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Title:The eco-epidemiology of Chagas disease risk in Panama
Author(s):Updyke, Erin Allmann
Director of Research:Allan, Brian F.
Doctoral Committee Chair(s):Allan, Brian F.
Doctoral Committee Member(s):Berenbaum, May R.; Suarez, Andrew V.; O'Dwyer, James P.
Department / Program:Entomology
Discipline:Entomology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Disease Ecology
Epidemiology
Entomology
Chagas
Abstract:Chagas disease is a vector-borne disease affecting between 5 to10 million people world-wide. It is spread by dozens of species of blood-feeding triatomines (Hemiptera: Reduviidae). Trypanosoma cruzi, a kinetoplastid protozoan parasite and causative agent of Chagas disease, is shed in the feces of triatomines during blood-feeding and must enter the bloodstream through the bite wound or mucous membranes. Intensive studies into the domestic transmission cycle of Chagas disease have elucidated important ecological and epidemiological risk factors for the regions of most intense transmission, particularly the “southern cone” of South America. In contrast, we know little about sylvatic transmission, whereby triatomine species living in natural environments are attracted to the human-built environment. This dissertation examines the factors that attract sylvatic vectors to the domestic environment in Panama, which species of kissing bugs may contribute to disease transmission, and how these factors vary across a human land-use gradient. First, I tested a new collection method that is simpler and more cost-effective than current methods to attract and capture sylvatic triatomines, an important step in monitoring triatomine populations and vector control. This new collection method, which uses a lightweight, inexpensive, cross-vane panel trap and an ultraviolet light, is as effective as traditional light trapping in attracting and capturing triatomines and can be deployed with far less human-power than typical sylvatic triatomine traps. Next, I examined the role of lesser-studied species of sylvatic triatomine in human disease transmission. Over two years of collections across central Panama, I collected 314 triatomines in four genera, Triatoma, Rhodnius, Panstrongylus, and Eratyrus, and tested specimens for infection with T. cruzi. I examined differences in infection prevalence among species, and found that, while R. pallescens was the most abundant triatomine collected throughout the study, P. geniculatus had significantly higher infection prevalence, and R. pallescens may account for only a portion of the total vector potential in this system. Additionally, I performed an eco-epidemiological investigation to examine the risk factors that may contribute to Chagas disease exposure risk across an urban-to-rural land-use gradient in central Panama. In total, 182 houses participated in an epidemiological survey to identify potential risk factors and completed sixteen months of in-home triatomine collections. I determined that land use context as well as the number of domestic animals, especially chickens, are significantly predictive of the density of triatomines as well as the density of infected triatomines collected around the home. Finally, I developed a mathematical model to predict the risk of Chagas disease infection for an individual over time based on parameters from my research including the abundances and T. cruzi infection rates of triatomines present around the home, and the factors that attract them to the household environment. This model also can be used to estimate the incidence of Chagas disease infection across Panama in specific land-use contexts and generates predictions in line with the World Health Organization’s estimates. Collectively, these studies provide insight into the transmission cycle of Chagas disease in Panama, which can be useful in other contexts where multiple triatomine species co-occur and which will be essential in achieving WHO’s goals of interruption of vectoral transmission of Chagas disease by 2020.
Issue Date:2018-07-09
Type:Text
URI:http://hdl.handle.net/2142/101689
Rights Information:Copyright 2018 Erin Updyke
Date Available in IDEALS:2018-09-27
2020-09-28
Date Deposited:2018-08


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