Continuous avoidance measures with or withoutacaricide in dust mite-allergic asthmatic childrenArieh Bahir, MD*; Arnon Goldberg, MD*; Yoseph A Mekori, MD*; Ronit Confino-Cohen, MD*;Haim Morag, MD†; Yosef Rosen, MD†; Dani Monakir, MD‡; Shmuel Rigler, MD‡;Avner Herman Cohen, MD§; Zeev Horev, MD§; Natan Noviski, MD�; and Avigdor Mandelberg, MD�

Background: Improvement in the quality of life in the Western world andincreased time spent indoors by children have enhanced the spread of house dustmites and increased the exposure time for sensitive children. Also, exposure tohouse dust mites in infancy and subsequent development of childhood asthma havebeen clinically linked. Recently, new acaricides have been developed.Objective: To test the efficacy of the new acaricide (esdepallethin and piperonyl

butoxide—“Acardust”) combined with environmental control compared with con-tinuous house dust mite avoidance measures.Method: Forty-six house dust mite-allergic, asthmatic children were evaluated

for 6 months in a prospective, randomized, double-blind, and placebo-controlledstudy. Patients were randomly allocated to active and placebo acaricide treatmentcombined with avoidance measures, whereas only continuous avoidance measureswere taken in the third group. Symptom score, medication usage, and peak flowmeasurements were recorded daily. The amount of house dust mite allergen in thedust vacuumed from the bedrooms was also measured.Results: Morning and evening peak expiratory flow rates and forced expiratory

volume in one second remained unchanged throughout the study period. In allgroups, the symptom scores improved significantly, whereas the amount of housedust mite allergen decreased significantly at the end of the trial.Conclusions: Continuous house dust mite avoidance measures have a significant

positive effect on the symptomology of children with mild or moderate asthma.“Acardust” combined with continuous house dust mite avoidance measures is notmore effective than continuous house dust mite avoidance measures alone in thetreatment of house dust mite-allergic, asthmatic children.

Ann Allergy Asthma Immunol 1997;78:506–12.

INTRODUCTIONAllergy to Dermatophagoides farinaeand Dermatophagoides pteronyssinusis an important causative factor for

asthma in childhood. The microclimateof the modern Western world houses(fitted carpets, soft furnishings, centralheating, double glazing, and often poorventilation) has provided the ideal hab-itat for the house dust mite.1 Indeed,the conclusions of the Second Interna-tional Workshop on dust mite allergensand asthma2 emphasized that mite sen-sitivity is strongly associated withasthma. In some areas, up to 80% ofasthmatic children or young adultshave strongly positive skin tests tomite extracts.The improvement in asthma that oc-

curs in hospital or at high altitude san-atoria can be attributed to reduced ex-posure to mite allergens.3 Reportedstudies on environmental measures un-

dertaken in patients’ houses have beensuccessful3,4 or debated.5,6 Those stud-ies are important because they demon-strate the need for continuous dust miteavoidance measure procedures to re-duce mite exposure. Indeed, clinicalimprovement can be achieved at homeonly if continuous dust mite avoidancemeasure procedures are taken. Simplyadvising patients to vacuum cleanmore often reduces neither symptomsnor mite-allergen levels.Recently, an association between

the presence of asthma and �2 �ggroup I allergen/g of dust in the housesof the asthmatic children has been sub-stantiated in case report studies7–9 andin a prospective study.10 The semi-quantitative assay (Acarex test) re-quires no expertise and can be com-pleted in about two minutes. Guanineis the major nitrogenous excretoryproduct of Arachnids, and measure-ment of guanine in house dust shouldgive an indication of the amounts ofmite allergen present.11,12 There is ev-idence also that use of the test in con-junction with eradication proceduresincreases patient compliance.13In the last decade, several products

to kill house dust mites have been mar-keted by various companies. The in-vestigation of a wide variety of chem-icals has shown that the killing ofhouse dust mite under laboratory con-ditions is a relatively simple task.Since there are few long-term, longitu-dinal, randomized control clinical tri-als, the following study was designedto test the efficacy of an acaricide-containing aerosol of esdepallethin andpiperonyl butoxide in comparison withcontinuous household avoidance con-trol.

