PREVALENCE AND DISTRIBUTION OF INDOOR ALLERGENS IN SINGAPORE

Background ann aims Immediate hypersensitivity to indoor allergens is known to be associated with allergic asthma, This study evaluated the prevalence and distribution of six indoor allergens in 956 dust sample s obtained from homes, childcare centres, schools, and a hospital in t ropical Singapore. Seasonality of mite allergens was also assessed. Me thods The major allergens of the Dermatophagoides spp. dust mites, Der p 1 and Der f 1; major cat and dog allergens, Can fl (dog) acid Fel d 1 (cat); and cockroach, Bla g 1, were measured by specific enzyme imm unoassays. Allergen levels of the storage mite, Blomia tropicalis (Blo t), were measured by a fluorescent allergosorbent test (FAST) inhibiti on assay. Results Our results showed that homes had significantly high er concentrations and prevalence of allergens compared with the other locations, except for Bla g 1, where higher mean levels were found in schools. Within the homes, the highest concentrations of mite allergen s were found in mattresses (geometric mean: 1.2 mu g/g dust Der p 1; 2 717 Allergen Units per gram dust [AU/g] Blo t), and carpets (1.5 mu g/ g Der p 1; 1620 AU/g Blo t), whilst Bla,ol was mainly concentrated in the storerooms (geometric mean = 3.5 units/g) and kitchens (geometric mean = 5.1 nnits/g). The major cat and dog allergens were well distrib uted and not confined to homes with pets. Their highest levels were fo und in dust of soft furnishings, carpets and mattresses. There was an absence of significant seasonal variation in Der p 1, Der f 1 and Blo t levels in the homes over a 1 year period. Conclusion The results ind icate that compared with public places, the home consitutes a major re servior of indoor allergens. Allergens of the storage mite, B. tropica lis, should be considered as a major allergenic component of dust in S ingapore.