing complaints in the workplace has been clearly documented, the relationship between poor air quality and health complaints is often controversial. The main causes of poor indoor air quality are an inadequate ventilation or fresh air intake, biologic contamination of the indoor environment, and an accumulation of noxious compounds. A list of important indoor air pollutants is shown in Table I. Because indoor allergen concentrations are higher in homes than in public places, a greater effort should be made to control allergens at home. A reason for this difference may be the more aggressive chemical treatment of carpets in public places. However, in some instances high mite, cat, and dog allergen levels have been detected in schools and day care centers. These findings have important implications for families who are practicing allergen avoidance at home because the effort and time spent controlling allergen exposure could be jeopardized by exposure in the school environment.' Studies conducted in schools have demonstrated that carpets contain high levels of a variety of allergens including pollen, cat, dog, food, mite, and mold allergens.2 Carpets in schools and homes are an important reservoir of allergens.

Mite allergen control with acaricide fails

Background: We compared the effects of an acaricide, benzyl benzoate, with the effects of baking soda control applied to bedroom and living room carpets on house dust mite allergen levels, lung function, and medication use in 12 adult patients with asthma for 12 months. Methods: This was a randomized, double-blind, placebo-controlled study. Patients were enrolled from the allergy clinic of a large tertiary care center in a metropolitan area. All patients had positive dust mite puncture test results. Six patients used benzyl benzoate, and six used baking soda. Other aggressive mite control measures were implemented uniformly in each group. Subjects were to make two carpet applications, at baseline and at 6 months according to the manufacturer's recommendations. Dust samples were collected in bedroom and living room carpets at 0, 3, 6, 9, and 12 months; and quantities of Der p I and Der f I allergens were determined. Spirometry was done every 3 months, and peak flow rates were recorded for 10 days after each dust sampling. Results: There were no significant differences in mean allergen levels between the two groups over time at either site. There were no significant changes in lung function or medication use for either group. Conclusions: Benzyl benzoate powder applications may not be effective when done according to manufacturer's instructions. Further studies are necessary to test effectiveness when applied more frequently and for longer periods. (J ALLERGY CLIN IMMUNOL 1994;94:27-32.)

Asthma severity and morbidity in a population sample of Sydney schoolchildren: Part II ‐ Importance of house dust mite allergens

Despite an increasing prevalence of childhood asthma, few studies have quantified the strength of associations between asthma and its aetiological factors. To quantify the risk factors associated with childhood asthma and to investigate the characteristics of children most at risk. We studied a population sample of 1339 schoolchildren aged eight-11 years living in Sydney, NSW. Questionnaires were used to measure respiratory illness, histamine inhalation test to measure airway hyperresponsiveness (AHR), skin prick tests to measure atopy and ELISA assay to measure house dust mite allergen (Der p I) levels. 'Current asthma' was defined as the presence of wheeze in the previous year and AHR. The mean Der p I level in 72 homes was 22.5 micrograms/gm dust which is high compared to suggested thresholds of 2 microgram/gm for sensitisation and 10 micrograms/gm for exacerbation of symptoms. Sensitisation to house dust mites was the most important risk factor for current asthma (odds ratio 7.0, 95% CI 9.4, 22.2). Sensitisation to ryegrass was of minor importance (odds ratio 2.0, 95% CI 1.4, 3.1). The presence of AHR was strongly related to the degree of sensitisation to house dust mite allergen and children with skin wheals greater than 4 mm had frequent morbidity caused by asthma. To reduce the high prevalence of childhood asthma in NSW, it is imperative that we design interventions which recognise that house dust mite allergens are a dominant risk factor and that children with large skin wheal reactions to this allergen are most at risk for severe illness including disturbed sleep, days missed from school and urgent medical attention.

Effect of dry cleaning on mite allergen levels in blankets.

Since one of the greatest reservoirs of allergens is the blanket, we assessed mite allergen levels in dust collected from five blankets by vacuuming before and after dry cleaning with perchlorethylene and compared the results with five control blankets. Assays with monoclonal antibodies showed that group I (Der p I and Der f I) mite allergen levels per g dust were 78% lower after dry cleaning. Group I allergen levels per m2 of dry-cleaned blankets were 98% lower. RAST inhibition showed that total allergen levels decreased 70% after dry cleaning. Mite allergens were not denatured by perchlorethylene. The effect of dry cleaning resulted from physical washing out of dust and allergens.

The effects of season, climate, and air-conditioning on the prevalence of Dermatophagoides mite allergens in household dust

Background: Clinical evidence reveals a strong relationship between dust mite allergen levels and asthma. This study suggests the relative importance and interactions among factors that influence mite allergen levels in human dwellings. Methods: Dermatophagoides pteronyssinus allergen ( Der p I) and D. farinae allergen ( Der f I) were measured in 536 dust samples collected from 424 homes across the United States. Results: There were distinct seasonal fluctuations of Der p I and Der f I. Der p I rapidly increased to peak in July then gradually decreased through October. Der f I slowly rose to peak later, around September, before declining. Different climates in regions of the United States had no significant affect on the quantity of Der p I or Der f I. However, regional climate differences seemed to influence the prevalence of either D. pteronyssinus or D. farinae. Air-conditioning significantly reduced ( p < 0.001) Der I mite allergens detected in the dust samples, and a tendency existed for Der f I to be higher than Der p I in air-conditioned homes. There was a significant ( p < 0.01) interaction between air-conditioning and seasons. The most dramatic affect was observed during the summer months, the cooling season, from approximately May to September. Conclusions: These findings show that distinct seasonal fluctuations exist of D. pteronyssinus and D. farinae mite populations, and suggest that differences in the microclimate within homes may have a dramatic affect on Dermatophagoides mite populations.

