Community-based surveillance and control of chagas disease vectors in remote rural areas of the Argentine Chaco: A five-year follow-up

Prevention of Chagas disease vector-borne transmission mostly relies on the residual application of pyrethroid insecticide. Persistent or recurrent house infestation after insecticide spraying remains a serious challenge in remote, resource-poor rural areas where public health services face substantial constraints. Here we use generalized estimating equations and multimodel inference to model the fine-scale, time-lagged effects of a community-based vector surveillance-and-response strategy on house infestation and abundance of Triatoma infestans in four rural communities of the Argentine Chaco over a five-year period. Householders and community leaders were trained to detect triatomines and spray with insecticides their premises if infested. House infestation and vector abundance were consistently higher in peridomestic habitats than in human habitations (domiciles). Householders supplemented with sensor boxes detected infested domiciles (67%) more frequently than timed-manual searches (49%). Of all houses ever found to be infested by timed-manual searches, 76% were sprayed within six months upon detection. Domestic triatomine abundance was significantly related to house-level insecticide spraying during the previous year (inversely) and current peridomestic abundance (positively). Peridomestic triatomine abundance significantly increased with current domestic bug abundance and maximum peridomestic abundance during the previous year, and was unaffected by insecticide spraying. Our study provides new empirical evidence of the interconnection and flow between domestic and peridomestic populations of T. infestans under recurrent insecticide treatments, and supports targeting both habitats with appropriate tactics for longer-lasting, improved vector control. Community-directed efforts succeeded in controlling domestic infestations and interrupting domestic transmission, whereas persistent peridomestic infestations demand sustained control efforts to address domestic reinvasions.