What allergen avoidance

WHAT YOU SOULD HAVE READ BUT ………………… 2018
Allergen
avoidance
Attilio Boner
University of Verona, Italy
attilio.boner@univr.it

The Kingston Allergy Birth Cohort:
Exploring parentally reported respiratory outcomes
through the lens of the exposome
North ML, Ann Allergy Asthma Immunol 2017;118:465-473
Background
• The Kingston Allergy Birth Cohort (KABC) is a prenatally recruited
cohort initiated to study the developmental origins of allergic disease.
Kingston General Hospital was chosen for recruitment because
it serves a population with notable diversity in environmental
exposures relevant to the emerging concept of the exposome.
Objective
• To establish a profile of the KABC using the exposome framework and
examine parentally reported respiratory symptoms to 2 years of age.

 Data on phase 1 of the
cohort (n = 560 deliveries)
 3 exposome domains of
general external
(socioeconomic status,
rural or urban residence),
specific external
(cigarette smoke,
breastfeeding, mold or
dampness), and
internal
(respiratory health,
gestational age).
Significant associations emerged
between parental reports of
wheeze or cough without a cold
and:
• prenatal cigarette smoke exposure
(HR = 3.1),
• mold or dampness in the home
(HR = 2.41), and
• the use of air fresheners
(HR = 2.11), in the early-life home
environment.

 Data on phase 1 of the
cohort (n = 560 deliveries)
 3 exposome domains of
general external
(socioeconomic status,
rural or urban residence),
specific external
(cigarette smoke,
breastfeeding, mold or
dampness), and
internal
(respiratory health,
gestational age).
Significant associations emerged
between parental reports of
wheeze or cough without a cold
and:
• prenatal cigarette smoke exposure
(HR = 3.1),
• mold or dampness in the home
(HR = 2.41), and
• the use of air fresheners
(HR = 2.11), in the early-life home
environment.
Breastfeeding,
older siblings,
and increased
gestational age
were associated
with decreased
respiratory
symptoms.

Mono and multifaceted inhalant and/or food allergen
reduction interventions for preventing asthma in children
at high risk of developing asthma.
Maas T, Cochrane Database Syst Rev 2009;(3):CD006480.
OBJECTIVES:
To assess effect(s) of monofaceted and multifaceted interventions compared with
control interventions in preventing asthma and asthma symptoms in high risk
children.
SEARCH STRATEGY:
We searched the Cochrane Airways Trials Register (December 2008).
SELECTION CRITERIA:
Randomised controlled trials of allergen exposure reduction for the primary
prevention of asthma in children. Interventions were multifaceted (reducing
exposure to both inhalant and food allergens) or monofaceted (reducing exposure to
either inhalant or food allergens)
Follow up had to be from birth (or during pregnancy) up to a minimum of 2 years of
age.

3 multifaceted
(reducing exposure to both
inhalant and food allergens)
and
6 monofaceted
(reducing exposure to either
inhalant or food allergens)
intervention studies
3271 children.
In children receiving a multifaceted
intervention vs usual care
OR for asthma
0.72
1.0 –
0.5 –
0.0
in children aged
< 5 years ≥ 5 years
0.52

3 multifaceted
and
6 monofaceted
3271 children.
OR for asthma
0.72
1.0 –
0.5 –
0.0
in children aged
0.52
The available evidence
suggests that the
reduction of exposure
to multiple allergens
compared to usual care
reduces the likelihood
of a current diagnosis
of asthma in children
(at ages < 5 years and
5 years and older).

3 multifaceted
and
6 monofaceted
3271 children.
OR for asthma
0.72
1.0 –
0.5 –
0.0
in children aged
0.52
Mono-intervention
studies have not
produced effects
which are
statistically
significant
compared with
control.

Something new in the air: paying for community-based
environmental approaches to asthma prevention and
control. Tschudy MM, J Allergy Clin Immunol 2017;140:1244-9.
•Approximately 80% of children with persistent asthma have evidence of
allergic sensitization, and home-based interventions primarily aimed at
reducing relevant allergen exposures have had beneficial effects on asthma.
1. Morgan WJ, Results of a home-based environmental intervention among urban children with asthma.
N Engl J Med 2004;351:1068-80.
2. Eggleston PA, Home environmental intervention in inner-city asthma: a randomized controlled clinical trial.
Ann Allergy Asthma Immunol 2005;95:518-24.
3. Butz AM, A randomized trial of air cleaners and a health coach to improve indoor air quality for inner-city children
with asthma and secondhand smoke exposure. Arch Pediatr Adolesc Med 2011;165:741-8.
4. Lanphear BP, Effects of HEPA air cleaners on unscheduled asthma visits and asthma symptoms for children exposed to
secondhand tobacco smoke. Pediatrics 2011;127:93-101.
5. Krieger JW, The Seattle-King County Healthy Homes Project: a randomized, controlled trial of a community health
worker intervention to decrease exposure to indoor asthma triggers. Am J Public Health 2005;95:652-9.
•The most recent update of the National Asthma Education and Prevention
Program guidelines endorse advising patients ‘‘to reduce exposure to
allergens and pollutants or irritants to which they are sensitive.’’
National Heart, Lung, and Blood Institute. Expert panel report 3: guidelines for the diagnosis and management of
asthma—full report 2007. Available at: www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf.

