Great flood and aeroallergen sensitization in children with asthma and/or allergic rhinitis

Background: Flooding may affect aeroallergen sensitization. Objective: To evaluate aeroallergen sensitization in children with asthma and/or allergic rhinitis (AR) by skin prick test (SPT) before and after the great flood of 2011 in Bangkok, Thailand. Methods: The study was performed retrospectively in asthma and/or AR children (aged 0-18 years) in Siriraj Hospital, Bangkok, Thailand from 2009 to 2013. All of the cases received SPT with common aeroallergens. Results: SPTs were performed from 2009-2013 in a total of 2,010 asthma and/or AR children and 58.2% and 60.5% showed positive results, respectively. Poly-sensitization to aeroallergens was found in 67.5% of asthma and 67.0% of AR SPT-positive patients. In the study period, Dermatophagoides pteronyssinus (Dp) and Dermatophagoides ferinae (Df) were the most common causes of aeroallergen sensitization (82.4% and 76.5%, respectively), followed by American cockroach (43.5%). After the severe flood in Bangkok in 2011, the trend of sensitization to American cockroach, Bermuda grass, Johnson grass, and Cladosporium spp. significantly decreased. However, the trend of sensitization to dog and Alterneria allergens in 2010 studied cases, significantly increased. During the study period, mean wheal diameter (MWD) of dog SPT was significantly associated with asthma severity, while the MWD of Dp SPT was significantly associated with AR severity. Conclusions: The aeroallergen sensitizations patterns had changed from previous years compared to the year during or after the flood. Thus, the great flood may have had a major impact on types of sensitization and the clinical patterns of airway allergy. Further confirmed by a prospective study is warranted.