Mayo Clinic Study Implicates Fungus As Cause Of Chronic Sinusitis
"We can now begin to treat the cause of the problem instead of the symptoms"
ROCHESTER, MINN. -- Mayo Clinic researchers say they have found the cause of most chronic sinus infections -- an immune system response to fungus. They say this discovery opens the door to the first effective treatment for this problem, for on of the most common chronic disease in the United States!
An estimated 37 million people in the United States suffer from chronic sinusitis, an inflammation of the membranes of the nose and sinus cavity. With the incidence increasing steadily over the last decade. Common symptoms are runny nose, nasal congestion, loss of smell and headaches. Frequently the chronic inflammation leads to polyps, small growths in the nasal passages which hinder breathing.
"Up to now, the cause of chronic sinusitis has not been known," say the Mayo researchers: Drs. David Sherris, Eugene Kern and Jens Ponikau , Mayo Clinic ear, nose and throat specialists. Their report appears in the September issue of the journal Mayo Clinic Proceedings.
"Fungus allergy was thought to be involved in less than ten percent of cases," says Dr. Sherris. "Our studies indicate that, in fact, fungus is likely the cause of nearly all of these problems. And it is not an allergic reaction, but an immune reaction."
The researchers studied 210 patients with chronic sinusitis. Using new methods of collecting and testing mucus from the nose, they discovered fungus in 96 percent of the patients' mucus. They identified a total of 40 different kinds of fungi in these patients, with an average of 2.7 kinds per patient.
In a subset of 101 patients who had surgery to remove nasal polyps, the researchers found eosinophils (a type of white blood cell activated by the body's immune system) in the nasal tissue and mucus of 96 percent of the patients.
The results, the researchers say, clearly portray a disease process in which, in sensitive individuals, the body's immune system sends eosinophils to attack fungi and the eosinophils irritate the membranes in the nose. As long as fungi remain, so will the irritation.
"This a potential breakthrough that offers great hope for the millions of people who suffer from this problem," says Dr. Kern. "We can now begin to treat the cause of the problem instead of the symptoms."
More research is underway at Mayo Clinic to confirm that the immune response to the fungus is the cause of the sinus inflammation. The researchers are also working with pharmaceutical companies to set up trials to test medications to control the fungus. They estimate that it will be at least two years before a treatment will be widely available.
The researchers distinguish chronic sinusitis -- sinusitis that lasts three months or longer -- from acute sinusitis, which lasts a month or less. They say that the cause of the acute condition is usually a bacterial infection.
Antibiotics and over-the-counter decongestants are widely used to treat chronic sinusitis. In most cases, antibiotics are not effective for chronic sinusitis because they target bacteria, not fungi. The over-the-counter drugs may offer some relief of symptoms, but they have no effect on the inflammation.
"Medications haven't worked for chronic sinusitis because we didn't know what the cause of the problem was," says Dr. Ponikau. "Finally we are on the trail of a treatment that may actually work."
Thousands of kinds of single-cell fungi (molds and yeasts) are found everywhere in the world. Fungal spores (the reproductive part of the organism) become airborne like pollen. Some people develop allergies to fungi. The new evidence from the Mayo study suggests that many people also develop a different kind of immune system response.
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Indoor Mold, Building Dampness Linked to Respiratory Problems and Require Better Prevention
Given the frequent occurrence of moisture problems in buildings and their links to respiratory problems, excessive indoor dampness should be addressed through a broad range of public health initiatives and changes in how buildings are designed, constructed, and maintained, said the committee that wrote the report.
"An exhaustive review of the scientific literature made it clear to us that it can be very hard to tease apart the health effects of exposure to mold from all the other factors that may be influencing health in the typical indoor environment," said committee chair Noreen Clark, dean, School of Public Health, University of Michigan, Ann Arbor. "That said, we were able to find sufficient evidence that certain respiratory problems, including symptoms in asthmatics who are sensitive to mold, are associated with exposure to mold and damp conditions. Excessive indoor dampness is a widespread problem that warrants action at the local, State, and National levels."
Excessive dampness influences whether mold as well as bacteria, dust mites, and other such agents are present and thrive indoors. Moreover, wetness may cause chemicals and particles to be released from building materials. Many studies of health effects possibly related to indoor dampness do not distinguish the specific health effects of different biological or chemical agents.
Through its careful review of the available scientific studies, the committee found sufficient evidence to conclude that mold and damp conditions are associated with asthma symptoms in asthmatics who are sensitive to mold, and to coughing, wheezing, and upper respiratory tract symptoms in otherwise healthy people. An uncommon ailment known as hypersensitivity pneumonitis also is associated with indoor mold exposure in genetically susceptible people. Damp conditions and all they entail may be associated with the onset of asthma, as well as shortness of breath and lower respiratory illness in otherwise healthy children, although the evidence is less certain in these circumstances. Likewise, the presence of visible mold indoors may be linked to lower respiratory tract illness in children, but the evidence is not as strong in this case."
Studies on animals and cell cultures in labs have found toxic effects from various microbial agents, raising concerns about whether these same agents growing in buildings can cause illness in people. Molds that are capable of producing toxins do grow indoors, and toxic and inflammatory effects also can be caused by bacteria that flourish in damp conditions, the report noted. Little information exists on the toxic potential of chemicals or particles that may be released when building materials, furniture, and other items degrade because of wetness. The committee recommended that current animal studies of short-term, high-level inhalation exposures to microbial toxins be supplemented with new research that evaluates the effects of long-term exposures at lower concentrations.
Moisture and mold problems stem from building designs, construction and maintenance practices, and building materials in which wetness lingers. Technical information describing how to control dampness already exists, but architects, engineers, building contractors, facility managers, and maintenance staff do not always apply this knowledge, the report says.
The committee had insufficient information to recommend either an appropriate level of dampness reduction, or a safe level of exposure to organisms and chemicals linked to dampness. Better standardized methods for assessing human exposure to these agents are greatly needed, the report says. It calls for studies that compare various ways to limit moisture or eliminate mold and to evaluate whether the interventions improve occupants' health.
The study was sponsored by the Centers for Disease Control and Prevention. The Institute of Medicine is a private, nonprofit institution that provides health policy advice under a congressional charter granted to the National Academy of Sciences. A committee roster follows.
INSTITUTE OF MEDICINE
Board on Health Promotion and Disease Prevention
Read about how your indoor air quality can be affected by multiple factors. Including, the understructure, ventilation and water intrusions.
