Search Results (1,035)

Due to climate effects and human influences, wildfire regimes in boreal forests are changing, leading to profound ecological consequences, including shortened fire return intervals and elevated tree mortality. However, a critical knowledge gap exists concerning the spatiotemporal dynamics of fire-induced tree mortality specifically within the vast North American boreal forest, as previous studies have predominantly focused on Mediterranean and tropical forests. Therefore, in this study, we used satellite observation data obtained by the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra MCD64A1 and related database data to study the spatial and temporal variability in burned area and forest mortality due to wildfires in North America (Alaska and Canada) over an 18-year period (2003 to 2020). By calculating the satellite reflectance data before and after the fire, fire-driven forest mortality is defined as the ratio of the area of forest loss in a given period relative to the total forest area in that period, i.e., the area of forest loss divided by the total forest area. Our findings have shown average values of burned area and forest mortality close to 8000 km²/yr and 40%, respectively. Burning and tree loss are mainly concentrated between May and September, with a corresponding temporal trend in the occurrence of forest fires and high mortality. In addition, large-scale forest fires were primarily concentrated in Central Canada, which, however, did not show the highest forest mortality (in contrast to the results recorded in Northern Canada). Critically, based on generalized linear models (GLMs), the results showed that fire size and duration, but not the burned area, had significant effects on post-fire forest mortality. Overall, this study shed light on the most sensitive forest areas and time periods to the detrimental effects of forest wildfire in boreal forests of North America, highlighting distinct spatial and temporal vulnerabilities within the boreal forest and demonstrating that fire regimes (size and duration) are primary drivers of ecological impact. These insights are crucial for refining models of boreal forest carbon dynamics, assessing ecosystem resilience under changing fire regimes, and informing targeted forest management and conservation strategies to mitigate wildfire impacts in this globally significant biome. Full article

As dengue is an increasing global health threat, a better understanding of the global circulation dynamics and its determinants would be helpful for precise prevention and control of dengue. The dynamics of global circulation of the four dengue virus serotypes were explored utilizing genetic sequences through a network-based method. Four new circulation indicators, including local intensity, betweenness centrality, tip frequency, and persistence time, were defined. Three circulation roles, including source, hub, and destination, were proposed on the basis of new indicators. Spatial and temporal changes of the three circulation roles, along with the persistence time, were explored. Important determinants were also evaluated by machine learning models. Thailand, Indonesia, and Vietnam in Asia and Venezuela and Colombia in Americas were the sources for all four serotypes in different decades. Destinations were observed mostly in island regions. Over the decades, the number of regions with different circulation roles and persistence of DENV-1 increased significantly. Climate and airline factors were involved in the important determinants to circulation roles and persistence of dengue. The roles identified in the global circulation of dengue and important determinants, including climate and airline factors, provide new insights into global dynamics and are beneficial for controlling dengue. Full article

The pepper weevil Anthonomus eugenii is a devastating pest native to Central America that can cause severe damage to over 35 pepper varieties. Global trade in peppers has significantly increased the risk of its spread and expansion. Moreover, future climate change may add more uncertainty to its distribution, resulting in considerable ecological and economic damage globally. Therefore, we employed an ensemble model combining Random Forests and CLIMEX to predict the potential global distribution of A. eugenii in historical and future climate scenarios. The results indicated that the maximum temperature of the warmest month is an important variable affecting global A. eugenii distribution. Under the historical climate scenario, the potential global distribution of A. eugenii is concentrated in the Midwestern and Southern United States, Central America, the La Plata Plain, parts of the Brazilian Plateau, the Mediterranean and Black Sea coasts, sub-Saharan Africa, Northern and Southern China, Southern India, Indochina Peninsula, and coastal area in Eastern Australia. Under future climate scenarios, suitable areas in the Northern Hemisphere, including North America, Europe, and China, are projected to expand toward higher latitudes. In China, the number of highly suitable areas is expected to increase significantly, mainly in the south and north. Contrastingly, suitable areas in Central America, northern South America, the Brazilian Plateau, India, and the Indochina Peninsula will become less suitable. The total land area suitable for A. eugenii under historical and future low- and high-emission climate scenarios accounted for 73.12, 66.82, and 75.97% of the global land area (except for Antarctica), respectively. The high-suitability areas identified by both models decreased by 19.05 and 35.02% under low- and high-emission scenarios, respectively. Building on these findings, we inferred the future expansion trends of A. eugenii globally. Furthermore, we provide early warning of A. eugenii invasion and a scientific basis for its spread and outbreak, facilitating the development of effective quarantine and control measures. Full article

