scholarly journals Potential Distribution Map of Culicoides insignis (Diptera: Ceratopogonidae), Vector of Bluetongue Virus, in Northwestern Argentina

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Cecilia A. Veggiani Aybar ◽  
Romina A. Díaz Gomez ◽  
María J. Dantur Juri ◽  
Mercedes S. Lizarralde de Grosso ◽  
Gustavo R. Spinelli
Keyword(s):  
Disease Transmission ◽  
Bluetongue Virus ◽  
Potential Distribution ◽  
Control Strategies ◽  
Area Under The Curve ◽  
Transmission Risk ◽  
Distribution Map ◽  
Northwestern Argentina ◽  
Jackknife Test ◽  
Maxent Model

Abstract Culicoides insignis Lutz is incriminated as a vector of bluetongue virus (BTV) to ruminants in America. In South America, almost all countries have serological evidence of BTV infections, but only four outbreaks of the disease have been reported. Although clinical diseases have never been cited in Argentina, viral activity has been detected in cattle. In this study, we developed a potential distribution map of Culicoides insignis populations in northwestern Argentina using Maximum Entropy Modeling (Maxent). For the analyses, information regarding both data of specimen collections between 2003 and 2013, and climatic and environmental variables was used. Variables selection was based on the ecological relevance in relation to Culicoides spp. biology and distribution in the area. The best Maxent model according to the Jackknife test included 53 C. insignis presence records and precipitation of the warmest quarter, altitude, and precipitation of the wettest month. Accuracy was evaluated by the area under the curve (AUC = 0.97). These results provide an important analytical resource of high potential for both the development of suitable control strategies and the assessment of disease transmission risk in the region.

scholarly journals Livestock movement informs the risk of disease spread in traditional production systems in East Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Divine Ekwem ◽  
Thomas A. Morrison ◽  
Richard Reeve ◽  
Jessica Enright ◽  
Joram Buza ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Production Systems ◽  
Control Strategies ◽  
Herd Size ◽  
Transmission Risk ◽  
Disease Spread ◽  
Transmission Potential ◽  
Spatial And Temporal Scales ◽  
Transmission Distance ◽  
Risk Of Disease

AbstractIn Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different pathogens can be transmitted at different spatial and temporal scales, remains a major challenge. We deployed Global Positioning System collars on cattle in 52 herds in a traditional agropastoral system in western Serengeti, Tanzania, to understand fine-scale movements and between-herd contacts, and to identify locations of greatest interaction between herds. We examined contact across spatiotemporal scales relevant to different disease transmission scenarios. Daily cattle movements increased with herd size and rainfall. Generally, contact between herds was greatest away from households, during periods with low rainfall and in locations close to dipping points. We demonstrate how movements and contacts affect the risk of disease spread. For example, transmission risk is relatively sensitive to the survival time of different pathogens in the environment, and less sensitive to transmission distance, at least over the range of the spatiotemporal definitions of contacts that we explored. We identify times and locations of greatest disease transmission potential and that could be targeted through tailored control strategies.

scholarly journals Maxent modelling for habitat suitability of vulnerable tree Dalbergia latifolia in Nepal

Silva Fennica ◽  
2021 ◽  
Vol 55 (4) ◽  
Author(s):  
Dipak Mahatara ◽  
Amul Acharya ◽  
Bishnu Dhakal ◽  
Dipesh Sharma ◽  
Sunita Ulak ◽  
...  
Keyword(s):  
Model Prediction ◽  
Habitat Suitability ◽  
Habitat Management ◽  
Natural Habitat ◽  
Area Under The Curve ◽  
Forest Conversion ◽  
Suitable Habitat ◽  
Timber Species ◽  
Jackknife Test ◽  
Maxent Model

Roxb., commonly known as rosewood, is one of the highly valuable tropical timber species of Nepal. The tree species was widely distributed in the past, however, over-exploitation of natural habitat, deforestation, forest conversion for agriculture, illegal logging and the invasion of alien species resulted in the classification of this species as vulnerable by the IUCN (International Union for Conservation of Nature) category. So, the prediction of habitat suitability and potential distribution of the species is required to develop restoration mechanisms and conservation interventions. In this study, we modelled the suitable habitat of over the entire possible range of Nepal using a Maxent model. We compiled 23 environmental variables (19 bioclimatic, 3 topographic and a vegetative layer), however, only 12 least correlated variables along with 43 spatially representative presence locations were retained for model prediction. We used a receiver operating characteristic (ROC) curve to assess the model’s performance and a Jackknife procedure to evaluate the relative importance of predictor variables. The model was statistically significant with an area under the curve (AUC) value of 0.969. The internal Jackknife test indicated that elevation was the most important variable for the model prediction with 71.3% contribution followed by mean temperature of driest quarter (9.8%). The most (>0.6) suitable habitat for the was 235 484 hectares with large sections of area in two provinces whereas, the western most provinces were not suitable for as per Maxent model. The information presented here can provide a framework for nature conservation planning, monitoring and habitat management of this rare and endangered species.Dalbergia latifoliaD. latifoliaD. latifoliaD. latifolia

scholarly journals Habitat Suitability Study of Hylomecon Japonica Based on Maxent Model in China

