Impact of Single and Multiple Residual Sprayings of Pyrethroid Insecticides Against Triatoma Dimidiata (Reduviiade; Triatominae), the Principal Vector of Chagas Disease in Jutiapa, Guatemala

Abstract

This study investigated the impact of single, double, and triple insecticide sprayings on indoor infestation of Triatoma dimidiata in Jutiapa, Guatemala. Up to three successive insecticide sprayings were applied in villages, where the indoor infestation index was > 5% before each spraying round or located adjacent to the persistently infested villages. Among 64 villages with single spraying, the mean indoor infestation index reduced from 20.8% to 1.4% after 12 months, but rose to 8.1% after 33 months. In 40 double-sprayed villages, it decreased from 41.9% to 11.9% by the first spraying and to 4.8% by the second spraying. For 12 villages with triple spraying, it reduced from 40.6% to 13.2%, 10.9%, and 4.1% through each spraying round. Geographic analysis showed that originally highly infested villages were spatially clustered and were likely to remain infested after the sprayings. Indoor infestation of T. dimidiata can be controlled with less than three rounds of spraying.

Environmental determinants of the distribution of Chagas disease vectors in south-eastern Guatemala

“…However, T. dimidiata has proven more challenging to control because it can re-infest previously sprayed villages (Nakagawa et al, 2003b). Between two and three rounds of residual sprayings are necessary to control T. dimidiata in a village, but the long-term effect of this approach is yet to be evaluated (Hashimoto et al, 2006).…”

Vector Blood Meals Are an Early Indicator of the Effectiveness of the Ecohealth Approach in Halting Chagas Transmission in Guatemala

“…5 The sustained reduction in infestation over the entire study is significant because many studies conducted in Central America and southern Mexico show that, without other interventions, T. dimidiata frequently reappears in houses after insecticide application, sometimes at pre-insecticide treatment levels. 2,3,23 This is likely because persistence of even residual insecticides in houses is limited perhaps to as little as 4 months, 24 probably less in the exposed peridomestic environment, 25 which serves as a reservoir for domestic insects. 26 The reduction in human-vector contact and domiciliary infestation is likely caused by removal of hiding places for the vectors and improved houses now refractory to insects.…”

“…In some localities it has successfully reduced infestation; however, in other localities insects rapidly reappear in houses after insecticide application. 2,3 A new Ecosystem approach to human health (Ecohealth) has been proposed as a more sustainable method of control, where the communities actively participate in ameliorating the conditions identified as most important in Chagas transmission. 4,5 Transmission of Chagas disease is dependent on a complex set of biological, environmental, sociological, and economic factors.…”

Triatomine Infestation in Guatemala: Spatial Assessment after Two Rounds of Vector Control

“…E-mail: jmanne@post.harvard.edu Jutiapa. 15,[17][18][19] This evaluation allows for a comprehensive assessment of the efficacy of the program, and it provides crucial information for targeting resources and improving spray operations in the future.…”

“…8,11 In addition to house spraying, other primary emphases of the program included local capacity building, community education, and community participation. [14][15][16] In 2005, JICA's involvement in the project officially ended, but the project continued under local government administration and with informal technical and financial support from JICA. In 2008, the World Health Organization certified Guatemala for the interruption of transmission by R. prolixus.…”