Cockroach allergen reduction by cockroach control alone in low-income urban homes: a randomized control trial.
ABSTRACT We previously reported significant reductions in cockroach allergen concentrations in urban homes by reducing cockroach infestations.
To determine the effectiveness of pest control performed by professional entomologists, compared with commercial companies, in reducing cockroach allergen.
This 3-arm randomized controlled trial enrolled 60 cockroach-infested homes in North Carolina. Homes were randomly assigned to a control group or 1 of 2 treatment groups. Treatment 1 had insecticide baits placed by entomologists from North Carolina State University. Treatment 2 received pest control from a randomly assigned commercial company. Vacuumed dust sampling and cockroach trapping were conducted at 0, 6, and 12 months. Dust samples were analyzed by ELISA.
In treatment 1 homes, there were significant reductions in geometric mean trap counts compared with control and treatment 2 homes at 12 months. Relative to control, significant 12-month reductions in Bla g 1 were evident in treatment 1 homes at all sampled sites, except bedroom floor. From baseline to month 12, geometric mean Bla g 1 concentrations (U/g) decreased from 64.2 to 5.6 in kitchen, 10.6 to 1.1 in living room, 10.7 to 1.9 on bedroom floor, and 3.6 to 2.3 in bed. Treatment 2 homes showed no significant 12-month allergen reductions versus control.
Reductions in Bla g 1 in cockroach-infested homes can be achieved by reducing infestations; however, the magnitude of allergen reduction is dependent on the thoroughness and effectiveness of cockroach eradication efforts.
Elimination of cockroaches is an effective method for reducing exposure to cockroach allergen.
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ABSTRACT: In the modern era, the prevalence of asthma and allergies are increasing. It has been speculated that environmental exposures are contributing to this rise. Several studies demonstrate that common indoor allergen exposures exacerbate asthma. Minimizing exposure to allergens and remediating the environment play a critical role in the treatment of asthma and allergies. The most effective environmental control measures are tailored multifaceted interventions which include education, thorough cleaning, using high-efficiency particulate air (HEPA) filters, integrated pest management, and maintenance of these practices.Current Allergy and Asthma Reports 03/2014; 14(3):419. · 2.75 Impact Factor
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ABSTRACT: Human asthmatics display considerable heterogeneity with regard to Th2-associated eosinophilic and Th17-associated neutrophilic inflammation, but the impact of the environment on these different forms of asthma is poorly understood. We studied the nature and longevity of asthma-like responses triggered by inhalation of allergen together with environmentally relevant doses of inhaled LPS. Ovalbumin was instilled into the airways of mice together with a wide range of LPS doses. Following a single OVA challenge, or multiple challenges, animals were assessed for pulmonary cytokine production, airway inflammation and airway hyperresponsiveness (AHR). Mice instilled with OVA together with very low doses (≤ 10(-3) µg) of LPS displayed modest amounts of Th2 cytokines, with associated airway eosinophilia and AHR after a single challenge, and these responses were sustained after multiple OVA challenges. When the higher but still environmentally relevant dose of 10(-1) µg LPS was used, mice initially displayed similar Th2 responses, as well as Th17-associated neutrophilia. After multiple OVA challenges, however, the latter animals also accumulated large numbers of allergen-specific T regulatory (Treg) cells having high display of inducible co-stimulatory molecule (ICOS). As a result, asthma-like features in these mice were shorter-lived than in mice sensitized using lower doses of LPS. The nature and longevity of Th2, Th17 and Treg immune responses to inhaled allergen are dependent on the quantity of LPS inhaled at the time of allergic sensitization. These findings might account in part for the heterogeneity of inflammatory infiltrates seen in lungs of asthmatics.Environmental Health Perspectives 10/2013; · 7.26 Impact Factor
