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1. Risk factors and select cardiac characteristics in dogs naturally infected with Trypanosoma cruzi presenting to a teaching hospital in Texas

   https://doi.org/10.1111/jvim.15516  

   Meyers, Alyssa C. ; Hamer, Sarah A. ; Matthews, Derek ; Gordon, Sonya G. ; Saunders, Ashley B. ( May 2019 , Journal of Veterinary Internal Medicine)

   Chagas disease, caused by the protozoan parasiteTrypanosoma cruzi, causes sudden death and chronic heart disease with no currently approved treatment.

   To report epidemiologic and select cardiac characteristics associated withT. cruziinfection in dogs presenting to a teaching hospital in Texas.

   Three hundred seventy‐five client‐owned dogs.

   A retrospective search of medical records identified dogs tested forT. cruziantibodies or with histologicT. cruziparasites. Data retrieved included signalment, location of residence, reported reason for testing, cardiac troponin I (cTnI) concentration, and ECG abnormalities.

   Trypanosoma cruzi‐infected dogs (N = 63, 16.8%) were significantly younger than negative dogs (N = 312) (mean, 5.9 ± 3.8 versus 7.4 ± 4.0 years;P = .007) with no difference by sex or breed. Ninety‐one breeds were tested; the highest percent infected were non‐sporting (10/35; 29%) and toy breed (10/42; 24%) groups. The odds of infection were 13 times greater among dogs with an infected housemate or littermate (95% confidence interval [CI], 3.94‐50.45;P< .001). Infected dogs were more likely to have ventricular arrhythmias (odds ratio [OR], 2.19; 95% CI, 1.15‐4.33,P = .02), combinations of ECG abnormalities (OR, 2.91; 95% CI, 1.37‐5.99;P = .004), and cTnI >0.129 ng/mL (ADVIA; OR, 10.71; 95% CI, 1.60‐212.21;P = .035).

   Dogs infected withT. cruziwere identified in Texas in many breed groups including breeds affected by well‐described heart diseases that mimic Chagas disease suggesting a need for increased awareness, including knowledge of when to consider testing.

    

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2. The distribution of triatomine (Hemiptera: Reduviidae) vectors of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) in Illinois and Missouri: historical records and specimen submissions from community science programs

   https://doi.org/10.1093/jme/tjad124  

   Santos, Ellen M. ; Santanello, Catherine D. ; Curtis-Robles, Rachel ; Killets, Keswick ; Lawrence, Gena ; Sevenshadows, Jet ; Mahoney, Meredith J. ; Baker, Molly ; Hamer, Sarah A. ; Poh, ed., Karen ( December 2023 , Journal of Medical Entomology)

   Triatomine species (kissing bugs) infected with Trypanosoma cruzi are found across the southern United States. The northern limits of Trypanosoma cruzi infected kissing bugs are less understood. The objective of this work was to describe the locations of kissing bugs from Illinois and Missouri based on historical records, submissions to Texas A&M University’s (TAMU) Kissing Bug Community Science Program and the Centers for Disease Control and Prevention (CDC), and records from online platforms (iNaturalist, BugGuide, and GBIF) up to and including 2022. A total of 228 records were discovered, including 186 from historical or observation platforms and 42 specimens submitted to TAMU or CDC. Species included Triatoma sanguisuga (221 total records, 9 nymphs) and Triatoma lecticularia (7 records). Notably, nearly all (24/26) records submitted to TAMU were collected indoors. Twelve of the 30 (40%) specimens tested were positive for the presence of T. cruzi, including parasite discrete taxonomic units TcI and TcIV. One triatomine sample had been found in a bed feeding on the submitter; this bug was positive for T. cruzi and had evidence of human blood in its gut. Records suggest a ubiquitous distribution in Missouri and potentially to the northernmost border in Illinois. Further investigations into triatomine distribution and infection status are needed within states assumed to be northern limits in order to create public health and veterinary health messaging and baseline distributional maps from which to measure future range shifts in relation to a changing climate.

    

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3. Insights from a comprehensive study of Trypanosoma cruzi: A new mitochondrial clade restricted to North and Central America and genetic structure of TcI in the region

   https://doi.org/10.1371/journal.pntd.0010043  

   Lima-Cordón, Raquel Asunción ; Cahan, Sara Helms ; McCann, Cai ; Dorn, Patricia L. ; Justi, Silvia Andrade ; Rodas, Antonieta ; Monroy, María Carlota ; Stevens, Lori ( December 2021 , PLOS Neglected Tropical Diseases)

   Dutra, Walderez O. (Ed.)

