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Fungal Spores Affect Kids’ Risk for Allergies
All fungi are not created equal — at least, not when it comes to allergies.
A new study shows that while some fungi may spark allergic reactions, as scientists
have long thought, other types may actually help prevent them.
Fungi are microscopic organisms that spread by releasing tiny spores into the
air. Several studies have linked moisture or fungi growing indoors, like mold
in the bathroom, with childhood asthma and allergy symptoms such as sneezing,
a runny nose and cough.
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| One type of fungus (a Penicillium) under the microscope.
A new study shows that different fungi can affect allergies in infants differently.
Image by Dr. Libero Ajello, courtesy of the Centers for Disease Control and
Prevention. |
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A University of Cincinnati research team led by Dr. Tiina Reponen, with funding
from NIH’s National Institute of Environmental Health Sciences, set out to look
at specific airborne fungal spores in homes to see if different types of fungi
affect allergies in infants differently. They collected air samples for 48 hours
in 144 homes with infants living in them and analyzed the fungi they found. They
then compared these findings with allergy symptoms in the infants and with skin
prick tests to see whether the infants had allergies to mold, pollen, dust mites,
pet dander and certain foods.
The researchers reported in an early online publication of Pediatric Allergy
and Immunology on June 12, 2006 that there were no significant associations
between allergy and total fungal spore concentrations. However, when they looked
more closely at what types of fungi were in the air, they found a much more
complicated story. The infants who were exposed to spores from a group of fungi
called Basidiomycota were more likely to have allergy symptoms. Those who were
exposed to spores from Penicillium/Aspergillus and Alternaria were more likely
to test positive for allergies in the skin prick tests.
On the other hand, those who were exposed to Cladosporium showed the opposite
effect, testing positive for fewer allergies. Some researchers believe that exposure
to certain microbes early in life may actually protect children from developing
allergy and asthma later in life — the emerging “hygiene hypothesis.” This
finding supports that hypothesis, but researchers can’t yet explain exactly why
some microbes might have this effect.
This study focused on infants, so these particular outcomes may not last. Long-term
follow-up will reveal how early exposure to fungi affects the development of
allergy and asthma later in life. This study does show, however, that the health
effects of being exposed to fungi are a lot more complex than many researchers
thought
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