The 2022–2023 outbreak of highly pathogenic avian influenza (HPAI) H5N1 in Chile caused extensive mortality in wild birds, domestic poultry, and marine mammals, highlighting the rapid transboundary spread of this emerging pathogen in South America. However, the evolutionary and ecological processes shaping viral dissemination within Chile have remained insufficiently characterized. Here, we integrated whole‐genome sequencing, Bayesian phylogeographic analyses, and ecological modeling to reconstruct introduction routes, diversification patterns, and environmental drivers of H5N1 circulation in Chile. All analyzed genomes belonged to clade 2.3.4.4b, genotype B3.2. Phylogenetic analyses revealed multiple Chilean subclusters, including a lineage characterized by PB2 F323L and D740N substitutions and a single virus carrying the previously mammalian‐associated PB2 D701N mutation. Phylogeographic inference identified strongly supported viral movements across South America, with Argentina acting as a major regional connector. Key diffusion pathways linked Peru to Chile and revealed extensive connectivity among Argentina, Chile, Brazil, Uruguay, and the Falkland Islands, delineating three interacting transboundary transfer systems along the Pacific Coast, the Southern Cone, and the Southwest Atlantic. Within Chile, viral population structure reflected ecological segregation. Northern lineages were predominantly associated with coastal and raptor species, whereas southern lineages were mainly linked to freshwater birds. Ecological modeling showed that H5N1 detection probability in wild birds increased with temperature and relative humidity and decreased with human population density, with freshwater species exhibiting the highest infection probability. Together, these results demonstrate how integrating genomic and ecological data provides an integrated framework for risk‐based surveillance and early warning, enabling the identification of high‐risk host groups, environments, and transboundary corridors critical for anticipating and mitigating the regional spread of emerging avian influenza viruses.
Franco Vega-Macaya, Constanza Díaz-Gavidia, Fernanda Sánchez-Rodríguez et al.· Transboundary and Emerging D...· 0 citations
INTRODUCTION
Hantavirus cardiopulmonary syndrome (HCPS) is a severe zoonotic disease caused by Orthohantavirus andesense (Andes virus, ANDV), with significant public health burden in Chile. Despite decades of surveillance, knowledge gaps remain regarding the ecological drivers of notification burden and the individual-level determinants of in-hospital mortality among hospitalized patients. This study aimed to address both dimensions simultaneously, providing a multilevel characterization of HCPS epidemiology in Chile from 2005 to 2022.
METHODS
Two complementary analyses were conducted. First, an ecological study examined district-level HCPS notifications (2005-2022) using a negative binomial mixed-effects model, with predictors including male population rate, urbanization proportion, population density, season and burned area due to forest fires during the most recent summer season. Second, an individual-level analysis of hospitalized HCPS patients (2010-2020) used a logistic mixed-effects model to identify correlates of in-hospital mortality among hospitalized patients, including age, sex, indigenous group affiliation, hospitalization duration and number of surgical interventions.
RESULTS
A total of 886 HCPS cases were notified across 187 districts, averaging 49.2 cases per year. Notifications were positively associated with higher male population rates and greater burned area due to forest fires, and negatively associated with urbanization and population density. Among 462 hospitalized patients, the in-hospital case-fatality ratio was 19.7%. Older age, female sex and indigenous group affiliation were significantly associated with higher in-hospital mortality risk among hospitalized patients. Shorter hospitalization duration and greater number of surgical interventions, as correlates of clinical severity and complexity, were also associated with in-hospital mortality among hospitalized patients.
CONCLUSIONS
HCPS notification burden in Chile is shaped by environmental and demographic factors, with forest fire activity representing a novel and actionable ecological risk indicator. In-hospital mortality among hospitalized patients is disproportionately concentrated in older, female, and indigenous populations, highlighting the need for targeted surveillance, equitable healthcare access and integrated One Health strategies to reduce the burden of HCPS in Chile.
Benjamín Diethelm-Varela, Nicolhole Atero, Fernanda Sánchez-Rodríguez et al.· Zoonoses and Public Health· 0 citations
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