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Asthma and its Environmental Triggers: Scientists Take a Practical New Look at a Familiar Illness
Scientists Take a Practical New Look at a Familiar Illness
Allergic asthma affects about 3 million children (8 to 12 percent of all children) and 7 million adults in the United States at a cost estimated at $6.2 billion a year. Asthma episodes, or attacks - with tightness in the chest and difficult breathing - often can be managed with drugs delivered by small pumps that patients carry, but they sometimes strike with life-threatening severity requiring emergency hospital treatment to forestall death.
Asthma both as an illness and as a cause of death has increased in the United States and other developed countries over the past 15 years despite significant improvements in outdoor air quality and in the face of major declines in other pulmonary diseases, such as tuberculosis and pneumonia.
Some people, in fact, theorize that the decline in serious illnesses may be a factor in the increase in allergic asthma. That is, they speculate, an under-utilized immune system may overreact to lesser threats or irritants, inappropriately producing antibody molecules that result in a release of histamine and other inflammatory substances in the lungs. Other researchers implicate the increased time youngsters spend indoors - and their resulting exposure to the carpeting and other allergen-catchers that people in developed nations surround themselves with.
There are other theories as well. What is known more clearly is that dust mites (which are living creatures that produce droppings that contain a highly allergenic protein), cockroaches, molds, pollens and domesticated animals produce some of the substances, called allergens, known to trigger asthma attacks. A study is now underway to determine the roles of other key environmental agents in asthma, both in bringing on respiratory crisis and initiating the illness in the first place. The research is being supported jointly by scientists at the National Institute of Environmental Health Sciences and the National Institute of Allergy and Infectious Diseases, two of the National Institutes of Health.
Managing the Illness
Reducing allergens - getting rid of the cat, and removing the teddy bears, rugs, curtains and lampshades in an asthmatic child's bedroom - can, along with medication, control most asthma. So NIEHS and NIAID have co-funded an effort to help asthma patients called TEAM, or Targeting the Environment and/for Asthma Management. Through grants, TEAM will support researchers at seven university research centers and one university data center. Their goal is to design and evaluate asthma intervention strategies for underserved, inner-city children, 4 to 12 years old.
The TEAM protocol includes asthma-related medical treatment delivered in a health care facility. A physicians' educational component provides state-of-the-art education and training for primary care physicians in the medical management of asthma.
Case management of asthmatics and their families is provided by the asthma case managers - registered nurses with specialized training in social work. The TEAM intervention component monitors and improves the asthma patients' indoor environment, cleaning up patient residences to reduce asthma episodes.
PREVENTION: NIPPING ASTHMA IN THE BUD
NIEHS scientists will find out if reducing dust mite and cockroach allergen levels in homes can prevent sensitization to these allergens and thus prevent asthma from developing.
"The hope is," as Newsweek reported in a cover story May 26, 1997, "that if kids encounter fewer allergens early in life, they'll be less likely to develop allergic responses.
"Next year the National Institute of Environmental Health Sciences will launch an elaborate, eight-year study to see if that strategy works. In the first phase, researchers will study 120 households to determine the best ways to reduce allergen levels. They'll cover mattresses, steam carpets, trap roaches and apply tannic acid* to any suspect surface.
"And once they perfect their technique, they'll enroll 500 high-risk newborns in a trial to gauge the effects. Half of the babies will be raised in allergen-free zones while the other half will serve as controls, and the scientists will track the kids' asthma rates.
"'Will we be able to reduce the prevalence of asthma in the community?' asks Dr. Darryl Zeldin, the NIEHS official overseeing the project. ?We don't know. Even with our best reducing agents, we may not be able to get the allergen levels low enough that kids aren't sensitized.'"
Other Research Adds New Knowledge
Five other NIEHS-funded studies that focus on asthma are looking at inner city cockroach allergen reduction; case management and environmental control in asthma; home endotoxin (a byproduct of the break-up of bacteria) and childhood asthma; environmental agents - asthma development and severity; and molecular markers for environmentally induced asthma.
Children with an asthmatic parent are much more likely to become asthmatic themselves - so there is probably an important genetic role in the disease. But by looking at the environmental aspect of asthma, researchers hope to make new inroads in this all-too-familiar and sometimes deadly disease.
*Tannic acid is used to denature mite allergens in carpeting.
For further information on Asthma see:
http://www.niehs.nih.gov/external/faq/alpha-a.htm#asthma - NIEHS Asthma Listing
For further information on diseases related to the environment, see the NIEHS Home Page.
NIEHS Fact Sheet #9, ASTHMA, 7/97
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