The numbers needed to treat were 30 ( 95 % confidence interval 20 to 59 ) for a lower risk of infection in children , 71 ( 48 to 143 ) for fewer reports of dengue illness , 17 ( 14 to 20 ) for the house index , 37 ( 35 to 67 ) for the container index , 10 ( 6 to 29 ) for the Breteau index , and 12 ( 7 to 31 ) for fewer pupae per person .