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Q+A-What experts worry about in the U.S. meningitis outbreak

Source: Thomson Reuters Foundation - Fri, 12 Oct 2012 10:36 PM
Author: Reuters
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By Julie Steenhuysen

CHICAGO, Oct 12 (Reuters) - The widening outbreak of fungal meningitis that has infected 184 Americans and killed 14 people is a new phenomenon for doctors, who typically only see such infections in patients with compromised immune systems.

When people do develop fungal infections, they normally get them from breathing in fungal spores, which can cause infections in the lungs of vulnerable patients, such as those who have had organ transplants. From the lungs, the infection can spread to the blood, and in rare cases to the central nervous system.

In this outbreak, however, the fungi were injected directly along the spines of patients receiving a steroid treatment for back pain. That raises new questions about whether the drugs commonly used to fight such infections will be as effective, how long it will take patients to recover and whether they may suffer damage from the treatment itself.

Dr. William Schaffner, an infectious diseases expert at the Vanderbilt University Medical Center in Nashville and past-president of National Foundation for Infectious Diseases, has been consulting with health department officials in Tennessee, where 50 people so far have been infected through spinal injections of the tainted pain medication.

In an interview, Schaffner describes some of his key concerns.

Q: What is your biggest worry at this point?

A: I want to make sure that all patients who have been exposed and develop symptoms go quickly to a healthcare provider and get an early diagnosis so we can initiate treatment. I'm concerned exactly how effective our treatment will be. It's certain some of these people, even if we can treat their infection, will be left with a disability, because these infections cause tissue damage. The damage will heal, we trust, but the function of the damaged part can't be restored. People who have had stroke syndromes, which are part of this, may be left with disabilities.

Q: What are the concerns with the antifungal drugs amphotericin B and voriconazole, which are being used to treat these patients?

A: The average doctor knows very little about them, has learned about them in medical school and has never used them (since). Using them takes great care. They are both administered intravenously. Patients will have to receive these drugs for some considerable time - weeks. We would hope to at least some time be able to discharge patients from the hospital. If they continue to need IV therapy, they may have to come back to the hospital to receive daily IV administration. Then, we would hope to transfer some of these people to oral voriconazole. Patients will have to continue to be monitored carefully. It's an elaborate course of therapy.

Q: What are the side effects we have to worry about.

A: Amphotericin B has a whole array of side effects. In fact, interns and residents who have a mordant sense of humor call it 'ampho-terrible.' Its most prominent side effect is that it can impair the function of the kidneys. Voriconazole can have adverse effects on the liver.

Q: What makes the patients in this meningitis outbreak different from past cases?

A: Normally, the people who acquire these infections are in some way immuno-compromised, usually bone marrow transplant or organ transplant recipients who are on high doses of steroids and the like. Most of the patients who received these spinal inoculations were somewhat older, because those are the people who get back pain. But they were not, by and large, a uniquely immuno-compromised population. That may account, in part, for why still only fortunately a small proportion of people who were exposed have become ill.

Q: Can we estimate how many people will get sick?

A: It's still very early days. At the moment, for every hundred or so patients who were exposed, it looks as though 5 percent or less are becoming infected. That is our current best estimate. We'll have to see how many more patients become sick. But so far the ratio of patients exposed to those who become ill is fortunately pretty low. I recognize that the absolute number of patients who have become ill is very substantial. Many, many more were exposed to these contaminated inoculations.

Q: Health officials have identified two types of fungi, aspergillus and exserohilum, as being primarily responsible for these infections. What do we know about them?

A: Out in the world, these fungi are very, very common. One (aspergillus) causes leaf mold. The other one is associated with rotting or deteriorating wood. Every once in awhile the wind comes along and blows these microscopic particles into the air, and we are all exposed to them. We inhale them, and nothing happens because these molds don't care to make us ill at all. That's not their business. They are innocuous, except if you happen to be immuno-compromised.

Now, these environmental fungi have somehow gotten into these vials of methylprednisolone. They have been inoculated next to our spines. In that circumstance, which is a unique ecologic niche, these fungi just do what they normally do. They start multiplying and, in effect, eating the tissue they are around, thereby causing an infection. That infection can sometimes result in meningitis. (Editing by Bill Trott)

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