2020 ◽  
Author(s):  
Cao Zhen ◽  
Zhang Xiaoyan ◽  
Xue Xuanji ◽  
Zhang Lei ◽  
Zhan Guanqun ◽  
...  
Keyword(s):  
Habitat Suitability ◽  
Potential Distribution ◽  
Mean Annual Temperature ◽  
Suitable Habitat ◽  
Entropy Model ◽  
Factors Affecting ◽  
Jackknife Test ◽  
Maxent Model ◽  
Growth Area ◽  
The Mean

Abstract Background: To understand the potential distribution and habitat suitability of H. japonica in China. And to provide guidance for the wild cultivation and standardized planting of H. japonica. Methods: The maximum entropy model (Maxent) and geographic information system (ArcGIS) were applied to predict the potential suitable habitat of H. japonica species, and the contribution of variables were evaluated by using the jackknife test. Results: The AUC value confirmed the accuracy of the model prediction based on 101 occurrence records. The potential distributions of H. japonica were mainly concentrated in Jilin, Liaoning, Shaanxi and other provinces (adaptability index>0.6). Jackknife experiment showed that the precipitation of driest month (35.6%), precipitation of wettest quarter (13.4%), the mean annual temperature (7.8%) and the subclass of soil (7.8%) were the most important factors affecting the potential distribution of H. japonica. Conclusion: The niche parameters of the most suitable growth area (adaptability index>0.8) for H. japonica were precipitation of driest month (5 mm), precipitation of wettest quarter (400-490 mm), the mean annual temperature (-2-4 °C) and the subclass of soil (Glossy Chernozem, Gleyic Lime, Haplic Gypsisols).

scholarly journals Predicting the Potential Distribution of Hylomecon japonica in China under Current and Future Climate Change Based on Maxent Model

2021 ◽  
Vol 13 (20) ◽  
pp. 11253
Author(s):  
Zhen Cao ◽  
Lei Zhang ◽  
Xinxin Zhang ◽  
Zengjun Guo
Keyword(s):  
Climate Change ◽  
Potential Distribution ◽  
Characteristic Curve ◽  
Future Climate Change ◽  
Mean Annual Temperature ◽  
Suitable Habitat ◽  
Entropy Model ◽  
Factors Affecting ◽  
Jackknife Test ◽  
Maxent Model

Hylomecon japonica is considered a natural medicinal plant with anti-inflammatory, anticancer and antibacterial activity. The assessment of climate change impact on its habitat suitability is important for the wild cultivation and standardized planting of H. japonica. In this study, the maximum entropy model (Maxent) and geographic information system (ArcGIS) were applied to predict the current and future distribution of H. japonica species, and the contributions of variables were evaluated by using the jackknife test. The area under the receiver operating characteristic curve (AUC) value confirmed the accuracy of the model prediction based on 102 occurrence records. The predicted potential distributions of H. japonica were mainly concentrated in Jilin, Liaoning, Shaanxi, Chongqing, Henan, Heilongjiang and other provinces (adaptability index > 0.6). The jackknife experiment showed that the precipitation of driest month (40.5%), mean annual temperature (12.4%), the precipitation of wettest quarter (11.6%) and the subclass of soil (9.7%) were the most important factors affecting the potential distribution of H. japonica. In the future, only under the shared socioeconomic Pathway 245 (SSP 245) scenario model in 2061–2080, the suitable habitat area for H. japonica is expected to show a significant upward trend. The area under other scenarios may not increase or decrease significantly.

scholarly journals Distribución potencial y notas acerca del coyote (Canis latrans) en Honduras

2019 ◽  
Vol 9 (1) ◽  
pp. 20
Author(s):  
Fausto Antonio Elvir-Valle ◽  
Héctor Orlando Portillo-Reyes ◽  
Leonel Edgardo Marineros-Sánchez
Keyword(s):  
Protected Areas ◽  
Potential Distribution ◽  
Canis Latrans ◽  
High Capacity ◽  
Area Under The Curve ◽  
Distribution Area ◽  
Distribution Map ◽  
Urocyon Cinereoargenteus ◽  
Buffer Zones ◽  
Presence Data

