Re-emergence of Yellow Fever in Colombia, Geographic Expansion and Impact on Vulnerable Populations

Abstract

Introduction: Yellow fever is a vector-borne viral disease endemic in the Americas and Africa, characterized by high lethality and lack of specific treatment. Despite the availability of an effective vaccine, outbreaks persist, even in non-endemic areas. Objective: To analyze the epidemiological evolution of yellow fever in Colombia between 2007 and 2025, focusing on the displacement of cases into non-endemic areas. Methods: A retrospective descriptive study was conducted using secondary data from the National Public Health Surveillance System and reports from the National Institute of Health. The study population comprised 87 confirmed yellow fever cases reported in the country during this period. Sociodemographic, geographic, clinical, and vaccination-related variables were analyzed. Results: Most cases occurred in men (86.2%), aged 20-24 years (23%), residing in rural areas (67.8%), and affiliated with the subsidized healthcare system (73.6%). A significant increase in cases was observed in 2024 (23) and 2025 (38), primarily in Tolima (54%), Meta (12.6%), and Caquetá (8.1%), all non-endemic regions. The case fatality rate was 53%, higher among those seeking care after the tenth day of symptom onset. Vaccination coverage was low, with only 9.52% and 10.5% of cases having a recorded vaccination history in 2024 and 2025, respectively. Conclusion: The findings suggest that social factors such as healthcare affiliation, rural residence, and low vaccination coverage contribute to the displacement of yellow fever cases to non-endemic areas. Strengthening surveillance, vaccination records, and preventive strategies in at-risk areas is urgently required to control the spread of the disease.