Seasonal variations in house dust mite allergens--significance for children with allergy

Allergenic proteins of the house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae and their major allergens Der p I and Der f I are one of the most significant environmental factors which may facilitate sensitization and allergic airway disease in childhood. In order to measure seasonal variations of mite allergen exposure, we collected mattress dust samples monthly in 13 homes over a period of 1 year. Der p I and Der f I were determined with a sandwich type ELISA. Mite allergen levels were significantly lower from January-June than from July-December (p less than 0.05) which was mostly due to Der p I variations. Only in 6 of the studied homes seasonal variations in mite allergen concentrations according to seasonal variations in outdoor humidity could be observed. In 7 homes mite allergen exposure stayed constant and seemed to depend only on indoor climate factors.     

Determinants of indoor allergens in tropical child care centers

Limited data are available about indoor allergen determinants in child care centers (CCCs) especially in the tropics. This information is important epidemiologically and clinically considering many children attend CCCs. The purpose of this study was to determine the allergen concentrations in CCCs and their associations with CCC characteristics and indoor air quality (IAQ). A panel of indoor allergens including Der p 1, Blo t 5, Fel d 1, Can f 1, Mus m 1, Bla g 1 and Asp f 1 were evaluated from dusts vacuumed from classroom floors of CCCs. Allergen levels were assayed with antibody-based bioplex array or enzyme-linked immunosorbent assays. Indoor temperature, relative humidity and air exchange rates were measured and CCC characteristics inspected. Allergen levels were linearly regressed with CCC characteristics and IAQ. The dominant allergens found in classroom floors were Der p 1, Blo t 5 and Fel d 1. Lower indoor temperatures were associated with higher Der p 1 while lower ventilation rates were associated with higher Blo t 5 concentrations. Prevalence of cat owners was found to be a predictor for Fel d 1 concentrations. Full or partial carpeting is associated with higher dust mite allergen levels. These findings provide information for future indoor allergen exposure assessment studies in CCCs and can be used for intervention with regard to allergen avoidance.     

Vacuum cleaning decreases the levels of mite allergens in house dust

To investigate the capacity of chemical treatment of surfaces and the difference in capacity among common vacuum cleaners to reduce mite allergen content in house dust, we recruited 52 families with allergic children. Ten families used their central vacuum cleaners. Forty-two families were randomly divided into four groups with 10 or 11 families in each. These families used cither new vacuum cleaners with either HEPA (High Efficiency Paniculate Air) or micro-filters, or their own vacuum cleaners with either tannic acid or placebo. Dust samples were collected from carpets and upholstered furniture in the living rooms and from the mattresses of the children at Days 0, 7, 21, and 35. Der p I and Der f I allergens were determined by sandwich ELJSA, After one week, tannic acid reduced the concentration of mite allergens/g of dust and the total amount/sampling area by 30% and 34%, respectively (p < 0.05), but there was no significant decrease in relation to placebo. After 5 weeks, central, HEPA- and micro-filter vacuum cleaners decreased the mite allergen concentration by 10–50% (p < 0.05) and the total amount of mite allergen from the investigated areas by 50–85% (p < 0.01). In relation to the placebo group the decrease was significant for HEPA-and micro-filter vacuums (p < 0.05), The total amount of mite allergens/ sampling area was more significantly (p < 0.05) reduced than the con-centration/g of dust. We conclude, that tannic acid reduces mite allergen concentrations in dust and total amount/sampling area for a short period of time. Central, HEPA- or micro-filter vacuum cleaners reduce mite ellergen concentrations and still more the total amount of mite allergen in house dust when used regularly for long periods. Therefore, when the total house is thoroughly cleaned, tannic acid should be applied to car pets and upholstery and low mite allergen levels maintained by using modern vacuum cleaners.     

