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Fungal Spores Affect Kids’ Risk for Allergies

One type of fungus (a Penicillium) under the microscope. A new study shows that different fungi can affect allergies in infants differently. Dr. Libero Ajello, courtesy of the Centers for Disease Control and Prevention.

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.

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.