Yellow fever in Latin America and the escalating risks in a changing eco-epidemiological landscape: a review.

Abstract

Yellow fever (YF) remains a major public health concern in Latin America. We characterise the early-2025 outbreak, compare it with prior waves-especially Southeast Brazil (2016-2018)-and examine environmental, structural, and policy-related drivers. We reviewed regional surveillance data and mortality records from January to April 2025, comparing them to historical outbreak data. Case fatality rate (CFR), geographic spread, and population vulnerability patterns were analyzed. We also reviewed published literature and health alerts to contextualize contributing factors. In 2025, 301 confirmed cases and 124 deaths were reported (CFR 41.1%), mostly in Bolivia, Brazil, Colombia, and Peru, concentrated among unvaccinated populations at the forest-urban interface. Transmission remains sylvatic, but peri-urban spillover risk is rising. Deforestation, climate variability, cross-border migration, and political instability heighten vulnerability; surveillance is fragmented and vaccine uptake insufficient in high-risk groups. YF is re-emerging through intertwined biological, ecological, and socio-political forces. Preventing another large-scale epidemic requires strengthened, integrated surveillance, including Non-Human Primates (NHP) epizootics, equity-centred immunisation in remote areas, and coordinated regional action focused on prevention, early detection, and health-system resilience.