Detection of Trypanosoma cruzi-infected triatomines in Iquitos: possible incipient colonisation in the largest metropolis of the Peruvian Amazon

Abstract

BACKGROUND While Chagas disease (CD) has been controlled in many South American regions, the Amazon basin has emerged as a new focus of transmission. Metropolitan Iquitos (Loreto, Peru), has recently shown signs of potential disease emergence. OBJECTIVE To assess the risk of CD transmission by evaluating triatomine presence and infection rates in households across Iquitos and nearby communities. METHODS Entomological surveillance was conducted in domestic and peridomestic environments, following blood donor screenings (2011-2018) that confirmed local Trypanosoma cruzi cases. Triatomines were collected manually, with traps, and through community reporting. Specimens were identified, epidemiological indices calculated, and infestation risk factors analysed using penalised logistic regression, receiver operating characteristic (ROC)/area under the curve (AUC) metrics, and exploratory principal component analysis (PCA). FINDINGS Of 142 houses visited, 113 were inspected, yielding a density index of 0.26. Nine houses were infested, mostly in Loboyacu, with 29 adult triatomines collected — by Rhodnius robustus (89.7%) and Panstrongylus geniculatus. T. cruzi infection was confirmed, and palm roofs emerged as the strongest predictor of infestation [odds ratio (OR) > 16, p < 0.001]. MAIN CONCLUSIONS This first evidence of T. cruzi circulation in sylvatic triatomines within Metropolitan Iquitos highlights an emerging risk of CD. Although vectors remain scarce, palm-roofed houses, deforestation, and urban expansion may facilitate future transmission.