Residual infestation and recolonization during urban triatoma infestans bug control campaign, Peru

Chagas disease vector control campaigns are being conducted in Latin America, but little is known about medium-term or long-term effectiveness of these efforts, especially in urban areas. After analyzing entomologic data for 56,491 households during the treatment phase of a Triatoma infestans bug control campaign in Arequipa, Peru, during 2003–2011, we estimated that 97.1 percent of residual infestations are attributable to untreated households. Multivariate models for the surveillance phase of the campaign obtainedduring 2009–2012 confirm that nonparticipation in the initial treatment phase is a major risk factor (odds ratio [OR] 21.5,95 percent CI 3.35–138). Infestation during surveillance also increased over time (OR 1.55, 95 percent CI 1.15–2.09 per year). Inaddition, we observed a negative interaction between nonparticipation and time (OR 0.73, 95 percent CI 0.53–0.99), suggesting that recolonization by vectors progressively dilutesrisk associated with nonparticipation. Although the treatmentphase was effective, recolonization in untreated households threatens the long-term success of vector control.