Sensitization patterns of allergens among asthmatics in Sri Lanka

Abstract

Introduction: The sensitization pattern among asthmatics in Sri Lanka is unknown. Objectives: To determine the sensitization pattern among asthmatics in Sri Lanka. Methodology: The study was carried out in forty physician-diagnosed asthmatic patients. Twenty two non-asthmatics were recruited as controls. Sensitization to 12 allergens was assessed by skin prick test using standardized allergen extracts. A skin wheal diameter, 3mm greater than the negative control was considered a positive reaction. Results: The mean age of asthmatics was 32.4 years (range 9Y59) and 57.5% were males. The mean age of controls was 32.2 years (range 14Y58) and 59.1% were males. The analysis of the data showed that 97.5% asthmatics had positive skin reaction to at least one allergen compared to 72.7% prevalence in the control group. The common allergens among asthmatics were Dermatophagoides pteronyssinus (77.5%), blomia (65.5%), cockroach (55%), storage mite (35%), latex (20%)), cat fur (17.5%), aspergillus (12.5%), grass pollen (12.5%), cow’s milk (12.5%) egg white (10%) cereals (7.5%) and dog hair (5.%). The pattern of sensitization among non-asthmatics was Dermatophagoides pteronyssinus (54.5%), cockroach (50%), blomia (36.4%), aspergillus (36.4%), grass pollen (27.3%), storage mite (22.7%), cow`s milk (18.2%), latex (13.6%), egg white (13.6%), cereals (13.6%), dog hair (9.1%) and cat fur (9.1%). Sixty two percent (n = 25) of the asthmatics had at least one other allergic manifestation while non-asthmatics with other allergic manifestation were 36.4% (n = 8). Other allergic manifestations in the asthmatic group were rhinitis alone 22 (55%), eczema alone 1(2.5%) and both rhinitis & eczema 2(5%) whereas in the non-asthmatic group it was rhinitis alone 7 (31%), eczema alone 0% and both rhinitis and eczema 1(4.5%). The pattern of sensitization for mites alone, cockroaches alone and mites and cockroaches in the asthmatic group with rhinitis (n = 24) was 23 (57%), 11(27%) and 11(27%) and in the non-asthmatic group with rhinitis (n = 7) was 3 (13%), 4 (18%) and 3 (13%) respectively. Conclusion: The results show that mites, and cockroaches are the most common sensitizing allergens in asthmatics and the commonest association of asthma was rhinitis in Sri Lanka.