Migration and the Emergence of Chagas Disease Vectors in the Growing City of El Pedregal, Peru

Abstract

The city of El Pedregal grew out of a desert, following an agricultural irrigation project in Southern Peru. We conducted door-to-door entomological surveys to document the emergence of triatomines and bed bugs into this new urban environment. We inspected 5,191 households for Triatoma infestans (known locally as the Chirimacha); 21 (0.41%) were infested. These were extremely spatially clustered (Ripley's K p-value <0.001 at various spatial scales). Using remote sensing we compared the year of construction of infested to un-infested households and found that infested houses were older than controls (Wilcoxon rank-sum: W=33; p=0.02). We confirmed infestations through a subsequent bed bug specific inspection in 34 households. These households were more spatially disperse across El Pedregal. To gain a better understanding of the socioeconomic context surrounding triatomine infestations, we conducted in-depth interviews with residents to explore their migration histories and previous experiences with Chirimachas. Main reasons for migration include searching for work on land, opportunity to buying a house, and scape adverse climate effects. Permanent migration flow and poor housing conditions propitiate suitable environment for emergence triatomine infestation. We discuss how changes in the landscape could potentially heighten vulnerability to vector-borne illnesses.