Effects of an acaricide on asthmatic children with house dust mite allergy

D'Allergen is a recently available acaricidal and allergen reducing agent. To study any beneficial effects of treating houses with this agent in asthmatic children with dust mite allergy, histamine bronchial responsiveness was measured in 18 children before and 6–8 weeks after their homes were treated with the agent. Comparisons were with nine similar asthmatics whose homes were not treated. The mean provocative concentration of histamine causing a 20% fall in forced expiratory volume in 1s (PC₂₀) increased from 1.02mg/L to 2.07mg/L in all 18 children who were studied (1.01 doubling doses). Bronchial responsiveness was relatively unchanged in a well matched control group of nine children studied over comparable time periods (PC₂₀ pre was 1.25 mg/L, PC₂₀ post was 0.67 mg/L). The results suggest that treating homes with D'Allergen reduces bronchial reactivity in asthmatic residents with house dust mite allergy.     

The effect of high-efficiency and standard vacuum-cleaners on mite, cat and dog allergen levels and clinical progress

The major triggers for allergic asthma are exposure to allergens of the house dust mite, Dermatophagoides pteronyssinus , and of pets. Unfortunately studies of techniques designed to reduce house dust mite and pet allergens have had mixed results. However, new so-called 'improved' products continue to appear on the market and require subjective evaluation. The homes of 60 house dust mite-allergic patients were studied to compare the effects of high-efficiency and standard vacuum-cleaners on allergen concentration. Der p 1 (house dust mite), Fel d 1 (cat) and Can f 1 (dog) allergens were measured in four separate locations in each home. Clinical analysis was by lung function, bronchodilator usage and histamine challenge techniques. There was a significant reduction in Fel d 1 (ng/m²) in dust samples from the living-room carpet (p = 0.046), bedroom carpet (p = 0.003) and mattress (p = 0.013) and living-room sofa (p = 0.005) after 12 months of using the high-efficiency cleaners, but only in the mattress sample using the standard cleaners (p = 0.014). Can f 1 (ng/g dust) was reduced in the mattress sample after using the high-efficiency vacuum-cleaners (p = 0.028), but not at other sites. Der p 1 levels were not significantly changed over this period. Clinically, patients in the high-efficiency group showed improvements in peak expiratory flow rate (PEFR) (p = 0.004), FEV₁ (p = 0.026) and bronchodilator usage (p = 0.005) after 12 months. When the cat-sensitive patients were analyzed separately, improvements in histamine PC₂₀ (p = 0.039) were also seen. Reducing Fel d 1 concentrations, in the absence of any change in Der p 1 concentrations, can produce significant improvements in the lung function of atopic, asthmatic patients. This effect was primarily achieved in those patients with cat sensitivity, but who did not possess a cat themselves.     

Allergens in urban schools and homes of children with asthma

To cite this article: Permaul P, Hoffman E, Fu C, Sheehan W, Baxi S, Gaffin J, Lane J, Bailey A, King E, Chapman M, Gold D, Phipatanakul W. Allergens in urban schools and homes of children with asthma. Pediatr Allergy Immunol 2012: 23: 543-549. ABSTRACT: Background: Most studies of indoor allergens have focused on the home environment. However, schools may be an important site of allergen exposure for children with asthma. We compared school allergen exposure to home exposure in a cohort of children with asthma. Correlations between settled dust and airborne allergen levels in classrooms were examined. Methods: Settled dust and airborne samples from 12 inner-city schools were analyzed for indoor allergens using multiplex array technology (MARIA). School samples were linked to students with asthma enrolled in the School Inner-City Asthma Study (SICAS). Settled dust samples from students' bedrooms were analyzed similarly. Results: From schools, 229 settled dust and 197 airborne samples were obtained. From homes, 118 settled dust samples were obtained. Linear mixed regression models of log-transformed variables showed significantly higher settled dust levels of mouse, cat and dog allergens in schools than homes (545% higher for Mus m 1, estimated absolute difference 0.55?μg/g, p?相似文献   

House dust mite allergen reduction and allergy at 4 yr: Follow up of the PIAMA-study

