House dust mite, cat, and cockroach allergen concentrations in daycare centers in Tampa, Florida

Background: Allergen exposure in early childhood is a risk factor for sensi tization and the development of asthma. Studies performed in Europe, New Ze aland, and Singapore indicated the presence of indoor allergens in childcar e centers and schools. However, the importance of indoor allergens in dayca re centers in humid and warm regions of the world is not known. Objective: To measure total mite counts, Der p 1, Der f 1, Fel d 1, and Per a 1 allergens in dust samples and mite allergen airborne concentrations in daycare centers in Tampa, Florida, United States. Methods: Twenty daycare centers were surveyed for mite, cat, and cockroach allergens in Tampa, FL. One dust and two air samples (one during the day an d one during the night) were collected in each center. Dust samples were ex tracted and analyzed for mite (Der p 1 and Der f 1), cat (Fel d 1), and coc kroach (Per a 1) allergens. Mite airborne allergen concentrations were anal yzed by RAST inhibition and expressed in standardized mite allergen units p er ml of air (AU/m(3)). Results: Mites were identified in 15 samples, and concentrations ranged fro m 10 to 1,200 mites/g (298 +/- 355.2). The most prevalent mite species was Dermatophagoides pteronyssinus ( Der p 1). Der p 1 and/or Der f 1 were dete cted in 10 daycare centers. Der p I was detected in eight centers and range d from 1 to 21.8 mug/g of dust (5.4 +/- 6.9); Der f 1 was detected in 3 cen ters and ranged from 0.2 to 2.1 mug/g of dust (1.3 +/- 0.9). Per a 1 and Fe l d 1 were detected in all centers in small quantities; Per a 1 ranged from 8 to 1,806 ng/g (263.1 +/- 449.7) and Fel d 1 from 0.2 to 120 U/g of dust (16.6 +/- 31.7), respectively. Airborne mite allergen was detected in 18 ce nters and ranged from 0.01 to 2.7 AU/m(3) during the day (0.2 +/- 0.6) and from 0.01 to 0.12 AU/m(3) during the night (0.06 +/- 0.03), P = 0.001. Conclusions: Mite, cat, and cockroach allergens are present in daycare cent ers in Tampa, FL. Mite allergen concentrations exceeded levels that have be en associated with sensitization and symptoms in allergic subjects in 40% o f these centers.