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Everything you might NOT want to know about these common allergy- and asthma-causing pests

Allergy and Asthma image

When most people think of allergy triggers, they often focus on plant pollens, dust, animals, and stinging insects. However, cockroaches also can trigger allergies and asthma.

Cockroach allergy was first reported in 1943, when skin rashes appeared immediately after the insects crawled over people’s skin. Skin tests first confirmed people had cockroach allergy in 1959.

In the 1970s, studies made it clear that people with cockroach allergies develop acute asthma attacks. The attacks occur after inhaling cockroach allergens, and they can last for hours.

Asthma has steadily increased over the past 30 years. It is the most common chronic disease of childhood. Now we know that the frequent hospital admissions of inner-city children with asthma often are directly related to their contact with cockroach allergens. From 23 percent to 60 percent of urban residents with asthma are sensitive to the cockroach allergen.

What causes the allergic reaction?
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. However, people with allergies have super-sensitive immune systems that react when they inhale, swallow, or touch certain harmless substances, such as pollen or cockroaches. These substances are the allergens.

When one roach is seen in the basement or kitchen, it is safe
to assume that at least 800 roaches are hidden.

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. Once they are in the home, they are hard to get rid of.

The amount of roach allergen in house dust or air can be measured. In dwellings where the amount is high, exposure is high, and the rate of hospitalization for asthma goes up.

Who develops cockroach allergy?
People with chronic severe bronchial asthma are most likely to have cockroach allergy. Also likely to have it are people with a chronic stuffy nose, skin rash, constant sinus infection, repeat ear infection, and asthma.

Cockroach allergy is a problem among people who live in inner cities or in the South and are of low socioeconomic status. In one study of inner-city children, 37 percent were allergic to cockroaches, 35 percent to dust mites, and 23 percent to cats. Those who were allergic to cockroaches and were exposed to the insects were hospitalized for asthma 3.3 times more often than other children were. This was true even when compared with those who were allergic to dust mites or cats.

What are its symptoms?
Symptoms vary. They may be mildly itchy skin, a scratchy throat, or itchy eyes and nose. Or the allergy symptoms can become stronger, including severe, persistent asthma in some people. Asthma symptoms often are a problem all year, not just in some seasons. This can make it hard to determine that a cockroach allergy is the cause of the asthma.

How is cockroach allergy diagnosed?
The National Heart, Lung, and Blood Institute recommends that all people with persistent asthma be tested for allergic response to cockroach, as well as to the other chief allergens – dust mites, cats, dogs, and mold.

Diagnosis can be made only by skin tests. The doctor scratches or pricks the skin with cockroach extract. Redness, an itchy rash, or swelling at the site suggests you are allergic to the insect. Cockroaches should be suspected, though, when allergy symptoms – stuffy nose, inflamed eyes or ears, skin rash, or bronchial asthma – persist year round.

Managing Cockroach Allergy
If you have cockroach allergy, avoid contact with roaches and their droppings. The first step is to rid your home of the roaches. Because they resist many control measures, it is best to call in pest control experts. For ongoing control, use poison baits, boric acid, and traps. Don’t use chemical agents. They can irritate allergies and asthma. In addition, never leave food and garbage uncovered.

To manage nasal and sinus symptoms, use antihistamines, decongestants, and anti-inflammatory medications. Your doctor will also prescribe anti-inflammatory medications and bronchodilators if you have asthma. If you keep having serious allergic symptoms, see an allergist about “allergy injections” with the cockroach extract. This can reduce symptoms over time.


Source: Asthma and Allergy Foundation of America,

This article was originally published in Coping® with Allergies & Asthma magazine, Spring/Summer 2010.