*The Allergy and Clinical Immunology Unit,Sapir Medical Center, Kfar Saba, affiliated toTel-Aviv University Sackler School of Medi-cine, Tel-Aviv, †The Pediatric Health Care Cen-ter, Kfar Saba, ‡The Pediatric Day Care Unit,Netanya, §The Pediatric Health Care Center,Petach-Tikva, �The Pediatric Pulmonary Ser-vice, Wolfson Medical Center, Holon, affiliatedto Tel-Aviv University Sackler School of Med-icine, Tel-Aviv, Israel.The study was supported by Trupharm, Israel

(Scat, France) which supplied the active andplacebo sprays.Received for publication July 5, 1996.Accepted for publication in revised form No-

vember 19, 1996.

506 ANNALS OF ALLERGY, ASTHMA, & IMMUNOLOGY

MATERIAL AND METHODSProtocolThe 6-month study was prospective,randomized, double-blind, and placebocontrolled. The seasons comprisedwinter and spring. Asthmatic children,aged 6 to 18 years old, were enrolled inthe study if the following criteria weremet: (1) mild to moderate asthma(American Thoracic Society)14; (2) du-ration of asthma longer than 1 year; (3)documented diagnosis of reversibleairway disease, ie, variation of forcedexpiratory volume in one second(FEV1) or peak expiratory flow (PEF)of �15% (a) before and after inhala-tion of a �-adrenergic agonist, (b) be-fore and after exercise, (c) diurnal vari-ation; and (4) no cigarette smoking athome during the study period. Chil-dren were excluded from the study forthe following reasons: (1) respiratorytract infection within the last month,(2) need for regular oral steroids, (3)use of oral or parenteral steroids withinthe last month, (4) need for regularantihistamines, (5) use of inhaled so-dium cromoglycate or inhalednedocromil sodium within the lastmonth, (6) initiation of immunother-apy within the past 6 months, or (7)hospital admission due to asthmawithin the past 6 months.Children from three pediatric health

centers (Kfar Saba, Netanya, Petach-Tikva) were recruited. All three cen-ters are located within a radius of 15km along the seashore, and they allshare similar weather conditions withrespect to air temperature and humid-ity. Before enrollment in the study,patients who fulfilled the inclusioncriteria were prick tested by a trainednurse under the supervision of aphysician, and the same equipmentand technique were used each time.Eleven inhalant allergens (CenterLaboratories, Port Washington, NY)were applied to each child (mixedgrasses, mixed trees, mixed weeds,mixed molds, Dermatophagoides fari-nae, Dermatophagoides pteronyssinus,house dust, cat, dog, feathers, andcockroach).

Histamine hydrochloride (10 mg/mL) and sodium chloride (9 g/L) wereapplied as control solutions. The reac-tions were recorded after 15 minutes.Only children with positive skin reac-tions (wheal diameter �3 mm) to ei-ther or both house dust mite extractswere enrolled in the study.On the first visit, patients were pro-

vided with a peak flow meter (Astech,Center Laboratories) and a daily diary(Table 1). After a run-in period of 2weeks, children who had not met anyof the exclusion criteria, had filled in atleast 75% of the daily diary, and hadan asthma score �2, were enrolled inthe study.After signing an informed consent,

children were randomly divided into

three groups: (1) avoidance group, pa-tients were given written instructionsregarding environmental control ofhouse dust mite (Table 2); (2) placebogroup, patients were given written in-struction regarding environmental con-trol with placebo acaricide; (3) Acar-dust group, patients were given writteninstructions with active acaricide, con-taining aerosol or esdepallethin 0.9%and piperonyl butoxide 7.2% (Acar-dust, Scat, France).The placebo group received a canis-

