Cockroach Sensitivity Research Articles

Sensitization to indoor allergens and the risk for asthma hospitalization in children.

Hospitalization for asthma continues to present a major health problem despite advances in our understanding that asthma is an inflammatory disease of the bronchi and that exposure to specific allergens can induce and worsen this inflammation. The role of sensitization to specific indoor allergens and hospitalization for acute asthma in children is unclear. The purpose of this study was to evaluate the independent contributions of sensitization to specific indoor allergens among children with asthma to the risk of hospitalization for asthma. The charts of 138 consecutive children with asthma, aged 5 to 18 years, seen at pediatric allergy clinics were reviewed to obtain the results of skin tests to cat, dog, cockroach, and dust mite allergens and the history of hospitalization for asthma within the year prior to the clinic visit. Logistic regression analysis was used to examine the association between indoor allergen sensitivity and other factors, and the risk of hospitalization for asthma. In univariate analyses, hospitalization for asthma was significantly associated with cockroach sensitivity (odds ratio [OR] = 2.2; 95% confidence interval [CI] = 1.1, 4.3); cat sensitivity (OR = 2.9; CI = 1.3, 6.4); black race (OR = 2.4; CI = 1.1, 5.1); public aid/self pay (OR = 2.3; CI 1.1, 4.9) and age, (OR [per year increase in age] = 0.8; CI = 0.7, 0.9). In a stepwise multiple logistic regression analysis, only cat sensitivity (OR = 3.8; CI = 1.5, 9.2), age (OR = 0.8; CI = 0.7, 0.9) and race (OR = 3.2; CI = 1.4, 7.5) entered into the model as significant independent predictors. Sensitivity to cat allergen may be an important determinant for asthma hospitalization in children. Sensitization to cockroach allergen per se was not found to be an independent risk factor. As observed in previous studies, younger and black children were at increased risk of hospitalization for asthma.

Evaluating the factors that relate to asthma severity in adolescents.

Over the past 5 years, we have been engaged in a cross-sectional evaluation of risk factors for higher asthma severity in adolescents aged 13-18. All recruitment takes place through public and private schools. The sample from which our current findings are derived includes 151 adolescents covering a wide spectrum of asthma severity and socioeconomic status (SES) and representing both African American and Caucasians. An asthma severity instrument has been developed and validated for the purpose of this study. This yields an asthma severity score which is a continuous variable. Female gender and the number of positive skin tests are the best independent correlates to the asthma severity score. Among the 18 aeroallergens used in the study, the American cockroach Periplaneta americana is the only one that relates to the asthma severity score in a stepwise regression model. The two other cockroaches, German and oriental, as well as the dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus, correlate with the asthma severity only in simple regression analysis. The relationship between asthma severity and cockroach sensitivity is strongest within the lowest-income per family member quartile. This is consistent with the additional observations that (1) significantly higher rates of sensitization for cockroaches are observed in the lowest-income quartile subjects and (2) higher levels of the cockroach allergen Bla g 1 are found in their homes. Preliminary analysis suggests that ethnic background may interact with environmental exposure in that, within the lowest-income quartile, Caucasians have lower sensitization rates to cockroaches and other allergens compared to African Americans. Within the Caucasian population, income does not appear to influence sensitization rates. The treatment that adolescents with asthma receive for their respiratory disease is characterized by an overall low rate of prescribed inhaled corticosteroids (37% in the moderately severe and severe groups). This inadequacy in treatment is accentuated by SES: 28% of adolescents in the highest and 6% in the lowest-income quartile are prescribed these medications. Our findings are consistent with the hypothesis that the higher asthma morbidity and mortality observed in the African American population is related to higher exposure and sensitization to allergens such as those from cockroaches that are more prevalent in lower SES environments. It is possible that genetic factors contribute to the higher degree of sensitization. In addition, individuals of low SES are subjected to inadequate medical management of their asthma.

Isolation and characterization of a clone encoding a major allergen ( Bla gBd90K) involved in IgE-mediated cockroach hypersensitivity

Previous studies have established that atopic individuals living in cockroach-infested housing become sensitized to cockroach aeroallergens and produce IgE antibodies to a variety of proteins. We describe the isolation of a complementary DNA clone from an expression library, constructed with messenger RNA from German ( Blattella germanica) cockroaches, which encodes a major allergen involved in mediating cockroach hypersensitivity. Approximately 0.2% of the clones from a lambda ZAP XR cDNA library bound IgE from a patient with cockroach sensitivity. A randomly selected subset of these clones revealed that they were either different isolates of the same gene or members of a closely related gene family. One of the largest clones (a 4 kb insert) from this subset, Bla g Bd90K hybridized to a single mRNA of approximately the same size. DNA sequence analysis showed that this gene consisted of seven 576 bp tandem repeats with a short unique region at either end. No significant sequence homologies were found between the cockroach clone and any other gene reported in the GenBank database. Serum from 17 of 22 (77%) patients with cockroach hypersensitivity identified IgE-binding recombinant protein expressed from clone Bla g Bd90K in Escherichia coli XL-Blue cells as determined by sodium dodecylsulfate–polyacrylamide gel electrophoresis/immunoblot analysis. This recombinant protein migrates with a molecular weight (90 kd) apparently similar to one identified in whole body extracts. We have identified and isolated a cDNA that encodes a major cockroach allergen ( Bla g Bd90K) present in German cockroaches. (J A LLERGY C LIN I MMUNOL 1996;98:172-80.)

Cockroach sensitivity in asthmatic Egyptian children

Cockroach-specific IgE antibodies (CR-IgE) were assayed in the sera of 51 asthmatic and 33 healthy, nonallergic children. Cockroach IgE was detected in 43 asthmatic children (84%), seven of whom showed a high CR-IgE response (> or = 1.5 IU/ml). Only three of the healthy children (9%) had a positive response, and none of them were in the strongly positive category. The difference from the asthmatic group was statistically significant (P < 0.001). Children with clinically mild asthma had a significantly lower CR-IgE positivity rate than moderate and severe cases. The presence of other allergic manifestations or family history of atopy had no relationship to CR-IgE, nor did the residency, age, duration of illness, or total serum IgE levels. However, the CR-IgE titres were positively correlated with the absolute eosinophil counts. Thus, cockroach antigens are common inhalant allergens in Egyptian asthmatic children.