Sensitization pattern of allergens among adolescent school children with asthma in a district of Sri LankaSensitization pattern of allergens among adolescent school children with asthma in a district of Sri Lanka

Abstract

INTRODUCTION: Asthma is one of the common diseases among adolescents in Sri Lanka. Identification of sensitisation pattern to common allergens is helpful in planning rational control measures, minimising restrictions and in adopting immunotherapy. OBJECTIVE: To assess the sensitisation pattern among school going adolescent asthmatic children in Gampaha district. MATERIALS AND METHODS: A cross sectional study was carried out in 42 randomly selected schools in the Gampaha district. Within each school, one class from grade 8, 9 and 10 was randomly chosen. Students with physician diagnosed asthma and reporting symptoms in the previous 12 months were tested together with a healthy sibling. Sensitisation to house dust mite (Dermatophagoides pteronyssinus), cockroach (Blattella germanica), and storage mite (Blomia) were assessed using standardised allergen extracts. A skin wheal diameter, 3mm or greater than the negative control, was considered positive. RESULTS: Of 94 students selected, 61 responded (64%). The mean age was 13.8 years (SD=0.94) in asthmatics and 13.0 years (SD=3.7) in controls. Among asthmatics majority (60.7%) were males, compared to 47.5% among controls. Forty eight (78.7%) asthmatics had positive skin reaction to at least one allergen; the prevalence in the control group was 16.4%. The commonest allergen among asthmatics was cockroach (60.7%) followed by house dust mite (49.2%) and blomia (45.9%) The prevalence among the controls was 15.3%, 5.1% and 8.5% respectively. The differences were statistically significant. CONCLUSION: A significantly higher prevalence of sensitisation to cockroaches, house dust mites and storage mite was seen among asthmatic adolescents compared to their healthy siblings.