Exposure to high allergen levels in early life is a risk factor for the development of allergy. We previously reported limited effects of mite allergen impermeable mattress covers in the prevention and incidence of asthma and mite allergy (PIAMA) cohort at the age of 1 and 2 yr. We now present the results of follow-up at 4 yr objectives. To examine the effects of early reduction of house dust mite (HDM) allergen exposure by means of mattress covers on the incidence of allergy and asthma symptoms in the PIAMA birth cohort at the age of 4 yr. High-risk children (allergic mother) were prenatally recruited and randomly allocated to three groups; receiving mite allergen impermeable mattress covers (n = 416), placebo covers (n = 394) or no intervention (n = 472). At 4 yr of age, atopy was assessed by questionnaire; specific Immunoglobulin E (IgE) to inhalant and food allergens was measured in serum. Dust samples collected from the children's mattresses were analysed for mite allergens. Dermatophagoides farinae1 allergen (Der f 1) levels in dust were reduced in the active group. However, Dermatophagoides pteronissinus 1 (Der p 1) levels, sensitization and atopic symptoms were similar in all groups. We found no effect of mite allergen impermeable mattress covers on sensitization and atopy at 4 yr. Moreover, the allergen reducing effects of the covers had disappeared for one of the two mite allergens that were measured.     

Concentrations of cat (Fel d 1), dog (Can f 1) and mite (Der f 1 and Der p 1) allergens in the clothing and school environment of Swedish schoolchildren with and without pets at home

To investigate whether our hypothesis that cat and dog owners bring allergens to public areas in their clothes was true or not, we studied the levels of Fel d 1, Can f 1, Der p 1 and Der f 1 in dust from the clothes and classrooms of children in a Swedish school. We also investigated the levels of allergen in different areas in the four classrooms used by the children. Thirty-one children were selected in four classes, forming three groups: cat owners, dog owners and children without a cat or dog at home. Furthermore, a group of children with asthma was included. Cat and dog allergens were detected in all 57 samples from clothes and classrooms. Mite allergen Der f 1 was detected in low concentrations in 6 out of 48 and Der p 1 in 5 out of 46 samples investigated. The concentrations of Can f 1 were higher than those of Fel d 1 in samples from clothes (geometric mean: 2676 ng/g fine dust and 444 ng/g) and classrooms (Can f 1: 1092 ng/g, Fel d 1: 240 ng/g). The dog owners had significantly higher concentrations of Can f 1 (8434 ng/g fine dust) in their clothes than cat owners (1629 ng/g, p <0.01), children without cat or dog (2742 ng/g, p < 0.05) and children with asthma (1518 ng/g, p < 0.001). The cat owners did not have significantly higher levels of Fel d 1 (1105 ng/g) in their clothes compared to the other three groups (D: 247 ng/g, nCnD: 418 ng/g, A: 386 ng/g) but the levels were significantly higher than for all children without a cat at home (345 ng/g, p < 0.05). No concentrations of mite allergen and low concentrations of Fel d 1 and Can f 1 were found in the children's hair. There were significantly higher concentrations of Fel d 1 and Can f 1 in dust from curtains than in samples from floors and bookshelves (p < 0.05). There was no significant difference between the allergen concentrations in samples from curtains and from desks and chairs, including the teachers' chairs, the only upholstered furniture in the rooms. Our results support the hypothesis that cat and dog owners bring allergens to public areas in their clothes and support other studies showing that textiles and upholstered furniture function as reservoirs of cat and dog allergens. Thus, children with asthma and other allergic diseases will be exposed to cat and dog allergens at school and by contact with pet owners, even if they avoid animal allergens at home.     