ter of acaricide identical to that of theAcardust group supplied by the com-pany. Both placebo and active acari-cide were applied twice to the mattressand the floors, according to the manu-facturer’s instructions (at the begin-ning of the study and 3 months later).The actual application of the acaricidespray was monitored by ascertainingthat the canister was empty, and ateach visit, the parents were checked toensure that all dust avoidance mea-sures were done appropriately.The study lasted 6 months, during

which patients completed a dailysymptom score and recorded theirmorning peak flow and evening peakflow results (Table 1). Upon theirmonthly visits to their pediatrician, pa-tients were physically examined andnew diaries were supplied. House dustspecimens were collected and exam-ined for their guanine content at thebeginning and at the end of the study.Patients were asked to vacuum at

maximal speed and to use a new emptycollecting bag. They were instructed tovacuum the dust for six minutes fromthe lower side of the mattress, for threeminutes from its upper sides, and forfive minutes from the bedroom floor.The amount of house dust antigen wassemi-quantitatively estimated using theAcarex test (Fison Corp, Bedford,Mass.). Acarex is a dipstick techniquewith litmus activator with methanoland a diazo compound.Guanine was extracted from raw

dust by potassium hydroxide, and theamount present was estimated by theintensity of color change on the teststrip. For the purposes of the test, itwas presumed that the guanine thus

Table 1. Symptom Score Diary

Symptom Score

Quality of sleep during night:Good 0Awake once 1Awake over course of time 2Awake most of the night 3

DyspneaNo 0Yes 1

Wheezing (check twice daily)No 0Few 1Many 2

CoughNo 0Few 1Many 2

SputumNo 0Little 1Much 2

RhinitisNo 0Present 1

SneezingNo 0Present 1

Peak flow measurement (specify ifbronchodilator preparationswere taken 4 hours beforemeasuring)

MorningEvening

School/kindergarten absence (days):Number of inhalations of

salbutamol/terbutalin per day:Other medication(s) per day:

VOLUME 78, MAY, 1997 507

identified, comes from mite feces andthat guanine levels related to the anti-genicity of the dust.13The results were rated as: none � 0,

very weak� 1, weak� 2, moderate�3, and strong � 4. On the last visit ofthe study, the parents were asked tograde the severity of their child’sasthma compared with the period be-fore starting the study, according to:same, better or worse.Statistical AnalysisComparisons between the treatmentgroups were made using an unpaired ttest and analysis of variance as appro-priate. Paired t test was used whencomparing the result at the beginningand the end of the treatment period.Power analysis was calculated for theprimary efficacy variable—the Acarextest (power calculated on zar 2nd ed).Parents’ assessment at the end of thestudy was evaluated using the ChiSquare test.

RESULTSOne hundred twelve asthmatic childrenfrom the three pediatric health carecenters were asked by their pediatri-cian to come to the first visit with thestudy principal investigator (AB), dur-ing the fall of 1993. Eighty-five asth-matic children (76%) were positive byprick test to both Dermatophagoidesfarinae and Dermatophagoides ptero-nyssinus, or to either. After 2 weeks of

a run-in period, 62 children started thestudy (the others did not complete aminimum of 75% of the daily diary).During the first 5 weeks of the study,16 children dropped out (6 from theAcardust group, 4 from the placebogroup, and 6 from the avoidancegroup) for the following reasons: 14,noncompliance; 1, irrelevant disease;and 1, change of residence. The demo-graphic data of the 46 asthmatic chil-dren who finished the 6-month studyare displayed in Table 3. There were87% of the children who were exclu-sively prick test dust mite allergic,while the other 13% were positive to

other allergens and were equally dis-tributed among the three groups.Monitoring of the Allergenicity ofHouse Dust Mite (Acarex test)We examined 41 children’s bedrooms’dust specimens. In all three studygroups, there was a statistically signif-icant improvement (mean score �standard deviation) of the Acardustgroup at the beginning of the study,3.6 � 0.7, and at the end, 3.3 � 0.9;placebo group, 3.3 � 0.6 to 2.9 � 0.8;and avoidance group, 3.5 � 0.6 to2.7 � 0.8 (Fig 1). The mean scoreimproved in all groups from 3.5 � 0.6to 2.9 � 0.9 (P � .001) (Fig 2). Therewas no statistical difference among thethree groups regarding the allergenic-ity (the Acardust group showed lessimprovement in the absolute value ofthe test, but without statistical signifi-cance).Power analysis indicates that there