•Approximately 80% of children with persistent asthma have evidence of
allergic sensitization, and home-based interventions primarily aimed at
reducing relevant allergen exposures have had beneficial effects on asthma.
1. Morgan WJ, Results of a home-based environmental intervention among urban children with asthma.
N Engl J Med 2004;351:1068-80.
2. Eggleston PA, Home environmental intervention in inner-city asthma: a randomized controlled clinical trial.
Ann Allergy Asthma Immunol 2005;95:518-24.
3. Butz AM, A randomized trial of air cleaners and a health coach to improve indoor air quality for inner-city children
with asthma and secondhand smoke exposure. Arch Pediatr Adolesc Med 2011;165:741-8.
4. Lanphear BP, Effects of HEPA air cleaners on unscheduled asthma visits and asthma symptoms for children exposed to
secondhand tobacco smoke. Pediatrics 2011;127:93-101.
5. Krieger JW, The Seattle-King County Healthy Homes Project: a randomized, controlled trial of a community health
worker intervention to decrease exposure to indoor asthma triggers. Am J Public Health 2005;95:652-9.
•The most recent update of the National Asthma Education and Prevention
Program guidelines endorse advising patients ‘‘to reduce exposure to
allergens and pollutants or irritants to which they are sensitive.’’
National Heart, Lung, and Blood Institute. Expert panel report 3: guidelines for the diagnosis and management of
asthma—full report 2007. Available at: www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf.
Emerging payment approaches offer new potential for coverage
of home-based environmental intervention costs.
These opportunities are becoming available as public and private insurers shift
reimbursement to reward better health outcomes, and their key characteristic
is a focus on the value rather than the volume of services.

Something new in the air: Paying for community-based
environmental approaches to asthma prevention and control.
Tschudy MM, J Allergy Clin Immunol. 2017 Nov;140(5):1244-1249.
•Over the past decade, there has been a growing appreciation of the importance of
indoor environmental exposures in asthma morbidity.
•There is also greater awareness that reducing these exposures should complement
such medical approaches as controller medication and allergen immunotherapy in
asthma management, particularly in children.
•Approximately 80% of children with persistent asthma have evidence of allergic
sensitization, and home-based interventions primarily aimed at reducing relevant
allergen exposures have had beneficial effects on asthma. 1-6
1. Morgan WJ, Results of a home-based environmental intervention among urban children with asthma. N Engl J Med 2004;351:1068-80.
2. Eggleston PA, Home environmental intervention in inner-city asthma: a randomized
controlled clinical trial. Ann Allergy Asthma Immunol 2005;95:518-24.
3. Butz AM, A randomized trial of air cleaners and a health coach to improve indoor air quality for inner-city children with asthma and secondhand smoke exposure. Arch
Pediatr Adolesc Med 2011;165:741-8.
4. Lanphear BP, Effects of HEPA air cleaners on unscheduled asthma visits and asthma symptoms for children exposed to secondhand tobacco smoke. Pediatrics
2011;127:93-101.
5. Krieger JW, The Seattle-King County Healthy Homes Project: a randomized, controlled trial of a community health worker intervention to decrease exposure to indoor
asthma triggers. Am J Public Health 2005;95:652-9.
6. National Heart, Lung, and Blood Institute. Expert panel report 3: guidelines for the diagnosis and management of asthma—full report 2007. Available at: www.nhlbi.
nih.gov/guidelines/asthma/asthgdln.pdf.

•In addition, indoor pollutants, such as fine and coarse particulate matter,
nitrogen dioxide, and carbon monoxide, have been linked to asthma morbidity.
•The major source of indoor fine particulate matter is secondhand
smoke exposure.
•The most recent update of the National Asthma Education and
Prevention Program guidelines endorse advising patients
‘‘to reduce exposure to allergens and pollutants or irritants
to which they are sensitive.’’
National Heart, Lung, and Blood Institute. Expert panel report 3: guidelines for the diagnosis
and management of asthma—full report 2007. Available at: www.nhlbi.
nih.gov/guidelines/asthma/asthgdln.pdf.

•Despite the recommendation in national asthma guidelines
to target indoor environmental exposures, most insurers
generally have not covered the outreach, education,
environmental assessments, or durable goods integral
to home environmental interventions.
•However, emerging payment approaches offer
new potential for coverage of home-based
environmental intervention costs.
•These opportunities are becoming available as public
and private insurers shift reimbursement to reward
better health outcomes, and their key characteristic
is a focus on the value rather than
the volume of services.

