Assessment of toxoplasma gondii exposure in carnivores of the Valdivian temperate Rainforest, Chile : insights from marine otters (lontra felina), american mink (neogale vison), and domestic cats (felis catus)
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Archivos
Fecha
2023
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Profesor/a Guía
Facultad/escuela
Idioma
en
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
Toxoplasma gondii es un parásito protozoario de distribución global de importancia en
salud pública y conservación de la biodiversidad. Comprender los factores que influyen
en la exposición de los animales a T. gondii es crucial para una gestión efectiva de la
enfermedad y los esfuerzos de conservación. Esta tesis doctoral tiene como objetivo
evaluar la exposición de carnívoros, específicamente nutrias marinas (Lontra felina),
visones americanos (Neogale vison) y gatos domésticos (Felis catus), a T. gondii en el
Bosque Lluvioso Valdiviano en Chile.
El primer capítulo examina la exposición a T. gondii en nutrias marinas. Se capturaron un
total de 30 nutrias marinas entre 2013 y 2021 a lo largo de la costa chilena.
Específicamente, 20 fueron obtenidas de las regiones costeras áridas del norte y centro,
mientras que 10 fueron muestreadas en la región sur lluviosa y templada, que abarca el
Bosque Lluvioso Valdiviano. Se emplearon muestras de suero de nutrias marinas para
evaluar la exposición a través de un método de ELISA indirecto comercial, realizado de
acuerdo con las instrucciones del fabricante. Los resultados revelan una exposición menor
(10%, 95% CI: 2.1-26.5%) en comparación con otros mustélidos acuáticos en Chile: 77%
(95% CI: 46-95%) en el huillín (Lontra provocax), 59% (95% CI: 47-70%) y 70% (95%
CI: 51-85%) en el visón americano. Se necesitan investigaciones adicionales para
explorar los factores asociados con la exposición a T. gondii en las nutrias nativas y
evaluar sus posibles efectos en las poblaciones de vida silvestre, en especial del huillín en
los hábitats de agua dulce del Bosque Lluvioso Valdiviano. Tomando en cuenta las
dificultades en el muestreo de nutrias silvestres, el visón americano, una especie alóctona
de mustélido semiacuático, se propone como un indicador para evaluar la amenaza de
contaminación patogénica en las nutrias nativas en este ecosistema. El segundo capítulo investiga la exposición a T. gondii y los hábitos alimenticios de
visones americanos y gatos domésticos mediante el análisis de isótopos estables. Al
explorar las relaciones estadísticas a través de modelos logísticos, este capítulo revela que
la proporción de presas con valores δ15N altos y pollos (Gallus gallus domesticus) tuvo
una asociación positiva y significativa con la exposición a T. gondii en visones
americanos. Además, observamos que la exposición de los gatos domestico a T. gondii
no tiene asociación significativa con ningún valor isotópico o presa en la dieta en el
Bosque Lluvioso Valdiviano.
El tercer capítulo explora las variables del paisaje asociadas con la exposición a T. gondii
en visones americanos y gatos domésticos a través de modelos de máxima entropía
(MAXENT). Los hallazgos resaltan la asociación entre hábitats de agua dulce de baja
altitud, paisajes antropogénicos y un mayor riesgo de exposición. Se requiere
investigación adicional para investigar el papel de los felinos silvestres nativos en la
diseminación de ooquistes de T. gondii en bosques nativos y en plantaciones de coníferas
en el Bosque Lluvioso Valdiviano.
En general, este estudio mejora la comprensión de la epidemiología de T. gondii en el
ecosistema del Bosque Lluvioso Valdiviano, proporcionando información sobre la
exposición a T. gondii en nutrias marinas, visones americanos y gatos domésticos. Los
hallazgos enfatizan la importancia de los factores sociales, ecológicos y ambientales en
la dinámica de transmisión de T. gondii, especialmente en áreas de alto riesgo como las
cuencas de los ríos Valdivia y Toltén. La investigación contribuye al desarrollo de
estrategias de salud pública y gestión de la conservación destinadas a mitigar el riesgo de
infección por T. gondii en poblaciones de vida silvestre y humanas en el Ecosistema del
Bosque Lluvioso Valdiviano.
