10The vector-borne parasite Trypanosoma cruzi infects seven million individuals globally 11 and causes chronic cardiomyopathy and gastrointestinal diseases. Recently, T. cruzi has emerged 12 in the southern United States. It is crucial for disease surveillance efforts to detail regions that 13 present favorable climatic conditions for T. cruzi and vector establishment. We used MaxEnt to 14 develop an ecological niche model for T. cruzi and five widespread Triatoma vectors based on 15 546 published localities within the United States. We modeled regions of current potential T. 16 cruzi and Triatoma distribution and then regions projected to have suitable climatic conditions 17 by 2070. Regions with suitable climatic conditions for the study organisms are predicted to 18 increase within the United States. Our findings agree with the hypothesis that climate change 19 will facilitate the expansion of tropical diseases throughout temperate regions and suggest 20 climate change will influence the expansion of T. cruzi and Triatoma vectors in the United 21 States. 22Author summary 23 Trypanosoma cruzi is a vector-borne parasite and the etiological agent of Chagas disease, 24 which is an emerging infectious disease in the United States. Current trends suggest climate 25 change can influence the distribution of vector-borne diseases through increases in suitable 26 climatic conditions for vectors and pathogens. This influence can lead to tropical disease 27 emergence in temperate regions. Currently, the best method for estimating distributional changes 28 and potential disease emergence in both well studied and underrepresented areas is ecological 29 niche modeling. We developed an ecological niche model to better understand the potential 30 future T. cruzi and Triatoma distribution in the United States and in Oklahoma, which is an 31 underrepresented state. Our ecological niche model incorporated 546 published localities and 19 32 bioclimatic variables. Our model predicts a potential range expansion of T. cruzi and 33 widespread Triatoma vectors throughout Oklahoma and the United States. Our model presents a 34 better understanding of the future epidemiology of T. cruzi and Triatoma vectors in Oklahoma 35 and the United States and contributes to disease surveillance efforts by predicting areas of 36 potential range expansion. 37 Introduction 38 Trypanosoma cruzi is a vector-borne hemoflagellate parasite and the etiological agent of 39 American Trypanosomiasis, also known as Chagas disease. Currently, T. cruzi infects seven 40 million people across 43 countries and up to 40% will develop Chagas disease, which causes 41 significant cardiomyopathy in adults and children, tissue fibrosis, lethargy, gastrointestinal 42 diseases such as megaesophagus and megacolon, and 10,000 deaths annually [1-5]. 43 Trypanosoma cruzi is transmitted when infected hematophagous triatomines (Hemiptera: 44 Reduviidae: Triatominae) feed on a host and defecate onto the host skin or mucous membranes, 45 thereby allowing the parasi...