•Several pilot programs
across the United
States are underway,
and as they prove their
value and as payment
increasingly becomes
aligned with better
outcomes at lower cost,
these efforts should
have a bright future
Integrated
Pest Management

Type of payment

Environmental Control: The First Tenet of Allergy.
Hauptman M, J Allergy Clin Immunol Pract. 2018;6(1):36-37.
•Environmental factors, particularly allergens
and pollutants, play a major role in both
asthma and allergy development and morbidity
in children.
•Emerging studies are identifying the importance of secondary environments
such as the school in asthma morbidity and school-based
environmental interventions have the potential to benefit
many children with asthma at a population level.
•With the potential for new payment models to include environmental
interventions, the insights in this issue are sure to contribute
to in-office decision making.

Reducing Environmental Allergic Triggers: Policy Issues.
Abramson SL. J Allergy Clin Immunol Pract. 2018;6(1):32-35.
The implementation of policies to reduce environmental allergic triggers can
be an important adjunct to optimal patient care for allergic rhinitis and
allergic asthma.
Policies at the local level in schools and other public as well as private
buildings can make an impact on disease morbidity.
The reduction of allergenic exposures can and should be affected by policies
with strong scientific, evidence based derivation.
However, a judicious application of the precautionary principle may be
needed in circumstances where the health effect of inaction could lead to
more serious threats to vulnerable populations with allergic disease.

SCIENTIFIC BASIS FOR POLICY IMPLEMENTATION
•Multiple studies have shown benefits of indoor environmental control measures
in reducing morbidity in allergic rhinitis and asthma.3-5
3. EPR-3. Expert panel report 3: guidelines for the diagnosis and management of asthma (EPR-3 2007). Bethesda, MD:
U.S. Department of Health and Human Services; National Institutes of Health; National Heart, Lung, and Blood Institute;
National Asthma Education and Prevention Program; 2007. NIH Publication Number 08-05846.
4. Matsui EC, Abramson SL, Sandel MT. Indoor environmental control practices and asthma management. Pediatrics
2016;138:e20162589.
5. Custovic A, van Wijk RG. The effectiveness of measures to change the indoor environment in the treatment of allergic
rhinitis and asthma: ARIA update (in collaboration with GA2LEN). Allergy 2005;60:1112-5.
•In childhood asthma, the benefit of a multifaceted approach to environmental
control was illustrated with a multicenter Inner City Asthma Study.6
6. Morgan WJ, Crain EF, Gruchalla RS, O’Connor GT, Kattan M, Evans R III, et al, Inner-City Asthma Study Group.
Results of a home based environmental intervention among urban children with asthma. N Eng J Med 2004;351:1068-80.
Such data can be used to influence policy by insurers regarding coverage for
environmental control measures.

“Allergists presenting a case-by-case
clinical justification to third-party
payers for the need and benefit of
high-efficiency particulate air filtration,
pest management, and other specific
environmental control measures
can be successful in obtaining
reimbursement for patients.”
S. L. Abramson, personal oral communication
with AAAAI members, March 2017.

•Ignoring allergen triggers for asthma and allergic
rhinitis can lead to uncontrolled symptoms that most
assuredly can affect quality of life. 11,12
12. Australian Centre for Asthma Monitoring. Measuring the impact of asthma
on quality of life in the Australian population. 2004. Available from:
http://www.asthmamonitoring.org/PDF/Asthma_QoL05.pdf. Accessed
November 20, 2017.
13. Meltzer EO, Bukstein DA. The economic impact of allergic rhinitis and
current guidelines for treatment. Ann Allergy Asthma Immunol
2011;106(Suppl):
S12-6.
•There are economic impacts as well that may be substantial.
13,14
14. Bahadori K, Doyle-Waters MM, Marra C, Lynd L, Alasaly K, Swiston J, et al.
Economic burden of asthma: a systematic review. BMC Pulm Med 2009;9:24.
15. D’Amato G, Vitale C, Lanza M, Molino A, D’Amato M. Climate change, air
pollution, and allergic respiratory diseases: an update. Curr Opin Allergy Clin
Immunol 2016;16:434-40.

CLIMATE CHANGE
Increases in temperature, carbon dioxide, and precipitation will stimulate the growth
of some allergenic plants and that would lead to higher pollen counts for a more
prolonged time period due to longer and more robust pollination. 15,16
15. D’Amato G, Vitale C, Lanza M, Molino A, D’Amato M. Climate change, air pollution, and allergic respiratory diseases: an
update. Curr Opin Allergy Clin Immunol 2016;16:434-40.
16. Lake IR, Jones NR, Agnew M, Goodess CM, Giorgi F, Hamaoui-Laguel L, et al. Climate change and future pollen allergy
in Europe. Environ Health Perspect 2017;125:385-91.
POLLEN ORDINANCES
Some cities have had pollen ordinances since the 1990s that prohibit the planting of
high pollinating male species of trees. 18-20
1
8. City of Albuquerque. Albuquerque Pollen Control Ordinance (Ord. 34-1994). Available from: http://www.cabq.gov/airquality/air-quality-
control-board/ regulations-and ordinances/Albuquerque%20Pollen%20Control%20Ordinance. pdf/view. Accessed November 20, 2017.
19. City of Phoenix. City Code No. 39-9: Airborne pollens. Available from: http://
www.codepublishing.com/AZ/Phoenix/?Phoenix39/Phoenix3909.html
20. ClarkCounty.ClarkCountyAeroallergenHistory andCycles.Available from: http://
www.clarkcountynv.gov/AirQuality/monitoring/Pages/Monitoring_PollenReports.aspx.

