Allergy to cockroaches in patients with asthma and rhinitis in an urban area (Madrid).

Previous studies have established that cockroach allergens are important sensitizing agents in the induction of rhinitis and asthma principally in urban areas. This study was undertaken to assess skin test reactivity and specific IgE antibody reactivity to extracts of Periplaneta americana (P.a.), Blattella germanica (B.g.), B. orientalis (B.o.), and a fecal extract of B. germanica (FEB.g.) in a group of patients with rhinitis and asthma living in an urban area in Europe. We examined clinical characteristics and aerollergen sensitivities of 171 consecutive Madrid urban patients with rhinitis and asthma who met the criteria for the study. A comprehensive clinical evaluation was followed by skin prick test with common allergens and saline extracts of P.a., B.g., B.o., and FEB.g. and measurement of serum specific IgE antibody to cockroach extracts. The age of patients ranged from 7 to 68 years (mean 20.4 +/- 16). A total of 153 (90.5%) subjects were atopic and 19 (10%) were considered nonallergic. Pollen sensitivity (66.5%) was most prevalent, distantly followed by sensitivity to cockroach (25.7%), mite (20%), cat (15.5%), Alternaria alternata (14.5%), dog (14%), and food (2%). Skin test reactivity to cockroach extracts was 37 (21.6%) to B.o., 20 (11.6%) to P.a., 19 (11.1%) to B.g. and five (2.9%) to FEB.g. Twenty-one of these patients had rhinitis, 19 rhinitis and asthma, and one only asthma; 26 had perennial symptoms, while 16 had seasonal (spring) symptoms; three (1.7%) patients had only positive prick test to cockroach; all had perennial rhinitis and/or asthma. Eighteen (10.5%) patients had specific serum IgE (RAST 1 or 2) to B.o., 13 (7.6%) to P.a., and six (3.5%) to B.g. Eighty (46.7%) patients had visual evidence of cockroach infestation in their home, mostly B.o.; 31 had positive prick test to cockroach (P < 0.0003). The results indicate that sensitivity to outdoor allergens (pollen) is more prevalent than to indoor allergens. Cockroach sensitization is the most important indoor allergen in our area, and B.o. accounts for most cockroach sensitization.