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ABSTRACT: Allergic asthma is thought to stem largely from maladaptive T helper 2 (Th2) responses to inhaled allergens, which in turn lead to airway eosinophilia and airway hyperresponsiveness (AHR). However, many individuals with asthma have airway inflammation that is predominantly neutrophilic and resistant to treatment with inhaled glucocorticoids. An improved understanding of the molecular basis of this form of asthma might lead to improved strategies for its treatment. Here, we identify novel roles of the adaptor protein, TRIF (TIR-domain-containing adapter-inducing interferon-β), in neutrophilic responses to inhaled allergens. In different mouse models of asthma, Trif-deficient animals had marked reductions in interleukin (IL)-17, airway neutrophils, and AHR compared with wild-type (WT) mice, whereas airway eosinophils were generally similar in these two strains. Compared with lung dendritic cells (DCs) from WT mice, lung DCs from Trif-deficient mice displayed impaired lipopolysaccharide (LPS)-induced migration to regional lymph nodes, lower levels of the costimulatory molecule, CD40, and produced smaller amounts of the T helper 17 (Th17)-promoting cytokines, IL-6, and IL-1β. When cultured with allergen-specific, naive T cells, Trif-deficient lung DCs stimulated robust Th2 cell differentiation but very weak Th1 and Th17 cell differentiation. Together, these findings reveal a TRIF-CD40-Th17 axis in the development of IL-17-associated neutrophilic asthma.Mucosal Immunology advance online publication, 2 July 2014; advance online publication, 2 July 2014; doi:10.1038/mi.2014.56.Mucosal Immunology 07/2014; · 7.54 Impact Factor
Environmental and occupational respiratory disorders
Cockroach allergen reduction by cockroach
control alone in low-income urban homes:
A randomized control trial
Michelle L. Sever, BS,aSamuel J. Arbes, Jr, PhD,aJ. Chad Gore, PhD,bRichard G.
Santangelo, BS,bBen Vaughn, MS,cHerman Mitchell, PhD,cCoby Schal, PhD,b
and Darryl C. Zeldin, MDaResearch Triangle Park, Raleigh, and Chapel Hill, NC
Background: We previously reported significant reductions in
cockroach allergen concentrations in urban homes by reducing
Objective: To determine the effectiveness of pest control
performed by professional entomologists, compared with
commercial companies, in reducing cockroach allergen.
Methods: This 3-arm randomized controlled trial enrolled 60
cockroach-infested homes in North Carolina. Homes were
randomly assigned to a control group or 1 of 2 treatment
groups. Treatment 1 had insecticide baits placed by
entomologists from North Carolina State University. Treatment
2 received pest control from a randomly assigned commercial
company. Vacuumed dust sampling and cockroach trapping
were conducted at 0, 6, and 12 months. Dust samples were
analyzed by ELISA.
Results: In treatment 1 homes, there were significant reductions
in geometric mean trap counts compared with control and
treatment 2 homes at 12 months. Relative to control, significant
12-month reductions in Bla g 1 were evident in treatment
1 homes at all sampled sites, except bedroom floor. From
baseline to month 12, geometric mean Bla g 1 concentrations
(U/g) decreased from 64.2 to 5.6 in kitchen, 10.6 to 1.1 in living
room, 10.7 to 1.9 on bedroom floor, and 3.6 to 2.3 in bed.
Treatment 2 homes showed no significant 12-month allergen
reductions versus control.
Conclusion: Reductions in Bla g 1 in cockroach-infested homes
can be achieved by reducing infestations; however, the
magnitude of allergen reduction is dependent on the
thoroughness and effectiveness of cockroach eradication efforts.
Clinical implications: Elimination of cockroaches is an effective
method for reducing exposure to cockroach allergen. (J Allergy
Clin Immunol 2007;120:849-55.)
