Chagas Disease Vector Control in a Hyperendemic Setting: the First 11 Years of Intervention in Cochabamba,Bolivia

Background:chagas disease has historically been hyperendemic in the bolivian department of cochabamba. in the early 2000s,an extensive vector control program was implemented; 1.34 million dwelling inspections were conducted to ascertain infestation (2000-2001/2003-2011),with blanket insecticide spraying in 2003-2005 and subsequent survey-spraying cycles targeting residual infestation foci. here,we assess the effects of this program on dwelling infestation rates (dirs).methodology/principal findings:program records were used to calculate annual,municipality-level aggregate dirs (39 municipalities); very high values in 2000-2001 (median: 0.77-0.69) dropped to ~0.03 from 2004 on. a linear mixed model (with municipality as a random factor) suggested that infestation odds decreased,on average,by ~28% (95% confidence interval [ci95] 6-44%) with each 10-fold increase in control effort. a second,better-fitting mixed model including year as an ordinal predictor disclosed large dir reductions in 2001-2003 (odds ratio [or] 0.11,ci95 0.06-0.19) and 2003-2004 (or 0.22,ci95 0.14-0.34). except for a moderate decrease in 2005-2006,no significant changes were detected afterwards. in both models,municipality-level dirs correlated positively with previous-year dirs and with the extent of municipal territory originally covered by montane dry forests.conclusions/significance:insecticide-spraying campaigns had very strong,long-lasting effects on dirs in cochabamba. however,post-intervention surveys consistently detected infestation in ~3% of dwellings,underscoring the need for continuous surveillance; higher dirs were recorded in the capital city and,more generally,in municipalities dominated by montane dry forest - an eco-region where wild triatoma infestans are widespread. traditional strategies combining insecticide spraying and longitudinal surveillance are thus confirmed as very effective means for area-wide chagas disease vector control; they will be particularly beneficial in highly-endemic settings,but should also be implemented or maintained in other parts of latin america where domestic infestation by triatomines is still commonplace. © 2014 espinoza et al.