ResumenEl coyote (Canis latrans) es la especie más grande de los dos representantes silvestres de la Familia Canidae para Honduras; el segundo es la zorra gris (Urocyon cinereoargenteus). Aunque en el país se cuenta con datos de registro de coyote, aun se carece de un mapa actual de su distribución. El objetivo de este análisis es presentar un mapa de distribución potencial actual para el país. Se estimó su distribución potencial con el Programa MaxEnt (Máxima Entropía), para el que se utilizaron 55 registros de la presencia de coyotes y 19 variables ambientales. También se usó el 80% de los registros (44) para ejecutar el modelo y el 20% como registros (11) de prueba al azar. Para evaluar el desempeño del modelo se consideró el valor del área bajo la curva (AUC) que fue de 0.936. El área de distribución potencial estimada es de 125,537 ha, que incluye 12 departamentos y 147 municipios ubicados en la parte occidente, centro y sur del país. La distribución estimada se da en áreas naturales no protegidas, en las zonas de amortiguamiento de áreas protegidas, el análisis descarta como sitios potenciales de distribución a los departamentos del caribe hondureño, parte este del departamento de Olancho y La Moskitia y el departamento de Gracias a Dios. De aquí se identificaron 12 categorías de uso de suelo que presentan condiciones para la permanencia y expansión de la especie. El coyote muestra una alta capacidad de adaptación y resiliencia en las áreas, lo que permite permanencia y estabilidad a sus poblaciones.Palabras clave: áreas protegidas, coyote, distribución potencial, expansión, Honduras.AbstractThe coyote (Canis latrans) is the largest species of the two wild representatives of the Canidae Family for Honduras, the second largest is the gray fox (Urocyon cinereoargenteus). In the country, registration data are available but there is no current distribution map for the coyotes. The objective of this analysis is to present a current potential distribution map for the country. The potential distribution was estimated using the MaxEnt Program (Maximum Entropy), 55 presence data and 19 environmental variables were used, 80% of the data (44) was used for the model and 20% as test data (11), to evaluate the performance of the model. The value of the area under the curve (AUC) was 0.936. The estimated potential distribution area is 125,537 ha, which includes 12 departments and 147 municipalities located in the west, center and south part of the country. The estimated distribution occurs in unprotected natural areas and buffer zones of protected areas, the analysis discards as potential distribution sites the department of the Honduran Caribbean, eastern part of the department of Olancho and La Moskitia in the department of Gracias a Dios. Twelve categories of land use are identified that present conditions for the permanence and expansion of the species. The coyote shows a high capacity for adaptation and resilience in the areas, which allows the permanence and stability of its populations.Key words: Coyote, expansion, Honduras, potential distribution, protected areas.

scholarly journals Methods to infer transmission risk factors in complex outbreak data

2011 ◽  
Vol 9 (68) ◽  
pp. 456-469 ◽  
Author(s):  
Simon Cauchemez ◽  
Neil M. Ferguson
Keyword(s):  
Risk Factors ◽  
Missing Data ◽  
Disease Transmission ◽  
Control Strategies ◽  
Model Fitting ◽  
Structured Populations ◽  
Transmission Risk ◽  
Effective Control ◽  
Reconstruction Methods ◽  
History Of

Data collected during outbreaks are essential to better understand infectious disease transmission and design effective control strategies. But analysis of such data is challenging owing to the dependency between observations that is typically observed in an outbreak and to missing data. In this paper, we discuss strategies to tackle some of the ongoing challenges in the analysis of outbreak data. We present a relatively generic statistical model for the estimation of transmission risk factors, and discuss algorithms to estimate its parameters for different levels of missing data. We look at the problem of computational times for relatively large datasets and show how they can be reduced by appropriate use of discretization, sufficient statistics and some simple assumptions on the natural history of the disease. We also discuss approaches to integrate parametric model fitting and tree reconstruction methods in coherent statistical analyses. The methods are tested on both real and simulated datasets of large outbreaks in structured populations.

scholarly journals Evaluating the Disaster Risk of the COVID-19 Pandemic Using an Ecological Niche Model