POLLEN ORDINANCES
•Having a balance between male and female plants as a strategy seems reasonable as
male plants produce the high amounts of pollen responsible for allergy symptoms.
Common separate-sexed trees include:
•Cedar (cedro),
•Juniper (ginepro),
•Cottonwood (pioppo),
•Mulberry (gelso),
•Ash (frassino),
•Poplar (pioppo),
•Box elder (sambuco),
•Willow (salice).

POLLEN ORDINANCES
•Having a balance between male and female plants as a strategy seems reasonable as
male plants produce the high amounts of pollen responsible for allergy symptoms.
Common separate-sexed trees include:
•Cedar (cedro),
•Juniper (ginepro),
•Cottonwood (pioppo),
•Mulberry (gelso),
•Ash (frassino),
•Poplar (pioppo),
•Box elder (sambuco),
•Willow (salice).
Fifty years ago, city trees were roughly
half male, similar to trees in nonurban areas.
However, because of government
preference for “litter-free”
(no nuts or fruit) trees, more highly
allergenic male clones were
then planted in cities.

OCCUPATIONAL EXPOSURES
•School is the occupational environment for many children,
and attention needs to be given to how well environmental
control measures are implemented there.
•Americans with Disabilities Act (ADA) policy and Section 504
of the Rehabilitation Act require schools to accommodate children
with disabilities, including allergies.
•In some instances,
this may involve:
•mold remediation;
•better air ventilation
•tune-up (ammodernare) of heating, ventilating,
and air conditioning systems; and
•proper cleaning of carpeting to reduce
mold and dust mite contamination.

School Environmental Intervention Programs.
Permaul P, J Allergy Clin Immunol Pract. 2018;6(1):22-29.
•Children spend 7 to 12 hours per day in school and daycare settings,
representing an occupational model for children.
•The common indoor allergens include: •house dust mites,
•cockroaches,
•rodents,
•furry pets such as cat and dog,
•molds.
successful home-based strategies currently
serve as the prototype for school-based
environmental interventions.

SCHOOL-BASED ASTHMA MANAGEMENT PROGRAMS
A number of national, state, and city governmental organizations such as:
•the American Lung Association,
•the Allergy and Asthma Foundation of America,
•the National Heart, Blood and Lung Institute,
•the Centers for Disease Control and Prevention’s National
Asthma Control Program, and
•the US Environmental Protection Agency
have developed a number of school-based asthma programs.

The
Environmental
Protection Agency
created the
Indoor Air Quality Tools
for Schools Program
with the aim of improving
environmental conditions
in schools.

The Indoor Air Quality
Tools for Schools Program
provides recommended actions
for teachers,
facilities staff, and
school officials such as
keeping ventilation units
in classrooms free of clutter (ingombrante),
reducing the number of items
made of cloth (stoffa) in the classroom,
removing classroom pets that cause allergic reactions or trigger asthma
attacks in students, and
reporting maintenance problems in classrooms immediately.

The School-Based Asthma Management Program
Lemanske RF, Creation and implementation of SAMPRO: a school-based asthma management
program. J Allergy Clin Immunol 2016;138:711-23.
and
the Centers for Disease Control and Prevention Healthy Schools Program
•offer toolkits to schools.
These toolkits help to develop asthma-friendly
Schools that provide appropriate school health
services for students with asthma and a safe
and healthy school environment to reduce
asthma triggers.

and
school-based
asthma
interventions:
Hester LL, Roles of the
state asthma program in
implementing multicomponent,
school-based asthma
interventions. J Sch Health
2013;83:833-41.
•ability to translate policies into action,
•provide resources,
•form connections between
schools and community stakeholders.

and
school-based
asthma
interventions:
Hester LL, Roles of the
state asthma program in
implementing multicomponent,
school-based asthma
interventions. J Sch Health
2013;83:833-41.
•ability to translate policies into action,
•provide resources,
•form connections between
schools and community stakeholders.
Environmental control measures can and should
supplement good asthma medical care.

Home Environmental Interventions for House Dust Mite.
Wilson JM, Platts-Mills TAE. J Allergy Clin Immunol Pract. 2018;6(1):1-7.
•Although the importance of house dust as an allergen source was recognized
as early as the 1920s and several immunochemists had searched for the
culprit allergen, the most important source of house dust allergens
was not recognized until 1967.
•Mite feces, are normally 20 to 30 μm in diameter and encased
in a peritrophic membrane that prevents them from breaking up,
so for years have been considered “too large” to enter the lungs.
•There is a progressive fall in the percentage of particles entering the
peripheral lung with increasing size, but even with sizes ≥ 20 μm,
10% will still enter the bronchial tree.
Svartengren M, Deposition of large particles in human lung. Exp Lung Res 1987;12:75-88.
Bates DV, Deposition and retention models for internal dosimetry of the human respiratory tract. Task Group on Lung
Dynamics. Health Phys 1966;12:173.