was 90% power to detect a differenceas small as 1 unit and there was 80%power to detect a difference as small as0.75 unit in the Acarex test (powercalculated on zar 2nd ed).Objective MeasurementsFEV1 (Fig 3). Overall, there was anincrease in the mean FEV1 from(73.5 � 13.2)% at the beginning of thestudy to (78.2 � 14.7)% at the endwithout statistical significance. There

Table 2. Instructions to Prevent Dust Accumulation in the Children’s Bedrooms

Change bedclothes, ie, mattress, rugs, curtains, upholstered furniture, toys, etc becausethey are a major source of house dust accumulation. Every object prone to accumulatedust is to be removed. Pillows or blankets made of goose, feather, or wool are forbiddento be used. Use only synthetic blankets and pillows.

Clothing should be stored in closed cupboards and it is advised to decrease the number ofgarments hanging in the cupboard. Books left in the room should be stored in a closedcabinet.

Dust mite avoidance measures:Daily: 1. Wash the floors and dust furniture with a damp cloth.

2. Shake the bed clothes outside the bedroom while the child is not around.Likewise, bed clothing should be left on the window sill.

Weekly: 1. Systematically vacuum the mattresses on both sides.2. It is necessary to thoroughly clean (with a damp cloth) shelves, pictures,

furniture, walls, drawers, and cupboards.3. Change the bed sheets and wash them in a washing machine at 60 °C or

hotter.Monthly: 1. Wash blankets and pillows at 60 °C.

Table 3. Patients’ Demographic Data

VariablesAcardust

Group N � 13Placebo

Group N � 17Avoidance

Group N � 16

Mean age, yr 9.2 � 2.4 10.4 � 2.6 11.8 � 3.2Age range, yr (6.5–13) (6–15) (7–16.5)Mean duration of asthma, yr 7.3 � 2.7 6.8 � 2.6 9.5 � 4.3Family and atopy history

Atopy in the family N (%) 7 (54%) 10 (59%) 11 (69%)Associated allergic rhinitis N (%) 5 (38%) 7 (41%) 7 (44%)Seasonality of asthmatic attacks N (%) 5 (38%) 6 (35%) 8 (50%)Carpet in the living room N (%) 5 (38%) 9 (53%) 4 (25%)Dust as a trigger by history* N (%) 7 (54%) 10 (59%) 11 (69%)

Baseline spirometryFEV1% predicted 72% 75% 72%Morning peak flow (L/min) 222 220 290Evening peak flow (L/min) 226 232 295

* Eighteen asthmatic children. Almost 40% of the children and their parents did not know at thebeginning of the study that there is a relation between house dust mite and the severity ofasthma.

508 ANNALS OF ALLERGY, ASTHMA, & IMMUNOLOGY

was no difference among the threegroups (including the spirometry re-sults after 3 months).Morning peak flow (Fig 4A). Over-

all, there was improvement in this pa-rameter during all 6 months (frommean morning peak flow of 245 � 85at the beginning to mean morning peakflow of 282 � 82 at the end) withoutstatistical significance among the threegroups and in the same group duringtime (Acardust P � .95; placebo P �.7; avoidance P � .8).Evening peak flow (Fig 4B). Over-

all, there was a mean nominal increasefrom 253 � 85 at the beginning to291 � 83 at the end, but without sta-tistical significance. No difference wasfound among the three groups andwithin the same group over time.Subjective MeasurementSymptom score and the use of inhaled�2 agonists. There was a statisticallysignificant decrease in the mean symp-tom score at the beginning (2.6 � 2)relative to the end of the study (1.5 �1.5) (P � .001). There was no differ-ence among the three study groups(Fig 5). There was also a small reduc-tion in the amount of �2-agonists usedby the children in all three groups dur-ing the study period. There was nosignificant difference in the use of �2-agonists among the three groups.Other concurrent medication. There

was no difference among the threegroups regarding use of topical ste-roids and cromoglycate during thestudy period.Parental AssessmentThere was no statistical differenceamong the three groups (chi squaretest; Table 4).