2021 ◽  
Vol 13 (21) ◽  
pp. 11667
Author(s):  
Ping He ◽  
Yu Gao ◽  
Longfei Guo ◽  
Tongtong Huo ◽  
Yuxin Li ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Control Strategies ◽  
Comprehensive Analysis ◽  
Information Support ◽  
Prevention Measures ◽  
Niche Model ◽  
Jackknife Test ◽  
Maxent Model ◽  
Epidemic Risk ◽  
Assessment Results

Since 2019, the novel coronavirus has spread rapidly worldwide, greatly affecting social stability and human health. Pandemic prevention has become China’s primary task in responding to the transmission of COVID-19. Risk mapping and the proposal and implementation of epidemic prevention measures emphasize many research efforts. In this study, we collected location information for confirmed COVID-19 cases in Beijing, Shenyang, Dalian, and Shijiazhuang from 5 October 2020 to 5 January 2021, and selected 15 environmental variables to construct a model that comprehensively considered the parameters affecting the outbreak and spread of COVID-19 epidemics. Annual average temperature, catering, medical facilities, and other variables were processed using ArcGIS 10.3 and classified into three groups, including natural environmental variables, positive socio-environmental variables, and benign socio-environmental variables. We modeled the epidemic risk distribution for each area using the MaxEnt model based on the case occurrence data and environmental variables in four regions, and evaluated the key environmental variables influencing the epidemic distribution. The results showed that medium-risk zones were mainly distributed in Changping and Shunyi in Beijing, while Huanggu District in Shenyang and the southern part of Jinzhou District and the eastern part of Ganjingzi District in Dalian also represented areas at moderate risk of epidemics. For Shijiazhuang, Xinle, Gaocheng and other places were key COVID-19 epidemic spread areas. The jackknife assessment results revealed that positive socio-environmental variables are the most important factors affecting the outbreak and spread of COVID-19. The average contribution rate of the seafood market was 21.12%, and this contribution reached as high as 61.3% in Shenyang. The comprehensive analysis showed that improved seafood market management, strengthened crowd control and information recording, industry-catered specifications, and well-trained employees have become urgently needed prevention strategies in different regions. The comprehensive analysis indicated that the niche model could be used to classify the epidemic risk and propose prevention and control strategies when combined with the assessment results of the jackknife test, thus providing a theoretical basis and information support for suppressing the spread of COVID-19 epidemics.

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

scholarly journals Feeding sites promoting wildlife-related tourism might highly expose the endangered Yunnan snub-nosed monkey (Rhinopithecus bieti) to parasite transmission

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eve Afonso ◽  
Rong Fu ◽  
Amaël Dupaix ◽  
Anne-Claude Goydadin ◽  
ZhongHua Yu ◽  
...  
Keyword(s):  
Disease Transmission ◽  
High Throughput Sequencing ◽  
Animal Health ◽  
Buffer Zone ◽  
Transmission Risk ◽  
Parasite Transmission ◽  
Rhinopithecus Bieti ◽  
Domesticated Animals ◽  
Feeding Sites ◽  
In The Wild

AbstractAn increasing number of studies have found that the implementation of feeding sites for wildlife-related tourism can affect animal health, behaviour and reproduction. Feeding sites can favour high densities, home range overlap, greater sedentary behaviour and increased interspecific contacts, all of which might promote parasite transmission. In the Yunnan snub-nosed monkey (Rhinopithecus bieti), human interventions via provisioning monkeys at specific feeding sites have led to the sub-structuring of a group into genetically differentiated sub-groups. The fed subgroup is located near human hamlets and interacts with domesticated animals. Using high-throughput sequencing, we investigated Entamoeba species diversity in a local host assemblage strongly influenced by provisioning for wildlife-related tourism. We identified 13 Entamoeba species or lineages in faeces of Yunnan snub-nosed monkeys, humans and domesticated animals (including pigs, cattle, and domestic chicken). In Yunnan snub-nosed monkeys, Entamoeba prevalence and OTU richness were higher in the fed than in the wild subgroup. Entamoeba polecki was found in monkeys, pigs and humans, suggesting that this parasite might circulates between the wild and domestic components of this local social–ecological system. The highest proportion of faeces positive for Entamoeba in monkeys geographically coincided with the presence of livestock and humans. These elements suggest that feeding sites might indirectly play a role on parasite transmission in the Yunnan snub-nosed monkey. The implementation of such sites should carefully consider the risk of creating hotspots of disease transmission, which should be prevented by maintaining a buffer zone between monkeys and livestock/humans. Regular screenings for pathogens in fed subgroup are necessary to monitor transmission risk in order to balance the economic development of human communities dependent on wildlife-related tourism, and the conservation of the endangered Yunnan snub-nosed monkey.

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