Key words: Cockroaches, cockroach allergen, Bla g 1, Bla g 2,
indoor allergens, intervention trial
Studies suggest that exposure to cockroach allergens is
one of the most important risk factors for asthma in inner-
city households. The National Cooperative Inner-City
Asthma Study found that asthma morbidity was highest in
children with both a positive skin test response and a high
exposure to the cockroach allergen Bla g 1 in the
bedroom.1In addition, a study of elderly patients with
asthma in New York City found that the most common
sensitization was to cockroach allergen, with 47% of the
subjects sensitized. Cockroach sensitization was also as-
sociated with a significant reduction in FEV1in this pop-
ulation.2The Inner-City Asthma Study (ICAS) found that
a significant reduction in cockroach allergen on the bed-
morbidity, as measured by symptom days, hospitaliza-
tions, and unscheduled doctor visits.3These findings indi-
cate that reducing exposure to cockroach allergens could
be a valuable strategy to improve the health of inner-city
We previously reported significant reductions in cock-
roach allergen levels (Bla g 1 and Bla g 2) in low-income,
infested, urban homes after implementing an integrated
pest management intervention consisting of resident ed-
ucation, intensive professional cleaning, and extensive
insecticide bait treatments that resulted in significant
reductions in cockroach infestations.4Surprisingly, Bla
g 1 and Bla g 2 concentrations decreased significantly in
the study’s control homes after these homes were treated
with insecticide bait alone at months 6 and 9. At the end
of the 12-month study, intervention homes and crossed-
over control homes had approximately the same level
of cockroach allergen at each location sampled.5The
crossed-over control homes received insecticide bait ap-
plications at months 6 and 9 but received no other inter-
ventions (ie, education or cleaning). Thus, in contrast
with other studies, highly effective cockroach eradication
alone significantly lowered allergen concentrations.6,7
Urban entomologists associated with the Entomology
Department at North Carolina State University (NCSU,
Raleigh, NC) performed insecticide applications in our
previous studies. The effectiveness of the treatment
Health Sciences, National Institutes of Health, Research Triangle Park;
bthe Department of Entomology, North Carolina State University, Raleigh;
andcRho, Inc, Chapel Hill.
Supported by the Intramural Research Program of the National Institutes of
Health, National Institute of Environmental Health Sciences, and by the
Blanton J. Whitmire Endowment at North Carolina State University.
Disclosure of potential conflict of interest: B. Vaughn and H. Mitchell are em-
ployed by Rho, Inc. The rest of the authors have declared that they have no
conflict of interest.
Received for publication December 22, 2006; revised May 25, 2007; accepted
for publication July 5, 2007.
Available online September 10, 2007.
Reprint requests: Darryl C. Zeldin, MD, NIEHS/NIH, PO Box 12233, MD
D2-01, Research Triangle Park, NC 27709. E-mail: firstname.lastname@example.org.
ICAS: Inner-City Asthma Study
NCSU: North Carolina State University
was demonstrated by profound reductions in trapped
cockroaches in infested homes (50-500 cockroaches
trapped at baseline in 18 traps deployed for 3 nights);
between 64% and 75% of the intervention homes had a
median of 0 cockroaches trapped at the conclusion of the
2 studies. Gel bait placement was guided by a thorough
visual inspection and layout maps of the homes, trap
counts, and insecticide label directions. Although we did
not actively attempt to prevent infestation (or reinfesta-
tion) by repairing cracks, holes, and so forth, and did not
educate residents about removing food and water sources
in our second intervention,5we successfully reduced
cockroach populations in infested homes by 99% to
100% (on the basis of comparisons of medians at baseline
and at 12 months).