•A study showed that nebulized large particle dust mite allergen
(median, 9.7 μm) induced BHR at a lower concentration
than did smaller particles (median, 1.1 μm).
Casset A, Bronchial challenge test in asthmatics sensitized to mites: role of particle size in bronchial response.
J Aerosol Med 2007;20:509-18.
•Thus, under conditions of gentle breathing a significant
proportion of large particles will enter the bronchi and these
particles can contribute to progressive inflammation of the
lungs.
•Natural exposure involves a small number of fecal particles
entering the lungs per day, which do not produce noticeable
symptoms or changes in lung function at the time of exposure, but +++ in
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BHR
BHR

•A study showed that nebulized large particle dust mite allergen
(median, 9.7 μm) induced BHR at a lower concentration
than did smaller particles (median, 1.1 μm).
Casset A, Bronchial challenge test in asthmatics sensitized to mites: role of particle size in bronchial response.
J Aerosol Med 2007;20:509-18.
•Thus, under conditions of gentle breathing a significant
proportion of large particles will enter the bronchi and these
particles can contribute to progressive inflammation of the
lungs.
•Natural exposure involves a small number of fecal particles
entering the lungs per day, which do not produce noticeable
symptoms or changes in lung function at the time of exposure, but +++ in
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BHR
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BHR

•Airway inflammation results from chronic exposure
to small numbers of relatively large particles which does not
cause immediate symptoms.
•This is in contrast to bronchial challenge with nebulized
droplets, which involves inhaling approximately 108 droplets
of about 2 μm diameter over 2 to 5 minutes, resulting
in a measurable decrease in lung function within 20 minutes.
•Furthermore, the inflammatory response to dust mite allergen involves
non-IgE mediated mechanisms, including T cells and innate immune cells.
•Taken together then “we have the enigma of the allergen that is most
strongly associated with asthma being invisible, lacking clearcut seasonality,
and rarely giving rise to respiratory symptoms at the time of exposure”.
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The importance of this background to any discussion
of dust mite avoidance includes that:
1) the patients’ clinical history will not give simple evidence
about the importance of mite exposure,
2) ideally you need evidence about allergen levels in the patient’s
house or at least in the community where the patient lives, and
3) it is clear that the process of recovery from prolonged allergen
exposure and consequent BHR takes months not days.

I. Bedroom
a. Cover mattress with plastic or fine woven fabric; cover pillows and comforters with fine
woven fabric; mattress pads, sheets and all blankets should be suitable for washing every 1-2
weeks
b. Remove carpet if possible; decrease upholstered furniture, drapes, clothing, etc.
c. Room air cleaner; best to use HEPA filter placed on polished floor
II. Whole House
a. Decrease to 45% relative humidity or less
b. Ventilate house at times when there is low outside humidity
c. Choose a house with 2nd floor bedrooms
d. Avoid concrete slabs (lastre in calcestruzzo) except in the basement and certainly avoid fitted
carpets on a concrete slab
III. Specific questions beyond the bedroom
a. Carpets should be area rugs if possible; ideally they should be cleaned or put out in the sun
and beaten
b. Vacuum carpets twice weekly
c. Avoid upholstered furniture as much as possible and reduce clutter to facilitate cleaning
Priorities in the approach to decreasing dust mite exposure

CONTROLLED TRIALS OF DUST MITE AVOIDANCE
Published controlled trials of mite avoidance include many where the design
clearly undermines the likelihood of a successful outcome.
The most obvious problems are studies that:
1) did not produce a significant decrease in mite allergens,68
2) included such aggressive cleaning of the blankets, sheets, and so forth in
both control and intervention arms that it was very unlikely that a mattress cover
would produce a significant change in exposure, 69
3) may have enrolled patients with multiple sensitivities without addressing the
allergens other than dust mites,70 and
4) enrolled patients with relatively well-controlled disease or minimal
dust mite allergen exposure at baseline.71

CHANGES THAT COULD HAVE INFLUENCED THE RELEVANCE OF
DUST MITE AVOIDANCE
Education
When dust mites were first recognized scientifically as an important cause of
allergic diseases, there was a major job to be done in educating the public about the
existence of these invisible spider-like animals in house dust.
Today, there is extensive public awareness of dust mites and patients
have no difficulty gaining information about the techniques of avoidance
(Google query: “Dust Mite Avoidance”).
Thus, today the major problem with education may be trying to control the accuracy
of the information that is available online.

