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

Abstract

Abstract. In 2000, the Guatemalan Ministry of Health initiated a Chagas disease program to control Rhodnius prolixus and Triatoma dimidiata by periodic house spraying with pyrethroid insecticides. The aim of this study was to characterize infestation patterns and analyze the contribution of programmatic practices to these patterns. Spatial infestation patterns at three time points were identified using the Getis-Ord Gi*(d) test. Logistic regression was used to assess predictors of reinfestation after pyrethroid insecticide administration. Spatial analysis showed high and low clusters of infestation at three time points. After two rounds of spray, 178 communities persistently fell in high infestation clusters. A time lapse between rounds of vector control greater than 6 months was associated with 1.54 (95% confidence interval = 1.07-2.23) times increased odds of reinfestation after first spray, whereas a time lapse of greater than 1 year was associated with 2.66 (95% confidence interval = 1.85-3.83) times increased odds of reinfestation after first spray compared with localities where the time lapse was less than 180 days. The time lapse between rounds of vector control should remain under 1 year. Spatial analysis can guide targeted vector control efforts by enabling tracking of reinfestation hotspots and improved targeting of resources.

Ecohealth Interventions Limit Triatomine Reinfestation following Insecticide Spraying in La Brea, Guatemala

“…Domestic infestation thereafter rose to 3.3% by 2009, but remained well within the target level of 5% set by the National Chagas Disease Control Project. 6 Peridomestic infestation similarly decreased from 9.8% to 1.5% after insecticide treatments in 2003 and then held steady near or below 2% for the remainder of the study. suggests that the vector is capable of rapidly colonizing when conditions are favorable, although the small number of homesteads infested over this period limits statistical analyses.…”

“…[5][6][7]13 Although a formal control was not present in this study, results from numerous studies have shown that residual insecticides alone cannot curtail reinfestation long term. [5][6][7][8][9]18,19,23 The time scale over which residual insecticides are effective varies regionally but is typically on the order of weeks in peridomestic environments and months in domestic habitats. In La Brea, annual interventions were thought necessary because of rapid reinfestation following treatment.…”

“…5 Although Guatemala, like its neighbors, has realized significant progress in vector control through insecticide spraying, estimates of the annual incidence of Chagas disease remain among the highest in Central America, due largely to regional differences in the effectiveness of control strategies. 3,[5][6][7][8][9] In view of these health challenges, current global economic constraints, and the understanding gained through past control initiatives, interest in developing new or improved, sustainable, and cost effective long-term controls is increasing. [10][11][12] Toward this end, Ecohealth approaches that integrate community participation, home improvements, and current ecological knowledge regarding the vector are being proposed as an alternative to, or in combination with, traditional insecticide controls.…”

Effectiveness of Large-Scale Chagas Disease Vector Control Program in Nicaragua by Residual Insecticide Spraying Against Triatoma dimidiata

“…Existence of such clusters vulnerable to the T. dimidiata reinfestation is compatible with the previous spatial study in Guatemala. 16 Probably in the high-risk clusters, the communities share the similar environmental or housing conditions and exchange vectors constantly among them. To address the reinfestation of T. dimidiata efficiently, the MoH's vector control program should pay more attention to the areas where some communities with high pre-spray infestation level are gathered.…”

“…Such reinfestation by T. dimidiata is likely to occur with the passage of time after spraying and in geographical hot spots. 16 In Nicaragua, the first national entomological survey was conducted in 1998-1999. Among 15 departments surveyed, R. prolixus and T. dimidiata were found in 6 and 15 departments, respectively.…”