Our studies show significant allergen reductions after
allergen source reduction through intensive cockroach
eradication. However, most previous cockroach allergen
intervention studies that contracted with commercial pest
control companies did not report either the specific pest
control tactics they deployed or changes in the cockroach
population (measured by trapping) during or after the
intervention.8Therefore, we cannot dismiss the concept
that failure to significantly reduce cockroach allergen
in most previous studies was a consequence of ineffec-
tive pest control. It is of paramount importance to com-
pare cockroach and allergen reductions imposed by a
cockroach control program conducted by professional
entomologists with contract-based services performed
by pest control companies. If cockroach population sup-
pression alone—especially conducted by pest control
companies—could be shown to reduce cockroach aller-
gen in inner-city homes, this finding could affect the
design of many future primary and secondary asthma
prevention trials, as well as day-to-day public health
The objective of this study was to determine the
effectiveness of pest control performed by professional
entomologists, compared with commercial companies, in
Enrollment and randomization
The addresses of approximately 150 potentially eligible, cock-
roach-infested homes were obtained from a real estate management
rise apartment buildings, located in the same metropolitan area of
North Carolina. The inclusion criteria required 50 to 1000 trapped
deployed for 3 nights throughout the home. Sixty homes were
enrolled, randomly assigned to 1 of 3 treatment groups by using a
randomized block design, and followed for 12 months. Baseline
characteristics of the enrolled homes are shown in Table I and did
were assigned to 1 of 4 local pest control companies by using a ran-
domized block design. Enrollment took place from November 2004
The occupants were compensated for their participation, and the
National Institute of Environmental Health Sciences Institutional
Review Board reviewed and approved this study.
Dust collection and analysis
In all homes, vacuumed dust samples were collected from the
kitchen floor, the living room floor,the bedroomfloor,and a bed by a
trained technician. Vacuumed dust samples were collected at months
0, 6, and 12 in all homes. Samples were collected using a Eureka
Mighty-Mite 7.0-A vacuum cleaner (Eureka Co, Bloomington, Ill)
with a dust collector (Indoor Biotechnologies, Charlottesville, Va)
placed on the distal end of the vacuum’s extension wand. Vacuumed
dust samples were sieved through 425-mm mesh, weighed, and
buffered saline containing 0.05% Tween 20/1.0% BSA for 1 hour on
a rocker platform at room temperature, cleared by centrifugation, and
aliquoted. All aliquots were stored at –208C until analysis. mAb-
basedELISA wasperformedto determinethelevels ofthe cockroach
allergens Bla g 1 (kit lot #2534) and Bla g 2 (kit lot #2499) by using
standard published techniques.9Allergen concentrations are pre-
sented here in units of allergen per gram of sieved dust for Bla g
1 and micrograms of allergen per gram of sieved dust for Bla g 2.
(Victor Roach Pheromone Trap; Woodstream, Lititz, Pa) were set in
the kitchen, living room, and bedroom (a total of 18 traps per home)
and the number of German cockroaches is reported.
Treatment 1 (professional entomologists)
Within approximately 1 week of each trapping visit, urban
entomologists associated with the Entomology Department at
NCSU treated the treatment 1 homes with insecticide gel bait.
Bait; Bayer Environmental Science, Research Triangle Park, NC),
0.05% abamectin (Avert Dry-Flowable Cockroach Bait; Whitmire
Micro-Gen Research Laboratories, Inc, St Louis, Mo), or 2.15% imi-
dacloprid (Pre-Empt Cockroach Gel Bait; Bayer Environmental
Science, RTP, NC) were placed at months 0, 1, 3, 6, and 9 if any
cockroaches weretrappedandconcentratedinthe areasof infestation
indicated by the trap counts. At the initial treatment visit, dots or
streaks of approximately 100 to 200 mg of bait were placed where
cockroaches tend to hide or forage, such as in kitchen and bathroom
cabinets, under and behind appliances, around pipes entering walls,
under furniture, and in cracks in walls or floors. The total amount
of bait used at this visit ranged from 15 to 180 g depending on
both the size of the dwelling and the severity of the infestation. At
subsequent visits, bait placement was less intense and was guided
by cockroach trap counts and visual inspections. When cockroach
populations did not decrease satisfactorily at follow-up visits, an-
other formulation that contained a different insecticide was used
alone or in conjunction with hydramethylnon. For the percentage
of the total mass of bait applied in the treatment 1 homes during
the study, hydramethylnon, abamectin, and imidacloprid represented
93.6%, 3.8%, and 2.7%, respectively. Each initial treatment required
approximately 1.5 person-hours, and follow-up insecticide applica-
tion generally required 0.25 to 0.5 person-hours. No other interven-
tions, such as cleaning or education, were performed.