Cystic echinococcosis is a zoonosis caused by the cestode Echinococcus granulosus sensu stricto. Population genetic studies and phylogeographic patterns are essential to understanding the transmission dynamics of this parasite under varying environmental conditions. In this study, the genetic diversity of E. granulosus s.s. was evaluated using 46 hydatid cyst samples obtained from sheep, goats, cattle, and humans across three regions of Chile: Coquimbo, La Araucanía, and Magallanes. Mitochondrial cox1 gene sequences were analyzed and compared with reference sequences reported from South America, Europe, Africa, Asia, and Oceania. In Chile, the EG01 haplotype was the predominant haplotype. A total of four haplotypes were identified, with low haplotype diversity (Hd = 0.461 ± 0.00637) and low nucleotide diversity (π = 0.00181 ± 0.00036). The haplotype network displayed a star-like configuration, with the EG01 genotype at the center, suggesting a potentially ancestral or widely distributed lineage. In Coquimbo (Tajima’s D = −0.93302, p = 0.061; Fu’s Fs = −0.003, p = 0.502) and Magallanes (Tajima’s D = −0.17406, p = 0.386; Fu’s Fs = −0.121, p = 0.414), both neutrality tests were non-significant, indicating no strong evidence for recent population expansion or selection. Star-like haplotype network patterns were also observed in populations from Europe, the Middle East, Asia, Africa, and Oceania, with the EG01 genotype occupying the central position. The population genetic structure of Echinococcus granulosus s.s. in Chile demonstrates considerable complexity, with EG01 as the predominant haplotype. Further comprehensive studies are required to assess the intraspecific genetic variability of E. granulosus s.s. throughout Chile and to determine whether this variability influences the key biological traits of the parasite. This structure may prove even more complex when longer fragments are analyzed, which could allow for the detection of finer-scale microdiversity among isolates from different hosts. We recommended that future cystic echinococcosis control programs take into account the genetic variability of E. granulosus s.s. strains circulating in each endemic region, to better understand their epidemiological, immunological, and possibly pathological differences. Full article

Introduction: Long COVID syndrome is defined as persistent or new symptoms that appear after an acute SARS-CoV-2 infection and last at least three months without explanation. It is estimated that between 10% and 20% of those infected develop long COVID; however, data is not precise in Latin America. Although high immunization rates have reduced acute symptoms and the pandemic’s impact, there is a lack of evidence of its efficacy in preventing long COVID in the region. Methods: This scoping review followed PRISMA-ScR guidelines. Studies on vaccinated adults with long COVID from Central and South America and the Caribbean were included (Mexico was also considered). A comprehensive search across multiple databases was conducted. Data included study design, participant characteristics, vaccine type, and efficacy outcomes. Results are presented narratively and in tables. Results: Out of 3466 initial records, 8 studies met the inclusion criteria after rigorous selection processes. These studies encompassed populations from Brazil, Mexico, Latin America, and Bonaire, with 11,333 participants, 69.3% of whom were female. Vaccination, particularly with three or more doses, substantially reduces the risk and duration of long COVID. Variability was noted in the definitions and outcomes assessed across studies. Conclusions: This scoping review highlights that SARS-CoV-2 vaccination exhibits potential in reducing the burden of long COVID in the Americas. However, discrepancies in vaccine efficacy were observed depending on the study design, the population studied, and the vaccine regimen employed. Further robust, region-specific investigations are warranted to delineate the effects of vaccination on long COVID outcomes. Full article

Bird migration routes across North America, which are often speculated upon at the microscale, are now subject to scrutiny using the ‘eBird’ database, the world’s largest data repository for the North American continent. This database has steadily accumulated data on resident and migratory birds, with annual data on both potentially revealing regional trends. Through analysis of eBird data accumulated since 1980, we identified regional trends indicating bird migration patterns across North America, delineating three primary regions within the North American flyway: the western, central and eastern flyways, with the latter further subdivided into three regions. These findings refine previous categorisations of the four major flyways, deepening our understanding of bird migration dynamics in North America. Full article