Childhood asthma and exposure to indoor allergens: lowmite levels are associated with sensitivity

The prevalence and level of sensitivity to indoor allergens were studied in relation to current exposure at home in 124 children with perennial asthma living in three climatic zones of Sweden. The house dust mite (HDM) allergen levels were higher in the South than in the North (p < 0.001), while cat and dog allergen levels tended to be higher in the North than the South (n. s.). Thirty-four percent of the children were sensitive to the HDM Dermatophagoides pteronyssinus , as determined by IgE antibodies in vitro, 27% were sensitive to D. farinae , 57% to cat and 55% to dog. Sensitivity to HDM was significantly more prevalent in Southern, than in Central and Northern Sweden (p=0.001) where the children were more often sensitive to pets (cat p=0.005, dog p= 0.002). A significant association between the concentration of Der p I and Derf I in the house dust and both the prevalence of sensitivity to HDM and the IgE antibody levels against mites was found even at concentrations well below the commonly suggested risk level for sensitisation of 2 μg/g dust. No relationship was found between pet allergen concentration in the home dust and sensitivity to pets, possibly because of exposure outside home, e. g. in schools and meeting places for leisure activities. Similarly, there was no consistent association between the level of mite or pet allergen exposure at home and asthma severity as judged by symptom and medication score. The study indicates that there is no threshold value for sensitisation to mite allergens in asthmatic children, and therefore, dust allergen levels at home should be kept as low as possible in homes of children at risk for asthma.     

Exposure to indoor allergens and development of allergy

House dust contains several indoor allergens which can elicit hypersensitivity and various atopic symptoms, especially in childhood. This review article focusses on house dust mite hypersensitivity to one of the most important species, Dermatophagoides , as a model. A clear dose-response relationship has been demonstrated between house dust mite allergen exposure in mattress dust samples and sensitization, i.e. serum IgE to Dermatophagoides and positive histamine release from basophil leukocytes to one of the major allergens from Dermatophagoides pteronyssinus, Der p I. 2 μg major allergen of Dermatophagoides /g of dust and 8 μg major allergen of cat/g of dust have been suggested to be threshold concentrations above which the risk of sensitization in genetically predisposed atopic children is significantly increased. Epidemiological studies showed house dust mite allergens to be one of the most important risk factors in the development of atopic airway disease. A relation between age at onset of the first wheezing episode and house dust mite allergen exposure at the age of 1 year has been observed. There are various factors influencing house dust mite growth, and many studies have been performed to reduce house dust mite allergen exposure. Until now, none of the approaches appeared to have achieved sufficient mite and mite allergen reduction.     

Low frequency of positive skin tests in asthmatic patients infected with Schistosoma mansoni exposed to high levels of mite allergens

Helminthic infections and allergic diseases are highly prevalent in many parts of the world. Although skin reactivity to indoor allergens is decreased in subjects from helminthic endemic areas, the degree of exposure to mite allergens has not yet been investigated in these areas. This study evaluated the association between exposure to dust mites and skin reactivity to mite allergens in subjects with a history of wheezing in the last 12 months selected from a rural endemic area for schistosomiasis (group I, n = 21), and two non- Schistosoma mansoni endemic locale, a rural area (group II, n = 21) and a urban slum area (group III, n = 21). All subjects were evaluated by skin prick tests with mite allergens, and for total and specific immunoglobulin E (IgE) against dust mites, antibodies for S. mansoni , and for intestinal parasites. Dust samples from each subjects' home were quantified for mite allergen and species of the mite identification. Except for S. mansoni infection which was more prevalent in group I than in groups II and III (p < 0.0001), the prevalence of intestinal parasites, and total and specific IgE levels were similar for all groups. Despite the levels of mite allergens and specifically to Der p 1 detected in dust samples of subjects home from all three areas, the frequency of positive skin reactivity to mite antigens was significantly lower (19.0%) in subjects from group I relative to group II (76.2%) and group III (57.1%; p < 0.001). This result suggests that S. mansoni infection could modulate the immediate hypersensitivity skin response to mite allergens in highly exposed subjects.     