J ALLERGY CLIN IMMUNOL
850 Sever et al
Treatment 2 (commercial companies)
Homes enrolled in the treatment 2 arm received pest control
companies were selected from a list of companies that provide home
extermination services under a 1-year contract. Companies that
proposed to use total release aerosols (ie, foggers or space sprays)
during telephone interviews were removed from the list and thus not
selected because this method has been shown to be less effective than
residual sprays or baits.10After a pest control company wasrandomly
assigned to a home, the study coordinator contacted that pest control
company on behalf of the resident. The study coordinator informed
the company that the home had cockroaches and the resident wanted
to set up a prepaid, 1-year contract for the treatment of the home.
The study coordinator did not inform the company that the home
was participating in a study. The contract was established in the
name ofthe resident,andthe initial treatmentappointmentwassched-
uled at the resident’s convenience. The study coordinator was present
details of the contract and to give the resident a money order with
which to prepay the 12-month contract. Exterminations were based
on the details specified in the 12-month contract with each company
lowed their own standard operating procedures in providing pest con-
trol services to the homes. Two of the companies’ annual contracts
included 12 visits, 1 included 7 visits, and 1 included 4 visits. All 4
companies used hydramethylnon in their treatments, but never alone.
Three companies also used an insect growth regulator, 3 companies
usedsynergized pyrethrins, and2 companies used residual pyrethroid
or occupant education, were conducted bythe study staff. Anyeduca-
tional materials or instructionsprovided bythe company for the occu-
pants were given to the occupants and verbally translated as needed.
Control homes (untreated)
0 to 12 months. After the 12 month visit was completed, these homes
received a thorough pest control service by NCSU entomologists.
For dust samples, treated and untreated control homes were
to 6 and 12 months of the log10-transformed concentrations were
analyzed by using a linear model in SAS Proc Mixed (SAS Version
9.1.3; SAS Institute, Cary, NC). Cockroach counts in each room and
for the whole residence were analyzed in the same manner, using
Statistical significance from a 2-tailed test was set at P ? .05.
Analyses were performed on all data that were available, and no
adjustments were made for multiple comparisons.
The treatment and control homes had similar baseline
characteristics, as shown in Table I. Evidence of cock-
roach activity, such as live and dead cockroaches and
cockroach stains, was observed in the majority of homes.
ducts for roach control in past month, and none of the
nator in the previous month.
This study was designed to recruit 20 homes in each of
the 3 arms with an expected loss to follow-up of 30% to
40%. With 20 homes per arm, we had greater than 90%
power to detect an effect on cockroach allergen levels of
the samemagnitudeasin ourpreviousstudy.5If 10homes
(50%) from each arm were lost to follow-up, we would
have approximately 70% power to detect the same effect.
Forty-eight of the 60 homes enrolled completed the first 6
ment 1 arm, 3 homes in the treatment 2 arm, and 5 homes
in the control arm were lost to follow-up, with occupant
relocation the predominant reason.At 12months, an addi-
tional 6 homes in treatment 1, 7 homes in treatment 2, and
3 homes in the control arm were lost to follow-up, again
with occupant relocation the predominant reason. Within
each of the study arms, comparisons of homes that com-
pleted the study and homes that were lost to follow-up
TABLE I. Baseline characteristics of control and treatment homes
(N 5 20)
(NCSU) (N 5 20)
(companies) (N 5 20)
Homes with poor housekeeping?
Homes in fair or poor condition?
Homes with cockroach stains in any room
Homes with living cockroaches in any room
Homes with dead cockroaches in any room
Homes that used off-the-shelf products for roach control
in past month
Homes that used an exterminator in past month
Median (minimum, maximum) no. of cockroaches trapped
205.5 (50, 909)426.5 (55, 992)308.5 (62, 984)
*There were no significant differences between the control and treatment homes.
