The protein in urine from rats and mice is a potent allergen. When it dries, it can become airborne. The two conditions that are necessary to support biological growth are nutrients and moisture. Mold, mildew and other biological contaminants can grow in contaminated central air handling systems. These systems can distribute the contaminants through the home.
Allergic reactions occur only after repeated exposure to a specific biological allergen.
However, that reaction may occur immediately upon reexposure or after multiple exposures over time. As a result, people who have noticed only mild allergic reactions, or none at all, may suddenly find themselves very sensitive to particular allergens. Infectious diseases, such as influenza, measles, tuberculosis, and chicken pox, are transmitted through the air. Some molds and mildews can release disease-causing toxins. These toxins can damage a variety of organs and tissues in the body, including the liver, central nervous system, digestive tract, and immune system.