{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T15:29:10Z","timestamp":1792682950475,"version":"4.5.0"},"posted":{"date-parts":[[2026,1,19]]},"group-title":"Infectious Diseases (except HIV\/AIDS)","reference-count":28,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T00:00:00Z","timestamp":1768780800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,8,27]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>Yellow fever virus (YFV) is transmitted by mosquitoes among humans and non-human primates (NHPs) in South America. The 2024-25 yellow fever (YF) outbreak was notable for its spread into new areas, including the department of Tolima in Colombia\u2019s Andean region. We investigated the eco-epidemiology of human and NHP YF cases to understand the patterns and factors associated with the Tolima outbreak.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Method<\/jats:title>\n                  <jats:p>We collected spatiotemporal, sociodemographic, and mortality data on human YF cases in Tolima, as well as the locations of deceased NHPs with YF. We then conducted exploratory, descriptive, and spatial statistical analyses to identify risk factors and hotspots for YF. We then used inferential spatiotemporal modeling to compare ecological and sociodemographic factors.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>From September 2024 to October 2025, 116 human and 53 non-human primate YF cases were detected in Tolima. Among the human cases, 77% were male (89\/116), and the median age was 47 (interquartile range 34-63). Of these cases, 45 (39%) died, and older age was associated with increased odds of death (adjusted odds ratio, 1.43 per 10 years; 95% confidence interval, 1.18-1.78). There was significant clustering among human and NHP cases. Higher rainfall and poverty\/deprivation were associated with increased YF incidence at the neighborhood level, and rainfall during the outbreak was above average due to La Ni\u00f1a.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>These findings demonstrate significant mortality from YF, which re-emerged in Tolima after nearly a century. Rural populations with greater ecological risk and poverty\/deprivation could benefit from targeted vaccination strategies for YF.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Summary<\/jats:title>\n                  <jats:p>Yellow fever re-emerged in Tolima, Colombia after nearly a century, causing mortality among humans and non-human primates. This outbreak occurred primarily in rural areas with low vaccination coverage, highlighting the need for preparedness in areas with similar risk factors.<\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.01.16.26344301","type":"posted-content","created":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T22:35:12Z","timestamp":1768862112000},"source":"Crossref","is-referenced-by-count":2,"title":["Yellow fever re-emergence in Tolima, Colombia 2024-25: an eco-epidemiological study"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9911-7839","authenticated-orcid":false,"given":"Seth D.","family":"Judson","sequence":"first","affiliation":[{"name":"Division of Infectious Diseases, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nicole","family":"Stephan","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sofia","family":"Machuca","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7363-8652","authenticated-orcid":false,"given":"Andr\u00e9s F.","family":"Henao-Mart\u00ednez","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4535-6521","authenticated-orcid":false,"given":"Gabriel","family":"Parra-Henao","sequence":"additional","affiliation":[{"name":"Centro de Investigaci\u00f3n en Salud para el Tr\u00f3pico, Universidad Cooperativa de Colombia, Santa Marta, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ricardo","family":"Vivas","sequence":"additional","affiliation":[{"name":"Direcci\u00f3n de Salud P\u00fablica, Secretaria de Salud del Tolima, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jose Fair","family":"Alarc\u00f3n-Robayo","sequence":"additional","affiliation":[{"name":"Direcci\u00f3n de Salud P\u00fablica, Secretaria de Salud del Tolima, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-7659-0836","authenticated-orcid":false,"given":"Mauricio Javier","family":"Vera Soto","sequence":"additional","affiliation":[{"name":"Subdirecci\u00f3n de Enfermedades Transmisibles, Ministerio de Salud y Protecci\u00f3n Social, Bogot\u00e1, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hern\u00e1n","family":"Vargas","sequence":"additional","affiliation":[{"name":"Direcci\u00f3n de Salud P\u00fablica, Secretaria de Salud del Tolima, Colombia"},{"name":"Grupo de investigaci\u00f3n cl\u00ednica y medicina traslacional, Hospital Federico Lleras Acosta, Ibagu\u00e9, Colombia"},{"name":"Grupo de inmunologia molecular, Universidad del Quind\u00edo, Armenia, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026083109500921000_2026.01.16.26344301v2.1","unstructured":"Yellow Fever: How three monkey deaths sparked a critical health alert in Colombia - PAHO\/WHO | Pan American Health Organization [Internet]. 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