?No recent cleaning, lack of organization, greasy cooking area, and clutter.
?At least 1 score of fair or poor condition for walls and ceilings, floors, or windows.
J ALLERGY CLIN IMMUNOL
VOLUME 120, NUMBER 4
Sever et al 851
did not reveal any significant differences in cockroach
Cockroach trap counts
Table II shows the median cockroach counts by group
assignment, visit, and sample location. Among treatment
1 homes, median cockroach counts were reduced to 0 by
month 6 and remained virtually unchanged from months
6 to 12. Among treatment 2 homes, median cockroach
line to 56 by month 6, and to 51 by month 12. The geo-
metric mean cockroach trap counts were analyzed by
treatment group and by whole home and room, and both
treatment 1 and treatment 2 showed significant reductions
at all locations compared with baseline (P < .001). For
treatment 1, geometric mean cockroach trap counts de-
creased after 12 months from 183.9 at baseline to 3.3 in
the kitchen (98% reduction), 43.5 to 1.9 in the living
room (96% reduction), and 19.2 to 1.7 in the bedroom
(91% reduction). For treatment 2, geometric mean cock-
roach trap counts decreased after 12 months from 152.1
at baseline to 28.8 in the kitchen (81% reduction), 62.1
to 11.6 in the living room (81% reduction), and 32.6 to
12.0 in the bedroom (63% reduction). Untreated control
homes did not show significant decreases in geometric
mean numbers of trapped cockroaches except in the living
room, where there was a reduction from 45.2 trapped
cockroaches at baseline to 19.7 at month 12 (56%
reduction; P 5 .02). In treatment 1 homes, there were sig-
nificant reductions in geometric mean cockroach trap
counts compared with both untreated control (P < .001)
and treatment 2 homes (P < .01) at 12 months.
Cockroach allergen levels
Fig 1 shows the geometric mean Bla g 1 concentrations
(U/g dust) in vacuumed dust by group assignment, visit
number, and sample location. In the control arm homes,
there were no significant changes in the Bla g 1 concentra-
tions at any location from 0 to 12 months. For treatment 1,
all locations (P < .001) at month 12 compared with base-
(P 5 .006), and living room (P < .001) compared with the
untreated control homes. From baseline to month 12, geo-
on the bedroom floor, and 3.6 to 2.3 in the bed. Treatment
1 also showed significant reductions compared with treat-
For treatment 2, there were significant reductions
compared with baseline in the bed (P 5 .01), bedroom
floor (P 5 .03), and living room samples (P 5 .02).
From baseline to month 12, geometric mean Bla g 1 con-
centrations for treatment 2 decreased from 66.9 to 43.0 in
the kitchen, 14.3 to 5.7 in the living room, 17.3 to 7.2
on the bedroom floor, and from 5.5 to 1.9 in the bed.
TABLE II. Median cockroach counts at the home and room levels*
Median cockroach count (no. with 0 count/total no.)
LocationMonthTreatment 1 (NCSU)Treatment 2 (companies)Controly
205.5 (0/20) Whole home0
48.5 (0/20)Living room
*Both treatment arms showed significant reductions at all locations compared with baseline (P < .001). In treatment 1 homes, there were significant reductions
in geometric mean cockroach trap counts compared with both untreated control (P < .001) and treatment 2 homes (P < .01) at 12 months.
?Control homes received insecticide bait application only at month 12. Trap counts at month 12 were determined before insecticide application.
J ALLERGY CLIN IMMUNOL
852 Sever et al
However, these changes were not significant compared
with untreated control homes.
on Bla g 2. For treatment 1, there were significant reduc-
tions in Bla g 2 concentrations (mg/g dust) in the bed,bed-
room floor, living room floor, and kitchen floor (P < .001
at all sites) at month 12 compared with baseline. At month
12, treatment 1 homes had a significant reduction in
Bla g 2 levels compared with untreated control homes in
the kitchen (P < .001) and living room (P 5 .002).