DISCUSSIONIn recent years, there is more conclu-sive evidence for the role of dust miteexposure in the sensitization to dustmite allergens and the development ofasthma.15,16 Furthermore, over the lastthree decades, the amount of timespent indoors has increased, ventila-tion of houses has diminished, thereare more furnishings, particularly car-pets, and the mean temperature in the

houses has risen. All these changes arefactors that may accelerate house dustmite survival. The conclusions of theseimpressive data are that house dustmite avoidance measures should be thefirst step in the preventive manage-ment of asthmatic children.17 It is notsurprising that there have been inten-sive efforts to develop better tech-niques for reducing mite exposure(including new acaricides). Thesetechniques should help every asthmaticchild, especially those with positiveprick test to Dermatophagoides fari-nae and/or Dermatophagoides pteron-yssinus (in the present study, like manyother previous studies,18,19 this ac-counts for about 70% to 80% of theasthmatic children).

In this randomized, double-blind,placebo-controlled 6-month study, wefound no significant differences in thebedroom allergen content between us-ing pyrethroids as acaricide or contin-uous dust mite avoidance measures.There were no significant changes inrespiratory status as determined by ob-jective criteria (FEV1 and PEF).The sensitivity of the study may not

have been adequate to detect changesin patients with mild asthma, thereforewe found no significant effect of housedust mite avoidance measures on pul-monary function, nevertheless im-provement in subjective symptomsusually precedes improved lung func-tion.20,21 Indeed in the present study,subjective evaluation for only 6

Figure 1. Acarex counts (mean � SEM) from day 0 and day 180. While the overall Acarex countdecreased significantly between days 0 and 180 (P � .05), there was no difference among the threegroups.

Figure 2. Overall Acarex counts (mean � SEM) in the three groups decreased significantly betweendays 0 and 180 (P � .001).

VOLUME 78, MAY, 1997 509

months using a daily diary shows alle-viation of disease symptoms due toenvironmental control in the children’sbedrooms. Power calculation has dem-onstrated that there is enough power tocompare the placebo and avoidancegroup to the Acardust group on themajor variable, the Acarex test. Bydefinition, the primary expected effectof the treatment (use of the acaricide)should be to lower the Acarex testcount, and all the other secondary ef-ficacy variables depend on this result.It is not surprising that our studyshowed no overall difference.Regarding the ineffectiveness of the

Acardust, incorrect application tech-niques of the acaricide product or mi-croclimates within the houses mayhave had a decisive effect on severalpossible biases that must be taken intoconsideration for the Dermatopha-goides population22 (indeed, in ourstudy we did not check these parame-ters, including the relative humidity inthe houses), and the Acarex test maynot reflect changes in allergen expo-sure as accurately as more direct mea-surements. Certainly, there is no agree-ment about the accuracy of the Acarextest to assess precisely the actual miteantigen level. Nevertheless, there isgood correlation between the Acarextest and the monoclonal antibody testfor dust mite antigen.23 We therefore

believe that the Acarex test is accuratefor detecting changes in mite antigen

levels that are high enough to be ofclinical importance.Over the last few years, a number of

products have been commercially mar-keted for reducing exposure to aller-gens of mites. Investigation of a widevariety of chemicals has shown thatkilling house dust mites under labora-tory conditions is a relatively simpletask, but the high degree of mite mor-tality achieved in laboratory experi-ments cannot be reproduced easily inthe home.2 Great variability is evidentbetween homes regarding reductions inallergen concentration. Most probably,the method of delivery of the acari-cides is an important determinant ofefficacy. Furthermore, the penetrationrate of currently available acaricidalspray, solutions, foams, or powder intomattresses or carpets cannot be evalu-ated fully.

Figure 3. There was no statistical difference in FEV1% predicted (mean � SEM) between thegroups.

