With cluster as the unit of analysis , serological evidence from intervention sites showed a lower risk of infection with dengue virus in children ( relative risk reduction @ % , @ % confidence interval @ % to @ % ) , fewer reports of dengue illness ( @ % , @ % to @ % ) , fewer houses with larvae or pupae among houses visited ( house index ) ( @ % , @ % to @ % ) , fewer containers with larvae or pupae among containers examined ( container index ) ( @ % , @ % to @ % ) , fewer containers with larvae or pupae among houses visited ( Breteau index ) ( @ % , @ % to @ % ) , and fewer pupae per person ( @ % , @ % to @ % ) .