47 research outputs found

    Understanding and predicting mosquito-borne disease under current and future scenarios of global change

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    There is a rapidly growing awareness of the influence of global change processes such as land-use, climate change and socioeconomic factors on the burden of mosquito-borne disease (MBD). Although individual effects of different processes on MBD risk have been studied widely, a holistic approach that considers the combined influence of different global change processes has rarely been implemented. Here, I evaluate the effects of different global change processes on MBD risk, both generally, and in a series of modelling studies using the understudied MBD, Japanese encephalitis (JE) as a case study. I integrate different data types and approaches from ecology and epidemiology, with the aim of informing public health decision-makers in the era of accelerating global change. Firstly, I synthesise current knowledge on relative and interacting effects of global change processes on MBD risk and examine how these factors have been incorporated into existing analyses, highlighting how future research could be improved. Secondly, I compile a vector surveillance database for the predominant vector of JE (Culex tritaeniorhynchus). I use a novel approach that leverages information from sparse vector surveillance data to predict seasonal vector abundance over large spatial scales, that has the potential to be used to provide guidance for the targeting of suitable interventions. I use this information in an epidemiological study of JE case surveillance data and show that human JE incidence is associated with climate, land-use and socioeconomic factors, and these factors can be used to predict JE outbreaks in north-eastern India. Thirdly, I examine possible trends in JE epidemiology by projecting into the future under various scenarios of global change to show divergence in JE risk and burden under different socioeconomic and environmental policy scenarios. Finally, I integrate the implications of these results into our understanding of the effects of global change processes on MBD, the epidemiology and control of JE, and a holistic approach to the understanding and prediction of MBD risk

    Natural or anthropogenic variability? A long-term pattern of the zooplankton communities in an ever-changing transitional ecosystem

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    The Venice Lagoon is an important site belonging to the Italian Long-Term Ecological Research Network (LTER). Alongside with the increasing trend of water temperature and the relevant morphological changes, in recent years, the resident zooplankton populations have also continued to cope with the colonization by alien species, particularly the strong competitor Mnemiopsis leidyi. In this work, we compared the dynamics of the lagoon zooplankton over a period of 20 years. The physical and biological signals are analyzed and compared to evaluate the hypothesis that a slow shift in the environmental balance of the site, such as temperature increase, sea level rise (hereafter called “marinization”), and competition between species, is contributing to trigger a drift in the internal equilibrium of the resident core zooplankton. Though the copepod community does not seem to have changed its state, some important modifications of structure and assembly mechanisms have already been observed. The extension of the marine influence within the lagoon has compressed the spatial gradients of the habitat and created a greater segregation of the niches available to some typically estuarine taxa and broadened and strengthened the interactions between marine species

    Relationship between synoptic circulations and the spatial distributions of rainfall in Zimbabwe

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    This study examines how the atmospheric circulation patterns in Africa south of the equator govern the spatial distribution of precipitation in Zimbabwe. The moisture circulation patterns are designated by an ample set of eight classified circulation types (CTs). Here it is shown that all wet CTs over Zimbabwe features enhanced cyclonic/convective activity in the southwest Indian Ocean. Therefore, enhanced moisture availability in the southwest Indian Ocean is necessary for rainfall formation in parts of Zimbabwe. The wettest CT in Zimbabwe is characterized by a ridging South Atlantic Ocean high-pressure, south of South Africa, driving an abundance of southeast moisture fluxes, from the southwest Indian Ocean into Zimbabwe. Due to the proximity of Zimbabwe to the Agulhas and Mozambique warm current, the activity of the ridging South Atlantic Ocean anticyclone is a dominant synoptic feature that favors above-average rainfall in Zimbabwe. Also, coupled with a weaker state of the Mascarene high, it is shown that a ridging South Atlantic Ocean high-pressure, south of South Africa, can be favorable for the southwest movement of tropical cyclones into the eastern coastal landmasses resulting in above-average rainfall in Zimbabwe. The driest CT is characterized by the northward track of the Southern Hemisphere mid-latitude cyclones leading to enhanced westerly fluxes in the southwest Indian Ocean, limiting moist southeast winds into Zimbabwe