Regional HIV-1 epidemics are evolving with distinct patterns in transmission routes, subtype distribution, and molecular transmission cluster (MTCs) characteristics. We analyzed 9500 HIV-1 cases diagnosed over 30 years using phylogenetic and network methods, integrating molecular, epidemiological, demographic, and behavioral data. Subtype A6 remains dominant nationally (80.6%), followed by 63_02A6 (7.9%), subtype B (5.6%), 02_AG_FSU (1.2%), 03_A6B (0.7%), and 14/73_BG (0.6%). Non-A6 infections were more common among males (OR 1.51) and men who have sex with men (OR 7.33). Network analysis identified 421 MTCs, with 256 active clusters. Clustering was more likely among young individuals (OR: 1.31), those not receiving antiretroviral therapy (OR: 2.70), and injecting drug users (OR: 1.28). Non-A6 subtypes showed a higher likelihood of clustering. Phylogenetic analysis revealed that local clusters of the major subtypes originated between the late 1970s (subtype B) and the mid-2000s (63_02A6) with links to populations in Eastern Europe, Central Asia (subtypes A6, 63_02A6, 02_AG_FSU, 03_A6B), and Western Europe and the Americas (subtype B, 14/73_BG). These findings indicate a complex, evolving regional epidemic transitioning from subtype A6 dominance to a more diverse mix of subtypes. The ability of non-A6 subtypes to form active MTCs suggests their establishment in the local population. Full article

Common ragweed, Ambrosia artemisiifolia (Asteraceae), is an invasive weed that causes problems in cropping systems and to human health both in its native range in North and Central America and the introduced range in Europe, Asia, Africa, and Australia. Ophraella communa, an herbivorous chrysomelid beetle from North America, was accidentally introduced into East Asia and Europe, where it significantly reduces weed populations and pollen production. Despite extensive research on its host specificity and risk assessment, the potential environmental risk of this biological control agent in southeastern Central Europe, one of the most heavily invaded areas by A. artemisiifolia, remains to be determined. This literature review attempts to summarize the results of host-range testing conducted so far and identifies plant taxa native to southeastern Central Europe that have not been tested yet. The results suggest that the host range of O. communa is not yet entirely clear, but may include some plant species from the tribes Heliantheae, Inuleae, Anthemideae, Cardueae, Astereae, and/or Coreopsideae. So far, only some of the 21 genera from those tribes with species in southeastern Central Europe have been tested. We therefore suggest further host specificity studies with representatives of these plant genera to fully assess the potential non-target risks by O. communa in agricultural and natural habitats. Full article

Background/Objectives: Clostridioides difficile infection (CDI) is a major cause of infectious diarrhea in the inpatient and community setting. Real-world data outside the strict environment of randomized controlled trials (RCTs) are needed to improve the quality of evidence. The aim of this study was to compare different clinical outcomes of CDI patients treated with fidaxomicin with those treated with vancomycin using a representative patient population in the United States of America (USA). Methods: Comprehensive real-world data were analyzed for this retrospective observational study, provided by the TriNetX database, an international research network with electronic health records from multiple USA healthcare providers. This includes in- and outpatients treated with fidaxomicin (FDX) or vancomycin (VAN) for CDI between 01/2013 and 12/2023. The following cohorts were compared: (i) patients treated with fidaxomicin within 10 days following CDI diagnosis (FDX group) vs. (ii) patients treated with vancomycin within 10 days following CDI diagnosis (VAN group). Outcomes analysis between the two cohorts was performed after propensity score matching and included event risk and Kaplan–Meier survival analyses for the following concomitant diseases/events occurring during an observational period of 12 months following CDI diagnosis: death, sepsis, candidiasis, infections caused by vancomycin-resistant enterococci, inflammatory bowel disease, cardiovascular disease, psychological disease, central line-associated blood stream infection, surgical site infection, and ventilator-associated pneumonia. Results: Following propensity score matching, 2170 patients were included in the FDX group and VAN groups, respectively. The event risk analysis demonstrated improved outcomes of patients treated with FDX compared to VAN in 6 out of the 10 events that were analyzed. The highest risk ratio (RR) and odds ratio (OR) were found for sepsis (RR: 3.409; OR: 3.635), candidiasis (RR: 2.347; OR: 2.431), and death (RR: 1.710; OR: 1.811). The Kaplan–Meier survival analysis showed an overall survival rate until the end of the 12-month observational period of 87.06% in the FDX group and 78.49% in the VAN group (log-rank p < 0.001). Conclusions: Our comparative event risk analysis demonstrated improved outcomes for patients treated with FDX compared to VAN in most of the observed events and underlines the results of previously conducted RCTs, highlighting the beneficial role of FDX compared to VAN. Further big data analyses from other industrialized countries are needed for comparison with our observations. Full article