Preventing Severe Asthma Exacerbations in Children.
A Randomized Trial of Mite-Impermeable
Murray CS, Am J Respir Crit Care Med. 2017;196:150-158
29.3%
41.5%
Mite
avoidance
Placebo
p = 0.047
% children with an exacerbation
in the 12 months follow-up
50 –
40 –
30 –
20 –
10 –
00 –
 Mite-sensitized children with
asthma (ages 3-17 yr) after
an emergency hospital
attendance with an asthma
exacerbation.
 Mite-impermeable
(active group, n=46)
or control
(placebo group, n=138)
bed encasings.

0.55
Mite avoidance
p <0.006
HR for emergency
hospital attendance
1.0 –
0.5 –
0.0 –
exacerbation.
or control
bed encasings.

0.55
Mite avoidance
p <0.006
HR for emergency
hospital attendance
1.0 –
0.5 –
0.0 –
exacerbation.
or control
bed encasings.
Mite-impermeable
encasings are
effective in reducing
the number of mite-
sensitized children
with asthma attending
the hospital with
asthma
exacerbations.

0.55
Mite avoidance
p <0.006
HR for emergency
hospital attendance
1.0 –
0.5 –
0.0 –
exacerbation.
or control
bed encasings.
No difference
between the groups
in the risk of
prednisolone use
for exacerbation
was found.

Mite Avoidance as a Logical Treatment for
Severe Asthma in Childhood. Why Not? Editorial
Platts-Mills TAE, Am J Respir Crit Care Med. 2017; 196:119-121
• The report by Murray and colleagues in this issue of the Journal has two
key strengths.
• First, by enrolling children who had experienced a recent asthma
exacerbation at 14 hospitals in Northern England, sufficient sample size
was attained to objectively monitor changes in acute episodes among mite-
sensitized children within a 12-month window.
• Second, the materials used for active and placebo bedding encasings were
carefully selected based on properties of fabrics known to prevent or
allow the passage of allergens.
• The protocol included washing instructions and treatment of relevant
beds, recognizing that children are not confined to a single bed.

• This strategy resulted in a highly significant decrease in levels of the
major dust mite allergen, Der p 1, in mattress dust obtained from the
active group, which was maintained at 1 year.
• Moreover, by multivariate analysis, the risk of exacerbations requiring
acute treatment was 45% lower in the active versus the placebo group
(P < 0.006).
• Although the majority of asthma exacerbations in children older than
3 years of age are triggered by infection with human rhinovirus, it is
increasingly clear that the risk of either current asthma or exacerbations
is related to both the presence and the levels of IgE antibodies to mite
or other allergens.

The relevance of allergen exposure at critical steps in the development
of severe exacerbations of asthma in at-risk children

of severe exacerbations of asthma in at-risk children
Acute exacerbations reflect the culmination of a series of pathogenic
processes in the susceptible host, which are influenced at each stage by
exposure to airborne particles derived from one or more major allergen
sources. Therapeutic interventions that influence asthma exacerbations
may act predominantly on the progression from sensitization to bronchial
inflammation. The synergistic effects of IgE and rhinovirus depend
on the preexisting inflammatory milieu in the asthmatic lung.

• The study by Murray and colleagues reinforces the notion that
mite allergy is a principal driver in asthma pathology, consistent with an
“allergen hierarchy” that may be geographically determined.
• As with all studies of avoidance, there are limitations.
Murray and colleagues used an intervention focused solely on bedding.
• Although removal of carpets and upholstered furnishings might further
reduce the burden of mite allergen, it would clearly be impossible to blind
those methods.

A Randomized Trial of Mite-Impermeable Bedcovers.
Murray CS, Am J Respir Crit Care Med. 2017;196(2):150-158
mite-sensitized children with
asthma (ages 3-17 yr) after an
emergency hospital attendance
with an asthma exacerbation to
receive mite-impermeable
(active group n°= 146) or
control (placebo group n°= 138)
bed encasings.
Follow-up 12 months
Der p 1 levels in child’s mattress (ng/m2)
at recruitment and 12 months
after intervention

bed encasings.
% children attending the hospital
with an exacerbation
in the 12 mo.follow-up
50 –
40 –
30 –
20 –
10 –
10 -
active group placebo group
29.3%
41.5%
P = 0.047

bed encasings.
in active group
vs placebo
HR of emergency
hospital attendance
1.0 –
0.5 –
0.0
0.55
P = 0.006

bed encasings.
Time to first hospitalization or emergency
department visit because of severe
exacerbation of asthma.
P = 0.006

Mite Avoidance as a Logical Treatment for Severe
Asthma in Childhood. Why Not? Editorial
Platts-Mills TAE, Am J Respir Crit Care Med. 2017;196(2):119-121.
•In 1970, when Cox and Altounyan presented data showing that seasonal
exposure of pollen-allergic subjects could increase BHR, and that this
reactivity could persist for 3 months after the season.
•Over the next 10 years emerged that moving mite-allergic children or adults to a
mountain resort or a hospital room produced highly significant decreases in BHR.
•Murray and colleagues (pp. 150–158) in this issue of the Journal performed a study
which included washing instructions and treatment of relevant beds, recognizing
that children are not confined to a single bed.
•This strategy resulted in a highly significant decrease in levels of the major dust
mite allergen, Der p 1, in mattress dust obtained from the active group, which was
maintained at 1 year.

