Cockroach Allergens Have Greatest Impact on Childhood Asthma
In Many U.S. Cities
New results from a nationwide study on factors that affect asthma
in inner-city children show that cockroach allergen appears to
worsen asthma symptoms more than either dust mite or pet allergens.
This research, funded by the National Institute of Environmental
Health Sciences (NIEHS) and the National Institute of Allergy and
Infectious Diseases (NIAID), part of the National Institutes of
Health, is the first large-scale study to show marked geographic
differences in allergen exposure and sensitivity in inner-city
children. Most homes in northeastern cities had high levels of
cockroach allergens, while those in the south and northwest had
dust mite allergen levels in ranges known to exacerbate asthma
The study results are published in the March issue of the Journal
of Allergy and Clinical Immunology.
“These data confirm that cockroach allergen is the primary
contributor to childhood asthma in inner-city home environments,” said
NIEHS Director Kenneth Olden, Ph.D. “However, general cleaning
practices, proven extermination techniques and consistent maintenance
methods can bring these allergen levels under control.”
Cockroach allergens come from several sources such as saliva,
fecal material, secretions, cast skins, and dead bodies. People
can reduce their exposure to cockroach allergen by eating only
in the kitchen and dining room, putting non-refrigerated items
in plastic containers or sealable bags, and taking out the garbage
on a daily basis. Other measures include repairing leaky faucets,
frequent vacuuming of carpeted areas and damp-mopping of hard floors,
and regular cleaning of counter tops and other surfaces.
NIH provided $7.5 million to researchers at the University of
Texas Southwestern Medical Center at Dallas and seven other research
institutions, including the Data Coordinating Center at Rho, Inc.,
for the three-year study.
“We found that a majority of homes in Chicago, New York
City and the Bronx had cockroach allergen levels high enough to
trigger asthma symptoms, while a majority of homes in Dallas and
Seattle had dust mite allergen levels above the asthma symptom
threshold,” said Dr. Rebecca Gruchalla, associate professor
of internal medicine and pediatrics at the University of Texas
Southwestern Medical Center and lead author of the study.
“We also discovered that the levels of both of these allergens
were influenced by housing type,” noted Gruchalla. “Cockroach
allergen levels were highest in high-rise apartments, while dust
mite concentrations were greatest in detached homes.”
While cockroach allergen exposure did produce an increase in asthma
symptoms, researchers did not find an increase in asthma symptoms
as a result of exposure to dust mite and pet dander. “Children
who tested positive for, and were exposed to, cockroach allergen
experienced a significant increase in the number of days with cough,
wheezing and chest tightness, number of nights with interrupted
sleep, number of missed school days, and number of times they had
to slow down or discontinue their play activity,” said Gruchalla.
While cockroaches are primarily attracted to water sources and
food debris, house dust mites, microscopic spider-like creatures
that feed on flakes of human skin, reside in bedding, carpets,
upholstery, draperies and other “dust traps.” Dust
mite allergens are proteins that come from the digestive tracts
of mites and are found in mite feces.
Researchers tested 937 inner-city children with moderate to severe
asthma symptoms. The children, ages 5 to 11, were given skin tests
for sensitivity to cockroach and dust mite allergens, pet dander,
and mold. Bedroom dust samples were analyzed for the presence of
each allergen type.
This study was part of the larger Inner-City Asthma Study, a cooperative
multi-center project comprised of seven asthma study centers across
the country. The goal of the study was to develop and implement
a comprehensive, cost-effective intervention program aimed at reducing
asthma incidence among children living in low socioeconomic areas.
The National Institute of Environmental Health Sciences is a federal
agency that conducts and funds basic research on the health effects
of exposure to environmental agents.
For more information, please contact John Peterson, public affairs
specialist with the NIEHS Office of Communications, at (919) 541-7860,
or call Anne Oplinger, writer/editor with the National Institute
of Allergy and Infectious Diseases’ Office of Communications,
at (301) 402-1663.