Comparison of techniques for detection of domestic infestations with Triatoma infestans in Brazil

The detection of infestations of Triatominae in houses in regions endemic for Chagas's disease is a criterion frequently used in the selection of areas, or of individual houses, for treatment in insecticide campaigns as well as in the evaluation of insecticide performance. Several different methods for detecting domestic infestations with Triatominae were compared: night capture, capture of five bugs with the aid of a flushing-out agent and use of card boxes of the Gómez-Núñez type. The flushing-out and Gómez-Núñez box methods were found to be equally sensitive, although each failed to detect some infestations which the other detected. The night capture method was slightly more sensitive but was found to be impractical for insecticide trials. Improvement to the flushing-out method, notably the introduction of a systematic search technique, made it much more sensitive than the Gómez-Núñez box method for heavily infested houses and for houses three months after insecticide treatment. Although the sensitivity of the Gómez-Núñez box method increases when the boxes are left in place for a long time, this also limits the value of the information obtained regarding the evaluation of insecticides. On the basis of the results presented, the flushing-out method using a systematic search of the house was found to be the most suitable sampling technique, but it is recognized that this method still has limitations.