Treatment 1 also resulted in significant reductions com-
room (P 5 .02). For treatment 2, there were significant re-
ductions compared with baseline in the bed (P 5 .002),
bedroom floor (P 5 .001), and living room samples (P 5
.005). There were no significant reductions in Bla g 2 for
FIG 1. Geometric mean Bla g 1 allergen concentrations (and SEs) from vacuumed dust samples in control
(solid line), treatment 1 (red dashed line), and treatment 2 (blue dashed line) homes.
FIG 2. Geometric mean Bla g 2 allergen concentrations (and SEs) from vacuumed dust samples in control
(solid line), treatment 1 (red dashed line), and treatment 2 (blue dashed line) homes.
J ALLERGY CLIN IMMUNOL
VOLUME 120, NUMBER 4
Sever et al 853
treatment 2 compared with untreated control homes, but
there were significant reductions in the control arm from
0 to 12 months in the bed (P < .001) and bedroom floor
(P 5 .006).
Spearman correlations were calculated between base-
line and 12-month cockroach counts and Bla g 1 levels.
The reductions in cockroach counts were significantly
correlated with the reductions in cockroach allergen
in the kitchen (Spearman correlation coefficient 5 0.46;
P 5 .008) and bedroom (Spearman correlation coeffici-
ent 5 0.43; P 5 .01). There was not a significant correla-
tion in the living room (Spearman correlation coefficient
5 0.19; P 5 .3).
This study corroborates our previous finding that
effective cockroach control alone, which significantly
decreases or eliminates cockroach populations, can result
in significantly reduced cockroach allergen levels in
settled dust samples. Unlike our previous interventions,
which consisted of intensive pest control and resulted
in large reductions in environmental cockroach allergen
used in this study, and the magnitude of the allergen
reduction was dependent on the thoroughness and effec-
tiveness of the cockroach eradication efforts. The treat-
ment 1 homes received a similar intervention to the
crossed-over control homes in our previous study,5and
the outcomes (cockroach reduction and allergen reduc-
by commercial pest control companies, also experienced
significant reductions in the number of cockroaches trap-
ped, but the magnitude of the reduction was significantly
remained relatively high after 12 months, and changes in
cockroach allergens were not different from those in
untreated control homes.
What are possible reasons for the differences in the 2
treatment arms? We believe the major differences were
related to the cockroach monitoring that guided bait
placement in treatment 1 homes, the types of pesticides
used, and the schedule and intensity of treatment. In the
treatment 1 arm, the cockroach populations were moni-
tored throughout the study with 18 sticky traps per home,
and homes were treated again if any cockroaches were
trapped at months 1, 3, 6, and 9. Treatment 1 also used
layout maps of each home, identified problem areas, and
out the entire home at baseline and as needed throughout
the 12 months of follow-up. Living rooms and bedrooms
in these homes harbored significant infestations (Table II)
that would likely reinfest other rooms if not eliminated.
Treatment 1 used highly effective, reduced toxicity gel
baits for every treatment and did not use any spray or
the fundamentals of integrated pest management, but with
1 major exception: preventing infestations (sealing cracks
and crevices, caulking, and structural repairs), which is
very labor-intensive and expensive, was beyond the scope
of this intervention study. The reduction of cockroaches
by monitoring-guided insecticide baiting has been previ-
ously shown to be similar to that in an integrated program
that included cleaning, resident education, and baiting.11
Moreover, the monitoring-guided approach has been
shown to be significantly more effective at reducing cock-
roach populations than baseboard and crack and crevice
In contrast, the commercial pest control companies in
treatment 2 used predominantly traditional or conven-
tional treatments, which generally consist of calendar-
based (monthly, bimonthly, or quarterly) applications of
spray and dust insecticide formulations to baseboards and
cracks and crevices.12,13None of the contracted pest con-
trol companies used traps to monitor the cockroach infes-
residents to treat other areas. The majority of their initial
treatments relied heavily on spray and dust formulations
and used smaller amounts of gel baits. Spray insecticide
label directions require that the contents of kitchen cabi-
nets be removed or covered to prevent contamination;
such preparations are generally left to residents, and non-
compliance may result in less thorough insecticide cover-
age. The majority of residents in treatment 2 complained
about the dusts, sprays, and work involved in cleaning
out cabinets, drawers, and so forth in their homes. These
complaints were relayed to the companies, and according
to resident reports and study staff observations, the types
of insecticides used in treatment 2 homes changed over
time to include more bait stations and gel baits.
