October 29, 2008
Does Mold Really Cause Sickness?
Flooding from Hurricane Katrina caused fungus expert Joan Bennett to believe in so-called toxic mold.
The black goo had caused her New Orleans home to smell terrible, and it was then she decided to change her research focus and find out if the fungi that took over most of the flooded homes on the Gulf Coast might make people ill.
"The overwhelming obnoxiousness of the odor and of the enveloping air made me start to believe in something that I had never believed in before -- sick building syndrome," said Bennett, of Rutgers University in New Jersey.
The research has proved harder than she originally thought.
Bennett says molds could cause illness in susceptible people through volatile organic compounds: gassy versions of chemicals produced as the organisms metabolize food.
So far, she's been unable to show this in the lab. She reported her findings to a joint meeting of the American Society for Microbiology and the Infectious Diseases Society of America.
Bennet has tested various molds on the laboratory roundworm C. elegans.
"Sometimes the worm swims away and sometimes the worm does nothing and sometimes the worm eats the fungus," Bennett said.
"I am actually looking for something that has never been discovered by methods that have never been worked out."
Hundreds of people have won lawsuits by claiming mold in their homes or work environments have made them ill.
Dr. David Denning of the University of Manchester in Britain agrees it is plausible that molds and fungi would emit volatile organic compounds.
The findings could form the basis of diagnosing fungal illness by using a breath test. Supposedly, people with fungal infections of the lungs, such as aspergillosis, would release these chemicals when they breathed.
"A certain group of severe asthmatics -- about a million people -- are sensitive to a number of different fungi," Denning said.
These include Aspergillus and Candida.
"This is almost certainly a genetic issue," he added. "If you have (a) predisposition (to asthma), you probably have an additional predisposition to fungal sensitization."
Dr. David Goldman, a pediatrician in the Bronx, New York, said asthma rates are disproportionately high.
Dr. Goldman blames Cryptococcus neoformins, a microbe found in pigeon droppings that causes disease in immune-compromised people.
"We believe this fungus contributes to asthma by modulating the immune response," Goldman said.
The doctors said treating patients with antifungal drugs like itraconozole and fluconazole relieved symptoms of patients with severe asthma; they also agreed it would likely take a combination of factors -- including a person genetically susceptible to molds and unusual fungal activity -- to cause any disease.
"It is probably a relatively temporary disease, not a life-threatening disease," Denning said.
"As we sit here we are probably breathing in hundreds of spores," Bennett added. "Usually we only get sick if our immune systems are compromised or if we have this genetic susceptibility to allergy."
Image Caption: The conidiophore of the fungal organism Aspergillus fumigatus. Obtained from the CDC Public Health Image Library.
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