Figure 4. No statistical difference found in morning peak flow rates (A) and evening peak flow rates(B) during the 6-month study period among the three groups.

510 ANNALS OF ALLERGY, ASTHMA, & IMMUNOLOGY

Recently, several new acaricidesfailed to prove effective when tested.The clinical effect of the acaricide de-pends, most probably, also on localclimatic conditions, and not only onthe quality of the specific product.Manjra et al24 in the Cape Peninsulademonstrated that at present it is notpossible to reduce Der p I antigen lev-els with the available acaricides (ben-zyl benzoate). Ridout et al25 using thesame acaricide on the Isle of Wight,concluded that a chemical acaricidemay help reduce house dust mite anti-gen levels, but is not by itself sufficientto reduce levels below those consid-ered critical for sensitization. Kalra etal26 emphasized that neither benzylbenzoate nor liquid nitrogen reducesthe concentration of Der p I for as longas 6 months after application. Tovey etal27 showed that tannic acid was onlytemporarily effective when applied atthe manufacturer’s recommendedlevel, and additional approaches wererequired to control the bulk of aller-gens in houses. Rieser et al28 evaluat-ing natamycin, showed not only nochange in clinical symptoms, but alsono change in allergen concentration.Marks et al29 tested the effectiveness ofhouse dust mite allergen avoidance

strategy. He concluded that in a highhouse dust mite allergen environment,simple chemical treatment, and en-casement of bedding is not sufficient tocause a sustained, beneficial reductionin allergen levels. Effective allergenavoidance requires an active strategyto remove allergen reservoirs and con-trol accumulating allergen within thehouse.In our study, we did not use mattress

and pillow covers, which can beviewed as a study limitation. If thesecovers were so crucial to the studyresults, we would not have found im-provement in the symptom scores forour three groups due to allergen over-load. In fact, we did find a decrease inthe severity of the disease as well as areduction in the dust load.The study was conducted primarily

in the winter months, during whichdust is the dominant allergen. Further-more, 87% of the children were exclu-sively prick test positive to house dustmites. The other 13% who wereequally distributed among the threegroups did not clinically deteriorate(measured by symptom score and lungfunction tests) during the weed season(late fall) when the study began or

during the blossoming season of thespring when the study ended.In conclusion, appropriate environ-

mental measures, such as continuoushouse dust mite avoidance measures inthe bedrooms of dust mite allergicasthmatic children, is likely to be animportant component in the manage-ment of those children. The result ofthis study confirms the finding of pre-vious studies about using acaricides.The role of acaricides needs to be bet-ter defined and further work is neces-sary concerning methods of applica-tion and clinical effectiveness of theseproducts.

ACKNOWLEDGMENTSDiklah Geva of the Edith WolfsonMedical Center, Holon, advised on sta-tistics. We are grateful also to Mrs. R.Zomer for prick testing, Mrs. R. Man-delberg for technical and Ms. YaelBen-Shimol for secretarial assistance,respectively.

REFERENCES1. International Workshop. Platts-MillsTAE, De Weck AL. Dust mite aller-gens and asthma: a worldwide prob-lem. J Allergy Clin Immunol 1989;83:416–27.

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Figure 5. While the overall symptom score decreased significantly during the 6-month study period,no difference was found among the three groups.

Table 4. Parental Assessment of Quality of Change

Acardust GroupN � 13

Placebo GroupN � 17

Avoidance GroupN � 16

Same 6 8 9Better 7 9 6Worse 0 0 1

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8. Peat JK, Britton WJ, Salome CM,Woolcock AJ. Bronchial responsive-ness in two populations of Australianschool-children III. Effect of exposureto environmental allergens. Clin Al-lergy 1987;17:297–300.

9. Arruda K, Rizzo MC, Chapman MD,et al. Exposure and sensitization todust mite allergens among asthmaticchildren in San Paulo, Brazil. Clin ExpAllergy 1991;21:433–40.

