Is vectorial transmission of T. cruzi an efficient route to support high infection rates in sylvatic hosts?

"La enfermedad de Chagas es causada por el parásito Trypanosoma cruzi y se transmite a los humanos por el gusano triatomino Rhodnius prolixus. En las zonas rurales de Colombia, la enfermedad incluye un ciclo silvestre y un ciclo doméstico en el que los seres humanos, insectos y reservorios (es decir, pequeños mamíferos) interactúan y se infectan con el parásito. Comúnmente se cree que la transmisión vectorial es la ruta principal para la migración de parásitos entre los elementos que interactúan. Estudios recientes sugieren un alto porcentaje (> 80%) de marsupiales infectados (Didelphis marsupialis) en el ciclo silvestre, lo que plantea la cuestión de si una proporción tan alta podría mantenerse mediante la transmisión vectorial actuando sola, una vía aparentemente ineficiente. Para investigar este asunto, desarrollamos un modelo matemático que describe la dinámica de transmisión en el ciclo silvestre considerando insectos-vectores y hospederos-mamíferos." -- Tomado del Formato de Documento de Grado."Chagas disease is caused by the parasite Trypanosoma cruzi and is transmitted to humans by the triatomine bug Rhodnius prolixus. In rural areas of Colombia the disease includes a sylvatic and a domestic cycle where humans, insects and reservoirs (i.e. small mammals) interact and become infected with the parasite. It is commonly believed that vectorial transmission is the main route for parasite migration between the interacting elements. Recent studies suggest a high percentage (>80%) of infected raccoons (Didelphis marsupialis) in the sylvatic cycle, raising the question of whether such a high proportion could be maintained by vectorial transmission alone, a seemingly inefficient pathway. To investigate this matter we developed a mathematical model that describes the transmission dynamics in the sylvatic cycle considering insect-vectors and hosts-mammals." -- Tomado del Formato de Documento de Grado.Magíster en Ingeniería AmbientalMaestrí

A mathematical model for toxins transport in a marine food web

Algunos casos de intoxicación ocasionados por el consumo de peces tóxicos se han reportado en los últimos años en varias regiones insulares de países tropicales. Problemas gastrointestinales, cardiovasculares y neurológicos están entre los síntomas más comunes de la ciguatera, enfermedad que afecta negativamente la economía de países del Caribe y el Pacífico que dependen de la pesca y el turismo. Con el propósito de entender el transporte de biotoxinas en la red trófica marina, proponemos un modelo depredador - presa con respuesta funcional Holling Tipo I basado en dos sistemas de ecuaciones diferenciales ordinarias no lineales, el cual es analizado bajo los enfoques cualitativo y numérico. Los resultados indican que la evolución del sistema de transporte y acumulación de toxina depende de la dinámica del sistema poblacional. / Abstract. Some diseases are caused by biotoxin accumulation in animal and plant bodies. This study proposes a predator-prey model with a Holling Type I functional response based on a system of six ordinary differential equations. The purpose of this study is to understand the biotoxin transport in a marine food web. The system exhibits eight steady points, but only four of them have mathematical sense. Both the steady conditions for these points and a numerical simulation are presented. The results of this study could be used as a tool in many ecological fields or used in natural resources improvement.Magister en Ciencias - Matemática AplicadaMaestrí

Higher Household Income and the Availability of Electronic Devices and Transport at Home Are Associated with Higher Waist Circumference in Colombian Children: The ACFIES Study

Background: The current “epidemic” of childhood obesity is described as being driven by modern lifestyles with associated socioeconomic and environmental changes that modify dietary habits, discourage physical activity and encourage sedentary behaviors. Objective: To evaluate the association between household income and the availability of electronic devices and transport at home, and the values of waist circumference (WC), as an indicator of abdominal obesity, in children and adolescents from Bucaramanga, Colombia. Methods: Cross-sectional study of public elementary and high school population, of low-middle socioeconomic status. Results: A total of 668 schoolchildren were recruited. After adjusting for potential confounders, significant positive associations between waist circumference and higher household income (p = 0.011), and waist circumference and the availability of electronic devices and transport at home (p = 0.026) were found. Conclusions: In low-middle socioeconomic status schoolchildren in a developing country, those from relatively more affluent families had greater waist circumference, an association that is opposite to that observed in developed countries. This finding could be related to higher income family’s ability to purchase electronic devices and motorized transport which discourage physical activity and for their children to buy desirable and more costly western fast food