Matsui EC, Wood RA, Rand C, et al. J Allergy Clin Immunol. 2003;112:87–92.
Purpose of the Study.
To evaluate the prevalence of cockroach allergen exposure in middle-class suburban environments and its relationship to sensitization.
A total of 339 children (6–17 years of age) with physician-diagnosed asthma were recruited from 3 pediatric practices located in suburban and rural counties surrounding Baltimore, Maryland, and from 1 practice located within Baltimore city. The children were required to have currently active asthma, and the families needed to agree to a home visit.
The families completed a demographic questionnaire, and an environmental technician conducted a house inspection and collected dust samples, which were analyzed for cat, dog, cockroach, and dust mite allergens. The children underwent skin testing with a sampling of perennial and seasonal allergens, including cat, dog, cockroach, and dust mite allergens.
Of the study children, 44% were male and 49% were white. Seventy-seven percent lived in rural or suburban areas, 53% of the families had an annual income of more than $50 000, and 49% of the mothers had college degrees. Thirty percent of the suburban-rural homes were found to have measurable cockroach antigen, whereas dust mite, cat, and dog allergens were detected for 40%. Only 5% of the suburban-rural homes with measurable cockroach antigen had evidence of cockroach infestation. Sensitization testing with perennial allergens revealed that 71% of subjects were sensitized to dust mite allergen, 29% to cat allergen, 76% to ≥1 seasonal outdoor allergen, and 10% to dog allergen. Cockroach allergen sensitization did discriminate between urban and suburban dwellers, identifying 35% of urban residents, compared with 21% of suburban-rural residents. A kitchen cockroach allergen (Bla g 1) level of >1 U/g was significantly associated with cockroach sensitization and was found in both urban and suburban groups.
The presence of cockroach allergen occurs more frequently in suburban middle-class homes than previously thought, and low-level exposure to this antigen is a risk factor for sensitization.
Cockroach antigen was demonstrated for a surprisingly high percentage of middle-class suburban homes. The results show that even low levels of exposure can cause sensitization. Interestingly, only a small percentage of homes in which cockroach antigen was identified exhibited evidence of infestation when examined by the environmental technician. The reason for this is not totally clear. This study suggests that reliance on questions about the presence of cockroach infestation in the home may underestimate the risk of cockroach exposure among children with asthma.