A History of Chagas Disease Transmission, Control, and Re-Emergence in Peri-Rural La Joya, Peru

Stephen Delgado,Andrew C Comrie,Manuela Renee Verastegui,Ricardo Castillo Neyra,Jenny Ancca Juárez,Michael Z Levy,César Náquira,Juan G Cornejo Del Carpio,Robert H Gilman,César D Bocángel,Charles R Sterling,Caryn Bern,Giovanna M Moscoso Apaza,Víctor R Quispe Machaca,Aaron W Tustin,Lily Chou Chu,Ricardo E Gürtler

doi:10.1371/journal.pntd.0000970

Abstract

BackgroundThe history of Chagas disease control in Peru and many other nations is marked by scattered and poorly documented vector control campaigns. The complexities of human migration and sporadic control campaigns complicate evaluation of the burden of Chagas disease and dynamics of Trypanosoma cruzi transmission.Methodology/Principal FindingsWe conducted a cross-sectional serological and entomological study to evaluate temporal and spatial patterns of T. cruzi transmission in a peri-rural region of La Joya, Peru. We use a multivariate catalytic model and Bayesian methods to estimate incidence of infection over time and thereby elucidate the complex history of transmission in the area. Of 1,333 study participants, 101 (7.6%; 95% CI: 6.2–9.0%) were confirmed T. cruzi seropositive. Spatial clustering of parasitic infection was found in vector insects, but not in human cases. Expanded catalytic models suggest that transmission was interrupted in the study area in 1996 (95% credible interval: 1991–2000), with a resultant decline in the average annual incidence of infection from 0.9% (95% credible interval: 0.6–1.3%) to 0.1% (95% credible interval: 0.005–0.3%). Through a search of archival newspaper reports, we uncovered documentation of a 1995 vector control campaign, and thereby independently validated the model estimates.Conclusions/SignificanceHigh levels of T. cruzi transmission had been ongoing in peri-rural La Joya prior to interruption of parasite transmission through a little-documented vector control campaign in 1995. Despite the efficacy of the 1995 control campaign, T. cruzi was rapidly reemerging in vector populations in La Joya, emphasizing the need for continuing surveillance and control at the rural-urban interface.

Highlights

An estimated 8 million people in Latin America are infected by the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease [1]
The historically rural problem of Chagas disease is increasing in urban areas in Latin America
We conducted a cross-sectional study in an urbanizing rural area in southern Peru, and we encountered a complex history of Chagas disease in this peri-rural environment

Summary

Introduction

An estimated 8 million people in Latin America are infected by the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease [1]. Trypanosoma cruzi is typically transmitted to humans and other mammals through contact with feces of an infected blood-feeding triatomine insect. The primary vector species in southern Peru is Triatoma infestans, which has adapted to live in and around human dwellings. Chagas disease is estimated to be responsible for the loss of 670,000 disability-adjusted life years (DALYs) and 14,000 human lives annually [4]. The history of Chagas disease control in Peru and many other nations is marked by scattered and poorly documented vector control campaigns. The complexities of human migration and sporadic control campaigns complicate evaluation of the burden of Chagas disease and dynamics of Trypanosoma cruzi transmission

Methods

Results

Discussion

Conclusion