Serial determinations of Der p 1 and Der f 1 show predominance of one Dermatophagoides species.

One dust sample each month was collected for an average of 11 months throughout the year from the bedroom carpet of 39 mite allergic, asthmatic individuals living in the Tampa Bay area of Florida. Dust samples were collected from a square meter area from the bedroom carpet for 2 min using a portable vacuum cleaner and analyzed using two-site monoclonal antibody assays. The geometric mean of Dermatophagoides allergens Der p 1 and Der f 1 levels measured in each individual home was used in the statistical analysis of the results and reflects the average allergen level per year per home. Der p 1 levels were greater than Der f 1 in 21 homes; five homes had between 1.1 and 5 times more; one home had between 5 and 10; and 15 had between 10 and 175. Der f 1 levels were greater than Der p 1 in 18 homes; seven homes had between 1.1 and 5 times more; four had between 5 and 10; and seven homes had between 10 and 44. Spearman rank analysis of the results yielded a negative correlation coefficient (Rho) = -0.213 (p = 0.19) between Der p 1 and Der f 1 levels. These data suggest that when mite allergen levels reach a geometric mean value of approximately 2 micrograms/gram of dust throughout a year, one mite species predominates over the other.