of severe exacerbations of asthma in at-risk children.
Acute exacerbations reflect the culmination of a series of
pathogenic processes in the susceptible host, which are
influenced at each stage by exposure to airborne particles
derived from one or more major allergen sources.
Therapeutic interventions that influence asthma
exacerbations may act predominantly on the progression
from sensitization to bronchial inflammation.
The synergistic effects of IgE and rhinovirus depend on
the preexisting inflammatory milieu in the asthmatic lung.

•There is convincing evidence from Dr. Boner’s group
in Italy that moving children with asthma
to a high-altitude environment where mite exposure
is negligible markedly reduces both BHR
and lung inflammation.
Piacentini GL, Bodini A, Costella S, Vicentini L, Mazzi P, Sperandio S, Boner AL. Exhaled nitric
oxide and sputum eosinophil markers of inflammation in asthmatic children. Eur Respir J
1999;13:1386–1390.
•It is not clear whether similar effects can be achieved
in the home environment, although decreases in BHR
have been achieved in many avoidance trials.

Indoor Environmental Interventions for Furry Pet Allergens,
Pest Allergens, and Mold: Looking to the Future.
Ahluwalia SK, J Allergy Clin Immunol Pract. 2018;6(1):9-19.
Recommendations for allergen abatement
IPM- Integrated pest management

Recommendations for allergen abatement
IPM- Integrated pest management
after removing a pet from the home,
it can take several months before
significant reductions
in allergen levels are achieved

FURRY PET ALLERGENS
•Fel d 1 and Can f 1, the respective major allergens for cats and dogs, are
found in the saliva, skin, and hair follicles of these animals.
•These pet allergens are predominantly carried on small particles
(<10-20 mm), allowing them to remain airborne for long periods of time and
adhere to clothing and surfaces.
•As a result, pet allergens are carried long distances, and are passively
transferred to environments where no pets may be present.
•Approximately 12% of the general population and 25% to 65%
of children with persistent asthma are sensitized to cat or dog
allergens

FURRY PET ALLERGENS
•Frequent washing of animals has been evaluated as a means of reducing
airborne allergen levels.
•Unfortunately, washing cats demonstrated no benefit or
transient benefit in airborne Fel d 1 levels that was
not sustained, even at 1 week postwashing.
•Dog washing reduced recoverable allergen levels from dog hair
and dander, but the results were short-lived unless the dog was
washed twice a week.

FURRY PET ALLERGENS
Given the difficulty in maintaining regular
washing of animals, particularly cats, along
with the transient benefit, these
interventions have understandably
not been widely embraced.

FURRY PET ALLERGENS
Evaluation of high efficiency
particulate air filters has also
been performed but with
largely negative results.

FURRY PET ALLERGENS
•Patients will commonly ask about obtaining
“hypoallergenic” dog breeds.
•There is no evidence to support the claim that
any breed of dog is “hypoallergenic.”
Butt A, Do hypoallergenic dogs exist? Ann Allergy Asthma Immunol 2012;108:74-6.
•In fact, the purportedly “hypoallergenic” breeds actually had higher Can f 1
levels in hair and coat samples than the “nonhypoallergenic” breeds.
Vredegoor DW, Can f 1 levels in hair and homes of different dog breeds: lack of evidence to
describe any dog breed as hypoallergenic. J Allergy Clin Immunol 2012;130:904-9.

MOUSE ALLERGEN
•The major mouse allergen, Mus m 1, is excreted in mouse urine.
•Mus m 1 is carried on small particles, mainly < 10 microns; thus, it remains
airborne for prolonged periods of time.
•About 75% to 80% of suburban homes have detectable mouse allergen
in settled dust.
•Concentrations of mouse allergen in settled dust are 100- to 1000-fold
higher among certain low-income, urban neighborhoods than among suburban
neighborhoods

MOUSE ALLERGEN
The presence of a cat in the home is associated with
lower mouse allergen concentrations; however,
most individuals with asthma demonstrate sensitization
to both mouse and cat, making acquisition
of a cat a poor solution for improving
asthma outcomes.
It is estimated that 18% to 51% of urban, low- income children are
sensitized to mouse.

Integrated Pest Management (IPM) is a multifaceted interventional approach that includes
1) vigorous cleaning,
2) meticulous food disposal,
3) sealing of holes and cracks in housing structures,
4) setting traps, and,
5) if necessary, application of rodenticide,
6) education about IPM.
MOUSE ALLERGEN
professionally delivered
IPM that resulted
in approximately
75% reduction in mouse
allergen concentrations

Integrated Pest Management (IPM) is a multifaceted interventional approach that includes
1) vigorous cleaning,
2) meticulous food disposal,
3) sealing of holes and cracks in housing structures,
4) setting traps, and,
5) if necessary, application of rodenticide,
6) education about IPM.
MOUSE ALLERGEN
professionally delivered
IPM that resulted
in approximately
75% reduction in mouse
allergen concentrations
Sufficiently large (50%-75%) reductions in mouse allergen
concentrations are correlated with significant and clinically
meaningful improvements in measures of asthma outcomes,
whereas smaller reductions
in the mouse allergen concentration
may not be associated with any significant effects.

