MOLD
ALLERGIES
Along with pollens from trees, grasses, and weeds, molds are an
important cause of seasonal allergic rhinitis. People allergic to molds may
have symptoms from spring to late fall. The mold season often peaks from
July to late summer. Unlike pollens, molds may persist after the first
killing frost. Some can grow at subfreezing temperatures, but most become
dormant. Snow cover lowers the outdoor mold count dramatically but does not
kill molds. After the spring thaw, molds thrive on the vegetation that has
been killed by the winter cold.
In the warmest areas of the United States, however, molds thrive all year
and can cause year-round (perennial) allergic problems. In addition, molds
growing indoors can cause perennial allergic rhinitis even in the coldest
climates.
When inhaled, microscopic fungal spores or, sometimes, fragments of fungi
may cause allergic rhinitis. Because they are so small, mold spores may
evade the protective mechanisms of the nose and upper respiratory tract to
reach the lungs.
In a small number of people, symptoms of mold allergy may be brought on or
worsened by eating certain foods, such as cheeses, processed with fungi.
Occasionally, mushrooms, dried fruits, and foods containing yeast, soy
sauce, or vinegar will produce allergic symptoms. There is no known
relationship, however, between a respiratory allergy to the mold Penicillium
and an allergy to the drug penicillin, made from the mold.
Which molds are allergenic?
Like pollens, mold spores are important airborne allergens only if they
are abundant, easily carried by air currents, and allergenic in their
chemical makeup. Found almost everywhere, mold spores in some areas are so
numerous they often outnumber the pollens in the air. Fortunately, however,
only a few dozen different types are significant allergens.
In general, Alternaria and Cladosporium (Hormodendrum) are the molds most
commonly found both indoors and outdoors throughout the United States.
Aspergillus, Penicillium, Helminthosporium, Epicoccum, Fusarium, Mucor,
Rhizopus, and Aureobasidium (Pullularia) are also common.