A comparative study of domestic survey techniques for the Chagas' disease vector Triatoma infestans

The detection of household infestations of Triatominae in regions endemic for Chagas' disease is a criterion frequently used in the selection of areas, or of individual houses, for treatment in insecticide campaigns as well as for the evaluation of insecticide performance. Several methods for the detection of domestic infestations with Triatominae were compared: diurnal capture of live bugs with the aid of a flushing-out agent, night-capture without using flushing-out agents and the use of cardboard boxes of the the Gómez-Núñez type. The flushing-out and Gómez-Núñez box methods were found to be equally sensitive, although each gave several houses as uninfested in which infestation was detected by the other method. The night-capture method was slightly more sensitive but was found to be impractical for large-scale surveys. Improvements 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 both heavily infested houses and for houses 3 months after insecticide treatment. Coating the inside surfaces of the boxes with adhesive did not increase the sensitivity of this method and, although this can be achieved by leaving the boxes in place for long periods of time, this also limits the value of the information thus obtained as regards 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.