COCKROACH ALLERGEN
•The 2 most common cockroaches in US homes are
the German cockroach (Blatella germanica)
and the American cockroach (Periplaneta americana).
•The major allergens for these species (Bla g 1, Bla g 2, and Per a 1) of
cockroach are found in the saliva, secretions, debris, and fecal material.
•Cockroach infestation is associated with the presence of highly dense
population, urban environment, and low socioeconomic status.

COCKROACH ALLERGEN
Substantial (80% to 90%) reductions in cockroach allergen levels can be
achieved using an Integrated Pest Management (IPM) approach to target
cockroach infestation in the home:
1) application of pesticide with bait,
2) sealing of cracks and holes,
3) vigorous cleaning aimed at reducing allergen reservoir, and
4) meticulous food disposal.

COCKROACH ALLERGEN
Substantial (80% to 90%) reductions in cockroach allergen levels can be
achieved using an Integrated Pest Management (IPM) approach to target
cockroach infestation in the home:
1) application of pesticide with bait,
2) sealing of cracks and holes,
3) vigorous cleaning aimed at reducing allergen reservoir, and
4) meticulous food disposal.
Clinical benefit has been observed with sufficiently
large (50% to 90%) reductions in cockroach exposure,
as measured by decreases in cockroach allergen
concentrations

DAMPNESS AND MOLDS
Common outdoor fungi include Alternaria and Cladosporium,
whereas fungi more commonly associated with indoor dampness
and water damage include Penicillium and Aspergillus.
“Outdoor” fungi are commonly found indoors, as they can be tracked in
through open windows and doors, and on clothing and pets.
The best predictors for indoor concentrations of fungi are
i) overall dampness in a home when windows are closed, and
ii) outdoor concentrations when windows are open.

DAMPNESS AND MOLDS
•Significant problems with mold in buildings are a direct
result of excessive moisture, which can result from
water intrusion, inadequate ventilation, defective plumbing,
or other building problems.
•Concentrations of fungal allergens in settled dust correlate with carbon
dioxide (CO2)levels, a marker of building ventilation, and they are highest at
ambient temperatures of 20°C to 22.5°C.
•Organic building material such as wood, cellulose, dry wall (cartongesso),
and cardboard (cartone) are most vulnerable to fungi.

DAMPNESS AND MOLDS
•General population estimates of the overall sensitization to fungal allergens
range from 8% to 14%, but the estimates are considerably higher in atopic
individuals.
•Associations between exposure to fungi and risk of respiratory symptoms
have been found regardless of sensitization status, but sensitization to
fungi is believed to increase the risk of morbidity.
•This observation suggests that fungi may also have
biologic effects through non-IgE-mediated mechanisms
because fungal components can directly activate
the innate immune system.

DAMPNESS AND MOLDS
•In children with sensitization and exposure to fungus, exposure
to Penicillium has been correlated with increased asthma exacerbations.
•Sensitivity to Aspergillus fumigatus has been associated
with severe persistent asthma in adults.
•Exposure and sensitization to Alternaria species
has been associated with increases in asthma symptoms,
bronchial hyperresponsiveness, and severe asthma exacerbations.

DAMPNESS AND MOLDS
Interventional studies have suggested a role for remediation
of dampness and mold to reduce adverse respiratory health
effects associated with dampness and mold exposure.
The interventions used have included multiple of the following modalities:
1) removal of mold from hard surfaces,
2) elimination of rainwater intrusion,
3) installation of ventilation systems, and
4) repair of plumbing leaks.

DAMPNESS AND MOLDS
Interventional studies have suggested a role for remediation
of dampness and mold to reduce adverse respiratory health
effects associated with dampness and mold exposure.
The interventions used have included multiple of the following modalities:
1) removal of mold from hard surfaces,
2) elimination of rainwater intrusion,
3) installation of ventilation systems, and
4) repair of plumbing leaks.
For patients with allergic asthma and
mold sensitization, use of
a central heating, ventilation, and air
conditioning (HVAC) system with
properly maintained filters
can help reduce transport
of outdoor fungal spores indoors.

•Care must be exercised when attempting to remove
visible mold and when using chlorine-based bleach
products to kill mold spores.
•The National Institute of Occupational Safety and
Health recommends the use of an N-95 mask at
minimum when removing visible mold.
•When using chlorine-based bleach products,
respirators with specific chemical cartridges are
necessary to prevent injury to the lung from the
chemical fumes.
DAMPNESS AND MOLDS

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