Breteau Index threshold levels indicating risk for dengue transmission in areas with low Aedes infestation.

We used Breteau Indices to - retrospectively - predict dengue transmission. The presence of one house block (on average about 50 houses) with a Breteau Index >or=4 in a neighbourhood (a block plus the surrounding blocks in a radius of 100 m) predicted transmission at the latter level with 81.8% sensitivity and 73.3% specificity during the first month of the Havana 2001 dengue outbreak. This result corroborates the external validity of this threshold, at least in situations with low infestations levels.