Sensitization to house dust mites: importance and possibilities of allergen elimination]

House-dust mite allergy (Dermatophagoides pteronissinus and Dermatophagoides farinae) is an important causative factor for allergic asthma or rhinitis in children. There is a clear relationship between the degree of allergen exposure and the subsequent development of asthma or the risk of sensitisation. It is therefore useful to know how intensive a patient is exposed to house-dust allergen. This can be managed either by counting all mites in the dust, by measuring of the content of Der p I and Der f I (major antigens of the two mites) per gram dust or using the Acarex test. These methods are also suitable for the control of sanitation measurements, e.g. avoidance of all dust sources in the bedroom and living-room, use of suitable materials for bedding, application of acaricide products and covering mattresses with polyurethane-coated materials.     

Placebo-controlled study of the mite allergen-reducing effect of tannic acid plus benzyl benzoate on carpets in homes of children with house dust mite sensitization and asthma

We studied the effect of a spray containing 1% benzyl benzoate, an acaricide, and 1% tannic acid (‘Lowal’; a protein‐denaturing substance), on concentrations of major allergens from house dust mite (HDM) species Dermatophagoides pteronyssinus and D. farinae (Der p 1 and Der f 1, respectively) in carpets. In a double‐blind, placebo‐controlled study with crossover design, 30 homes of children with HDM sensitization and asthma were included. All houses showed ≥ 400 ng/g of Der p 1 + Der f 1 in carpet dust. The first treatment was performed on day 0 (group 1 active treatment, n = 15; group 2 placebo treatment, n = 15). After 2 and 8 weeks, dust samples were collected for quantification of mite allergens. After a 2‐week washout period, the second treatment was performed (group 1 placebo treatment; group 2 active treatment). Again, carpet dust was collected after 2 and 8 weeks. Twenty‐two of 30 families completed the trial: 14/15 in group 1 and eight of 15 in group 2. On day 0, there was no significant difference in mite allergen exposure between group 1 and group 2 (1,498 vs. 2,239 ng/g of Der p 1 + Der f 1, respectively). In group 1, the geometric mean for the difference of mite allergen concentration comparing day 0 and week 6 was 196 ng/g (95% CI: ?7,161 and 8,401) for the first treatment (active) and 15 ng/g (95% CI: ?1,079 and 1,292) for the second treatment (control). In group 2, the difference was 66 ng/g (95% CI: ?398 and 1,515) for the first treatment (control) and 609 ng/g (95% CI: 186 and 9,264) for the second treatment (active). Comparing placebo and active treatment in total, there was a significant decrease following placebo treatment after 14 days (p = 0.026). After 8 weeks, active treatment was superior to placebo treatment (p = 0.049), but the allergen reduction achieved was < 20% (median 1,500 ng/g on day 0 vs. 1,250 ng/g after 8 weeks). We conclude that the slight mite allergen reduction on carpets achieved by the treatment with ‘Lowal’ is unlikely to achieve worthwhile clinical benefit either in the treatment of mite‐sensitive patients or in primary or secondary prophylaxis.     

Domestic aeroallergen levels in Barcelona and Menorca (Spain)

Exposure to common indoor allergens is known to be associated with sensitization and triggers of asthma. Levels of allergens have been barely described in Mediterranean countries. This study reports domestic allergen levels among the general population of two regions of Spain. Dust samples were collected from living rooms and mattresses in homes of infants in Barcelona (n = 366) and Menorca (n = 475) and assayed for house dust mite ( Der p 1 ) and cat allergen ( Fel d 1 ) concentrations by enzyme-linked immunoabsorbent assay (ELISA). Geometric mean values (95% CI) of Der p 1 were 0.77 µg/g (0.65, 0.92) in living rooms and 0.68 (0.56, 0.82) in children's mattresses in Barcelona, and 9.06 (7.93–10.34) and 3.12 (2.71–3.59) in Menorca, respectively. Fel d 1 levels were 0.37 µg/g (0.31, 0.45) and 0.14 (0.12, 0.18) in Barcelona, and 0.42 (0.35, 0.50) and 0.20 (0.18, 0.24) in Menorca. Home characteristics were not consistently related to levels of aeroallergens in either location. Differences in Der p 1 levels in the two locations indicate that levels cannot be extrapolated from one part of a country to another with any certainty. Additionally, allergen reduction measures related to indoor sources must be specific to each location.     