Although we had 2 local, 1 regional, and 1 national com-
mercial company involved in this study, treatment 2 re-
sults may not be typical of all commercial companies.
The homes in this study were all cockroach-infested row
homes and low-rise apartments with adjacent units not in-
volved in the intervention. These homes are similar to
those found in other urban areas,11,12,14-16although they
may not be representative of cockroach infested homes
in high-rise apartment buildings.
Despite significant reductions in cockroaches in treat-
ment 2 homes (eg, 83% in the kitchen), allergen levels
changed only marginally (eg, 35.7% in the kitchen). This
suggests the possibility that there is a threshold level of
cockroach infestation, above which drastic decreases in
cockroach allergen, like those seen in the treatment 1, are
unlikely. This threshold may represent a level of active
cockroaches that disseminate allergen in feces and other
secretions during normal foraging activities. The treat-
ment 1 homesreceived additional bait placement after any
trapping visit in which more than 1 cockroach was
trapped. In other words, the goal of treatment 1 was
eradication of cockroaches, not merely population control
or management.Althoughthis islikelyalsothe goalofthe
commercial pest control companies that treated homes in
this study, they had no means of assessing their effective-
ness without monitoring the pest population.
J ALLERGY CLIN IMMUNOL
854 Sever et al
The total cost of treatment 1 was estimated at $281 per
home for 12 months of follow-up including cockroach
trapping, counting, and bait placement. The cost of the
bait placement ranged from approximately $61 to $124
with a median cost of $80 for 12 months of treatment. The
costover12months forthe cockroach traps, laborto place
and retrieve the traps, and labor to count the traps was
$201 per home. The median cost for a 12-month contract
with the commercial pest control companies in treatment
2 was $475.
One limitation of this study is the lack of health
outcome data to correlate with the reductions in cock-
roaches and cockroach allergen. This study did not
undertake health outcome measures because we felt it
was necessary to confirm our intervention methods were
effective before enrolling children or adults with asthma
into a clinical trial. We are currently planning a multicen-
ter clinical trial with children with moderate to severe
asthma who are both sensitized and exposed to cockroach
allergen. The intervention from treatment 1 will be imple-
mented in their homes, and health outcomes will be
monitored. On the basis of data from ICAS showing a
significant correlation between Bla g 1 reductions (44%
reduction from a baseline median of 0.2 U/g dust) and
decreased asthma morbidity,3we anticipate that by reduc-
ing cockroach numbers and allergen to the degree demon-
strated in the current study, a significant improvement in
asthma morbidity will be achieved.
In this study, commercial pest control companies
were not as successful at removing cockroaches and
their allergens from homes in inner-city multiunit
dwellings as a group of entomologists; however, these
companies did demonstrate effectiveness in reducing
cockroach counts compared with control as well as
allergen concentrations within homes. To improve their
effectiveness, we would suggest additional training for
pest control operators to increase their knowledge
about the most effective treatments and education of
patients to be diligent in reporting cockroach sightings
to the companies and requesting additional service
By monitoring cockroach trap counts and intensively
treating infested homes with highly effective gel bait
preparations, cockroach populations can be dramatically
reduced almost to the point of eradication. This reduction
in cockroach infestation leads to a large reduction in
cockroach allergen as well. The magnitude of the allergen
reduction is dependent on the success of the cockroach
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J ALLERGY CLIN IMMUNOL
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