Fungus Targeted for Sinus Infections

Researchers say they have found the cause of most chronic sinus infections -- an immune system response to fungus.

That's why antibiotics and over-the-counter decongestants commonly used to treat chronic sinusitis in most cases are not effective -- those drugs target bacteria, not fungi, Mayo Clinic scientists say. About 37 million people suffer from chronic sinusitis, an inflammation of the membranes of the nose and sinus cavity that lasts for three months or more. The problem is on the rise. Symptoms are runny nose, nasal congestion, loss of smell and headaches.

Researchers say that up to now, they hadn't been able to pinpoint the cause and believed only 10 percent of cases were related to fungus. But in the journal Mayo Clinic Proceedings, researchers say new studies show almost all chronic sinusitis cases are caused by fungus and stress. It's not an allergic reaction but an immune system reaction.

For some people, their immune systems send eosinophils to attack fungi, and the eosinophils irritate the membranes in the nose. As long as fungi remain, so will the irritation. Mayo is working with pharmaceutical companies on clinical trials of drugs that control fungus.