Cat and dog allergen in mattresses and textile-covered floors of homes which do or do not have pets, either in the past or currently

The aim of this study was to measure the levels of cat and dog allergen in homes of families that had either never kept pets or kept or had kept cats or dogs. From a small residential area outside Stockholm consisting of 250 houses with similar exteriors 70 homes were included. Dust samples were collected from mattresses and textile-covered floors. The levels of cat and dog allergen were analysed by ELISA. Fel dl was found in mattress dust in all 70 homes, median 0.5 μg/g [0.24–8.89 μg/g (quartiles)] and textile-covered floors 0.7 μg/g (0.20–2.52 μg/g). Can fl, was found in 98% of the collected samples, mattress dust 1.89μg/g (0.70–9.20 μg/g) and textile-covered floor dust 2.5 μg/g (1.04–2.72 μg/g). There was a positive correlation (p < 0.001) between allergen levels in dust from mattresses and textile-covered floors for both Fel dl(r = 0.68) and Can fl (r = 0.78). The highest levels of cat and dog allergen were found in homes with furred pets (p < 0.001). A significant (p < 0.001) difference was seen in the levels of Fel dl and Can f 1 between the homes of former pet-owners and homes without pets. In summary; cat and dog allergens are present in homes regardless of whether such animals live in the house or not. Mattresses seem to be an underestimated reservoir for pet allergens even in homes without pets. It is important to note that the homes of former pet owners have much lower levels of allergen than current pet owners.     

The influence of exposure to house dust mite, cat, pollen and fungal allergens in the home on primary sensitisation in asthma

The homes of 68 atopic asthmatic children were studied to estimate the concentrations of perennial and seasonal aeroallergens (Der pl, Fel d1, grass pollen, tree pollen, Cladosporium , Aspergillaceae and Alternaria ) to which children were likely to have been exposed during their first few months of life, by sampling in the child's month of birth. There was a strong association between the presence or absence of the house dust mite allergen Der p1 in the air with the skin test and IgE antibody test results (p < 0.001), with a similar association for cat allergen Pel d 1 (p < 0.01), when using a low volume sampler (equivalent to the minute tidal volume of a small baby). No significant correlation was found between levels of allergen in carpet dust and air in the same room. There was a strong indication that the presence of a cat at birth was linked with a higher risk of development of allergy to cat, but high levels of Fel d 1 were sometimes found in homes even when there was no cat present, indicating that allergen may be introduced from other sources. The levels of tree pollen were significantly higher in the homes of tree pollen-allergic children than in the homes of patients without this sensitivity (p < 0.01); and the degree of sensitivity, determined by RAST, correlated significantly to the level of tree pollen in the home (p < 0.001). However, no relationship was found between specific sensitivity and the levels of Cladosporium , Aspergillaceae, Alternaria or grass pollen measured in the homes. The effect of high allergen exposure was most prominent in children under 7 yr and not beyond that age.     

Risk factors for asthma in inner city children.

Inner city children have the highest prevalence and the highest mortality rates for asthma in the United States. The purpose of this study was to evaluate sensitization and exposure to common indoor allergens among children aged 3 years to 15 years seen for treatment of asthma at Grady Memorial Hospital, Atlanta, Ga. Eighty children in this study were enrolled in the emergency department and 64 in hospital clinics. Dust from 57 homes, assayed for three indoor allergens (dust mite, cat, and cockroach), revealed similar exposure for asthma and control groups. Sixty-nine percent of the children with asthma had IgE antibodies to dust mite, cockroach, or cat; only 27% of the control subjects were similarly sensitized (p < 0.001). Of 35 children with asthma 21 had both sensitization and significant exposure to the relevant allergen; this was true for only 3 of 22 control subjects (odds ratio, 9.5; p < 0.001). Neither sensitization nor exposure to cat allergen was common in this population. The results show that black children in inner city Atlanta are exposed to high levels of mite and cockroach allergens and that a high proportion of the children with asthma are sensitized to these allergens; the combination of sensitization and exposure is a major risk factor for asthma in this population.     

