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The good news is that New Orleans isn´t any worse than it ever was for allergies. The bad news — and this isn´t news to anyone that suffers from allergies — is that the city has always had a high allergen load. Dr. Carolyn Daul, a physician at Allergy, Asthma & Immunology Associates (3939 Houma Blvd., Suite 200, Metairie, 885-2122) who holds advanced degrees in microbiology and immunology, says residents should be concerned with the quality of air that surrounds them. Daul takes a few minutes to explain what allergies are, why people get them and that New Orleans has not suddenly been transformed into a noxious city with deadly molds and spores ready to attack your body at any moment.

Q: What are some of the basic causes of allergies?

A: Most allergies are caused by airborne allergens. These are small things, microscopic, that are in the air, and when you breathe them in, they land on your respiratory tract that includes your nose, eyes, sinuses and your lungs. Everybody´s respiratory tract absorbs allergens, but not everybody has allergies. The airborne allergens are things like dust mites, dog dander, cat dander, tree pollen, grass pollen and seed pollen. Occasionally, there are people with food allergies, but those most likely manifest in the skin, although they can produce other symptoms like respiratory symptoms.

Q: Where are allergic reactions most likely to manifest?

A: People who have allergies have an allergic immune system that´s underneath the respiratory-tract lining. When the allergen diffuses through the lining, it meets an allergic immune system that can recognize it, and then you start seeing symptoms of that recognition and contact. It depends on what target organ we´re talking about as to what symptoms you´re going to see. So from a respiratory point of view, your eyes are going to get red, watery and itchy — they´re not going to do much more than that, because [those are] the only symptoms that they can express. Your nose is going to get congested, runny, itchy and sneezing, because those are the symptoms it expresses. Now in your chest, you start with shortness of breath, trouble breathing, wheezing and coughing, things like that. That´s the reason that the target organs of allergy are where your allergic immune system lives.

Q: So why do some people get allergies and others don´t?

A: People with allergies have a special protein that´s called an allergic antibody (IgE). Underneath the lining of the respiratory tract are a set of cells everybody has called mast cells; they are also underneath the lining of the gastrointestinal tract and underneath the skin. That´s why those are the target organs of allergies. If people that make IgE, the allergic antibody protein, get enough quantity to recognize a specific allergen — mast cells have little receptors on their surface for IgE that act like sponges, sopping up all the IgE a person makes— the IgE combines with the specific allergen and triggers the mast cells to release what´s inside of them — histamines and other mediators, and that´s what causes the symptoms. It´s kind of a perversion of a system that´s supposed to ward off parasites. In a third-world country, you would have a parasitic load that the system would be trying to fight. When you´re not living in a third-world country, the system wants to help, but it´s counterproductive and keys in on allergens instead.

Q: What about people who don´t have allergies?

A: They don´t have the genetic capacity to make that allergic antibody.

Q: So would those people be in trouble in a country with parasites?

A: Well they might make it then, and there are other mechanisms for parasites. Twenty-five percent of the population has this genetic ability to make allergic antibodies — most of us don´t make it to any great extent. That´s why it´s genetic; you inherit the ability to make that antibody; it runs in families.

Q: When do allergies become dangerous?

A: Usually with venom allergies and food allergies. With venom allergies, [the venom is] injected by bees, wasps, hornets or something like that, and you can get some systemic reactions, which can be serious and life threatening. Same thing can happen to people with food allergies and sometimes with drug allergies.

Q: In general, what allows an allergen to cause allergic reactions?

A: Allergens are usually a given size and have some chemical and physical properties that allow them to be recognized by the allergic immune system. For example, a grass allergen is a small protein that is part of the grass pollen. When the grass pollen lands on your nose, it dissolves and frees the protein, allowing it to be recognized by the allergic immune system.

Q: Are there more airborne contaminants after the storm than before?

A: There aren´t more allergens out there than there always have been. What we have is a change in the quality of air. After Katrina, there was a lot of removal of sheetrock and moving things around so that allowed some things to get loose and get into the air. Plus, since it was a very dry period of time right after the storm, there wasn´t a lot of rain to wash the contaminants out of the air.

Q: We keep hearing about the dangers of mold. Has the amount of mold dramatically increased?

A: After Katrina, the molds were accidental tourists. They are molds that normally live outside, and the floodwaters picked up these molds and brought them into houses and wet the houses down. Molds like to live in a very humid environment, and they grew in the houses.

Q: If these molds are normally outside, weren´t people affected by these molds pre-Katrina?

A: Absolutely. If you look at our pollen count and compare it to our mold count, our mold count outnumbers our pollen count any day of the year. We´re a moldy city. The danger now is a higher concentration of mold in the house for people who are allergic to mold. For most people that´s not the case, you just need respiratory protection when you´re tearing out the sheetrock, so that stuff doesn´t get in their lungs.

Q: What can people who have mold allergies and are rebuilding do to ensure their houses are mold free?

A: Once you take the sheetrock off, remediate the molds and have a house that´s not wet anymore, the molds will cease to be there. You can use chemicals on your studs to make sure you´ve cleaned them off and things like that. You have to remove anything that´s been contaminated with mold, whether it´s your sheetrock, carpeting or your insulation. Whatever it is has to be removed from your house. Wooden floors can be sanded and refinished. Most molds aren´t medically dangerous.

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