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, 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.
Its incidence has been 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.
This story has been adapted from a news release issued by Mayo
Clinic.
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