Role of Cockroach Allergen in Causing Morbidity

ABSTRACT & COMMENTARY

Synopsis: Exposure to cockroach allergen has an important role in explaining the frequency of asthma-related health problems in inner-city children.

Source: Rosenstreich DL, et al. N Engl J Med 1997;336: 1356-1363.

As part of a multi-centered study from eight inner-city areas within the United States, 476 children ages 4-9 were studied for their immediate hypersensitivity to cockroach, house dust mite, and cat allergens, as measured by their major allergen found in household dust, using a monoclonal-antibody-based, enzyme-linked immunosorbent assay.

In analyzing the bedrooms of the children, it was found that 50.2% had high levels of cockroach allergen, 9.7% had high levels of dust mite allergen, and 12.6% had high levels of cat allergen. Children allergic to cockroach and exposed to high levels of this allergen had significantly greater numbers of hospitalizations, unscheduled medical visits, days of wheezing, missed days of school, and loss of sleep at night for both the children and their parents. These patterns were not found for combinations of allergy to dust mite or cat dander or high levels of these allergens. Thus, exposure to cockroach allergen has an important role in explaining the frequency of asthma-related health problems in inner-city children.

COMMENT BY SHELDON L. SPECTOR, MD

It has long been recognized that a positive skin test to cockroach allergen was a common finding in the indigent population and a very uncommon finding in suburban clinics.1 Studies of hospital emergency room patients presenting with asthma confirmed a significant association between cockroach sensitivity and asthma.2

The present study confirms earlier reports that cockroaches are an important urban source of allergen. However, it extends the data from others by showing an association of cockroach allergen to typical parameters of asthma exacerbations, such as symptomatic wheezing, hospitalizations, or unscheduled medical or emergency room visits for asthma. The investigators did not find a relationship between their pulmonary function measurement (i.e., peak expiratory flow rate) and cockroach sensitivity. However, compliance in filling out the diaries was inadequate, and there was a design problem, since bronchodilators could have been taken at virtually any time in relation to the peak expiratory flow rate.

Today, public awareness of dust mite sensitivity is much greater than that of cockroach sensitivity. In some ways, it was surprising that the levels of house dust mite, which was reported to be an important allergen in many other parts of the United States, did not prove to be as important as cockroach exposure in the inner-city sampling.

There is a relationship between dust mite exposure and emergency room visits, as well as asthma severity. Avoidance of allergens is not always possible or feasible. With regard to dust mite, if a person lives in an apartment or dwelling owned by a landlord, it is virtually impossible to remove carpets imbedded with mites. Also impractical are studies moving a patient to a hospital room or sanitorium, which has been effective in decreasing hyperreactivity and controlling symptoms.3,4 With time, there is improvement in asthma symptoms and bronchial hyperreactivity.5,6

Similarly, reduction of exposure to cockroach allergen would be an expected benefit in the management of those who have cockroach sensitivity. But, again, the difficulty in removing cockroaches from the environment is impractical, expensive, requires the use of safe insecticides, and elimination of cockroaches in virtually all apartments within a complex. Although present solutions for environmental control may not be ideal, at least recognition of the importance of some of these allergic triggers are an important first step toward their eventual elimination.

References

1. Bernton HS, et al. Br J Dis Chest 1972;66:61.

2. Pollart S, et al. J Allergy Clin Immunol 1991;87:505.

3. Platts-Mills TAE, et al. Lancet 1982;2:675.

4. Vervioet D, et al. J Allergy Clin Immunol 1982;69:290.

5. Walshaw MJ, Evans CC. Q J Med 1986;58:199.

6. Ehnert B, et al. J Allergy Clin Immunol 1991;87:320.