Species-specific IgE recognition of cockroach allergens in human–dog dyads sharing the same household

Introduction Allergic diseases commonly affect both humans and companion animals, yet little is known about how shared household environments influence allergen recognition across species. Cockroach allergens are major contributors to human allergic disease, yet their immunological impact on cohabiting dogs has not been systematically evaluated. Using a One Health–informed comparative approach, we investigated cockroach IgE recognition profiles in 68 human–dog dyads residing in shared domestic environments. Methods We assessed household characteristics, allergic histories, and cockroach infestation patterns through structured questionnaires. Serum IgE reactivity to Periplaneta americana allergens was analyzed by immunoblotting in paired owner–dog samples. Results Concurrent allergic conditions were identified in 52.9% of owner–dog pairs. Cockroach activity was most frequently reported in kitchens (61.4%), with additional evidence near dog feeding bowls (10.0%) and sleeping areas (4.3%), indicating common environmental exposure. Comparative immunoblot analysis revealed both shared and species-specific IgE recognition patterns. Per a 1, Per a 3, Per a 4, and Per a 9 were recognized in both species, whereas dogs showed higher recognition frequencies for Per a 4 (69%) and Per a 9 (40%), while owners more frequently recognized Per a 1 (34%), Per a 3 (34%) and Per a 7 (26%). Discussion These findings suggest that shared household exposure does not necessarily produce identical allergen recognition profiles and support the concept of species-specific allergen recognition under common environmental conditions. This study provides new insights into comparative allergy between humans and companion dogs and highlights the importance of considering both host biology and household exposure when investigating environmental allergic diseases.