Dust from carpeted and smooth floors. V. Cat (Fel d I) and mite (Der p I and Der f I) allergen levels in school dust. Demonstration of the basophil histamine release induced by dust from classrooms.

Sixty dust samples from schools in Norway were analysed for major allergens from cat and mite after sampling with the regularly used vacuum cleaners for 5 days and with a new model vacuum cleaner for 10 days, respectively. The major feline allergen Felis domesticus allergen I (Fel d I) was detected in all the classrooms, with ranges from 12 to 16,840 ng/m2 floor area. The mean Fel d I concentration was about 11 times higher per unit area carpeted floors as compared with smooth floors after the 10 days sampling period. Mite allergens Dermatophagoides pteronyssinus allergen I (Der p I) and Dermatophagoides farinae allergen I (Der f I) were detected in very low concentrations, with ranges from < 1 ng to 104 ng/m2 floor area. These findings suggest that the school is a protective environment against mite infestation, while the prevalence of cat allergens in classrooms seems higher than previously assumed. Basophil histamine release was measured after provocation with 20 dust extracts from 10 different schools. In nine of the 10 schools examined, the basophil histamine release caused by challenge with carpet dust was higher than the corresponding release with smooth floor dust. The calculated floor areas in each school in which dust led to 15% histamine release were from 2 to 55 times larger for smooth floors compared with carpeted floors. These results emphasize previous findings regarding higher allergen concentrations in classrooms with carpeted floors.

Effective education of adults with asthma who are allergic to dust mites

The effects of supplementary computer instruction in house dust mite—avoidance measures on adherence to implementing measures, on home dust mite—allergen levels, and on symptomatology were investigated in 52 adult patients with mite-associated asthma. Twenty-six patients received conventional instruction (counseling and written instruction) and the other 26 patients received conventional plus 22 minutes of interactive computer-assisted instruction. Instructions were aimed at mite-avoidance measures. Pre- and postinstruction dust samples were collected, and adherence was monitored. All patients kept symptom diaries twice a day. Patients' progress was followed for 12 weeks, and all patients completed the study. Adherence, number of observed and self-reported mite-avoidance measures implemented after visit, was higher for the computer group ( p = 0.023). The computer-instructed group achieved significantly lower levels of mite allergen in bedroom carpets ( p = 0.004) with mean levels of mite allergen declining from 6.5 ± 7.6 to 2.2 ± 4.3 μg/gm of dust (two-site monoclonal antibody assays), whereas levels for the conventional-instructed group did not change. Moreover, by study weeks 9 and 10, the computer-instructed group was significantly less symptomatic ( p = 0.033). Mean symptom scores for this group decreased from 12.4 to 7.7, compared with 16.4 to 14.3. Conventional instruction supplemented with computer instruction is suggested in mite education.

House dust mite allergen levels and an anti‐mite mattress spray (natamycin) in the treatment of childhood asthma

Natamycin, a fungicide marketed as Tymasil, is claimed to reduce house dust mite numbers and would therefore be expected to improve asthma in children with mite sensitivity. We have tested this assertion by a double-blind, placebo-controlled trial. There was no significant effect on levels of Der p I in mattress dust between active and placebo groups at the end of the spraying period. Histamine inhalation challenge PC20, clinic visit symptom scores and lung function tests reflecting either large or small airways obstruction were also unchanged. Therefore this product is not a therapeutic option for mite-allergic patients using the manufacturer's recommended dose and method of administration. Other factors influencing the Der p I levels were also investigated. Of these, only month of measurement and bedroom wall humidity showed any association.

407 Mite allergen levels in house dust: Application of a two-site monoclonal (Mab) ELISA assay for major allergens

407 Mite allergen levels in house dust: Application of a two-site monoclonal (Mab) ELISA assay for major allergens

Reduction of house dust mite allergen levels in the home: use of the acaricide, pirimiphos methyl.

House dust mite sensitivity is very common in patients with bronchial asthma, yet dust mite avoidance frequently receives little attention in clinical management. It is likely that any reduction in allergen levels associated with routine cleaning is insufficient to allow clinical improvement. In the present study the acaricide pirimiphos methyl is shown to reduce the levels of Dermatophagoides pteronyssinus, antigen P1 in homes. Following a single application the level of antigen P1 in dust from carpets was reduced by up to 73% and by more than 50% in soft furnishings. Serial sampling showed a reduction for 6 weeks under conditions where carpets and chairs treated with solvent showed a progressive rise in allergen level. Furthermore the survival of mites in cultures or infested carpet segments was markedly inhibited, with antigen P1 accumulation reduced by greater than 90%. These results suggest major reductions in house dust mite allergen levels in the home can be achieved.