   More than 100 years since the first description of Chagas Disease and with over 29,000 new cases annually due to vector transmission (in 2010), American Trypanosomiasis remains a Neglected Tropical Disease (NTD). This study presents the most comprehensive Trypanosoma cruzi sampling in terms of geographic locations and triatomine species analyzed to date and includes both nuclear and mitochondrial genomes. This addresses the gap of information from North and Central America. We incorporate new and previously published DNA sequence data from two mitochondrial genes, Cytochrome oxidase II (COII) and NADH dehydrogenase subunit 1 (ND1). These T . cruzi samples were collected over a broad geographic range including 111 parasite DNA samples extracted from triatomines newly collected across North and Central America, all of which were infected with T . cruzi in their natural environment. In addition, we present parasite reduced representation (Restriction site Associated DNA markers, RAD-tag) genomic nuclear data combined with the mitochondrial gene sequences for a subset of the triatomines (27 specimens) collected from Guatemala and El Salvador. Our mitochondrial phylogenetic reconstruction revealed two of the major mitochondrial lineages circulating across North and Central America, as well as the first ever mitochondrial data for TcBat from a triatomine collected in Central America. Our data also show that within mtTcIII, North and Central America represent an independent, distinct clade from South America, named here as mtTcIII NA-CA , geographically restricted to North and Central America. Lastly, the most frequent lineage detected across North and Central America, mtTcI, was also an independent, distinct clade from South America, noted as mtTcI NA-CA . Furthermore, nuclear genome data based on Single Nucleotide Polymorphism (SNP) showed genetic structure of lineage TcI from specimens collected in Guatemala and El Salvador supporting the hypothesis that genetic diversity at a local scale has a geographical component. Our multiscale analysis contributes to the understanding of the independent and distinct evolution of T . cruzi lineages in North and Central America regions. 

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4. Hopf bifurcation in an age-structured predator–prey system with Beddington–DeAngelis functional response and constant harvesting

   https://doi.org/10.1007/s00285-024-02070-3  

   Wu, San-Xing ; Wang, Zhi-Cheng ; Ruan, Shigui ( April 2024 , Journal of Mathematical Biology)

   In this paper, an age-structured predator–prey system with Beddington–DeAngelis (B–D) type functional response, prey refuge and harvesting is investigated, where the predator fertility functionf(a) and the maturation function$$\beta (a)$$$\beta \left(a\right)$are assumed to be piecewise functions related to their maturation period$$\tau $$$\tau$. Firstly, we rewrite the original system as a non-densely defined abstract Cauchy problem and show the existence of solutions. In particular, we discuss the existence and uniqueness of a positive equilibrium of the system. Secondly, we consider the maturation period$$\tau $$$\tau$as a bifurcation parameter and show the existence of Hopf bifurcation at the positive equilibrium by applying the integrated semigroup theory and Hopf bifurcation theorem. Moreover, the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are studied by applying the center manifold theorem and normal form theory. Finally, some numerical simulations are given to illustrate of the theoretical results and a brief discussion is presented.

    

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5. Neglected tropical diseases risk correlates with poverty and early ecosystem destruction

   https://doi.org/10.1186/s40249-023-01084-1  

   Magalhães, Arthur Ramalho ; Codeço, Cláudia Torres ; Svenning, Jens-Christian ; Escobar, Luis E. ; Van de Vuurst, Paige ; Gonçalves-Souza, Thiago ( December 2023 , Infectious Diseases of Poverty)

   Neglected tropical diseases affect the most vulnerable populations and cause chronic and debilitating disorders. Socioeconomic vulnerability is a well-known and important determinant of neglected tropical diseases. For example, poverty and sanitation could influence parasite transmission. Nevertheless, the quantitative impact of socioeconomic conditions on disease transmission risk remains poorly explored.

   This study investigated the role of socioeconomic variables in the predictive capacity of risk models of neglected tropical zoonoses using a decade of epidemiological data (2007–2018) from Brazil. Vector-borne diseases investigated in this study included dengue, malaria, Chagas disease, leishmaniasis, and Brazilian spotted fever, while directly-transmitted zoonotic diseases included schistosomiasis, leptospirosis, and hantaviruses. Environmental and socioeconomic predictors were combined with infectious disease data to build environmental and socioenvironmental sets of ecological niche models and their performances were compared.

   Socioeconomic variables were found to be as important as environmental variables in influencing the estimated likelihood of disease transmission across large spatial scales. The combination of socioeconomic and environmental variables improved overall model accuracy (or predictive power) by 10% on average (P < 0.01), reaching a maximum of 18% in the case of dengue fever. Gross domestic product was the most important socioeconomic variable (37% relative variable importance, all individual models exhibitedP < 0.00), showing a decreasing relationship with disease indicating poverty as a major factor for disease transmission. Loss of natural vegetation cover between 2008 and 2018 was the most important environmental variable (42% relative variable importance,P < 0.05) among environmental models, exhibiting a decreasing relationship with disease probability, showing that these diseases are especially prevalent in areas where natural ecosystem destruction is on its initial stages and lower when ecosystem destruction is on more advanced stages.

   Destruction of natural ecosystems coupled with low income explain macro-scale neglected tropical and zoonotic disease probability in Brazil. Addition of socioeconomic variables improves transmission risk forecasts on tandem with environmental variables. Our results highlight that to efficiently address neglected tropical diseases, public health strategies must target both reduction of poverty and cessation of destruction of natural forests and savannas.

    

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