The job of immune system cells is to find foreign substances such as viruses and bacteria and get rid of them. Normally, this response protects us from dangerous diseases. People with allergies have supersensitive immune systems that react when they inhale, swallow or touch certain harmless substances such as pollen or cockroaches. These substances are the allergens. Cockroach allergen is believed to derive from feces, saliva and the bodies of these insects.
Cockroaches live all over the world, from tropical areas to the coldest spots on earth.
Studies show that 78 percent to 98 percent of urban homes have cockroaches. Each home has from 900 to 330,000 of the insects. Private homes also harbor them, especially if the homes are well insulated. When one roach is seen in the basement or kitchen, it is safe to assume that at least 800 roaches are hidden under the kitchen sink, in closets and the like. They are carried in with groceries, furniture and luggage used on trips.