10. Sporik R, Holgate S, Platts-Mills TAE,Cogswell J. Exposure to house dustmite allergen (DER P I) and the devel-opment of asthma in childhood.N Engl J Med 1990;323:502–7.

11. Pauli G, Hovet C, Tenabene A, et al.Guanine and mite allergenicity inhouse dust. Clin Allergy 1988;18:383–92.

12. Ransom JH, Leonard J, WassersteinRL. Acarex test correlates with mono-clonal antibody test for dust mite. JAllergy Clin Immunol 1991;87:886–8.

13. Bronswi JK, Jemhva N, Bischoff E, etal. Evaluating mite (Acari) allergenic-ity of house dust by guanine quantifi-cation. J Med Entomol 1989;26:55–9.

14. American Thoracic Society. Chronicbronchitis, asthma, and pulmonary em-physema. Am Rev Respir Dis 1987;136:224–5.

15. Blumenthal M, Blumenthal M, Bous-quet J, et al. Evidence for an increasein atopic disease and possible causes.Clin Exp Allergy 1993;23:484–92.

16. Hide D, Matthews S, Matthews L, etal. Effect of allergen avoidance in in-fancy on allergic manifestation at age

two years. J Allergy Clin Immunol1994;93:842–6.

17. Arshad S, Matthews S, Gant C, HideD. Effect of allergen avoidance on de-velopment of allergic disorders in in-fancy. Lancet 1992;339:1493–7.

18. Murray AB, Fergusson MB, MorrisonBJ. Sensitization to house dust mites indifferent climatic areas. J Allergy ClinImmunol 1985;76:108–12.

19. Dowse GK, Turner KJ, Stewart CA, etal. The association between Dermato-phagoides mites and the increasingprevalence of asthma in village com-munities within the Papua New Guineahighlands. J Allergy Clin Immunol1985;75:75–83.

20. Kharitonov SA, Tares DH, BarnesPJ. Inhaled glucocorticoids decreasenitric oxide in exhaled air of asthmaticpatients. Am J Respir Crit Care Med1996;153:454–7.

21. Vathenen AS, Knox AJ, WisniewskiA, Tatterfield AE. Time course ofchanges in bronchial reactivity with aninhaled corticosteroid in asthma. AmRev Respir Dis 1991;143:1317–21.

22. Litner TJ, Kathy A, Brame BS. Theeffect of season, climate, and air-conditioning on the prevalence of Der-matophagoides mite allergens inhousehold dust. J Allergy Clin Immu-nol 1993;91:862–7.

23. Colloff MJ. House dust mites. II.Chemical control. Pesticide Outlook1990;1:3–8.

24. Manjra A, Berman D, Toerien A, et al.The effects of a single treatment of anacaricide, acarosan, and a detergent,Metsan, on Der P I allergen levels in

the carpets and mattresses of asthmaticchildren. South African Med J 1994;84:278–80.

25. Ridout S, Twiselton R, Matthews S, etal. Acarosan and the Acarex test in thecontrol of house dust mite allergens inthe home. Br J Clin Pract 1993;47(3):141–4.

26. Kalra S, Crank P, Hepworth J, et al.Concentrations of the domestic housedust mite allergen Der p I after treat-ment with solidified benzyl benzoate,Acarosan or liquid nitrogen. Thorax1993;48:10–3.

27. Tovey ER, Marks CB, Matthews M, etal. Changes in mite allergen Der p I inhouse dust following spraying with atannic acid/acaricide solution. Clin JExp Allergy 1992;22:67–74.

28. Rieser J, Ingram D, Mitchell EB,Warner JV. House dust mite allergenlevel and an anti-mite mattress spray(Natamycin) in the treatment of child-hood asthma. Clin Exp Allergy 1990;20:561–7.

29. Marks GB, Tovey ER, Green W, et al.House dust mite allergen avoidance: arandomized, controlled trial of surfacechemical treatment and encasement ofbedding. Clin Exp Allergy 1994;24:1078–83.

Request for reprints should be addressed to:Arieh Bahir, MDAllergy & Clinical Immunology UnitMeir Hospital44281 Kfar SabaIsrael

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