Toxoplasma gondii is a globally distributed protozoan parasite that poses significant public health and biodiversity conservation concerns. Understanding the factors influencing the exposure of animals to T. gondii is crucial for effective disease management and conservation efforts. This doctoral thesis aims to assess the exposure of carnivores, specifically marine otters (Lontra felina), American mink (Neogale vison), and domestic cats (Felis catus), to T. gondii in the Valdivian temperate rainforest in Chile. The first chapter examines T. gondii exposure in marine otters, A total of 30 marine otters were captured and sampled between 2013 and 2021 along the Chilean coastline. Specifically, 20 were obtained from the arid northern and central coastal regions, while 10 were sampled from the rainy and temperate southern region, encompassing the Valdivian Temperate Rainforest. Marine otter´s serum samples were employed to assess exposure through a commercial indirect ELISA method, conducted in accordance with the manufacturer's instructions. Results reveal a lower exposure (10%, 95% CI: 2.1- 26.5%) compared to other aquatic mustelids in Chile: 77% (95% CI: 46-95%) in the Southern River otter (Lontra provocax), 59% (95% CI: 47-70%) and 70% (95% CI: 51- 85%) in the American mink. Further investigations are necessary to explore the factors associated with T. gondii exposure in native otters and evaluate its potential effects on wildlife populations, particularly the endangered southern river otter (Lontra provocax) within freshwater habitats of the Valdivian temperate Rainforest. Taken into account the difficulties in otter sampling, the alien American mink, a sympatric semi-aquatic mustelid, could be a proxy for assessing the threat of pathogenic pollution on native otters in this ecosystem. The second chapter investigates T. gondii exposure and dietary habits of American minks and domestic cats using stable isotope analysis. By exploring statistical relationships through logistic models, this chapter reveal that the proportion of high δ15N values preys and chickens (Gallus gallus domesticus) had a positive and significant association with T. gondii exposure in American minks. Also, we observed that domestic cat’s exposure to T. gondii has no significant association to any isotope value or prey item in their diet in the Valdivian temperate rainforest. The third chapter explores the landscape variables associated with T. gondii exposure in American minks and domestic cats thought maximum entropy algorithm models (MAXENT). The findings highlight the association between low altitude freshwater habitats, anthropogenic landscapes, and increased risk of exposure. Additional research is warranted to investigate the role of native wild felids in the dissemination of T. gondii oocysts in natural broadleaf forest and in conifer plantation in the Valdivian temperate rainforest ecosystem. Overall, this study enhances the understanding of T. gondii epidemiology in the Valdivian temperate rainforest ecosystem, providing insights into T. gondii exposure in marine otters, American minks, and domestic cats. The findings emphasize the importance of social, ecological, and environmental factors in the transmission dynamics of T. gondii, particularly in high-risk areas like the Valdivia and Tolten River basins. The research contributes to the development of public health and conservation management strategies aimed at mitigating the risk of T. gondii infection in both wildlife and human populations in the Valdivian Temperate rainforest Ecosystem.
Toxoplasma gondii is a globally distributed protozoan parasite that poses significant public health and biodiversity conservation concerns. Understanding the factors influencing the exposure of animals to T. gondii is crucial for effective disease management and conservation efforts. This doctoral thesis aims to assess the exposure of carnivores, specifically marine otters (Lontra felina), American mink (Neogale vison), and domestic cats (Felis catus), to T. gondii in the Valdivian temperate rainforest in Chile. The first chapter examines T. gondii exposure in marine otters, A total of 30 marine otters were captured and sampled between 2013 and 2021 along the Chilean coastline. Specifically, 20 were obtained from the arid northern and central coastal regions, while 10 were sampled from the rainy and temperate southern region, encompassing the Valdivian Temperate Rainforest. Marine otter´s serum samples were employed to assess exposure through a commercial indirect ELISA method, conducted in accordance with the manufacturer's instructions. Results reveal a lower exposure (10%, 95% CI: 2.1- 26.5%) compared to other aquatic mustelids in Chile: 77% (95% CI: 46-95%) in the Southern River otter (Lontra provocax), 59% (95% CI: 47-70%) and 70% (95% CI: 51- 85%) in the American mink. Further investigations are necessary to explore the factors associated with T. gondii exposure in native otters and evaluate its potential effects on wildlife populations, particularly the endangered southern river otter (Lontra provocax) within freshwater habitats of the Valdivian temperate Rainforest. Taken into account the difficulties in otter sampling, the alien American mink, a sympatric semi-aquatic mustelid, could be a proxy for assessing the threat of pathogenic pollution on native otters in this ecosystem. The second chapter investigates T. gondii exposure and dietary habits of American minks and domestic cats using stable isotope analysis. By exploring statistical relationships through logistic models, this chapter reveal that the proportion of high δ15N values preys and chickens (Gallus gallus domesticus) had a positive and significant association with T. gondii exposure in American minks. Also, we observed that domestic cat’s exposure to T. gondii has no significant association to any isotope value or prey item in their diet in the Valdivian temperate rainforest. The third chapter explores the landscape variables associated with T. gondii exposure in American minks and domestic cats thought maximum entropy algorithm models (MAXENT). The findings highlight the association between low altitude freshwater habitats, anthropogenic landscapes, and increased risk of exposure. Additional research is warranted to investigate the role of native wild felids in the dissemination of T. gondii oocysts in natural broadleaf forest and in conifer plantation in the Valdivian temperate rainforest ecosystem. Overall, this study enhances the understanding of T. gondii epidemiology in the Valdivian temperate rainforest ecosystem, providing insights into T. gondii exposure in marine otters, American minks, and domestic cats. The findings emphasize the importance of social, ecological, and environmental factors in the transmission dynamics of T. gondii, particularly in high-risk areas like the Valdivia and Tolten River basins. The research contributes to the development of public health and conservation management strategies aimed at mitigating the risk of T. gondii infection in both wildlife and human populations in the Valdivian Temperate rainforest Ecosystem.
Notas
Tesis (Doctor en Medicina de la Conservación)
Palabras clave
Toxoplasma Gondii, Nutrias Marinas, Visón Americano, Gatos, Investigaciones, Chile, Valdivia