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Proportion of dust mites-infested houses (mean ± SD per house) in October 1999 pre-intervention, compared with 2000 and 2001 (quarterly surveys) after 1 and 2 years of enhanced intervention in the form of repetitive health education on aeroallergen control. Df, Dermatophagoides farinae; Dp, Dermatophagoides pteronyssinus; Tp, Tyrophagus putrescentiae.
