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Asthma
Linked to Cat & Alternaria Mold Allergies
By
Robin Lloyd, LiveScience Senior Editor
More than 50
percent of the current asthma cases in the U.S. are the result of allergies,
especially to cats, according to a new National Institutues of Health (NIH)
study.
Asthmatics, people
with
allergies and doctors alike have long debated possible
connections between pets, dust, ragweed, mold, fungus, foods, cockroaches,
traffic exhaust, smog, pollen, trees blooming, leaves falling ... and
wheezing attacks, which can be terrifying and life-threatening.
The lack of
consensus can be maddening for those who stay up at night with kids gasping
for breath, wondering what can be done. Some parents have wondered if
children diagnosed with asthma, and medicated for the condition, don't
actually have an untreated allergy instead.
The new research
shows that 56.3 percent of asthma cases can be attributed to atopy, or
allergies, which result from
gene-environment interactions and can be measured by a positive
skin test to substances in the environment, said Darryl C. Zeldin, a senior
investigator at the National Institute of Environmental Health Sciences,
part of the NIH.
Cat allergens were
found to account for 29.3 percent of the asthma cases, followed by the
fungus Alternaria at 21.1 percent and White Oak at 20.9 percent.
White Oaks are long-lived trees native to eastern North America and found as
far west as Texas and Minnesota.
"This study tells
us that allergy is a major factor in asthma," said Peter Gergen of the
National Institute of Allergy and Infectious Diseases (also part of NIH),
lead author of the study available online today in the Journal of
Allergy and Clinical Immunology. "But this study also tells us that
thee are many people who get asthma who don't have allergies. We need to do
more research to understand what is causing the
asthma that is not related to allergies."
Other allergens
were tested, such as ragweed, dustmites, Russian thistle, Bermuda grass,
peanuts, perennial rye and german cockroach, but only cats, the fungus and
white oak were positively and independently associated with asthma.
"Sensitization to
cat appears to be a strong risk factor for asthma in this study," Zeldin
said. Some research suggests that exposure to cats early in life may protect
children from allergies, but if children have cat allergies or get
asthma-like symptoms, parents should consult their physician about whether
to get rid of pets.
About 10,500
individuals were tested for their link to atopy, or allergies, as
part of the Third National Health and Nutrition Examination Study, a
national representative sample of the U.S. population.
"This study
confirms that the environment plays a major role in the development of
asthma," Zeldin said. "Given the complexity of this disease it won't be
easy, but if we can prevent or reverse atopy, we could reduce a large
proportion of asthma cases." |