    Hunting Wildlife in the Tropics and Subtropics

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    The hunting of wild animals for their meat has been a crucial activity in the evolution of humans. It continues to be an essential source of food and a generator of income for millions of Indigenous and rural communities worldwide. Conservationists rightly fear that excessive hunting of many animal species will cause their demise, as has already happened throughout the Anthropocene. Many species of large mammals and birds have been decimated or annihilated due to overhunting by humans. If such pressures continue, many other species will meet the same fate. Equally, if the use of wildlife resources is to continue by those who depend on it, sustainable practices must be implemented. These communities need to remain or become custodians of the wildlife resources within their lands, for their own well-being as well as for biodiversity in general. This title is also available via Open Access on Cambridge Core

    New tools to prevent the endemism of bluetongue

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    Tesis inédita de la Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Sanidad Animal, leída el 09-05-2022La lengua azul es una enfermedad vírica, vectorial y transfronteriza, transmitida principalmente por especies del género Culicoides y que afecta esencialmente a rumiantes, con un gran impacto socioeconómico y sobre la sanidad animal en las regiones donde está presente. Por ende, es una enfermedad de declaración obligatoria para la Organización Mundial de Sanidad Animal (OIE). A finales del siglo XX, se la consideraba una enfermedad exótica en Europa, no obstante, desde1998 se ha experimentado una incesante introducción y posterior circulación de diferentes cepas del virus de la lengua azul (VLA), el agente etiológico responsable de la enfermedad. Su importancia para el sector ganadero justifica el estudio de la enfermedad y su epidemiología para prevenir el endemismo de ésta en ciertas áreas de Europa y concretamente en España. Por tanto, el principal objetivo de esta tesis titulada “Nuevas herramientas para la prevención del endemismo de la lengua azul”, es el de desarrollar y aplicar herramientas que posibiliten mejorar los planes de vigilancia activa, control y erradicación de la enfermedad en España...Bluetongue is a transboundary arboviral disease transmitted mainly by species of the genus Culicoides. It affects essentially ruminants and has a great socioeconomic and animal health impact in areas where is present. Hence, it is a notifiable disease for the World Organization for Animal Health (OIE). At the end of the 20th century, it was considered an exotic disease in Europe, however, since 1998 there has been an incessant introduction and subsequent circulation of different strains of the bluetongue virus (BTV), the etiological agent of the disease. Its importance for the livestock industry justifies the study of the disease and its epidemiology to prevent its endemism in certain areas of Europe and specifically in Spain. Thus, the main objective of this thesis entitled “New tools to prevent the endemism of bluetongue”, is to develop and apply tools to improve active surveillance, control and eradication plans for bluetongue in Spain...Fac. de VeterinariaTRUEunpu

    Biodiversity of the Gulf of Guinea Oceanic Islands

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    This open access book presents a comprehensive synthesis of the biodiversity of the oceanic islands of the Gulf of Guinea, a biodiversity hotspot off the west coast of Central Africa. Written by experts, the book compiles data from a plethora of sources – archives, museums, bibliography, official reports and previously unpublished data – to provide readers with the most updated information about the biological richness of these islands and the conservation issues they face. The Gulf of Guinea Oceanic Islands (Príncipe, São Tomé and Annobón and surrounding islets) present extraordinary levels of endemism across different animal, fungi and plant groups. This very high endemism likely results from the long geological history of the islands and their proximity to the diversity-rich continent. Many researchers, students and conservationists from across the globe are interested in documenting biodiversity on the islands, understanding the evolutionary origins of this diversity, and mitigating the impacts of global change on this unique archipelago. This book aims to be a primer for a broad audience seeking baseline biodiversity information and to serve as a roadmap for future research efforts aiming to fill knowledge gaps in understanding and conserving the unparalleled biodiversity of the Gulf of Guinea islands

    Utilización de la Teledetección para la modelización y control de presencia de garrapatas en un proceso de cambio climático. Validación de variables y relaciones fenológicas.