Guadua amplexifolia J. Presl is a Neotropical bamboo native to southern Mexico through Central America to Colombia, where it thrives in riparian zones of the San Jorge River basin. Despite its ecological and socio-economic importance, its environmental dynamics and provision of ecosystem services remain poorly understood. This study (1) quantifies spatial and temporal land use/cover changes in the municipality of Montelíbano between 2002 and 2022 and (2) evaluates the ecosystem services that local communities derive from in 2002, 2012, and 2022, and they were classified in QGIS using G. amplexifolia. We applied a supervised classification of Landsat imagery (2002, 2012, 2022) in QGIS, achieving 85% overall accuracy and a Cohen’s Kappa of 0.82 (n = 45 reference points). For the social assessment, we held participatory workshops and conducted semi-structured interviews with artisans, fishers, authorities, and NGO representatives; responses were manually coded to extract key themes. The results show a 12% decline in total vegetated area from 2002 to 2012, followed by an 8% recovery by 2022, with bamboo-dominated stands following a similar pattern. Communities identified raw material provision (87% of mentions), climate regulation (82%), and cultural–recreational benefits (58%) as the most important services provided by G. amplexifolia. This is the first integrated assessment of G. amplexifolia’s landscape dynamics and community-valued services in the San Jorge basin, highlighting its dual function as a renewable resource and a natural safeguard against environmental risks. Our findings offer targeted recommendations for management practices and land use policies to support the species’ conservation and sustainable utilization. Full article

Dual mycorrhizal symbiosis, i.e., the association with both arbuscular and ectomycorrhizal fungal symbionts, is an ambiguous phenomenon concurrently considered as common among various genetic lineages of trees and a result of bias in data analyses. Recent studies have shown that the ability to form dual mycorrhizal associations is a distinguishing factor for the continental-scale invasion of alien tree species. However, the phylogenetic mechanisms that drive it remain unclear. In this study, all the evidence on root-associated symbionts of Juglandaceae from South and North America, Asia, and Europe was combined and re-analysed following current knowledge and modern molecular-based identification methods. The Juglandaceae family was revealed to represent a specific pattern of symbiotic interactions that are rare among deciduous trees and absent among conifers. Closely related phylogenetic lineages of trees usually share the same type of symbiosis, but Juglandaceae contains several possible ones concurrently. The hyperdiversity of root symbionts of Juglandaceae, unlike other tree families, was concurrently found in Central and North America, Asia, and Europe, indicating its phylogenetic determinants, which endured geographical isolation. However, for many Juglandaceae, including the invasive Juglans and Pterocarya species, this was never studied or was studied only with outdated methods. Further molecular research on root symbionts of Juglandaceae, providing long sequences and high taxonomic resolutions, is required to explain their ecological roles. Full article

This study examines the complex interactions among soil moisture, evaporation, extreme weather events, and lightning, and their influence on fire activity across the extratropical and Pan-Arctic regions. Leveraging reanalysis and remote-sensing datasets from 2000 to 2020, we applied cross-correlation analysis, a modified Mann–Kendall trend test, and assessments of interannual variability to key variables including soil moisture, fire frequency and risk, evaporation, and lightning. Results indicate a significant increase in dry days (up to 40%) and heatwave events across Central Eurasia and Siberia (up to 50%) and Alaska (25%), when compared to the 1980–2000 baseline. Upward trends have been detected in evaporation across most of North America, consistent with soil moisture trends, while much of Eurasia exhibits declining soil moisture. Fire danger shows a strong positive correlation with evaporation north of 60° N (r ≈ 0.7, p ≤ 0.005), but a negative correlation in regions south of this latitude. These findings suggest that in mid-latitude ecosystems, fire activity is not solely driven by water stress or atmospheric dryness, highlighting the importance of region-specific surface–atmosphere interactions in shaping fire regimes. In North America, most fires occur in temperate grasslands, savannas, and shrublands (47%), whereas in Eurasia, approximately 55% of fires are concentrated in forests/taiga and temperate open biomes. The analysis also highlights that lightning-related fires are more prevalent in Eastern Europe and Southeastern Asia. In contrast, Western North America exhibits high fire incidence in temperate conifer forests despite relatively low lightning activity, indicating a dominant role of anthropogenic ignition. These findings underscore the importance of understanding land–atmosphere interactions in assessing fire risk. Integrating surface conditions, climate extremes, and ignition sources into fire prediction models is crucial for developing more effective wildfire prevention and management strategies. Full article