Prenatal exposure to mite and pet allergens and total serum IgE at birth in high-risk children

To examine the relationship between prenatal exposure to mite, cat and dog allergens and total serum IgE at birth in newborns at high risk of asthma. In the homes of 221 newborns with at least one first-degree relative with asthma, concentrations (ng/g dust) of allergens of house dust mite (mite), cat and dog were measured at the fourth to sixth month of pregnancy in dust samples from the maternal mattress and living room. At day 3-5 after birth, total IgE was measured in capillary heel blood. A total number of 174 blood samples were available (11 mothers refused newborn's blood sampling, and in 36 cases the blood sample was too small for analysis). In 24% of the newborns, total IgE was elevated (cut-off value 0.5 IU/ml). A significant dose response relationship was found between increasing mite allergen levels [divided in quartiles ng/g dust (qrt)] and the percentage of elevated IgE: first qrt (0-85 ng/g) 13%; second qrt (86-381) 19%; third qrt (382-2371) 26%; fourth qrt (> or =2372) 42%, respectively, p=0.01. This relationship remained significant after adjusting for passive smoking, maternal and paternal mite allergy, socio-demographic factors, birth characteristics and (breast) feeding practice in the first week of life. In high-risk newborns, prenatal exposure to mite allergens, but not to cat and dog allergens from dust of the living room and of the maternal mattress was associated with total serum IgE at birth.     

Endotoxin exposure and symptoms in asthmatic children

Endotoxins (ET) are pro-innammatory substances present in hou.sc dust which may increase non-specific bronchial reactivity in asthmatic patients. Endotoxins (EU/g) and Der p I levels were compared in the homes often asthmatic and ten control children, aged 6-16 years, living in Sao Paulo, Brazil. The houses were visited once a month from February 1993 lo February 1994 and dust samples were collected from the bedding and floor of each subject's house. No significant differences were observed in ET and Derp 1 levels in the homes of asthmatics and controls. The highest ET levels were detected in January and November, whereas the lowest levels were detected in April and August (p < 0.05). demonstrating a distinct seasonal distribution. The highest Der p I levels in bedding were observed in July and the lowest in February (p < 0.05). while Derp I levels in floor did not show significant differences throughout the year. Symptom and medication scores were evaluated monthly in the group of asthmatic children. There was a significant correlation (p < 0.05. r = 0.63) between clinical symptom scores and ET exposure, however no significant correlation was found for mite exposure (p > 0.05. r = 0.19). The results suggest that ET exposure exacerbates asthmatic symptoms in mite allergic, asthmatic children.     

Predictive features for persistence of atopic dermatitis in children

Allergen exposure plays an important role in atopic dermatitis (AD). Because immunological mechanisms underlying asthma and AD have great similarities, we evaluated whether features such as allergen sensitization, immune response, disease severity and duration or allergen exposure could be considered predictive for AD persistence. Seventy-one AD children (age range 14–158 months) were enrolled and followed for 3 consecutive years for AD severity using the SCORAD index (SI). At enrollment, reactivity to inhalant and food allergens using the skin prick test (SPT) and house dust mite (HDM) atopy patch test (APT), and HDM allergens in house dust were evaluated. After 3 years, 38 children outgrew their AD (AD^– group), while in 33 AD persisted (AD⁺ group). At enrollment, AD⁺ children had a higher SI, higher rate of positivity to SPT and APT for mites (p = 0.001), and higher environmental exposure to HDM allergens (p = 0.035). The AD⁺ children developed more respiratory symptoms in comparison to AD^– children (p < 0.001). None of the AD^– children presented APT positivity. In our study population, positivity of SPT and APT for HDM, environmental allergen exposure levels and severity of the disease at enrollment presented a significant predictive power towards AD persistence. Subjects with positive skin reactivity to HDM should be considered at risk of AD persistence and of possible development of allergic respiratory disorders.