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    Las garrapatas (Ixodidae) son ectoparásitos hematófagos que actúan como vectores de propagación de numerosas enfermedades infecciosas, víricas y bacterianas, tanto a animales como a seres humanos. Estos ácaros de tamaño macroscópico están identificados como los artrópodos que causan mayores pérdidas económicas en el sector ganadero y mayores problemas de salud pública en la sociedad. Con 900 especies diferentes, se encuentran presente en los cinco continentes habitados y son numerosos los registros que señalan que en las últimas décadas se está produciendo un incremento generalizado en el alcance y magnitud de las enfermedades transmitidas por garrapatas en todo el planeta. En el caso concreto de Europa, situada en la región del Paleártico occidental, se están recogiendo en los últimos años datos que muestran la presencia de nuevas especies y la ampliación de los límites ecológicos de algunas asentadas desde que existen registros, como, por ejemplo, Ixodes ricinus (la más común en suelo europeo). Diversas investigaciones señalan al aumento de temperatura provocado por el cambio climático como responsable de esta situación, si bien existen otros factores que pueden coadyuvar como los cambios en los usos del suelo, el paisaje y la disponibilidad de hospedadores.La presente tesis tiene como objetivo general validar la utilidad de variables obtenidas mediante teledetección para la modelización y control de presencia de garrapatas en el Paleártico occidental, concretamente en el continente europeo. Con este fin, se estudia el uso de series multitemporales derivadas del sensor MODIS situado a bordo de las plataformas satelitales Terra y Aqua. En concreto se analizan las variables de temperatura de superficie y el índice de vegetación NDVI proporcionadas por este sensor y se comparan con otras variables relacionadas con ellas que son usadas comúnmente en la bibliografía como factores marcadores de la fenología de las garrapatas y su presencia.Así, en primer lugar, se evaluaron los errores sistemáticos que ofrece la variable temperatura de superficie de MODIS para su utilización en la modelización de garrapatas. Para ello, se tomó como referencia una red de estaciones meteorológicas repartidas por el conjunto del área de estudio y se comparó, espacial y temporalmente, los datos adquiridos por éstas con la información adquirida por el sensor espacial usando como marco de referencia espacial regiones ecológicas. Se constató la necesidad de un adecuado filtrado y procesado de los datos para optimizar la calidad de los mismos. Asimismo, se confirmó su validez para estimar temperatura máxima y mínima, ajustando muy bien en latitudes medias, pero con errores significativos asociados a motivos geográficos (Cuenca Mediterránea y Europa del Norte), temporales (hora de paso) y técnicos que limitan su uso en aplicaciones ecológicas. Finalmente, se demuestra la importancia de los errores detectados en las estimaciones de MODIS con respecto a los datos de temperatura del aire a través de un modelo de desarrollo de Ixodes ricinus, obteniéndose diferencias en los modelos de distribución anual de un 36%.Ampliando esta revisión, se comparó de igual forma las variables de temperatura de superficie de MODIS con distintas fuentes de datos climáticas interpoladas de uso científico (ECA&D y WorldClim) que consideran la temperatura del aire. Estas tres series de datos se comparan teniendo en cuenta dos tamaños de píxel y los distintos tipos de climas existentes. De este modo, se contrastó la importancia del conocimiento y tratamiento de los datos a distintas escalas temporales y espaciales y se reafirmó la utilidad de MODIS y sus limitaciones con respecto de los datos interpolados tradicionales para ser tenida en cuenta en estudios sobre presencia de garrapatas.Dado que el índice de vegetación NDVI es, junto a precipitación, la variable más frecuentemente utilizada en modelos de distribución de especies como sustituta de la variable presencia de agua en la atmósfera, se compararon en el área de estudio los valores de NDVI obtenidos por MODIS con datos de precipitación y con datos de humedad relativa y déficit de saturación para el conjunto de la serie temporal contemplada. A la escala temporal y espacial analizada, los patrones de precipitación no tienen relación alguna con la humedad relativa y el déficit de saturación, mientras que estas dos variables sí que presentan correlación con el NDVI, lo que habilita el uso de este índice espectral como alternativa, si bien es de reseñar que ésta correlación es baja y su uso como estimador directo debe realizarse con precaución y analizando cada caso.Finalmente, una vez analizadas ambas variables y conocidas sus limitaciones, se analizó la correlación de las variables temperatura de superficie y NDVI de MODIS con la actividad acumulada de las fases larva y ninfa de la garrapata Ixodes ricinus en dos puntos de España (localizados en las provincias de Huesca y de La Rioja) para una serie temporal de capturas de garrapatas de 7 años (2001-2007). Para estas localizaciones puntuales, los resultados obtenidos permiten correlacionar interanualmente la fase larva y ninfa con un margen de error de más-menos veinte días definiendo un método sencillo de prevención y control de esta fase.En conclusión, en el contexto de las series multitemporales de productos de teledetección de media resolución espacial, se han aplicado procesos metodológicos y generado información que permite avanzar en el desarrollo de modelos de predicción del ciclo de vida de las garrapatas. Los resultados obtenidos señalan que, a la escala y resolución espacial empleada, aunque existen limitaciones sistemáticas en el uso de la variable de temperatura de superficie y del índice de vegetación NDVI, estas permiten ajustar en localizaciones concretas modelos del ciclo de vida de estos artrópodos, permitiéndose así identificar los períodos de riesgo y facilitar la toma de decisiones respecto su control y prevención.<br /