Uncaria tomentosa (Ut) is a Rubiaceae widely used in Peru’s traditional medicine. It is mainly known by the vernacular name of Cat’s claw due to its morphological aspects and is found in tropical low mountain forests of Central and South America. A decoction of Ut bark, root and leaves is used traditionally for different health problems, including arthritis, weakness, viral infections, skin disorders, abscesses, allergies, asthma, cancer, fevers, gastric ulcers, haemorrhages, inflammations, menstrual irregularity, rheumatism, urinary tract inflammation and wounds, among others, which gave rise to scientific and commercial interest. The present paper reviews research progress relating to the ethnobotany, phytochemistry and pharmacology of Ut, and some promising research routes are also discussed. We highlight the centrality of its different biological activities, such as antioxidant, anti-inflammatory, antiproliferative, antiviral, and antinociceptive, among others. Recently, studies of the health effects of this plant suggest that novel nutraceuticals can be obtained from it and applied as a preventive or prophylaxis strategy before the start of conventional drug therapy, especially for patients who are not prone to conventional pharmacological approaches to diseases. The present work emphasizes the current pharmacological properties of Uncaria tomentosa, evidencing its therapeutic benefits and encouraging further research on this medicinal plant. Full article

Ponderosa pine (Pinus ponderosa Lawson & C. Lawson) forests in the western United States have experienced reduced fire frequency since Euro-American settlement, usually because of successful fire suppression policies and even without such human impacts at remote sites in the Great Basin and Mojave Deserts. In an effort to improve our understanding of long-term environmental dynamics in sky-island ecosystems, we developed tree-ring chronologies from ponderosa pines located in the Sheep Mountain Range of southern Nevada, inside the Desert National Wildlife Refuge (DNWR). After comparing those dendrochronological records with other ones available for the south-central Great Basin, we analyzed their climatic response using station-recorded monthly precipitation and air temperature data from 1950 to 2024. The main climatic signal was December through May total precipitation, which was then reconstructed at annual resolution over the past five centuries, from 1490 to 2011 CE. The mean episode duration was 2.6 years, and the maximum drought duration was 11 years (1924–1934; the “Dust Bowl” period), while the longest episode, 19 years (1905–1923), is known throughout North America as the “early 1900s pluvial”. By quantifying multi-annual dry and wet episodes, the period since DNWR establishment was placed in a long-term dendroclimatic framework, allowing us to estimate the potential drought resilience of its unique, tree-dominated environments. Full article

Spruce beetle (Dendroctonus rufipennis (Kirby)) is a major cause of spruce (Picea spp.) mortality in western North America. We synthesized the literature on the chemical ecology of spruce beetle, focusing on efforts to reduce host tree losses. This literature dates back to the mid-20th century and focuses on spruce beetle populations in Alaska, U.S., western Canada, and the central and southern Rocky Mountains, U.S. Spruce beetle aggregation pheromone components include frontalin (1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane), seudenol (3-methyl-2-cyclohexen-1-ol), MCOL (1-methyl-2-cyclohexen-1-ol), and verbenene (4-methylene-6,6-dimethylbicyclo[3.1.1]hept-2-ene). The attraction of spruce beetle to one aggregation pheromone component is enhanced by the co-release of other aggregation pheromones and host compounds (e.g., α-pinene). Several baits that attract spruce beetles are commercially available and are used for survey and detection, population suppression, snag creation, and experimental purposes. The antiaggregation pheromone is MCH (3-methyl-2-cyclohexen-1-one), which has been evaluated for reducing colonization of felled spruce since the 1970s. Beginning in the early 2000s, MCH has been evaluated for protecting live, standing spruce from colonization by and mortality attributed to spruce beetle. With a few exceptions, significant reductions in levels of spruce beetle colonization and/or spruce mortality were reported. More recent efforts have combined MCH with other repellents (e.g., nonhost compounds) in hope of increasing levels of tree protection. Today, several formulations of MCH are registered for tree protection purposes in the U.S. and Canada. Full article