Source: DGNews  |  Posted 9 years ago

By Roberta Friedman
Special to DG News

SAN ANTONIO, TX -- November 21, 2002 -- People with asthma appear to have a high incidence of allergy to animals and mold, according to research conducted in the San Francisco Bay area on the west coast of the United States.

The finding from a retrospective study was presented at a symposium here November 17 at the meeting of the American College of Allergy, Asthma & Immunology (ACAAI).

Chart review of 400 consecutive patients seen at the University of California, San Francisco, United States, showed that patients with asthma were twice as likely to be allergic to animal dander and mold than were patients with allergic rhinitis.

The investigators documented allergies by records from skin prick tests carried out between 2000 and 2001. A positive test results was defined as a wheal of 4 mm in size or more with accompanying erythaema. Women made up 65 percent of the study group, and 35 percent of the subjects had asthma, with or without allergic rhinitis. Rhinitis alone occurred in 56 percent.

More than 87 allergens were tested. Regression analysis revealed the link of asthma to mold and animal dander.

Dog allergy affected 32.6 percent of asthmatics and 16.6 percent of people with only allergic rhinitis. Cat allergy rates were 48.9 percent and 24.4 percent respectively. Mold allergy appeared at rates of 40.7 percent and 25.8 percent respectively for the allergic asthmatics, and for those with only the allergic rhinitis.

Rates of pollen allergies did not differ between the groups, nor did allergies to cockroaches.

Logistic regression that took into account allergic rhinitis, and age, gender, as well as allergies to pollen, dust and roaches, showed statistical significance for the association of asthma with mold and animal allergies.

This type of analysis found no significant association of any specific allergens with allergic rhinitis. However, dust mite allergy was accompanied by allergy to such indoor allergens as molds, roaches, and animals. But only one seasonal pollen allergy, weed pollen, had a link to dust mite allergy.

The study investigators speculate that the smaller size of certain antigens may explain the associations. Mold spores and dander are smaller relative to the other antigens studied, said Ainlin Xu, clinical fellow in the University of California, San Francisco's department of medicine, division of pulmonology, who presented the study. "Their smaller size," Dr. Xu said, "makes it easier for them to reach the lower airways" and facilitate sensitization.