    Identifying spanish areas at more risk of monthly BTV transmission with a basic reproduction number approach

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    Bluetongue virus (BTV) causes a disease that is endemic in Spain and its two major biological vector species, C. imicola and the Obsoletus complex species, differ greatly in their ecology and distribution. Understanding the seasonality of BTV transmission in risk areas is key to improving surveillance and control programs, as well as to better understand the pathogen transmission networks between wildlife and livestock. Here, monthly risk transmission maps were generated using risk categories based on well-known BTV R0 equations and predicted abundances of the two most relevant vectors in Spain. Previously, Culicoides spp. predicted abundances in mainland Spain and the Balearic Islands were obtained using remote sensing data and random forest machine learning algorithm. Risk transmission maps were externally assessed with the estimated date of infection of BTV-1 and BTV-4 historical outbreaks. Our results highlight the differences in risk transmission during April-October, June-August being the period with higher R0 values. Likewise, a natural barrier has been identified between northern and central-southern areas at risk that may hamper BTV spread between them. Our results can be relevant to implement risk-based interventions for the prevention, control and surveillance of BTV and other diseases shared between livestock and wildlife host populations

    Modelling the monthly abundance of Culicoides biting midges in nine European countries using Random Forests machine learning

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    Background: Culicoides biting midges transmit viruses resulting in disease in ruminants and equids such as bluetongue, Schmallenberg disease and African horse sickness. In the past decades, these diseases have led to important economic losses for farmers in Europe. Vector abundance is a key factor in determining the risk of vector-borne disease spread and it is, therefore, important to predict the abundance of Culicoides species involved in the transmission of these pathogens. The objectives of this study were to model and map the monthly abundances of Culicoides in Europe. Methods: We obtained entomological data from 904 farms in nine European countries (Spain, France, Germany, Switzerland, Austria, Poland, Denmark, Sweden and Norway) from 2007 to 2013. Using environmental and climatic predictors from satellite imagery and the machine learning technique Random Forests, we predicted the monthly average abundance at a 1 km2 resolution. We used independent test sets for validation and to assess model performance. Results: The predictive power of the resulting models varied according to month and the Culicoides species/ensembles predicted. Model performance was lower for winter months. Performance was higher for the Obsoletus ensemble, followed by the Pulicaris ensemble, while the model for Culicoides imicola showed a poor performance. Distribution and abundance patterns corresponded well with the known distributions in Europe. The Random Forests model approach was able to distinguish differences in abundance between countries but was not able to predict vector abundance at individual farm level. Conclusions: The models and maps presented here represent an initial attempt to capture large scale geographical and temporal variations in Culicoides abundance. The models are a first step towards producing abundance inputs for R0 modelling of Culicoides-borne infections at a continental scale
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