Dr. H. James Wedner of the Washington University School of Medicine in St. Louis says after the water recedes, damp homes and businesses are fertile grounds for mold growth, which can cause allergic reactions and asthmatic symptoms.

"Mold loves water," says Wedner. "When your building is flooded, it's very difficult to dry it out quickly and completely, and that allows mold to grow. Walls made of Sheetrock soak up water far above the floodline, and mold can be hidden under wallpaper, carpet and floorboards and in ceiling tiles, furniture and clothing."

Molds -- and mildew, a type of mold -- are fungi, which reproduce by releasing spores. Inhaling the spores causes allergic reactions in some people. Symptoms of mold allergy include itchy, watery eyes; itchy, runny nose; headaches above and below the eyes; itchy ears and changes in hearing; itchy throat and palate; difficulty breathing; coughing; and shortness of breath.

Mold reaction can be treated by antihistamines or steroids and immunotherapy -- allergy shots -- which allow the immune system to build up a tolerance to the allergen.